congestion

Cities need to move carefully to get TNC benefits

By Brian Lutenegger A new report examines existing research and new data on the impact of Transportation Network Companies (TNCs) like Uber and Lyft on U.S. cities. TNCs can have negative impacts on urban areas by contributing to traffic congestion—but, if planned and regulated properly, can

Is traffic congestion a good thing?

By Brian Lutenegger Researchers at the University of Colorado at Denver and Florida Atlantic University sought to answer this question: Is the fear of the negative economic effects of traffic congestion justified, or is congestion merely a nuisance with little economic impact? The researchers

Efficient networks take work: Traffic management and Braess’ paradox

By Chris McCahill 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.

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

By Sam Sklar The borough of Leonia, NJ, has decided to close most of its local roads to non-residents during peak morning and afternoon periods, the New York Times reports. As Google Maps and Waze (owned by Google) have sent more commuters onto local streets in an attempt to avoid highway

Traffic enforcement observations target Uber and Lyft drivers as largest offenders

By Sam Sklar A recent scan from San Francisco’s Police Department found that Uber and Lyft drivers were responsible for nearly 65 percent of traffic infractions in bike- and transit-only lanes. The overwhelming majority of these tickets, for all vehicles and for Uber and Lyft vehicles, cited

A framework for determining where congestion really matters

By Eric Sundquist These two things are true: 1) Travelers dislike slow traffic, and 2) slow traffic is sometimes an inescapable result of things that people do like—cities with popular destinations. Conventional transportation practice responds well to No. 1, with well-known standards for delay

What HOV requirements in Jakarta can teach us about congestion

By Sam Sklar According to a new paper from three researchers at Harvard and MIT, removal of a strict High-Occupancy Vehicle (HOV) policy had negative effects on traffic in Jakarta, Indonesia, the world’s second largest metropolitan area. Congestion increased even on streets with no

Study of variable speed limits highlights the trade-off of throughput and safety

By Sam Sklar Varying a posted speed limit based on current conditions can improve operations and safety in congested work zones, a team from Missouri found.  This study from the University of Missouri-Columbus, called “Evaluation of Variable Advisory Speed Limits in Congested Work Zones,”

Reducing traffic congestion in cities by delivering goods at night

By Logan Dredske Shifting store, restaurant, and other business deliveries to nighttime hours could reduce traffic congestion within cities. A study conducted by the KTH Integrated Transport Research Lab (ITRL) in Stockholm, Sweden, has found that scheduling deliveries to businesses during

As federal government mulls performance measures, the TTI congestion report returns

By Eric Sudquist The timing is apparently coincidental, but the Texas Transportation Institute issued its latest estimate of traffic congestion costs in late August, just as US DOT seems to be finishing work on its MAP-21-mandated performance measures on congestion and system performance. The TTI