Legacy Book

You are here

Chapter 3: Passenger Transportation System

Overview of the Passenger Transportation System

The passenger transportation system is a network of highways, railroads, airports, public transit systems, and waterways that serves over 300 million U.S. residents and foreign visitors. It comprises more than 4 million miles of roads, 11,000 miles of transit rail directional route-miles, 21,000 miles of Amtrak routes, 19,000 airports, and about 25,000 miles of navigable waterways.

Table 3-1 Passenger Transportation Infrastructure: 2000, 2010, and 2014

Public Roads and Vehicles

Composed of over 4.1 million miles of interstate highways, arterials, and local routes, the highway network has expanded since 2010. Between 2010 and 2014, miles of public road grew by 2.7 percent and lane-miles increased by 2.2 percent, while traffic volume grew 2.0 percent. Local roads are by far the most extensive, comprising 2.8 million miles (69.5 percent of total system miles.) Interstate highways handled the highest volumes of traffic as measured by vehicle-miles traveled, 24.8 percent in 2014, but accounted for only 1.1 percent (about 47,700) of total system miles.

Table 3-2 Highway Transportation System: 2000, 2010, and 2014

The National Highway System (NHS) is a network of about 230,000 miles of interstates and other roads essential to the Nation’s economy, defense, and mobility. While only 5.5 percent of the Nation’s total route mileage and 9.0 percent of the total lane-miles were on the NHS, these roads carried 54.9 percent of total vehicle-miles traveled in 2013. Passenger vehicle traffic on the NHS, excluding large trucks and buses, is concentrated in and around large cities. In 2011, 28.4 percent of passenger vehicle traffic was on the NHS. While the majority (69.9 percent) of NHS mileage is rural, only 8.1 percent of passenger vehicle traffic took place in a rural setting.

Figure 3-1 Passenger Vehicle Traffic on the National Highway System: 2011

Road congestion is one of the major causes of travel time delay and negatively impacts transportation system reliability. In 2011 peak-period congestion resulted in traffic dropping below posted speed limits on 13,500 miles, or 6 percent, of the National Highway System. This congestion created stop-and-go conditions on an additional 8,700 miles of road.

Figure 3-2 Peak-Period Congestion on the National Highway System: 2011

The Planning Time Index (PTI) is a reliability measure that estimates the extra time one should plan for a trip. For example, for a PTI of 1.5, a traveler should allow 50 percent more time in order to arrive on time 19 out of 20 times. In other words, 30 extra minutes should be budgeted for a trip that would typically take 60 minutes in free flow conditions. Overall congestion worsened from 2013 to 2014. Based on PTI data for 52 metropolitan statistical areas (MSAs), travelers had to plan more than double the free-flow travel time to arrive “on-time” for 19 out of 20 trips. Between December 2013 and December 2014, the PTI increased in 43 of the 52 MSAs.

Figure 3-3 Highway Reliability as Measured by the Planning Time Index: January 2013–December 2014

In the Nation’s urban areas, commuters spent 6.9 billion hours in congestion, wasting 3.1 billion gallons of fuel in 2014. This congestion cost the economy an estimated $160 billion, an increase of 40.4 percent since 2010. Overall measures of congestion delay and cost have increased in post-recession years. From 2013 to 2014, the annual delay per auto commuter increased in 96 (95 percent) of the 101 largest urban areas.

Table 3-3 Estimated Annual Congestion Delay and Costs: 2000, 2010, and 2014

Although ranking first for their respective population groups, the Washington, DC, and Honolulu, HI, urban areas experienced slight decreases in delay since 2010. Delay per auto commuter fell 3.2 and 2.0 percent respectively. In 2014 Washington, DC, averaged 82 hours of average annual delay per auto commuter. This delay was the highest of the 471 urban ares included in the study. Congestion worsened in urban areas of all sizes. San Jose, CA, experienced the largest growth in congestion since 2010, a 13.6 increase in delay. The Austin, TX, area followed with a 13.0 percent increase.

Table 3-4 Most Congested Urban Areas by Annual Hours of Delay per Auto Commuter: 2000, 2010, and 2014


Despite record levels of air travel since the recession ended, the number of airports, aircraft, and pilots shrank between 2010 and 2014. The number of certificated and generation aviation airports declined 2.5 percent, the aircraft fleet fell 8.4 percent, while the pilot pool fell 5.4 percent.

