Can We “Fight” Congestion?

April 13, 2017 by Dan Hennessey

Recently, the Texas Transportation Commission approved $620 million for improvements to four Austin-area highways.  These funds would pay for overpasses along Highway 360, as well as improvements on I-35 near Downtown, flyover connectors at US-183 and I-35, and lane additions along US-183.  The common theme among these four projects: increased vehicle capacity.

It is probable, in isolation, that these projects will decrease vehicle travel times in the immediate vicinity of the construction work.  It is even more likely that the increased capacity will simply shift bottlenecks downstream and cause more congestion somewhere else.  Even as jurisdictions develop policies to prioritize safety or the climate, they continue to chase congestion with big-budget infrastructure projects.

Last week, a freeway section in the greater Atlanta area collapsed – for an area notorious for its vehicle congestion, commuters were confronted with potential for an even worse experience on Monday morning.  So what happened?

“Arguably, our mental model of traffic is just wrong. We tend to think of traffic volumes, and trip-making generally as inexorable forces of nature. The diurnal flow of 250,000 vehicles a day on an urban freeway like I-85 is just as regular and predictable as the tides. What this misses is that there’s a deep behavioral basis to travel. Human beings will shift their behavior in response to changing circumstances. If road capacity is impaired, many people can decide not to travel, change when they travel, change where they travel, or even change their mode of travel. The fact that Carmageddon almost never comes is powerful evidence of induced demand: people travel on roadways because the capacity is available for their trips, and when the capacity goes away, so does much of the trip making.”

It’s not just adding vehicle capacity that creates additional congestion.  Other policies, like the provision of free parking, can incentivize driving and encourage sprawl, which can be in direct contrast to those stated safety and climate priorities:

“But most developers create the number of parking spaces they are compelled to build and no more. In 2004 London abolished minimum parking requirements. Research by Zhan Guo of New York University shows that the amount of parking in new residential blocks promptly plunged, from an average of 1.1 spaces per flat to 0.6 spaces. The parking minimum had boosted supply far beyond what the market demanded.”

Source: Institute for Transportation & Development Policy

While perhaps obvious, free parking is not free.  Parking requirements increase the cost of development, and those costs are passed down to tenants of both residential and commercial buildings.  Some cities are now not only removing parking minimums, but increasing costs for providing parking spaces at all.  Unnecessary parking supply drives up rents and prices for goods and services.  From the same article from The Economist:

“The ever-growing supply of free parking in America is one reason why investments in public transport have coaxed so few people out of cars, says David King of Arizona State University. In 1990, 73% of Americans got to work by driving alone, according to the census. In 2014, after a ballyhooed urban revival and many expensive tram and rapid-bus projects, 76% drove.”

Too often, transportation professionals plan for one thing: moving cars as fast as possible during rush hours.  We provide parking at every potential destination to decrease travel times.  As we’ve mentioned before, that manner of thinking creates improvements that do not provide significant return on investment.  When we remember that we are trying to move people to connect destinations, we can prioritize investments.

Do you have questions about congestion, traffic or general transportation? We’ve got a team of experts that are ready with answers. Contact us today.

Written by Dan Hennessey

Dan Hennessey

Dan Hennessey, P.E., PTOE is Director of Transportation Engineering at BIG RED DOG. Dan holds a Master’s Degree in Civil Engineering (Transportation) from the University of California, Berkeley and a Bachelor of Science in Civil Engineering from The Ohio State University. Dan is responsible for managing our Raving Fans and prospective clients, overseeing the performance of our traffic and transportation engineering design staff, steering our marketing strategy, and spearheading our community outreach and volunteer efforts. Dan’s professional experience and expertise focuses on Traffic Impact Analysis (TIA) studies, highway, freeway and arterial operations analysis, signal coordination and synchronization, traffic signal design, travel demand forecasting, and pedestrian and bicycle facility design.