When did the key advances in vehicle suspension happen?

When did the key advances in vehicle suspension happen?

Technologies called "suspensions" support the comfort of passengers in wheeled vehicles. In the era of draft animals, carriage suspensions apparently started with hanging the passenger compartment by iron chains; then replacing the chains with less noisy leather straps; then mounting the same on an iron elliptical leaf spring; then stacking several leaf springs; and today's standard for passenger vehicles is coil springs.

When were these advances developed and popularized?

The first suspension system has been designed for the light chariots of Ramses around the year of 1296 B.C.

hanging the passenger compartment by iron chains or leather straps

It is likely that Roman carriages (1 BC) employed some form of suspension on chains or leather straps, as indicated by carriage parts found in excavations.

iron elliptical leaf spring

Leaf springs have been around since the early Egyptians. Ancient military engineers used leaf springs in the form of bows to power their siege engines, with little success at first. The use of leaf springs in catapults was later refined and made to work years later. Springs were not only made of metal, a sturdy tree branch could be used as a spring, such as with a bow. Horse-drawn carriages and the Ford Model T used this system, and it is still used today in larger vehicles, mainly mounted in the rear suspension

stacking several leaf springs

The venerable leaf spring, which some manufacturers still use in rear suspensions today, was invented by Obadiah Elliot of London in 1804. He simply piled one steel plate on top of another, pinned them together and shackled each end to a carriage.

coil springs

Coil springs first appeared on a production vehicle in 1906 by Alanson Brush in the Brush Runabout made by the Brush Motor Company. Today, coil springs are used in most cars.

How to Inspect a Used Car

CARS.COM — Much of the test drive should happen before you actually drive. It’s tempting to hop in the car and take it for a spin, but it’s wise to inspect the car carefully before and after the drive to determine its condition and attempt to confirm the answers the seller gave you before you arrived.

Remember that a used car’s current condition and the way it was cared for are at least as important as the style, features and fit when it was new. When you’re done with this test drive, you may not know for sure if the car is mechanically sound without the help of a mechanic, but you may know if it’s definitely not — and be able to rule it out without paying up to $100 for a professional used-car inspection to tell you so. You’re also looking for smaller problems that may help you reduce the price.

Wear clothing you don’t mind getting dirty, bring a flashlight, a flat refrigerator magnet and always, always inspect cars in daylight. You can do this while the seller (or salesperson, if it’s at a dealership) looks on, or ask for a few minutes alone with the vehicle if you need to conduct your inspection in private.

Rust Can’t Hide

Despite advances in manufacturing, rust remains one of a greatest enemies on a used car — one you should be able to detect on your own. Rust is generally more damaging to a car’s appearance and value than to its ability to get you where you need to go. It’s expensive to repair well on any vehicle and nearly impossible to reverse.

Start at the Bottom

Start by looking at the car’s undercarriage (underside). Use your flashlight to inspect the floor pans (the metal that forms the floors) and frame rails (the structural members that run around the perimeter of the car’s underbelly). Inspect for rust. Also look for marked differences in the condition of different sections. One pristine or freshly painted section in an otherwise moderately rusty vehicle is a reliable indication that part of the vehicle was repaired. Did the seller disclose any accidents in the vehicle history?

While you’re down there, look up into the wheel wells for rust. Take note if the vehicle seems to be dripping anything (check out the driveway and garage floor if you can), and look for rust and signs of wear on the muffler and exhaust pipes.

The Tires

Don’t get up yet. The tires tell a lot about a used car and how it’s been driven and cared for. You’re looking for several signs:

Overall wear: Do the tires have enough tread on them to be safe, or are they bald (or close enough to it) that you’ll have to replace them soon? Look for tread-wear indicators, which become visible when the tread has worn down far enough that the tires need to be replaced. The indicators are ridges that run across the surface of the tires, perpendicular to the sidewall. Each tire has six of these indicators evenly spaced around its circumference. The location of each is marked by an arrowhead found on the sidewall, typically at the base of the tread.

If you’re not sure about the wear indicators, try the penny test: Hold a penny, head side toward you, and insert the top of Lincoln’s head into the tire tread until the coin’s edge rests in the groove. If you can see the top of Honest Abe’s noggin from the side of the tire, the tread is probably worn too far. If the top of Lincoln’s head disappears into the groove, your tire has some life left. It’s simple: If you see Abe’s head, there’s not enough tread. Repeat with all tires.

Uneven wear: Have all the tires worn evenly from one sidewall to the other? Try the penny test to verify a difference. Tires should wear evenly. If they don’t, it’s likely the car has been in an accident and/or is out of alignment.

This does not compute: Does the car have low mileage but worn-out tires? Why the contrast? Maybe the odometer is not accurate. It’s not a crime to put used tires on a car, but you should try and find out what’s behind the disparity. The same is true if the car has low mileage yet brand-new tires. Perhaps the owner decided to upgrade, had a blowout or simply replaced all four tires. It can’t hurt to ask about anything that just doesn’t make sense.

The Walkaround

Whether you’re shopping a used car from a private seller or a new car at a dealer, the walkaround is essential. Stroll around the car looking for rust, dents and dings. Check how well the hood, doors and trunk/hatch lid meet the body. All should close and seal well and rest on the same plane. Try all the doors and their windows and locks. (With a convertible, try the doors and windows with the roof up and down.) Some of these tests may seem unnecessary, but every little problem could become your problem, and every shortcoming can be used to drive the price down.

Whip out that refrigerator magnet (the flexible kind that looks like a business card is best). Place it on at least one point of every major panel of the car’s exterior. It should stick. If it doesn’t, it means one of three things:

  • The panel has been repaired with Bondo, fiberglass or some other nonmetallic dent filler.
  • The car is made of fiberglass, as it is with the Chevrolet Corvette.
  • That particular panel is nonmetallic or nonmagnetic (aluminum).

In the latter two cases, chances are that the whole vehicle, or like panels, will also not support the magnet. Whole panels — let alone whole cars — are seldom rebuilt with body filler, so you’ll know you’re onto something if the magnet doesn’t stick to part of a panel or one of four doors. Be aware that bumpers and grilles tend to be molded from plastic nowadays.

Warning: Be sure only to use a pliable magnet, or place a piece of paper or cloth between a metal or ceramic magnet and the car. You don’t want to scratch the paint.

The Trunk or Hatch

Check out the trunk (or “hatch,” if the car is a hatchback, SUV or minivan). If possible, lift the carpet and check for rust. Will the cargo capacity meet your needs? Is the spare tire in its proper location, full of air and in good condition? Pay attention to how simple or difficult it is to lift the trunk or hatch lid. Does it stay up or fall on your head? Will you be likely to hit your head on it even if it stays up?

