Sunday, September 27, 2009
Trafficking in Congestion
Traffic abounds, billions are spent on new roads and traffic lights, yet traffic grows exponentially worse. Is it possible that there is money to be made here and certain people don't actually want the traffic problem alleviated?
A March 2008 report on CNNMoney.com summarized several reports on traffic. In it, the motorist advocacy group Automobile Association of America (AAA) said accidents cost Americans $164.2 billion each year, an annual per person cost of $1,051, while the Texas Transportation Institute estimated that congestion costs the nation $67.6 billion each year, or $430 per person. "Nearly 43,000 people die on the nation's roadways each year," AAA President Robert L. Darbelnet said in the report. Sadly, this statistic is largely ignored in favor of more compelling human drama such as the 100 annual deaths suffered from accidental drowning. Methods to reduce sharply this tragic number can be summarized in three basic areas: public policy paradigm shifts, innovative road and intersection design, and public education. The barrier to implementation is in integrating modern traffic concepts among groups that have little understanding of their inter-dynamic role in traffic flow.
Public policy – ideally the easiest barrier to overcome – has proven to be the most difficult. Public works offices are often headed by engineers who last studied traffic theory in the 1950’s. An irrational and myopic fear of job losses in the construction industry and traffic signal trades, results in hysterical resistance to new traffic-flow models. Public officials are inundated with (dubious) statistic-packed reports from the traffic-light camera industry, which promise 100% traffic light compliance while (conflictingly) producing overstuffed coffers of collected fines. The well known public advocacy group, Transportation Alternatives, has published over a thousand articles and news releases extolling red light cameras, yet not a single one of those articles questions the validity of the studies, or reports on studies that dispute those results. Why? In 2004 the Washington Post reported that Washington DC’s red-light cameras generated more than 500,000 violations and $32 million in fines over a six year period. City officials unanimously declared the move a success, claiming that the cameras made the busy roads safer.
But the Washington Post analysis of crash statistics shows that the number of accidents has gone up at intersections with the cameras, the same or worse than at traffic signals without the devices. The Post story reported that three outside traffic specialists independently reviewed the data and said they were surprised by the results. Their conclusion: The cameras do not appear to be making any difference in preventing injuries or collisions. "The data are very clear," the Post quoted Dick Raub, a traffic consultant and a former senior researcher at Northwestern University's Center for Public Safety. "They are not performing any better than intersections without cameras." So what is the success then, other than of having found a new way to generate city income?
Critically, understanding the intellectual processes drivers use when negotiating our roads are terribly misunderstood, and need to be raised to a level of awareness that engineering departments can capitalize on in some areas, while working to mediate in others. These paradigm shifts cannot be understated. The key to reducing congestion and traffic fatalities is innovative road and intersection design using knowledge about how drivers negotiate the road. For example, how many of you have had this experience: You are in the right lane of an interstate going through a city, traveling at 65 mph, when someone enters the highway from a ramp on your right. The person entering appears to be accelerating, but at the moment he pulls in front of you, you realize he is only doing about 50 mph and you brake to slow down. Patiently, you wait for him to speed up but he doesn’t. After about a minute you move out to the left, pass him, and get back in the right hand lane some distance ahead, resuming your earlier speed. About one minute later (sometimes one and a half) he passes you, only now he’s traveling in excess of 70. If this only happened once in your lifetime of driving, then obviously the guy was an idiot; rude, selfish, and a terrible driver. But it’s not once is it?
In fact this happens thousands of times a minute all over the country. People enter a highway at less than the cruising speed of traffic causing drivers behind them to brake, only to actually assume highway speed one to two minutes later. During peak highway usage periods, it only takes one person to do this, and the domino effect of braking results in the reduction of flow velocity for the entire grid. Where are the studies of this, an obviously psychoanalytical part of driver speed-processing? How might we exploit the results of those studies?
