Efficient networks take work: Traffic management and Braess’ paradox

Not all roads are created equal. In fact, adding certain roads to a system can actually slow down traffic under the right circumstances. This is a fairly well known phenomenon called Braess’ paradox, named after the German mathematician who first wrote about it in 1968. Fortunately, researchers have studied this occurrence extensively and developed methods for knowing when it can happen and how to prevent it. A new study published in the Journal of Transportation Engineering lays out fairly straightforward methods to identify troublesome links.

When Waze clogs the streets, can communities close them to outsiders?

Reacting to drivers using apps to bypass clogged highways, the borough of Leonia, NJ, has decided to close most of its local roads to non-residents during peak morning and afternoon periods. Many question whether this is a wise or even legal option. In the short run, the shutdown of local roads might make residents happy; but in the longer term, residents could face worsened regional congestion as traffic is forced onto clogged arterials. In dense networks, these local roads can sometimes act like important release valves.

Costs for Pedestrian and Bicyclist Infrastructure Improvements: A Resource for Researchers, Engineers, Planners, and the General Public (Pedestrian and Bicycle Information Center, 2013)

This report provides infrastructure cost estimates for pedestrian and bicycle treatments, infrastructure, and amenities from across the country. Costs vary widely, but the report includes high, low, and median costs from a variety of sources.

SSTI’s scenario analysis tool unveiled; will allow DOTs to better engage with land use authorities

Transportation agencies traditionally have to chase land use development, spending scarce funds to provide new roadway capacity, when better land-use patterns could have greatly reduced travel demand. SSTI’s new scenario analysis tool, developed for DelDOT, provides a way for transportation providers to influence land use development for the better.