Featuring developments in Federal highway policies, programs, and research and technology.
|This magazine is an archived publication and may contain dated technical, contact, and link information.|
|Federal Highway Administration > Publications > Public Roads > Vol. 57· No. 1 > Highway, Bridge, and Transit Conditions and Performance|
HIGHWAY, BRIDGE, AND TRANSIT CONDITIONS AND PERFORMANCE: 1993
This article was adapted from and summarizes the 1993 Highway, Bridge and Transit Conditions and Performance (C&P) Report. The C&P Report is a biennial report that provides Congress and other decision makers with an ongoing appraisal of the current condition and performance of the U.S. highway system.
Our nation's productivity and international competitiveness depends on fast and reliable transportation. As we move toward the 21st century, the status of our highways, bridges, and transit is of paramount importance to the vitality of our economy.
Americans travel roads and highways more often than any other mode of transportation. Highways provide the United States with an efficient network for moving people and goods. More than 90 percent of all travelers and 75 percent of the value of all goods and services are conveyed on highways. Growth in productivity in virtually every sector of the nation's economy depends upon adequate transportation.
The C&P Report covers all of the nation's roads and bridges, including all public-use highway and bridge infrastructure and all privately owned toll facilities. Among other subjects, the report provides assessments of system characteristics, trends, highway investment, and investment levels needed to meet future demands.
The information for the report was compiled at the end of 199l by the states and reported to the Federal Highway Administration (FHWA) in summer of 1992. FHWA assembled and analyzed the information and prepared the report. The report was presented to Congress on January 15, 1993.
Prior to this C&P Report, highway/bridge analyses and transit analyses were submitted as separate reports. Because of the complementary nature of these modes of transportation, discussions of highways and transit have been merged. Future reports will build upon this merger, with common data systems and analytical procedures developed to support more rigorous and consistent multimodal analyses of investment options.
This C&P Report includes, for the first time, information on environmental impacts. This reflects the need for surface transportation to meet environmental goals and standards as well as mobility goals and standards.
Future travel forecasts used to estimate investment requirements were developed by the states. All investment estimates are for the period January 1, 1992 through December 31, 2011 and are expressed in 1991 dollars.
Highway and Transit Finance
System Condition and Performance
Highway, Bridge, and Transit Investment Requirements
The National Highway System
The Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991 established a new National Highway System (NHS), consisting of approximately 155,000 miles (249,440 kilometers) of highways. This designation can vary by 15 percent in either direction. Although the states will designate the majority of NHS, the interstate system (45,300 mi or 72,900 km), the Strategic Highway Corridor Network (STRAHNET)(15,000 mi or 24,140 km), major STRAHNET connectors (2,200 mi or 3,540 km), and ISTEA-specified high-priority corridors (4,500 mi or 7,240 km) must be included. NHS highways -- together with all other arterials, rural major collectors, and urban collectors -- will be eligible for federal aid.
Designation of the flexible mileage portion of the NHS will be carried out by the states in cooperation with metropolitan planning organizations and the Department of Transportation; this designation will be submitted to Congress by December 18, 1993. As a prelude to NHS designation, states are reclassifying their roads and streets to establish an updated principal arterial system.
NHS will be the major focus of federal highway investments for the future. The system is expected to carry the bulk of interstate and interregional travel and commerce. The benefits of making these investments are manifold, including: economic growth; national security; intermodal connectivity; system connectivity; safety; the ability to accommodate expanded trade between Canada, Mexico, and the United States; and the ability to sustain a growing tourism industry. Future editions of the C&P Report will include NHS statistics and investment analyses.
System Conditions and Performance
Highway operating characteristics
Continuing growth in travel is causing increasing highway congestion, particularly in urbanized areas. The percentage of peak hour travel on urban interstate highways that occurred under congested or severely congested conditions exceeded 70 percent in 1991, up from 55 percent in 1983. Urban interstate peak hour congestion has grown at an average annual rate of 3 percent since 1983.
The percentage of congested peak hour travel on other freeways and expressways (OF&E) in urban areas increased from 49 percent in 1983 to more than 61 percent in 1991. Urban peak hour congestion on OF&E has grown at an average annual rate of 2.8 percent since 1983.
For urban interstate peak hour travel, more than 55 percent of the congested travel and more than 73 percent of the highly congested travel occurs in the most populous 33 urbanized areas. Approximately 37 percent of the mileage, almost 41 percent of the lane-miles, and more than 53 percent of the travel on non-local urban roads occurs in these 33 areas. However, more than 65 percent of the overall peak hour congested urban travel is in these same areas.