The major cause of traffic congestion is traffic that is stopped, because stopped traffic needs time and distance to get up to speed again. If we think of roads in terms of flow and capacity, traffic signals are obviously the biggest impediment to flow. Yet what is generally ignored, especially by local road engineering departments, is that they are also the greatest impediment to capacity. Capacity, or that amount of road available to the number of vehicles present, is really what makes or breaks congestion. At a routine four-way traffic light intersection, between 50% and 75% of road capacity is shut off at any one time as the light cycles between allowing flow in any single direction. If you’ve ever sat at a red light intending to go straight, and looked past the intersection to the road directly ahead of you and noticed that no cars were traveling on it at all, while behind you traffic was stacked up, what you were seeing was inefficiency to capacity. This image, courtesy of Google Earth, illustrates the loss of capacity created by a typical traffic light intersection. This is normal stopped traffic, at De Zavala and I-10, San Antonio, Texas. (Click image to enlarge)
One method to recapture that capacity involves replacing stop light intersections with continuous flow intersections. The simplest of these are called roundabouts. With roundabouts, all roads leading out of an intersection experience continuous flow. During periods of normal traffic they function as yield sign intersections – no one need stop if the entrance is clear. When flow if greater, drivers must wait their turn to transverse the intersection, and the roundabout functions as a traffic light. For a side-by-side comparison of the De Ze Zalla / I-10 intersection and a similar intersection constructed without traffic lights, follow this link.
The major cause of traffic related injury is the side impact collision. Roundabouts entirely eliminate side impact collisions. In a 2000 study by the Maryland Department of Transportation, six-months of data collected on a single intersection converted to a roundabout revealed a 67% reduction in accidents, with a 100% reduction in fatalities. 100 percent!
They concluded that the accidents that had happened, tended to be of the sideswipe variety, which cause less damage and injuries, because movements are all converted to right turns. (Click image to enlarge.)
If damages and injuries are reduced, it follows that insurance payouts are reduced as well, so why aren’t big insurance companies Like State Farm, Allstate, or Geico aligned behind roundabouts, the way they outwardly support intersection cameras? Could it be that they have determined that the increased insurance fees they charge to people who are ticketed by traffic cameras, outweigh the increased revenue retention they would enjoy from simply having less and lower costing accidents?
The Federal Highway Administration (FHWA) publishes a 275 page instruction guide for roundabout construction aimed at local engineering departments. The Transportation Research Board, National Research Council, publishes one as well. Yet I’ve not met a single local engineer from any locality I’ve inquired at who will admit to having heard of either of these documents. This needs to change.
The third element to improving traffic flow requires a relationship between our officials and the media. To be successful, a far-reaching media campaign must be realized to raise public awareness on the major causes of congestion, many of which are related to simple ignorance on the part of motorists. Habits engrained from years of driving on less populated roads must adjust to new realities and driving habits. Examples of these are the proper way to enter onto a highway, or ironically, the purpose of a yield sign, (it really is not just another type of stop sign). In 1966, when the United Kingdom decided to replace the majority of their traffic lights with roundabouts, they embarked on a two-year public education campaign. U.S. municipalities implementing signal-less intersections such as Alaska, Maryland, New York, and California, are doing the same today.
Finally, an economic point overlooked entirely at the local level is the impact of traffic on net sales revenue. Although hard to quantify, local business should be asking themselves how many dollars are slipping through their hands as people choose to forgo the traffic mess and shop from home. Although it's reasonable that most people prefer to shop by seeing and handling the goods they want to buy, something is causing millions of Americans to forgo traditional brick and mortar shopping habits. The internet has seen astronomical increases in sales. Broadwavestudios.com reports that according to ComScore, Inc, an intenet data collection company, online consumer spending grew 26 percent in 2006 to $24.4 billion. That money is coming from somewhere. Perhaps our local officials should be concentrating less on how much money they can generate from red light cameras, and instead focus on how increased vehicle traffic is negatively affecting local sales tax receipts.
Elly Martin, a spokesperson for the National Highway Traffic Safety Administration (NHTSA), said that the ultimate cost of traffic might be even greater than the AAA study. A study by NHTSA concluded, "…the cost to society was $230.6 billion in 2000 and … is even greater today." Troy Green, AAA's public relations manager said, "(we are looking for)…leadership at the national, state and local levels," in support of what he called, "…a public health challenge."