The Engine Compartment

You don’t have to be a mechanic to learn something about a car and its owner by inspecting the engine compartment. Pop the hood and perform these checks:

  • Take a good look at the overall condition. Is the engine clean, or are there signs of leaking oil or other fluids? Take a mental picture, because you’ll want to look again after your test drive.
  • Check for rust, particularly on the shock or strut towers, the points at the corners near the windshield to which the front suspension is anchored.
  • Do you see any sign of fresh paint (or paint that is clearly newer than elsewhere on the car)? Have any of the rubber bumpers been painted over? These can be signs of an accident or simply a re-paint job.
  • With the engine turned off, check the underside of the fan belts (the surface that comes in contact with the pulleys) for cracks and obvious wear.
  • Pull the oil dipstick, wipe it clean with a rag, and reinsert and remove it. Is the level correct? Is the oil dark and dirty? Both are signs that the car isn’t getting the care it deserves. You can also look for beads of water on the oil clinging to the dipstick, which could reflect a leak — and a costly head gasket problem.
  • If the engine hasn’t run for hours and the radiator is cool to the touch, remove the radiator cap carefully and slowly using a rag (the car’s coolant system is pressurized and can spray, causing injury open it only if you know it’s cool). Is there a layer of oily film floating on the top? Is the coolant clean and green or rust-colored? A layer of film is caused by oil, which reflects a costly head gasket problem. A rusty color is caused by (you guessed it) rust, which reflects that the vehicle has been neglected.

Start It

Go ahead and start the car. Does it start easily? Run smoothly? Don’t hesitate to test all the lights and signals, inside the car and outside. Same thing for the wipers, heat and air conditioning, and cigarette lighter.

For more visuals on what to check for when inspecting a used car, check out our video above.

How Car Suspensions Work

When people think of automobile performance, they normally think of horsepower, torque and zero-to-60 acceleration. But all of the power generated by a piston engine is useless if the driver can't control the car. That's why automobile engineers turned their attention to the suspension system almost as soon as they had mastered the four-stroke internal combustion engine.

The job of a car suspension is to maximize the friction between the tires and the road surface, to provide steering stability with good handling and to ensure the comfort of the passengers. In this article, we'll explore how car suspensions work, how they've evolved over the years and where the design of suspensions is headed in the future.

If a road were perfectly flat, with no irregularities, suspensions wouldn't be necessary. But roads are far from flat. Even freshly paved highways have subtle imperfections that can interact with the wheels­ of a car. It's these imperfections that apply forces to the wheels. According to Newton's laws of motion, all forces have both magnitude and direction. A bump in the road causes the wheel to move up and down perpendicular to the road surface. The magnitude, of course, depends on whether the wheel is striking a giant bump or a tiny speck. Either way, the car wheel experiences a vertical acceleration as it passes over an imperfection.

Without an intervening structure, all of wheel's vertical energy is transferred to the frame, which moves in the same direction. In such a situation, the wheels can lose contact with the road completely. Then, under the downward force of gravity, the wheels can slam back into the road surface. What you need is a system that will absorb the energy of the vertically accelerated wheel, allowing the frame and body to ride undisturbed while the wheels follow bumps in the road.

The study of the forces at work on a moving car is called vehicle dynamics, and you need to understand some of these concepts in order to appreciate why a suspension is necessary in the first place. Most automobile engineers consider the dynamics of a moving car from two perspectives:

  1. Ride - a car's ability to smooth out a bumpy road
  2. Handling - a car's ability to safely accelerate, brake and corner

These two characteristics can be further described in three important principles - road isolation, road holding and cornering. The table below describes these principles and how engineers attempt to solve the challenges unique to each.

A car's suspension, with its various components, provides all of the solutions described.

Let's look at the parts of a typical suspension, working from the bigger picture of the chassis down to the individual components that make up the suspension proper.

­The suspension of a car is actually part of the chassis, which comprises all of the imp­ortant systems located beneath the car's body. These systems include:

  • The frame - structural, load-carrying component that supports the car's engine and body, which are in turn supported by the suspension
  • The suspension system - setup that supports weight, absorbs and dampens shock and helps maintain tire contact
  • The steering system - mechanism that enables the driver to guide and direct the vehicle
  • The tires and wheels - components that make vehicle motion possible by way of grip and/or friction with the road

So the suspension is just one of the major systems in any vehicle.

With this big-picture overview in mind, it's time to look at the three fundamental components of any suspension: springs, dampers and anti-sway bars.


Today's springing systems are based on one of four basic designs:

  • Coil springs - This is the most common type of spring and is, in essence, a heavy-duty torsion bar coiled around an axis. Coil springs compress and expand to absorb the motion of the wheels.
  • Leaf springs consist of several layers of metal (called "leaves") bound together to act as a single unit. Leaf springs were first used on horse-drawn carriages and were found on most American automobiles until 1985. They are still used today on most trucks and heavy-duty vehicles.
  • Torsion bars use the twisting properties of a steel bar to provide coil-spring-like performance. This is how they work: One end of a bar is anchored to the vehicle frame. The other end is attached to a wishbone, which acts like a lever that moves perpendicular to the torsion bar. When the wheel hits a bump, vertical motion is transferred to the wishbone and then, through the levering action, to the torsion bar. The torsion bar then twists along its axis to provide the spring force. European carmakers used this system extensively, as did Packard and Chrysler in the United States, through the 1950s and 1960s.
  • Air springs consist of a cylindrical chamber of air positioned between the wheel and the car's body, use the compressive qualities of air to absorb wheel vibrations. The concept is actually more than a century old and could be found on horse-drawn buggies. Air springs from this era were made from air-filled, leather diaphragms, much like a bellows they were replaced with molded-rubber air springs in the 1930s.

Based on where springs are located on a car — i.e., between the wheels and the frame — engineers often find it convenient to talk about the sprung mass and the unsprung mass.

Springs: Sprung and Unsprung Mass

The sprung mass is the mass of the vehicle supported on the springs, while the unsprung mass is loosely defined as the mass between the road and the suspension springs. The stiffness of the springs affects how the sprung mass responds while the car is being driven. Loosely sprung cars, such as luxury cars (think Lincoln Town Car), can swallow bumps and provide a super-smooth ride however, such a car is prone to dive and squat during braking and acceleration and tends to experience body sway or roll during cornering. Tightly sprung cars, such as sports cars (think Mazda Miata), are less forgiving on bumpy roads, but they minimize body motion well, which means they can be driven aggressively, even around corners.

So, while springs by themselves seem like simple devices, designing and implementing them on a car to balance passenger comfort with handling is a complex task. And to make matters more complex, springs alone can't provide a perfectly smooth ride. Why? Because springs are great at absorbing energy, but not so good at dissipating it. Other structures, known as dampers, are required to do this.

Unless a dampening structure is present, a car spring will extend and release the energy it absorbs from a bump at an uncontrolled rate. The spring­ will continue to bounce at its natural frequency until all of the energy originally put into it is used up. A suspension built on springs alone would make for an extremely bouncy ride and, depending on the terrain, an uncontrollable car.

Enter the shock absorber, or snubber, a device that controls unwanted spring motion through a process known as dampening. Shock absorbers slow down and reduce the magnitude of vibratory motions by turning the kinetic energy of suspension movement into heat energy that can be dissipated through hydraulic fluid. To understand how this works, it's best to look inside a shock absorber to see its structure and function.