Highway physical characteristics
Table 1 - Estimated highway mileage by pavement condition, functional system, and year
Table 1 compares pavement condition, based on the pavement serviceability rating system, by functional system over time. Between 1983 and 1991, the percentage of pavements in poor condition (those needing improvement now) decreased or maintained a stable condition for all functional systems, rural and urban. The total mileage in the mediocre pavement category (those needing improvements in the near future, generally within the next 5 years) has become relatively stable. For the interstate functional systems, the mileage in the mediocre category is within 2 percent of the value for 1983. For other arterial systems, the percentage of miles in the mediocre category ranges from a low of 7.3 for rural other principal arterials to a high of 14.7 for urban minor arterials.
The pavement rated as fair will likely need improvement in the 5- to 10-year range, and pavement in good condition will not likely need improvement for 10 to 15 years or more.
The mileage in poor condition in most states has declined over the past few years. This represents a real accomplishment in addressing the worst pavement needs. However, because of traffic loads and the environment, pavements will continue to deteriorate, and substantial resurfacing and rehabilitation programs will be required to maintain pavement structure in an acceptable condition.
The percentage of interstate, arterial, and collector bridges classified as structurally deficient increased from 1984 to 1992 -- rising from 13.2 to 14.3 percent. Generally, the higher functional systems have fewer deficient bridges than lower systems. However, the proportion of interstate bridges classified as structurally deficient increased from 5.1 percent in 1984 to 6.8 percent in 1992. This is indicative both of the heavy use of the interstate system and the fact that many of these bridges are nearing the point when rehabilitation will be required.
Most bridges that are structurally deficient are not in danger of collapse, but they are likely to be load-posted so that heavier trucks will be required to take an alternative, longer route. Functionally deficient bridges are those that do not have adequate lane widths, shoulder widths, or vertical clearances to serve traffic demand or whose waterway may allow occasional flooding of the roadway.
The major increase in functionally deficient bridges between 1988 and 1990 -- especially on the interstate system -- resulted from changes in the Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation's Bridges. More specific criteria are used to assess condition and identify deficient bridges. In 1992, 25.3 percent of the interstate bridges were classified as being deficient, compared to 13.1 in 1984.
Fatality rates decreased from 1983 to 1991 for both rural and urban interstate, other arterials, and collectors. Rates ranged from a high of 3.27 per 100 million vehicle miles traveled on rural collectors to a low of 0.67 on urban interstate highways. The fatality rates on the interstate highways -- the system with the lowest accident rate -- decreased from 1.50 in 1983 to 1.25 in 1991 in rural areas and from 1.01 to 0.67 in urban areas. Overall fatality rates are 2.76 for rural highways and 1.32 for urban highways, with an overall average of 1.91.
Although fatality rates decreased to a historic low in 1991, the National Highway Traffic Safety Administration estimated that the total economic cost to the nation of motor vehicle crashes in 1990 was more than $137 billion.
Environmental conditions and performance
The environmental consequences of transportation arise from both construction and use. Indices of performance pose both conceptual and practical challenges. However, an initial set of categories were identified: air quality, water quality, wetlands, energy, noise, land and open space, threatened and endangered species, and community impacts.
Progress is being made in each of these categories. As an example, there was significant progress in reducing the overall levels of the major transportation-related air pollutants over the last decade. According to the Environmental Protection Agency's National Air Quality and Emissions Trends Report in 1990, pollution from carbon monoxide, lead, nitrogen monoxide, and smog were all reduced along the nation's highways from 1981 to 1990 despite a 39-percent increase in vehicle miles traveled. Emissions of carbon monoxide were down by 39 percent, of lead by 85 percent, of nitrogen dioxide by 6 percent, and of smog (hydrocarbons) by 12 percent.
Transit service quality
The perception of quality among customers and potential customers is an important determinant of transit use and is often more important than the cost of the fare. According to National Personal Transportation Survey (NPTS) data, the majority of transit users spend very little time waiting for service. Approximately 47 percent of transit trips involve one or more transfers. In addition, approximately 17 percent of transit trips involve a transfer from a private vehicle -- e.g., park and ride situations. According to NPTS 1990 data, over 40 percent of all transit commuters reported trip times of 10 minutes or less; nearly 87 percent of transit riders arrive at work in less than half an hour.
Bus and paratransit condition
The Federal Transit Administration has established minimum requirements for the period of time an asset must remain in mass transit service before it will be considered eligible for replacement. If it were possible for transit agencies to replace vehicles on this schedule, the average age of each type of vehicle would be one-half the useful life guideline. In reality, however, the average fleet age for all classes of buses and paratransit vehicles is greater than the optimum guideline. As a result, there is a backlog of overage vehicles of each type in need of replacement.
