As noted in a previous PPS blog post, an organization called Transportation Construction Coalition (TCC) commissioned preparation of a report called On A Crash Course: The Dangers & Health Costs of Deficient Roadways. I would like to add a few observations to the great article written by Renee Espiau entitled “The Myth of the Great Wide Way” and posted by Craig Raphael on July 7.
The TCC report, while not being taken too seriously amongst transportation professionals, has received a lot of media attention, probably due to a concerted effort by the TCCs media relations department. In the interest of full disclosure, readers who may potentially be influenced by this research should understand that the TCC is not an independent organization with an unbiased interest in whether more and bigger roads get built. The TCC consists of 28 national construction organizations and labor unions, with two roadway design organizations thrown in for good measure. It is co-chaired by the American Road & Transportation Builders Association and the Associated General Contractors of America.
This is not a bad thing. I spent 34 years helping a state DOT build roads myself. But let’s not accept this as independent research.
Readers should also be aware of the major assumptions made in the report.
First, by their own admission, for vehicles other than large trucks, the TCC had no real data on whether road conditions actually contributed to the crash or not. The report is completely silent on whether this is really appropriate considering the huge difference in handling characteristics of cars versus large trucks. This is particularly true regarding events where vehicles left the roadway and collided with a fixed object such as a tree or bridge abutment.
Second, the TCC report admits that it does not contain adequate information on travel speeds: “In the 2006 CDS, 61% of cases have missing values for reported travel speed.” The most current information available was from 1986, and even then, the data was from only a fraction of the universe representing crash data collection.
These two major gaps in the research are particularly troubling when applied to urban arterials. We are being told by the TCC — frightened actually — into believing that we need to ramp up our “Forgiving Highway” approach. Straighten and widen our roads or our lives will be at peril! The Forgiving Highway approach was cultivated on the Proving Grounds of General Motors almost 5 decades ago and has worked marvelously for the Interstate Highways and other freeways.
The problem is that modern transportation engineering, giddy over the success of application of Forgiving Highways to our Freeways, began to apply the same principles to local streets and the in-between class of roads: arterials. It was logical to think this way, and still is OK on rural arterials, where killer trees and ditches should be addressed. However, the method is counterproductive in urbanized areas. An increasing body of research is revealing what Eric Dumbaugh (a brilliant young researcher at Texas A&M) talks about in several papers. “Livable Streets,” those designed in harmony to support (not ignore) the urban context, induce drivers to travel at speeds appropriate for urban environments. His research shows the Forgiving Highway concept applied to urban arterials actually increases midblock crashes and also sideswipes and encounters with poles, trees and other fixed objects.
I am a career transportation engineer, so I obviously believe in safety. But Dumbaugh’s research confirms what I began to understand during the last 15 years of my career. Indiscriminately widening and straightening roads is not automatically safer. Site specific engineering analysis of crashes needs to be applied before deciding on how to make a road safer. Sometimes slowing it down is better. Interestingly, some folks at PennDOT came to the same conclusion. Their back-of-the-envelope research revealed that crash rates increased on half of about two dozen of their “safety” projects. The only conclusion that makes sense is that motorists, feeling safer at higher speeds, drove faster. Sometimes, upgrading one section of roadway might actually induce motorists to speed into a hazard on the adjacent section.
Am I anti construction and jobs? Absolutely not. Collectively it would cost just as much if not more to deploy a national safety program that rebuilds roadsides instead of clearing them out. The construction industry, which has helped America build the greatest system of high speed roads in the history of the world, can now help save lives by gearing up to help us build the rest of the transportation network: both slow and fast! I am sure that the Transportation Construction Coalition is well intended and wants to make our roads safer as well as create jobs. I urge them to “look before they leap” before using their substantial resources to promote and lobby for application of the Forgiving Highways paradigm to all of our roads.