Table 3-5 Air Transportation System: 2000, 2010, and 2014

The U.S. airline passenger load factor— a measure that compares system use as a proportion of system capacity—rose from 72.6 in January 2003 to 84.3 in December 2015. After the recent recession, the load factor generally increased because use, measured in revenue passenger-miles, increased at a faster pace than capacity, measured in available seat-miles. In December 2015 use and capacity reached all-time highs, and the monthly, seasonally adjusted load factor was the third highest on record.

Figure 3-4 U.S. Airline Revenue Passenger-Miles, Available Seat-Miles, and Load Factor: January 2003–December 2015

During the last decade, U.S. airline on-time performance was at its lowest in 2007 when 24.1 percent of flights were delayed. The percentage of delayed flights rose to another high in 2014, before falling to 18.3 percent in 2015. The average length of flight delays has increased since 2010, reaching 58.9 minutes in 2015.

Figure 3-5 Percentage of Flights Delayed and Average Length of Delay: 2004–2015

In 2015, 37.9 percent of the delayed arrivals were delayed for less than 30 minutes. Slightly fewer flights, 30.8 percent of delayed arrivals, were delayed between 30 and 59 minutes, while just over 11 percent of delayed arrivals were delayed for more than 2 hours.

Figure 3-6 Delayed Flights by Length of Time Delayed: 2015

Flight delays result from a variety of reasons, ranging from extreme weather to disruptions in airline carrier operations. The combined effects of nonextreme weather conditions, airport operations, heavy traffic volume, and air traffic control delays (i.e., National Aviation System) contributed to 22.9 percent of delays in 2015, a 10.6 percentage point improvement from 2004. Flight delays can ripple through the U.S. aviation system as late arriving flights delay subsequent flights. Late arriving aircraft were the cause of 39.8 percent of delays in 2015.

Figure 3-7 National Flight Delays by Cause: 2004–2015

Flight cancellations are more likely to occur in the winter due to the impact of snow and ice on flight operations. Nine of the top 10 months for flight cancellations between January 2003 and January 2016 occurred in the winter; the only exception was October 2012 when Hurricane Sandy struck the east coast.

Table 3-6 Average On-Time Arrivals and Cancellations by Month: January 2003–January 2016

Table 3-7 Top 10 Worst Months for Canceled Flights Due to Weather: January 2003–January 2016

Among large airports, LaGuardia Airport had the highest percentage of flights delayed in 2015. Palm Beach International Airport had the most delayed flights for medium-sized airports, with 22.2 percent of flights delayed.

Figure 3-8 Large and Medium Airports by Enplanements and Overall Delay: 2015

Public Transit

More than 800 urban transit agencies and 1,500 rural and tribal government transit agencies offer transit service. Since 2000 rail transit (commuter rail, heavy rail, and light rail) has expanded to cover over 11,000 directional route-miles and include over 3,000 rail transit stations. Buses accounted for about half, 47.5 percent, of the over 132,000 transit vehicles in 2014.

Table 3-8 Public Transit System: 2000, 2010, and 2014

Based on results from the American Community Survey, 12.6 percent of the U.S. population self-identified as having a disability in 2014. In 2014, 78.0 percent of transit stations complied with the Americans with Disabilities Act (ADA), which requires agencies to provide accommodations for individuals with disabilities at public transit facilities. The number of accessible stations has increased since 2000. In 2014, 97.0 percent of bus stations and 88.6 percent of light rail stations were compliant with the ADA.

Figure 3-9 Stations Compliant with the Americans with Disability Act: 2000–2014

Passenger Rail

Amtrak is the primary operator of intercity passenger rail service in the United States. Amtrak operated over 21,300 route miles in 2014 and more than 500 stations that served 46 states and Washington, DC. Amtrak’s fleet of rail cars and locomotives decreased by 32.7 and 25.4 percent, respectively, between 2000 and 2010 due to an aging fleet. However, between 2010 and 2014, the fleet has grown as Amtrak began replacing and adding to its fleet as part of a decade-long improvement effort.

Table 3-9 Passenger Rail System: 2000, 2010, and 2014

In fiscal year (FY) 2015, Amtrak achieved 71.2 percent on-time performance, down 1.2 percentage points from the previous year. Delays were more likely to occur on track owned by another (host) railroad than on track owned by Amtrak. In FY2014 host railroads were responsible for 63.1 percent of delayed time, and Amtrak was responsible for 24.0 percent.

Figure 3-10 Amtrak On-Time Performance: FY2000–FY2015

Figure 3-11 Amtrak Delay by Responsible Party: FY2015

Updated: Tuesday, June 27, 2017