Since 1990, the total fleet size has not changed noticeably, but the average age of the vehicles has increased.
Detailed information is available on the condition of the nation's rail system from the Rail Modernization Study published in 1987. Specific definitions were developed for each of five condition levels--excellent, good, fair, poor, and bad. The key condition level is good, which is defined as "good working order and requiring only nominal or infrequent minor repairs."
Maintenance yards and facilities are in the most need of improvement because only 17 percent of the yards and 28 percent of the facilities were rated as being in good or better condition. Also in need of substantial improvement are elevated rapid rail structures (with only 19 percent in good or better condition), stations (29 percent), and bridges (32 percent). Substations are in the best overall shape; 66 percent is in good or better condition. Commuter rail vehicles are also generally well off; 49 percent of locomotives and 55 percent of unpowered cars are in good or better condition.
Highway, Bridge, and Transit Investment Requirements, 1992-2011
The following provides estimates for total capital investments required by all units of government to achieve specified levels of overall system condition and performance for all highways, bridges, and transit systems for the period 1992-2011. Future travel forecasts used to estimate investment requirements were developed by the states. All investment estimates included in this article are for the period January 1, 1992, through December 31, 2011, and are expressed in 1991 dollars.
Table 2 - Investment scenarios
Investment requirements are presented in table 2 as two scenarios:
Highway and bridge requirements
Estimates of highway and bridge investments requirements were prepared based on sophisticated engineering-based models -- i.e., the Highway Performance Monitoring System (HPMS) Analytical Process and the Bridge Needs and Investment Process (BNIP). The highway and bridge estimating procedures received input from HPMS and National Bridge Inventory (NBI) data bases.
HPMS contains information about physical conditions and use for more than 100,000 non-local highway sections. The HPMS analytical procedure uses this data to simulate highway investment decisions and predict system performance.
NBI contains detailed information about all highway bridges in the country. Using this data, BNIP compares bridge conditions to a prescribed set of minimum bridge condition standards. Deficiencies are noted, and the appropriate improvement is simulated.
HPMS data suggests that highway travel will increase at an average annual rate of about 2.5 percent through 2011. That is slightly below the average 3-percent increases for the past decade.
The "backlog" of highway and bridge deficiencies is the cost of bringing the current system up to minimum standards from its existing conditions and performance status. As of December 31, 1991, the cost of eliminating the backlog of highway deficiencies was estimated at $212 billion for all existing arterials and collectors. This amount is $7 billion more than the comparable figure from 1989; the increase is attributed to deterioration in overall average system performance.
Approximately 42 percent of the highway backlog is pavement cost; the remaining 58 percent is the cost of adding capacity to restore system performance to minimum capacity performance standards. The urban backlog is twice as high as rural backlog, reflecting the capacity deficiencies in the larger urban areas. Backlog deficiencies are fairly evenly distributed among the functional highway systems.
As of December 31, 1991, backlog requirements on the nation's highway bridges were $78 billion. The cost to eliminate the backlog of bridge deficiencies could increase to as much as $112 billion, depending on the number of years required to meet that objective, because of the deferred capital cost of bridge repair. The bridge backlog estimates have decreased significantly from the $91 billion estimate in 1989 because of bridge improvements and revisions in the rating criteria.
The average annual cost through 2011 to repair all backlog deficiencies and keep all highways above the specific minimum condition and performance level standards through 2011 is $59.1 billion. This figure includes an estimated $4.8 billion in annual capital savings from the coordinated traffic management program. The average annual investment required to repair, replace, or widen all backlog and accruing bridge deficiencies on all highway bridges through 2011 is $8.2 billion.
The "cost-to-improve" scenario would result in modest improvements in overall pavement conditions on the higher functional systems. It would increase the average pavement condition to approximately a 3.5 pavement serviceability rating. Consequently, pavements would have, on average, between 8 and 12 years of remaining design life.
System performance on rural and many urban highways would improve under this scenario, supporting at least a minimum level of service during the daily peak period of demand. The scenario would eliminate most highly congested conditions and improve performance on high-volume highways soon to be congested.
Under this scenario, conditions and performance would be superior to today's but substantially below the design and performance standards expected of new, or nearly new, roads. No section of road would be in poor condition.
The magnitude of new capacity required to improve conditions to or above the minimum condition standard for performance is unlikely to occur, given the extensive right-of-way acquisition, social dislocation, air quality, and noise effects that would result from such an effort.
