Overview
The costs associated with traffic congestion are high and continue to rise. The 2012 Urban Mobility Report, published by the Texas A&M Transportation Institute, cites the following facts:
- The total financial cost of congestion in 2011 was $121 billion, up $1 billion from the year before and translating to $818 per U.S. commuter and 5.5 billion h in additional travel time.
- Of that $121 billion, about $27 billion represents wasted time and diesel fuel from trucks moving goods on the system.
- Fuel wasted in congested traffic reached 2.9 billion gallons— enough to fill the New Orleans Superdome four times.
- In 2012, carbon dioxide emissions attributed to traffic congestion were 56 billion pounds or about 380 pounds per automobile commuter (1).
Traffic experts describe traffic as being either “recurring” or “nonrecurring.” Recurring congestion is predictable, associated for example with rush hour. Recurring congestion is both the plague and a hallmark of economically thriving regions. Nonrecurring congestion describes unexpected traffic jams that develop as a result of unpredictable events such as weather or traffic incidents. Nonrecurring congestion accounts for nearly half of all traffic congestion. Furthermore, nonrecurring congestion negatively impacts travel time reliability or predictability on roadways. Motorists, including commuters and freight road users, continue to affirm that they value travel time reliability of roadways more highly than travel time itself. This observation is based on interviews with commuters and large and small freight carriers at metropolitan/regional planning organizations in Atlanta, Georgia, and Minneapolis/St. Paul, Minnesota, in 2009 and 2010. The interviews were conducted in conjunction with the Federal Highway Administration Office of Freight, Management and Operations, Peer-to-Peer Program.
Traffic incidents—which include anything that happens on a roadway that impacts traffic ranging from disabled vehicles to fender-benders to vehicle crashes—account for up to 25% of all congestion and 40% of nonrecurring congestion (2). Bottlenecks caused by “rubbernecking” alone can drop a highway’s capacity an additional 12.7%, even if a lane is not closed (3). Finally, reliability and safety problems on roadways are inextricably interlinked. Every minute an incident is not cleared endangers other motorists and responders through an increasing risk of secondary incidents, which further propagate traffic congestion. Faster incident clearance means safer roadways for motorists and incident responders who are in harm’s way while attending to an incident; it can also improve the reliability of our nation’s roadways by restoring travel lanes more quickly to pre-incident conditions.