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Wednesday, June 27, 2012

Traffic–Innovative Ways To Improve It

In one of the more interesting books I have read recently – Traffic – author Tom Vanderbilt suggests that that social and psychological factors are as responsible for most of the congestion, accidents, and maddening delays that we face on the road. The book is as much about human perception as it is about traffic, and therefore it is well worth reading.  In 2008 when the book came out, Mary Roach of the New York Times, wrote a book review http://www.nytimes.com/2008/08/10/books/review/Roach-t.html?pagewanted=all and summarized it well:

Traffic jams are not, by and large, caused by flaws in road design but by flaws in human nature. While this is bad news for drivers — there’s not much to be done about human nature — it is good news for readers of Tom Vanderbilt’s new book. “Traffic” is not a dry examination of highway engineering; it’s a surprising, enlightening look at the psychology of human beings behind the steering wheels.

A good example is the following:

An estimated 12.7 percent of the traffic slowdown after a crash has nothing to do with wreckage blocking lanes; it’s caused by gawkers. Rubberneckers attend to the spectacle so avidly that they themselves then get into accidents, slamming into the car in front of them when it brakes to get a better look or dig out a cellphone to take a picture. (This happens often enough for traffic types to have coined a word for it: “digi-necking.”)

Traffic planners have tried everything to anticipate and stay ahead of such psycho-drivers, to no avail; and often their solutions become part of the problem:

Exasperated highway professionals have actually tried erecting anti-rubbernecking screens around the scenes of accidents, but the vehicle toting the screen typically gets caught in the traffic jam it’s meant to prevent.

Moreover, Vanderbilt adds, “there is the interest in the screen itself.” Drivers will slow down to look at anything: “Something as simple as a couch dumped in a roadside ditch can send minor shudders of curiosity through the traffic flow.

Traffic always slows down when construction barriers are placed on the sides of the road.  Although the lanes themselves have not been narrowed, and there is always some shoulder, there is a psychological sense of being hemmed it.  Once the barriers end, and drivers can see to the open fields, traffic speeds up. 

Many times I have been caught in a traffic jam only to find that there was no real reason for it; that is, no construction, no accident, no rubbernecking.  Traffic analysts have shown that an unnecessary slowdown by one car in a heavily-travelled, high-speed highway, can have repercussions miles back.  Tunnels are the only traffic environment in which strong, demanding signs to ‘Keep Up Speed’ are posted throughout.  Tunnels are the worst places for driving – they are narrow, dark, noisy, with many grades.  While there are few accidents because no one feels safe in them and, as above, tend to pay more attention to driving, the tendency is always to slow down.  Efforts to keep speed up do not adversely affect safety and increase flow.

Traffic problems are not only a function of human fallibility – although the book focuses on it – but also changes in social patterns.  We simply drive more, and do so for less compelling reasons than we used to.  Instead of buying at the local supermarket, we will drive an extra few miles to Whole Foods to get that special cut of beef or organic carrots.  Or going out for coffee:

So much of Starbucks’s revenue now comes from drive-through lanes that the company will put stores across the street from each other, sparing drivers “the agony of having to make a left turn during rush hour.”

When we drive more, we park more; and in most urban areas parking is at a premium.  To avoid paying at a lot, we will circle endlessly waiting for a space to materialize.  That circling causes delays for thru-drivers who must sit behind the seekers and then wait for the inexperienced parallel parker to give it at least three goes.

Despite the fact that traffic congestion has spawned thousands of traffic planners, solutions have been few and far between, and most have unintended consequences:

Traffic does not yield to simple, appealing solutions. Adding lanes or roads is a short-lived fix. Widen one highway, and drivers from another will defect. Soon that road is worse than it was before. The most effective, least popular solution — aside from the currently effective, unpopular solution of [higher-priced] gasoline — is congestion pricing: charging extra to use roads during rush hours. For unknown reasons, Americans will accept a surcharge for peak-travel-time hotel rooms and airfares but not for roads.

There is always a political debate about road-widening or new construction; but the builders always seem to win.  The demands of commuters in a highly-congested metropolitan areas are vocal, immediate, and insistent; and it takes more political courage than can be found in local and state governments to refuse expansion.  A few years ago Fairfax County, Virginia, a suburb of Washington, DC imposed a moratorium on building because it simply was not able to build the infrastructure – including roads – to keep up with demand.  Of course, as land and property values kept climbing because of the emerging high-tech industries in the suburbs, the County relented.