A shock absorber is basically an oil pump placed between the frame of the car and the wheels. The upper mount of the shock connects to the frame (i.e., the sprung weight), while the lower mount connects to the axle, near the wheel (i.e., the unsprung weight). In a twin-tube design, one of the most common types of shock absorbers, the upper mount is connected to a piston rod, which in turn is connected to a piston, which in turn sits in a tube filled with hydraulic fluid. The inner tube is known as the pressure tube, and the outer tube is known as the reserve tube. The reserve tube stores excess hydraulic fluid.

When the car wheel encounters a bump in the road and causes the spring to coil and uncoil, the energy of the spring is transferred to the shock absorber through the upper mount, down through the piston rod and into the piston. Orifices perforate the piston and allow fluid to leak through as the piston moves up and down in the pressure tube. Because the orifices are relatively tiny, only a small amount of fluid, under great pressure, passes through. This slows down the piston, which in turn slows down the spring.

Shock absorbers work in two cycles — the compression cycle and the extension cycle. The compression cycle occurs as the piston moves downward, compressing the hydraulic fluid in the chamber below the piston. The extension cycle occurs as the piston moves toward the top of the pressure tube, compressing the fluid in the chamber above the piston. A typical car or light truck will have more resistance during its extension cycle than its compression cycle. With that in mind, the compression cycle controls the motion of the vehicle's unsprung weight, while extension controls the heavier, sprung weight.

All modern shock absorbers are velocity-sensitive — the faster the suspension moves, the more resistance the shock absorber provides. This enables shocks to adjust to road conditions and to control all of the unwanted motions that can occur in a moving vehicle, including bounce, sway, brake dive and acceleration squat.

Uber's self-driving cars are a key to its path to profitability

Its co-founder and ousted CEO Travis Kalanick sold all his stock and left the company's board late last year. Uber sold its much fast-growing food-delivery Eats division in India and public markets have voted by sending the stock steadily down since its debut as investors question its path to profitability.

"The vision for growth is absolutely there. But growth where it makes sense." Dara Khosroshahi, Uber's CEO told CNBC's Andrew Ross Sorkin during an interview at the World Economic Forum in Davos, Switzerland. Unsaid in Khosrowshahi's statement is the pivot to profitability in a market environment that's stopped giving loss making "unicorns" a free pass.

Khosrowshahi's goal is to get Uber to profitability by 2021. And the sharpest arrow in the company's arsenal to achieving profitability is also the least understood. Uber's self-driving unit, the Advanced Technologies Group (ATG), has an estimated valuation of over $7 billion, representing more than10% of Uber's current market cap of about $61 billion.

And yet, Uber's management or even the analyst community rarely discuss it. But speaking to those in the know you get a sense that this group which houses Uber's self-driving car ambitions is the real key to Uber owning the future of mobility, a space that's now seeing fierce competition from tech and automakers alike.

So why the hub-hub around self-driving, especially for a money losing ride hailing platform like Uber?

The driver represents the single largest expense in non-autonomous ride-sharing at 80% of the total per mile cost, according to estimates by research firm Frost & Sullivan. By removing the driver from the equation, fully autonomous vehicles dramatically lower the cost of a ride while boosting its addressable market. Already offering software as a service, Uber plans to take the bet further by making the cost of rides so low (between its fleet of human and robot cars) that vehicle ownership becomes obsolete.

If done right Uber's looking at a sizable slice of a very big pie. Realistic estimates for autonomous ride-hailing are still tough given regulatory hurdles. Yet, investment firm ARK's research suggests that the 10-year net present value of this opportunity exceeds $1 trillion today and should hit $5 trillion by 2024 and $9 trillion by 2029. Of note, ARK is historically bullish on next generation technology bets, using the thesis to make investments.

"ATG is a growth play for Uber," said Eric Meyhofer, the head of ATG at Uber. He was among the 40 to 50 people, many from Carnegie Mellon's Robotics Institute, who left academia to fulfill the promise of bringing to market the new concept of a robotaxi. In 2015, under then-CEO Kalanick, the company had an ambitious target of achieving autonomy at scale by 2020.

Learning from their much documented downfall thereafter, including a fatal crash involving a self-driving Uber car in Tempe, Arizona, Uber's ATG has a new scaled down, multi-pronged approach for its self-driving ambitions.

A long-term vision with short term goals, Uber ATG is focused on limited geographic presence and limited "autonomous capabilities." ATG doesn't want to solve every self-driving problem, everywhere, all-of the time as they compete with the likes of Tesla, Alphabet's Waymo, Lyft, GM and Didi Chuxing.

Instead ATG plans only to introduce self-driving to new markets when it's technologically feasible, safe and cost effective.

"The goal is to create a cheaper, better and safer automated option for consumers using Uber's ride-hailing service," Meyhofer said, adding that the technology has to pass through three stages: developing, piloting and commercialization. Uber's ATG unit is currently in the development stage.

Cheaper means reducing the cost per mile of a self-driven ride to below that of an UberX ride today. A goal that's still "ways off," according to Uber ATG's spokeswoman.

Better indicates making the ride a luxurious experience while reducing customer wait times. To this end Uber, partnered with Volvo and Toyota to co-engineer what Meyhofer calls the most "opulent" self-driving ride experience on the market.

Goal three, and probably the most important for Uber's ATG unit, is safety, which could make or break the company's self-driving ambitions. Regulators could also cause delays over safety concerns.

Today, Uber tests self-driving cars on roads in Pittsburgh. But before a self-driving Uber car even hits the road, ATG performs multiple rounds of software simulations to make sure its nearly perfect.

"But this is a mistake," Jeff Schneider, a former Uber ATG engineering manager, said. "The pull back in road testing across the industry is not what will make the technology better. Those who get back on the road and test will take the lead."

Schneider left the company in 2018 to return to academia as a faculty professor with a specialization in machine learning and robotics at Carnegie Mellon's Robotics Institute.

But Meyhofer said getting the software right is equally as important.

"We've amassed petabytes of data by now, probably far more than Netflix," Meyhofer said.

Developing a self-driving vehicle has two components: the software (the driver) and the hardware (the vehicle to be driven), Meyhofer said.

Various ATG teams in Pittsburgh, San Francisco, Washington D.C. and Toronto are working on building 3D maps, databases for machines to learn from and creating software for "perfect driving."

For testing, humans drive the Uber's modified Volvo XC90 on the streets. The first pass on a route is to map out the area. The second pass by a human-driven vehicle through the previously mapped areas is for the "perfect drive," or the best version of perfect human driving. The data collected from "good driving behavior" feeds into Uber's self-driving algorithm to teach the software how to drive on its own in the mapped area.

In many ways building self-driving technology is like teaching a teenager how to drive, equipping them with all the essential information, rules of the road, driving temperament and hours of practice in the hope that there will be no incidents once a computer takes the wheel.

Engineers run through real-world simulations to test the software's navigational capabilities in "auto" mode if left on its own. Each simulation leads to software tweaks to make the driving better.

