Traffic Congestion

If you’ve ever driven in an urban area you’ve undoubtedly been there: stranded in a traffic jam where vehicles seem as if they’re mired in a very thick, very gooey form of molasses. Time stands still, radiators burst, and tempers reach fever pitches. Getting caught in a traffic jam engenders an irritating feeling of helplessness, aggravated by the fact that empowerment is the watchword in today’s world. While your car usually gives you the freedom figuratively to soar like a bird, empowering you to do things previous generations could only dream of, in a traffic jam, your car simply is an expensively upholstered space to in which to pass time as what could have been a productive trip degenerates into a morass of frustration, irritation and wasted effort.


Many of us regard traffic jams as random occurrences, like earthquakes, tornadoes or funny jokes in a Jay Leno monologue. And while some traffic jams are random, in many areas across the country traffic jams crop up with the regularity of the sun rising over the eastern horizon and with the predictability of a "Brady Bunch" episode. In the argot of the traffic engineers, these are "bottlenecks," which are defined as places where the capacity of a section of a highway is often exceeded. In these problem areas, traffic flow breaks down; speeds drop and time turns to lead. One of the most irritating aspects of these "bottlenecks" is that traffic engineers know exactly where they are and can predict with uncanny accuracy their occurrences. In fact, anyone among us who is an urban traffic veteran knows the whereabouts of local bottlenecks and can recount special tactics to avoid them, some of which involve the use of the dreaded "surface streets."


In fact, not only do the traffic experts know where the bottlenecks will develop, they also know why. The fact is that regularly occurring bottlenecks have very mundane causes: the narrowing of a roadway into fewer lanes, tollbooths, entrance and exit ramps, and close side clearances such as bridge rails or medians. Particularly troublesome are so-called "weaving areas" where vehicles must cross several lanes to get to and from entry and exit points.


One might legitimately ask, if traffic engineers know where the trouble spots are and what causes them, why don’t they do something about them? On a macro scale the answer is simple: it’s just too big a job.


Consider these facts complied by the American Road & Transportation Builders Association: Over the past 30 years, while the U.S. population has increased 30 percent, the number of licensed vehicles has increased 87 percent. During the same three-decade period, vehicle miles traveled in the U.S. have increased 130 percent, while new highway capacity has only increased five percent.


When you reflect on the number of construction zones you see each week you might find it amazing that in 30 years highway capacity has increased by just a measly five percent, but most road "construction" that you see is really repair, which, of course, does not increase highway capacity. And, as the problem has been growing worse over the last three decades, it promises to deteriorate still further in the future.


The Census Bureau has estimated the U.S. population will grow by 60 million between 1995 and 2020. According to Dr. Bill Buechner, ARTBA Vice President of Economics & Research, we will have 246 million motor vehicles on America's highways by 2009, a 14 percent increase from 1999, and highway travel is expected to increase 40 percent by 2015.


While the vast majority of our highway system can accommodate increased traffic loads with little difficulty, the highways in some of our most important urban areas are clearly being overtaxed. In these areas bottlenecks present a genuine problem that has many sides.


"Traffic congestion has become a major problem on many of our highways, and it's occurring at predictably overcrowded spots-bottlenecks," said William D. Fay, president and CEO of the American Highway Users Alliance, a public information and lobbying organization. "Freeing these bottlenecks is a critical starting point for curing the gridlock on our roadways."


To help us better understand the dynamics of bottlenecks and their cost the AHUA commission a recent study called "Unclogging America's Arteries: Prescriptions for Healthier Highways." The study was conducted by veteran transportation research organization Cambridge Systematics.


The study pinpointed the nation's top 18 bottlenecks, which are located in nine metropolitan areas. Not surprisingly, southern California, which has seen its traffic problems become the butt of jokes for decades, led the list with four of the 18, including the absolute worst, but major bottlenecks were also identified in such diverse locales as Albuquerque, Atlanta, Boston, Chicago, Denver, Houston, Seattle, and Washington, DC. The bottlenecks have become so notorious in their individual areas that some have acquired nicknames like "The Big Dig" in Boston, "The Mixing Bowl" in the Washington, D.C., metroplex, "The Big I" in Albuquerque and "The Hillside Strangler" in suburban Chicago.