Rather than addressing the congestion issue by deflating demand, politicians and traffic planners increase demand through continuous building.  I have been travelling the New Jersey Turnpike for decades, and each time I think that it has reached its outer limits in terms of new lanes, new ones are added.  Something is ripped out, razed, or bulldozed to make way for even more travellers.

Sometimes traffic planners make bad decisions on where to put new roads or mass transit.  In Washington a metro line was not built to Tysons Corner, once a modest shopping mall, but now a small city.  They used what information they had, but how were they to know that Tysons would become a shoppers’ mecca?  Or how were they to know that the Dulles, Virginia area would become Silicon Valley-on-the-Potomac?  The congestion on roads from DC out to Dulles are as bad as any in the area, and only now are regional authorities building an extension of the Metro to relieve the congestion.   The Virginia Greenway, very hotly debated as a way to relieve congestion in Fairfax County, has never been used as planned; and the new cross-county highway in Montgomery County, Maryland, is suffering from the same lack of use.

Traffic suggests many ingenious ways to improve traffic flow without major public works, focusing on human perception and behavior.  They have experimented, for example, with the length of the white dotted lines down the middle of the road.  Shorter lines at closer intervals give the impression of higher speed, thus slowing drivers down.  Experiments with the size, color, luminescence, and placement of signs are designed to make reading easier, thus enabling motorists to keep up their speed. 

One of the most ingenious is encouraging drivers to use both lanes right up until a lane closure.  Right now the ‘Merge’ signs are posted at least a quarter-of-a-mile before the merge, resulting in one congested lane and one free one.  Under this system, those who zip down the free lane and force a merge with the more law-abiding and patient motorists are given the finger.  Traffic planners have suggested that if signs were posted instructing drivers to use both lanes and then to provide an alternate merge, traffic would improve and tempers would remain in check.  It is all about fairness.

Vanderbilt also gets into the causes for crashes, and cites innovative examples to keep people alert and awake.  Many interstates, particularly in the Midwest and West are long, flat, and monotonous.  Researchers have found that by simply adding inexpensive diversity – a slight curve or rise in the roadway – drivers pay more attention to their driving. The right perceptual balance between too much signage on the roadside and too little is always sought to guide driving.

Vanderbilt cites a statistic that nearly 80 percent of crashes involve drivers not paying attention for up to three seconds. Thus the places that seem the most dangerous — narrow roads, hairpin turns — are rarely where people mess up. “Most crashes,” Vanderbilt writes, “happen on dry roads, on clear, sunny days, to sober drivers.” For this reason, roads that could be straight are often constructed with curves — simply to keep drivers on the ball.

One of the particularly important insights of the book is that ‘feeling safe kills’, and that there are some counter-intuitive measures to improve safety:

Americans think roundabouts are more dangerous than intersections with traffic lights. Roundabouts require you to adjust your speed, to merge, in short, to pay attention. At an intersection, we simply watch the light. And so we may not notice the red-light runner coming at us or the pedestrian stepping off the curb. A study that followed 24 intersections that had been converted from signals or stop signs to roundabouts showed an almost 90 percent drop in fatal crashes after the change.

Many more examples of counter-intuitive thinking illustrate the way we drive, what we are thinking when we are, and why we get into accidents:

For similar reasons, S.U.V.’s are more dangerous than cars. Not just because they’re slower to stop and harder to maneuver, but because — by conferring a sense of safety — they invite careless behavior. “The safer cars get,” Vanderbilt says, “the more risks drivers choose to take.” (S.U.V. drivers are more likely to not bother with their seat belts, to talk on cellphones, and to not wear seat belts while talking on cellphones.) So it goes for much of the driving universe. More people are killed while crossing in crosswalks than while jaywalking. Drivers pass bicyclists more closely on a road with bike lanes than on one without.

It should not be a surprise to learn that the safest airports are those where the pilots have to be especially vigilant.  Anyone who has landed in Hong Kong’s old airport (you can see the whites of their eyes as you fly a few feet over the apartment buildings), wonders why there are few crashes; but when pilots are on high alert – like drivers – they do a better job.

In conclusion, this book is a page-turner.  We all drive and have been frustrated by traffic, and in many cases we wonder why the congestion or delays occur.  Not only does this book disaggregate the causes of congestion and crashes, but suggests the innovative ways traffic planners are devising to reduce both.  Fascinating reading.  

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