Internally, the ATG units' policies are scrutinized by their self-driving safety and responsibility advisory (SARA) board created in the aftermath of the Tempe crash. The board reviews, advises and suggests changes to ATG's policies on a quarterly basis.

Finally, the self-driven vehicle is ready to take the road, but only with a human driver, known in the company as a "mission specialist" behind the wheel. While human driver provides no input unless required, they stay with their hands floating above the steering wheel, so engineers back at home base can compare simulation to actual performance.

"The ultimate north star for the company is Level 4 autonomy," Meyhofer said.

The industry defines Level 4 as "attention off" driving, that is the vehicle can take control under most
circumstances and performs all critical functions, even making decisions like when to change lanes, and using a turn signal, on its own. But a key point to Level 4 is that the vehicle cannot operate in 100% of the conditions and therefore a human is required.

Sounds ambitious? It is. But don't expect Uber to be on the sidelines until it achieves complete Level 4 autonomy.

Meyhofer brought about a radical new approach to thinking about autonomy. Think about a self-driving car that's completely autonomous, but only when making right turns on a predetermined route. In the Uber ATG-defined autonomous world, this is a "limited operational domain" vehicle that could be deployed as a "self-driven ride" in Uber's fleet.

It also underscores the out-of-the-box thinking Uber has deployed to retain investor confidence in its future bets while it still struggles to make a profit in its current business verticals.

"I worry that ATG is throwing good money after bad. Even in my conversations with them there seems to be almost of a 'we have to do it' versus 'we want to do it' approach," said Bernstein analyst Mark Shmulik. Shmulik rates the stock as "outperform" with a price target of $40, while estimating the company will grow at a 30% rate over the next three years.

"ATG is not trying to build a robot car," Meyhofer said. The grand plan is to build a self-driving ride sharing service that's better, cheaper and safer than available transportation options, and integrate it to complement Uber's current human-driven fleet.

But competition is building fast around the company with Waymo, GM and several others all working on self-driving technology.

"Essentially it comes down to the way the market plays out," Shmulik said. "If Waymo becomes the predominant Autonomous Vehicle Operating System, then Lyft (and their partnership with Waymo) should realize margin expansion faster than Uber."

Uber's strategy is to be selective about where it launches self-driving cars. Instead of launching everywhere, Uber plans to map pockets of various cities that fit the most favorable profile for a self-driven vehicle, taking factors like weather, population density and road conditions into account.

For example, the company has identified the residential neighborhood of Squirrel Hill in Pittsburgh for deployment of self-driving cars with plans to expand in future. There are similar pockets identified in San Francisco, Toronto and Dallas, while simulating simulations for each of those cities takes place first at ATG's offices in Pittsburgh.

This is also where Uber outshines the likes of Tesla or GM's Cruise unit, which don't have comparable riding data to leverage. An opportunity for Uber, as it analyzes its own ride-hailing usage patterns to identify opportunities most conducive for the self-driving unit to offer a self-driven ride that's cheaper than riding with a human.

This caps the big shift for the ATG in the last two years: a multi-pronged, cost-driven approach to self-driving where they aren't trying to be all autonomous, everywhere, at all times. Instead, Uber plans to make bets where it's the most efficient to deploy self-driving cars

The future of the Uber ride-hailing app is to offer a menu of services to get people and services around. That ranges from the human-driven UberX car to a self-driving car on a predetermined route to a fully autonomous vehicle that can take you anywhere.

Overall, the hope is that spectrum can help reduce Uber's costs and bring it to the profitability investors have been looking for over the past year.


An impressive balance of performance and styling, the CTS Coupe (discontinued in 2014) boasted deeply sculpted lines and a highly responsive 318-hp 3.6L direct-injection engine. The CTS Coupe also featured amenities like Adaptive Remote Start, keyless access and available Side Blind Zone Alert.

Achievements in Public Health, 1900-1999 Motor-Vehicle Safety: A 20th Century Public Health Achievement

Systematic motor-vehicle safety efforts began during the 1960s. In 1960, unintentional injuries caused 93,803 deaths (1) 41% were associated with motor-vehicle crashes. In 1966, after 5 years of continuously increasing motor-vehicle-related fatality rates, the Highway Safety Act created the National Highway Safety Bureau (NHSB), which later became the National Highway Traffic Safety Administration (NHTSA). The systematic approach to motor-vehicle-related injury prevention began with NHSB's first director, Dr. William Haddon (2). Haddon, a public health physician, recognized that standard public health methods and epidemiology could be applied to preventing motor-vehicle-related and other injuries. He defined interactions between host (human), agent (motor vehicle), and environmental (highway) factors before, during, and after crashes resulting in injuries. Tackling problems identified with each factor during each phase of the crash, NHSB initiated a campaign to prevent motor-vehicle-related injuries.

In 1966, passage of the Highway Safety Act and the National Traffic and Motor Vehicle Safety Act authorized the federal government to set and regulate standards for motor vehicles and highways, a mechanism necessary for effective prevention (2,3). Many changes in both vehicle and highway design followed this mandate. Vehicles (agent of injury) were built with new safety features, including head rests, energy-absorbing steering wheels, shatter-resistant windshields, and safety belts (3,4). Roads (environment) were improved by better delineation of curves (edge and center line stripes and reflectors), use of breakaway sign and utility poles, improved illumination, addition of barriers separating oncoming traffic lanes, and guardrails (4,5). The results were rapid. By 1970, motor-vehicle-related death rates were decreasing by both the public health measure (deaths per 100,000 population) and the traffic safety indicator (deaths per VMT) ( Figure 2 ) (1).

Changes in driver and passenger (host) behavior also have reduced motor-vehicle crashes and injuries. Enactment and enforcement of traffic safety laws, reinforced by public education, have led to safer behavior choices. Examples include enforcement of laws against driving while intoxicated (DWI) and underage drinking, and enforcement of safety-belt, child-safety seat, and motorcycle helmet use laws (5,6).

Government and community recognition of the need for motor-vehicle safety prompted initiation of programs by federal and state governments, academic institutions, community-based organizations, and industry. NHTSA and the Federal Highway Administration within the U.S. Department of Transportation have provided national leadership for traffic and highway safety efforts since the 1960s (2). The National Center for Injury Prevention and Control, established at CDC in 1992, has contributed public health direction (7,8). State and local governments have enacted and enforced laws that affect motor-vehicle and highway safety, driver licensing and testing, vehicle inspections, and traffic regulations (2). Preventing motor-vehicle-related injuries has required collaboration among many professional disciplines (e.g., biomechanics has been essential to vehicle design and highway safety features). Citizen and community-based advocacy groups have played important prevention roles in areas such as drinking and driving and child-occupant protection (6). Consistent with the public/ private partnerships that characterize motor-vehicle safety efforts, NHTSA sponsors "Buckle Up America" week (this year during May 24-31), which focuses on the need to always properly secure children in child-safety seats (additional information is available by telephone, [202] 366-5399, or on the World-Wide Web at http://www.nhtsa.dot.gov).