While it is obvious that urban traffic bottlenecks cost us time, what is less obvious, but still very real, is their costs in traffic deaths and injuries, poorer air quality; wasted fuel and lost productivity. Bottlenecks aren’t just a nuisance; lack of adequate capacity on the highways in these stress points actually causes traffic accidents, spews pollutants into the air in greater concentrations and requires the useless burning of fossil fuels.


"Our overstressed road system needs additional capacity at key points. Providing that capacity by removing strategic bottlenecks, as part of an overall program of congestion relief, will reduce the amount of time commuters have to spend on the road, save hundreds of lives, prevent thousands of injuries, and help us safeguard the environment," said the study.


The study found that if the worst bottlenecks in America were eliminated the positive impact would be staggering. Specifically, it said fixing the nearly 170 traffic bottlenecks nationwide will, over the 20-year life of the improvements:

  • Prevent almost 290,000 crashes, involving 1,150 fatalities and 141,000 injuries

  • Nearly cut pollution at the bottlenecks in half, reducing carbon monoxide by 45 percent and VOC by 44 percent (while nitrogen oxides will increase slightly by six percent)

  • Cut carbon dioxide emissions by 71 percent

  • Reduce delays by an average of 19 minutes per trip -- nearly 40 minutes per day for commuters who must negotiate a bottleneck in both morning and evening rush hours

Analytic modeling methods were used to project the impact of improvements, finding significant gains in safety, air quality and travel time at each site over the 20-year life of the improvements, despite additional delays during construction. Actual improvements guided the analysis at bottlenecks where specific congestion fixes are already underway or being planned, while bottlenecks where such repairs and remedies are under consideration were analyzed conservatively based on improvements that would bring traffic flow to a minimum acceptable level.


The problems created by bottlenecks is so dizzying that if engineers could simply eliminate America’s biggest bottleneck — the intersection of the San Diego Freeway (I-405) and the Santa Monica Freeway (I-10) in west Los Angeles — it would result in 4,560 fewer crashes, including 18 fatalities and 2,240 injuries; reductions in carbon monoxide by 33 percent, smog-causing volatile organic compounds (VOC) by 33 percent, nitrogen oxides by eight percent and carbon dioxide by 53 percent; and a 15-minute reduction in delays per trip.


Unfortunately, it will take far more than the snap of a finger to cure America’s bottlenecks, but the technology to make huge dents in the problem exists.


In order to relieve congestion, ARTBA believes the nation and individual localities should develop a balanced approach to transportation planning that recognizes the American people's right to choose their means of travel. It includes:

  • Adding road capacity where appropriate and requested by state and local decision-makers. Common sense dictates that additional highway capacity is necessary to meet the growth in the economy and population.

  • Improved "incident management" by local authorities. A February 1997 study by the American Trucking Associations Foundation found that up to 60 percent of all time lost in traffic congestion in major urban areas is caused by incidents like accidents, flat tires and vehicular breakdowns.

  • Making better use of synchronized traffic signalization and other "smart road" technologies to increase traffic flow.

  • An improved and more efficient public transit system, including bus service that depends on adequate road capacity.

The AHUA study largely agreed, saying, "While past experience shows that no single strategy can adequately address the problems of metropolitan congestion, the good news is that there are effective solutions .... A balanced, comprehensive approach to traffic congestion that uses all the tools at our disposal can lessen the stifling gridlock found on many of our highways."


The study cited mass transit, high-tech traffic management systems, reversible commuter lanes and moveable barriers, as well as additional road capacity as a combined solution to the problem of traffic congestion and bottlenecks. It cautioned that the costs of the solution are high, but it noted that the dollar value of time and fuel wasted in traffic congestion was a whopping $74 billion in 1996, the last year for which reliable figures exist.


"What the study tells us is--there's hope," said Fay. "Eliminating specific chokepoints on our major highways would bring enormous relief to frustrated drivers. For the sake of public safety, an improved environment and a better overall quality of life, it's an investment worth making."


Nerad has experienced several of the nation’s worst traffic bottlenecks firsthand in commutes from his home in Southern California.