The efficient and reliable movement of goods is important to the U.S. economy. Travel time and speed are two indicators of transportation system performance. Slower speeds and unreliable travel times caused by congestion, weather, and other factors diminish productivity, increase fuel costs, and reduce operations efficiency.
The U.S. Department of Transportation, Federal Highway Administration, in cooperation with private industry, measures the speed and travel-time reliability of more than 500,000 trucks on 25 freight-significant corridors on an annual basis. Average truck speeds drop below the base free-flow speed of 55 miles per hour (mph) on interstates near major urban areas, border crossings and gateways, and in mountainous terrain.
Analysis has shown truck speed decreases in urban areas. The Federal Highway Administration uses Freight Performance Measurement Program data to measure truck speeds within 14 very large Census Metropolitan Statistical Areas. In 2015, 7 of the 14 metropolitan areas had average truck speeds of less than 55 mph on their interstate highways, with San Francisco the slowest at 47.61 mph and Los Angeles at 47.93 mph.
Truck speed and travel time reliability data can be used to identify and quantify major freight truck chokepoints and bottlenecks along highways that are critical to the Nation’s freight transportation system. The Federal Highway Administration developed a freight congestion index that ranks congestion’s impact on freight movement. The index factors in both the number of trucks using a particular highway facility and the impact that congestion has on the average speed of those vehicles.
On weekdays, average speeds during peak periods (between 6:00 a.m. and 9:00 a.m. and between 4:00 p.m. and 7:00 p.m.) are typically lower than those recorded during nonpeak periods. Freight traveling across urban interstate interchanges is affected to the greatest degree by peak-period congestion.
Several monitored locations have recorded noticeable improvements in performance from 2013 to 2014 when considering average travel speed over a 24-hour period. Locations along I-35 in the Minneapolis-St. Paul area have seen the greatest improvement in overall and peakperiod average speeds, while I-95 in the Richmond area has shown the largest improvement in nonpeak-period average speeds.
Intercity travel-time is a key freight performance measure. It influences logistics, operational strategies, and load optimization. The Federal Highway Administration analyzed the minimum and maximum truck travel times of key city-pair origins and destinations. Travel time between Philadelphia and New York City, San Francisco and Sacramento, and San Diego and Los Angeles have the highest percent difference between the shortest and longest recorded trip times in 2015.
Recurring congestion caused by volumes of passenger vehicles and trucks that exceed capacity on roadways during peak periods is concentrated primarily in major metropolitan areas. In 2012 peak-period congestion resulted in traffic slowing below posted speed limits on 12,200 miles of the National Highway System and created highly congested (stop-and-go) conditions on an additional 7,000 miles.
Assuming no changes in network capacity, increases in truck and passenger vehicle traffic are forecast to expand areas of recurring peak-period congestion to 35 percent of the National Highway System (NHS) in 2045, compared with 8 percent in 2012. This will slow traffic on 22,700 miles of the NHS and create stop-and-go conditions on an additional 55,800 miles, almost eight times more than that of 2012.
Congested highways carrying a large number of trucks substantially impede interstate commerce, and trucks on those segments contribute significantly to congestion. On highways carrying more than 8,500 trucks per day, recurring congestion slows traffic on 1,600 miles and creates stop and go conditions on another 800 miles of the National Highway System.
Assuming no change in network capacity, the number of National Highway System miles with recurring congestion and traveled by a large number of trucks is forecast to increase significantly between 2012 and 2045. On highways carrying more than 8,500 trucks per day, recurring congestion will slow traffic on close to 3,700 miles and create stop-and-go conditions on an additional 13,000 miles.
Border crossings are potential bottlenecks in the freight transportation network. The Federal Highway Administration monitors truck crossing times at 15 designated truck-lanes at U.S.- Canada border crossings. At all but two crossings, transit times were longer for inbound U.S. traffic than for travel to Canada.
The U.S. Department of Transportation in partnership with the Texas Department of Transportation also measures transit times from Mexico to the Unites States at the Bridge of the Americas and the Pharr-Reynosa International Bridge. The data are collected using radio frequency identification technology installed at the start of the crossing (typically the end of the queue) and at the vehicle safety inspection station exit (the end of the crossing trip). Vehicle identification information is anonymously collected and time-stamped at each reader station, and travel time (including vehicle inspection time) is calculated between the reader stations.