Alcohol-impaired drivers. Annual motor-vehicle crash-related fatalities involving alcohol has decreased 39% since 1982, to approximately 16,000 these deaths account for 38.6% of all traffic deaths (9,10). Factors that may have contributed to this decline include increased public awareness of the dangers of drinking and driving new and tougher state laws stricter law enforcement an increase in the minimum legal drinking age prevention programs that offer alternatives such as safe rides (e.g., taxicabs and public transportation), designated drivers, and responsible alcohol-serving practices and a decrease in per capita alcohol consumption (5,6).

Young drivers and passengers. Since 1975, motor-vehicle-related fatality rates have decreased 27% for young motor-vehicle occupants (ages 16-20 years). However, in 1997 the death rate was 28.3 per 100,000 population--more than twice that of the U.S. population (13.3 per 100,000 population) (9). Teenaged drivers are more likely than older drivers to speed, run red lights, make illegal turns, ride with an intoxicated driver, and drive after drinking alcohol or using drugs (11). Strategies that have contributed to improved motor-vehicle safety among young drivers include laws restricting purchase of alcohol among underaged youths (6) and some aspects of graduated licensing systems (e.g., nighttime driving restrictions) (12).

Pedestrians. From 1975 to 1997, pedestrian fatality rates decreased 41%, from 4 per 100,000 population in 1975 to 2.3 in 1997 but still account for 13% of motor-vehicle-related deaths (9). Factors that may have reduced pedestrian fatalities include more and better sidewalks, pedestrian paths, playgrounds away from streets, one-way traffic flow, and restricted on-street parking (6).

Safety belts. In response to legislation, highly visible law enforcement, and public education, rates of safety belt use nationwide have increased from approximately 11% in 1981 to 68% in 1997 (8). Safety belt use began to increase following enactment of the first state mandatory-use laws in 1984 (6). All states except New Hampshire now have safety-belt use laws. Primary laws (which allow police to stop vehicles simply because occupants are not wearing safety belts) are more effective than secondary laws (which require that a vehicle be stopped for some other traffic violation) (6,13). The prevalence of safety belt use after enactment of primary laws increases 1.5-4.3 times, and motor-vehicle-related fatality rates decrease 13%-46% (13).

Child-safety and booster seats. All states have passed child passenger protection laws, but these vary widely in age and size requirements and the penalties imposed for noncompliance. Child-restraint use in 1996 was 85% for children aged less than 1 year and 60% for children aged 1-4 years (14). Since 1975, deaths among children aged less than 5 years have decreased 30% to 3.1 per 100,000 population, but rates for age groups 5-15 years have declined by only 11%-13% (9). Child seats are misused by as many as 80% of users (15-17). In addition, parents fail to recognize the need for booster seats for children who are too large for child seats but not large enough to be safely restrained in an adult lap-shoulder belt (18).

Despite the great success in reducing motor-vehicle-related death rates, motor-vehicle crashes remain the leading cause of injury-related deaths in the United States, accounting for 31% of all such deaths in 1996 (CDC, unpublished data, 1999). Furthermore, motor-vehicle-related injuries led all causes for deaths among persons aged 1-24 years. In 1997, motor-vehicle crashes resulted in 41,967 deaths (16 per 100,000 population), 3.4 million nonfatal injuries (1270 per 100,000 population) (9), and 23.9 million vehicles in crashes cost estimates are $200 billion (1).

  • continue efforts shown to reduce alcohol-impaired driving and related fatalities and injuries.
  • promote strategies such as graduated licensing that discourage teenage drinking and other risky driving behaviors such as speeding and encourage safety belt use.
  • enhance pedestrian safety, especially for children and the elderly, through engineering solutions that reduce exposure to traffic and permit crossing streets safely and by encouraging safer pedestrian behaviors, such as crossing streets at intersections, and increasing visibility to drivers and driver awareness of pedestrians.
  • accommodate the mobility needs of persons aged greater than 65 years--a population that will almost double to 65 million by 2030--through a combination of alternative modes of transportation (e.g., walking and better public transportation) and development of strategies to reduce driving hazards (6,19).
  • encourage the 30% of the population who do not wear safety belts to use them routinely.
  • encourage proper use of age-appropriate child-safety seats and booster seats, especially for older children who have outgrown their child seats but are too small for adult lap-shoulder belts.
  • conduct biomechanics research to better understand the causes of nonfatal disabling injuries, in particular brain and spinal cord injuries, as a foundation for prevention strategies.
  • develop a comprehensive public health surveillance system at the federal, state, and local levels that track fatal and nonfatal motor-vehicle-related injuries and other injuries and diseases (i.e., outpatient and emergency department visits, hospitalizations, disabilities, and deaths) as a basis for setting prevention and research priorities.

Reported by: Div of Unintentional Injury Prevention, National Center for Injury Prevention and Control, CDC.

Roebling and the Brooklyn Bridge

On June 12, 1806, John A. Roebling, civil engineer and designer of bridges, was born in Mühlhausen, Prussia. The Brooklyn Bridge, Roebling’s last and greatest achievement, spans New York’s East River to connect Manhattan with Brooklyn. When completed in 1883, the bridge, with its massive stone towers and a main span of 1,595.5 feet between them, was by far the longest suspension bridge in the world. Today, the Brooklyn Bridge is hailed as a key feature of New York’s City’s urban landscape, standing as a monument to progress and ingenuity as well as symbolizing New York’s ongoing cultural vitality.

New York & Bridges from Brooklyn. Irving Underhill, c1913. Panoramic Photographs. Prints & Photographs Division

John A. Roebling came to design suspension bridges through his earlier work on canals. Trained as an engineer at Berlin’s Royal Polytechnic Institute, Roebling emigrated to the United States in 1831, helping to settle the farming community of Saxonburg in western Pennsylvania. He was soon employed to work on the extensive canal system then being built for travel across the state. One element of that system was a series of inclined planes used to haul barges along railway tracks over steep terrain. Troubled by their reliance on dangerously breakable hemp rope, in about 1839, Roebling turned his efforts toward the manufacture of strong but flexible wire rope as an alternative. Roebling’s invention soon was being used by the Allegheny Portage Railroad he received a patent for his “new and Improved Mode of Manufacturing Wire Ropes” in 1842.

Roebling quickly found additional uses for his invention. His first wire cable suspension bridge (1844-45) was a wooden aqueduct that carried Pennsylvania’s main east-west canal above and across the Allegheny River into downtown Pittsburgh. He received additional patents in 1846 and 1847. Roebling’s Delaware Aqueduct (1847-48) followed closely on his earlier design and is the oldest surviving suspension bridge in America. In pursuing these projects, Roebling developed a viable method of spinning the heavy wrought iron wire cables on site, as well as a simple and secure way to anchor them—both of which made the construction of long suspension bridges feasible.

Roebling moved his family to Trenton, New Jersey, in 1848, where he established a business manufacturing twisted wire cable for a wide variety of engineering applications. (This successful business continued as the John A. Roebling’s Sons Company through the mid-twentieth century.) Bridges that Roebling designed, such as the Niagara River Gorge Bridge (1855) and Pittsburgh’s Sixth Street Bridge (1859) were admired for their technical innovation as well as their expressive design. His Covington & Cincinnati Suspension Bridge (1856-67), which was itself the longest suspension bridge of its time, served in part as a prototype for his monumental East River project.

On the Promenade, Brooklyn Bridge, New York. Strohmeyer & Wyman, c1899. Stereograph Cards. Prints & Photographs Division

New Yorkers had long desired a bridge directly linking Manhattan and Brooklyn, which were by 1860 the country’s first and third largest cities, respectively. Roebling’s first plan for an East River bridge, developed in the 1850s, was nearly as ambitious as the one that was eventually built. In late 1866, a private Brooklyn-based venture called The New York Bridge Company was founded (with the infamous Boss Tweed as a trustee). Roebling—whose Cincinnati bridge had just opened to great acclaim—was soon hired as chief engineer.

Roebling planned his Manhattan and Brooklyn Bridge (its most official name at the time) to be made with newly available steel wire, which allowed it to be stronger, larger, and longer then any bridge yet built. The two-tier design External offered cable car transportation as well as roadways for vehicles and an elevated pedestrian promenade. The project soon met with full approval, receiving New York state funding as well as Congressional authorization by 1869.

In July 1869, soon after construction of the Brooklyn Bridge began, John Roebling died from tetanus contracted when his foot was crushed in an accident on site. Almost immediately, Roebling’s 32-year-old son and partner, Washington A. Roebling, was named chief engineer in his place. Other mishaps, including an explosion, a fire, contractor fraud, and Washington Roebling’s own illness, hampered timely completion of the project.

Pressurized pneumatic caissons, eventually sunk to a depth of 44.5 feet on the Brooklyn side and 78.5 feet on the Manhattan side, provided dry underwater space for workers to dig the bridge’s foundations down to solid rock. Alas, working in the caissons often brought on “the bends”—a serious medical condition caused by moving too quickly out of a high-pressure atmosphere. Washington Roebling himself was among the many workers permanently impaired (or in some cases killed) by this little-understood “caisson disease,” now known to be decompression sickness. As a result of his disability, after 1872, Washington Roebling’s wife, Emily, became actively involved in supervising construction—carrying messages and instructions back and forth between the bed-ridden chief engineer and his staff.

New York—Completing A Great Work—Lashing the Stays of the Brooklyn Bridge / from a sketch by a staff artist. Illus. in: Frank Leslie’s Illustrated Newspaper, April 28, 1883, [149]. Prints & Photographs Division

In 1876, with the bridge towers completed to their final height of 277 feet above water, construction of the four great cables that suspend the bridge’s roadway began. The longest and heaviest cables that had ever been made (containing over 14,000 miles of wire weighing almost 3,500 tons) were created using the same method that John A. Roebling had patented some thirty years before. Because of the scale of the operation, just making the cables took eighteen months. When it came time to finally build the bridge’s deck, steel-manufacturing technology had improved so much that it was possible to use steel instead of iron, further strengthening the bridge. With the deck floor in place, the bridge’s supporting trusses were assembled and the visually stunning diagonal stays that stabilized the cable system were installed.

The Brooklyn Bridge opened to citywide celebration on May 24, 1883. Over the next hundred years, the bridge became part of the romance of New York City. Poets and artists have long found the bridge a worthy subject and the Brooklyn Bridge continues to serve as the backdrop in countless photographs and films.

On September 11, 2001, the Brooklyn Bridge took on a different form of symbolism. In the wake of the attacks on the World Trade Center, thousands of pedestrians used the bridge to escape Lower Manhattan on foot.

Night View Looking NW Showing Bridge Lighted. Jet Lowe, photographer, 1982. Brooklyn Bridge Spanning East River…Brooklyn, New York County, NY. Historic American Buildings Survey/Historic American Engineering Record/Historic American Landscapes Survey. Prints & Photographs Division New Brooklyn to New York via Brooklyn Bridge, no. 2. James H. White, production United States: Edison Manufacturing Co., 1899. Inventing Entertainment: the Early Motion Pictures and Sound Recordings of the Edison Companies. Motion Picture, Broadcasting & Recorded Sound Division

11 Scientific Advances Of The Past 100 Years Gave Us Our Entire Universe

The SDSS view in the infrared - with APOGEE - of the Milky Way galaxy as viewed towards the center. . [+] 100 years ago, this was our conception of the entire Universe.

Exactly 100 years ago, our conception of the Universe was far different from what it is today. The stars within the Milky Way were known, and were known to be at distances up to thousands of light years away, but nothing was thought to be further. The Universe was assumed to be static, as the spirals and ellipticals in the sky were assumed to be objects contained within our own galaxy. Newton's gravity still hadn't been overthrown by Einstein's new theory, and scientific ideas like the Big Bang, dark matter, and dark energy hadn't even been thought up yet. But during each decade, huge advances were made, all the way up to the present day. Here's a highlight of how each one moved our scientific understanding of the Universe forward.

The results of the 1919 Eddington expedition showed, conclusively, that the General Theory of . [+] Relativity described the bending of starlight around massive objects, overthrowing the Newtonian picture.

The Illustrated London News, 1919

1910s — Einstein’s theory confirmed! General Relativity was famed for making the explanation that Newton’s gravity couldn’t: the precession of Mercury’s orbit around the Sun. But it isn’t enough for a scientific theory to explain something we’ve already observed it needs to make a prediction about something that’s yet to be seen. While there have been many over the past century — gravitational time dilation, strong and weak lensing, frame dragging, gravitational redshift, etc. — the first was the bending of starlight during a total solar eclipse, observed by Eddington and his collaborators in 1919. The observed amount of bending of starlight around the Sun was consistent with Einstein and inconsistent with Newton. Just like that, our view of the Universe would change forever.

Hubble's discovery of a Cepheid variable in Andromeda galaxy, M31, opened up the Universe to us. . [+] Image credit: E. Hubble, NASA, ESA, R. Gendler, Z. Levay and the Hubble Heritage Team.

E. Hubble, NASA, ESA, R. Gendler, Z. Levay and the Hubble Heritage Team

1920s — We still didn’t know there was a Universe out there beyond the Milky Way, but that all changed in the 1920s with the work of Edwin Hubble. While observing some of the spiral nebulae in the sky, he was able to pinpoint individual, variable stars of the same type that were known in the Milky Way. Only, their brightness was so low that they needed to be millions of light years away, placing them far outside the extent of our galaxy. Hubble didn’t stop there, measuring the recession speed and distances for over a dozen galaxies, discovering the vast, expanding Universe we know today.

The two bright, large galaxies at the center of the Coma Cluster, NGC 4889 (left) and the slightly . [+] smaller NGC 4874 (right), each exceed a million light years in size. But the galaxies on the outskirts, zipping around so rapidly, points to the existence of a large halo of dark matter throughout the entire cluster.

Adam Block/Mount Lemmon SkyCenter/University of Arizona

1930s — It was thought for a long time that if you could measure all the mass contained in stars, and perhaps add in the gas and dust, you’d account for all the matter in the Universe. Yet by observing the galaxies within a dense cluster (like the Coma cluster, above), Fritz Zwicky showed that stars and what we know as “normal matter” (i.e., atoms) was insufficient to explain the internal motions of these clusters. He dubbed this new matter dunkle materie, or dark matter, an observation that was largely ignored until the 1970s, when normal matter was better understood, and dark matter was shown to exist in great abundance in individual, rotating galaxies. We now know it to outmass normal matter by a 5:1 ratio.

The timeline of our observable Universe's history, where the observable portion expands to larger . [+] and larger sizes as we move forward in time away from the Big Bang.

1940s — While the vast majority of experimental and observational resources went into spy satellites, rocketry and the development of nuclear technology, theoretical physicists were still hard at work. In 1945, George Gamow made the ultimate extrapolation of the expanding Universe: if the Universe is expanding and cooling today, then it must have been hotter and denser in the past. Going backwards, there must have been a time where it was so hot and dense that neutral atoms couldn’t form, and before that where atomic nuclei couldn’t form. If this were true, then before any stars ever formed, that material the Universe began with should have a specific ratio of the lightest elements, and there ought to be a leftover glow permeating all directions in the Universe just a few degrees above absolute zero today. This framework is today known as the Big Bang, and was the greatest idea to come out of the 1940s.

This cutaway showcases the various regions of the surface and interior of the Sun, including the . [+] core, which is where nuclear fusion occurs. The process of fusion, in Sun-like stars as well as its more massive cousins, is what enables us to build up the heavy elements present throughout the Universe today.

Wikimedia Commons user Kelvinsong

1950s — But a competing idea to the Big Bang was the Steady-State model, put forth by Fred Hoyle and others during the same time. Spectacularly, both sides argued that all the heavier elements present on Earth today were formed in an earlier stage of the Universe. What Hoyle and his collaborators argued was that they were made not during an early, hot and dense state, but rather in previous generations of stars. Hoyle, along with collaborators Willie Fowler and Geoffrey and Margaret Burbidge, detailed exactly how elements would be built up the periodic table from nuclear fusion occurring in stars. Most spectacularly, they predicted helium fusion into carbon through a process never before observed: the triple-alpha process, requiring a new state of carbon to exist. That state was discovered by Fowler a few years after it was proposed by Hoyle, and is today known as the Hoyle State of carbon. From this, we learned that all the heavy elements existing on Earth today owe their origin to all the previous generations of stars.

If we could see microwave light, the night sky would look like the green oval at a temperature of . [+] 2.7 K, with the "noise" in the center contributed by hotter contributions from our galactic plane. This uniform radiation, with a blackbody spectrum, is evidence of the leftover glow from the Big Bang: the cosmic microwave background.

1960s — After some 20 years of debate, the key observation that would decide the history of the Universe was uncovered: the discovery of the predicted leftover glow from the Big Bang, or the Cosmic Microwave Background. This uniform, 2.725 K radiation was discovered in 1965 by Arno Penzias and Bob Wilson, neither of whom realized what they had discovered at first. Yet over time, the full, blackbody spectrum of this radiation and even its fluctuations were measured, showing us that the Universe started with a “bang” after all.

The earliest stages of the Universe, before the Big Bang, are what set up the initial conditions . [+] that everything we see today has evolved from. This was Alan Guth's big idea: cosmic inflation.

E. Siegel, with images derived from ESA/Planck and the DoE/NASA/ NSF interagency task force on CMB research

1970s — At the very end of 1979, a young scientist had the idea of a lifetime. Alan Guth, looking for a way to solve some of the unexplained problems of the Big Bang — why the Universe was so spatially flat, why it was the same temperature in all directions, and why there were no ultra-high-energy relics — came upon an idea known as cosmic inflation. It says that before the Universe existed in a hot, dense state, it was in a state of exponential expansion, where all the energy was bound up in the fabric of space itself. It took a number of improvements on Guth’s initial ideas to create the modern theory of inflation, but subsequent observations — including of the fluctuations in the CMB, of the large-scale structure of the Universe and of the way galaxies clump, cluster and form — all have vindicated inflation’s predictions. Not only did our Universe start with a bang, but there was a state that existed before the hot Big Bang ever occurred.

The remnant of supernova 1987a, located in the Large Magellanic Cloud some 165,000 light years away. . [+] It was the closest observed supernova to Earth in more than three centuries.

Noel Carboni & the ESA/ESO/NASA Photoshop FITS Liberator

1980s — It might not seem like much, but in 1987, the closest supernova to Earth occurred in over 100 years. It was also the first supernova to occur when we had detectors online capable of finding neutrinos from these events! While we’ve seen a great many supernovae in other galaxies, we had never before had one occur so close that neutrinos from it could be observed. These 20-or-so neutrinos marked the beginning of neutrino astronomy, and subsequent developments have since led to the discovery of neutrino oscillations, neutrino masses, and neutrinos from supernovae occurring more than a million light years away. If the current detectors in place are still operational, the next supernova within our galaxy will have over a hundred thousand neutrinos detected from it.

The four possible fates of the Universe, with the bottom example fitting the data best: a Universe . [+] with dark energy. This was first uncovered with distant supernova observations.

E. Siegel / Beyond The Galaxy

1990s — If you thought dark matter and discovering how the Universe began was a big deal, then you can only imagine what a shock it was in 1998 to discover how the Universe was going to end! We historically imagined three possible fates:

  • That the expansion of the Universe would be insufficient to overcome everything’s gravitational pull, and the Universe would recollapse in a Big Crunch.
  • That the expansion of the Universe would be too great for everything’s combined gravitation, and everything in the Universe would run away from one another, resulting in a Big Freeze.
  • Or that we’d be right on the border between these two cases, and the expansion rate would asymptote to zero but never quite reach it: a Critical Universe.

Instead, though, distant supernovae indicated that the Universe’s expansion was accelerating, and that as time went on, distant galaxies were increasing their speed away from one another. Not only will the Universe freeze, but all the galaxies that aren’t already bound to one another will eventually disappear beyond our cosmic horizon. Other than the galaxies in our local group, no other galaxies will ever encounter our Milky Way, and our fate will be a cold, lonely one indeed. In another 100 billion years, we’ll be unable to see any galaxies beyond our own.

The fluctuations in the Cosmic Microwave Background were first measured accurately by COBE in the . [+] 1990s, then more accurately by WMAP in the 2000s and Planck (above) in the 2010s. This image encodes a huge amount of information about the early Universe.

ESA and the Planck Collaboration

2000s — The discovery of the Cosmic Microwave Background didn’t end in 1965, but our measurements of the fluctuations (or imperfections) in the Big Bang’s leftover glow taught us something phenomenal: exactly what the Universe was made of. Data from COBE was superseded by WMAP, which in turn has been improved upon by Planck. In addition, large-scale structure data from big galaxy surveys (like 2dF and SDSS) and distant supernova data has all combined to give us our modern picture of the Universe:

  • 0.01% radiation in the form of photons,
  • 0.1% neutrinos, which contribute ever so slightly to the gravitational halos surrounding galaxies and clusters,
  • 4.9% normal matter, which includes everything made of atomic particles,
  • 27% dark matter, or the mysterious, non-interacting (except gravitationally) particles that give the Universe the structure we observe,
  • and 68% dark energy, which is inherent to space itself.

The systems of Kepler-186, Kepler-452 and our Solar System. While the planet around a red dwarf star . [+] like Kepler-186 are interesting in their own rights, Kepler-452b may be far more Earth-like by a number of metrics.

2010s — The decade isn't out yet, but so far we've already discovered our first potentially Earth-like habitable planets, among the thousands and thousands of new exoplanets discovered by NASA's Kepler mission, among others. Yet, arguably, that's not even the biggest discovery of the decade, as the direct detection of gravitational waves from LIGO not only confirms the picture that Einstein first painted, of gravity, back in 1915. More than a century after Einstein's theory was first competing with Newton's to see what the gravitational rules of the Universe were, general relativity has passed every test thrown at it, succeeding down to the smallest intricacies ever measured or observed.

Illustration of two black holes merging, of comparable mass to what LIGO has seen. The expectation . [+] is that there ought to be very little in the way of an electromagnetic signal emitted from such a merger, but the presence of strongly heated matter surrounding these objects could change that.

SXS, the Simulating eXtreme Spacetimes (SXS) project (http://www.black-holes.org)

The scientific story is not yet done, as there's so much more of the Universe still to discover. Yet these 11 steps have taken us from a Universe of unknown age, no bigger than our own galaxy, made up mostly of stars, to an expanding, cooling Universe powered by dark matter, dark energy and our own normal matter, teeming with potentially habitable planets and that's 13.8 billion years old, originating in a Big Bang which itself was set up by cosmic inflation. We know our Universe's origin, it's fate, what it looks like today, and how it came to be this way. May the next 100 years hold just as many scientific advances, revolutions, and surprises for us all.

There are several sensors located in the vehicle that provide data and feedback for the air suspension control unit. Some of these components include:

  • ESP control module
  • Engine control module
  • Transmission control module
  • Instrument cluster
  • Steering angle sensor
  • Comfort and sport switch
  • Level adjustment switch
  • Vertical and horizontal accelerometers
  • Front axle level sensors
  • Airmatic pressure sensor

Air Filter

Most owners don’t even know that there is an air suspension compressor filter. After all, it is well hidden. The air suspension compressor filter should be replaced as it is considered a maintenance item. If the filter gets clogged, it can dramatically impact the life and efficiency of the air suspension compressor. The filter part number A2203200069 costs only a few dollars when purchased online.

Check the price on Amazon.

A deep history

AT STREET LEVEL, lowrider clubs are deeply respected organizations. In the Valley, names like Primeros, Dedication, Wild Bunch, Integrity and Viejitos are akin to lowrider royalty. Each vehicle represents decades of meticulous expertise in automatives, and each is a palette for self-expression, says Denise Sandoval, a professor at Cal State Northridge and a veteran researcher and curator on lowrider culture.

“Lowriding is about firme cars, yes, but it’s the people around or inside the cars that are just as important,” Sandoval says.

Some saw a cruise one night and never turned back.

In 1970, Arthur Monarque returned from military service in East Asia and landed at a sister’s house in the Estrada Courts in Boyle Heights. A nephew first took him to Whittier Boulevard to see the cars cruising. “The Mexicans were all dressed Ivy League, continental and had cars, and I was like, ‘Wow. The Chicanos I was looking for,’” Monarque recalls.

Soon after, Monarque moved to the Valley and joined the scene there. “At that time,” he says, “I had two ’64 Impalas and one 1951 Deluxe two-door hard-top.”

Back then, he says, the cruise for people who loved cars happened on Wednesdays. Valley cruisers met up at burger stand parking lots, where they exchanged details about house parties for the upcoming weekend.

“So they would cruise, pass around word of mouth, before cellphones,” he says, and the process repeated.

Now 72, Monarque still lives in the Valley and shows up regularly to the cruise nights and car club meetups at local parks. He also noticed the buzz in interest during the pandemic.

“They got to get out. They’re frustrated at home. And that’s what cruising does. You get out,” he laughs.

The Carranza family worked on the McGrath Family Farm for more than 20 years. Just as they sought to go into the strawberry business on their own, the coronavirus hit.

Cruising in some form has been popular in the Valley likely since the first U.S. teenagers got their hands on their own wheels, maybe as early as the 1930s, says Kevin Roderick, author of “The San Fernando Valley: America’s Suburb.” Van Nuys was also one the earliest boulevards in the city to get street lighting, he notes.

“Customizing and hot rods were a very big thing in the postwar San Fernando Valley,” Roderick adds. “There were lots of wide open streets to race on. Everybody had a garage where they could tinker with an engine or invent a new paint design, and Van Nuys Boulevard provided a public arena for showing off your creation.”

Oriol, the photographer, says that at a basic level, the dropped, slow-rolling automobile will always remain a renegade, even if brands and marketing firms bank on its imagery. “Any lowrider is a moving violation, right off the bat,” he says. But, he notes, “I get pulled over now by cops who want to take selfies of the car.”

Today, both police authorities and car club cruisers say relations are better than they’ve ever been. Car clubs often team up with police stations for toy drives and fundraisers. “I remind them I appreciate them,” says Kristan Delatori, the senior lead officer of the area that includes Van Nuys Boulevard and who helped negotiate the change in location for the local cruise.

Part of the shift is about the big-tent nature of the scene. The Aguirres identify as Christians and are respected as lowriders in their Lancaster community. Cruising may never totally shed its previous connotations, Lona Aguirre says, but it’s no bother to them.

“We both lived in the gang life. I’m tattooed all over,” she says. “But they have no idea that I own a school, my husband is a chemist. It’s a judgement. . We love what we do. This is who we are.”

On a cool spring evening, the lowriders return. Dropped Cadillacs and Impalas. Modified pickup trucks and vans blasting rap. Every so often, there are vintage cars, or pre-1960, that are referred to affectionately as “bombs” or “bombas.”

There are even a few hot rods, customized to look like they just rode off a nearby studio set for a talkie. They all ride slow, windows down. Up and down, north and south, for hours.

Sometimes the inspiration strikes and the lowriders start hopping. No police came by for most of this night, except for the occasional requests to get pedestrians with cameras out of traffic lanes.

The new location seems to be fitting along fine with the regulars, says Joey Smith, 55, as he watches with his car club, Los Primeros.

“You know, you can three-wheel, hop, but once you start holding up traffic and spinning in the middle of the street, then it kind of creates problems,” Smith says.

He grew up in Sunland and Tujunga and now lives in Chatsworth. He is driving a 1964 Impala SS, painted cobalt blue. It was his father’s. “We always wanted him to join a club, but he never wanted to join a club,” he says.

Smith also inherited a vintage automobile after his dad died.

“I put a new motor in it, put air-ride [suspension] on it, and I joined the club,” he says. “It’s got a 350 motor, 360 horsepower. You can see the rest. It’s just beautiful.”