The average annual cost to maintain existing highways through 2011 is estimated at $46.4 billion. This figure includes savings from the coordinated traffic management program.
The average annual cost to maintain overall bridge conditions as they were reported on June 30, 1992, is estimated at $5.2 billion annually through 2011. This investment level would maintain the current total number and distribution of structurally deficient and functionally obsolete bridges.
Under this scenario, the backlog would remain essentially unchanged over the 20-year analysis period. Conditions described earlier would be maintained except in the larger urbanized areas, where further deterioration can be expected because of the capacity constraints imposed in the analysis.
Table 3 - Investment requirements for highways and bridges vs. related capital outlay, 1991-2011 (projecting 2.5% growth rate in vehicle miles traveled (all estimates expressed in billions of 1991 dollars and do not reflect inflation)
(1) See Table 4(2) Data is not available to disaggregate "local" capital outlay by urban and rural categories; therefore, the total 1991 related capital outlay included spending while rural and urban subtotals do not include this spending. Local spending in 1991 was 5.7 billion.
Table 3 summarizes annual investment requirements to meet each scenario target for all urban and rural areas. The table shows total 20-year investment requirements categorized as pavement and capacity improvements, with annualized totals. The annualized total is the 20-year total divided equally. Under the cost-to-improve scenario, two-thirds of total investment would occur in urban areas; capacity improvements would account for about half of total investment.
Table 3 compares highway and bridge capital requirements for 1992-2011 with actual 1991 capital expenditures by state and local governments. The cost-to-improve scenario would require a total annual investment in highway infrastructure of $67.3 billion -- more than twice what was spent in 1991 for corresponding capital improvements. Increasing investment in infrastructure from its 1991 level of $32.1 billion to $67.3 billion would require spending an additional 1.6 cents per mile of travel. The "cost-to-maintain" scenario would require an additional 0.9 cents per mile of travel.
Total spending capital for highways and bridges would need to increase by $35.2 billion annually in 1991 dollars to improve 1991 overall conditions and performance. If funded by motor fuel taxes, this increase in spending would require a fuel tax increase of approximately 27 cents per gallon. To provide the $19.5 billion required to maintain 1991 conditions, a fuel tax increase of 15 cents per gallon would be required.
Table 4 - Annual cost to maintain scenario for 1991 Highway and bridge condition and performance.
Table 4 graphically illustrates the investment stream on a year-to-year basis for the cost-to-maintain scenario. Pavement and bridge requirements are essentially the same annually over the 20-year period, reflecting the continuing nature of system condition maintenance. The "ramping" of total investment requirements to meet existing and anticipated growth in travel is illustrated by the increasing capacity requirements shown. All values are in 1991 dollars and do not reflect any inflation in highway construction costs over the period.
The transit backlog includes the estimated costs of replacing all bus and rail transit equipment that has exceeded its usable design life. Eliminating the backlog would bring the average fleet age down to the minimum useful life standards and bring rail equipment and facilities to good condition. The total transit backlog is estimated at $17.6 billion or $0.9 billion per year if eliminated over the 20-year period.
The cost-to-improve scenario is estimated at $131.8 billion for the period 1992-2011. This cost would require an annual investment of $6.6 billion, assuming that the backlog would be eliminated over 20 years.
At this investment level, transit services will increase over a 20-year period to about 283 million revenue vehicle hours per year, thereby providing capacity to accommodate about 64 billion passenger miles per year, compared with 38 billion passenger miles today. In addition, the backlog of deferred rail and bus modernization and rehabilitation needs would be eliminated, restoring those systems to good condition and bringing them up to modern transit standards.
The cost-to-maintain scenario is estimated at $77.8 billion through 2011 or $3.9 billion per year. This figure is the investment needed to maintain current levels of service. At this level of investment, facilities and equipment would be maintained in their current state of repair. The estimate also includes the additional investment level needed to extend coverage and improve service levels to maintain current trends in growth in transit patronage. It includes low capital demand management as well as new starts at historical levels.
At this level of investment, the amount of transit service provided would increase at a rate of 0.8 percent per year, consistent with the increase in transit patronage over the last 10 years. In 20 years, this would result in an increase in capacity of 17 percent, raising the total amount of transit service from the present 169 million revenue vehicle hours to about 198 million revenue vehicle hours. This increase in capacity could accommodate an increase in passenger miles from the present 38 billion to about 44 billion.
Under this scenario, transit vehicles would be replaced at about the current rate, which is slightly slower than optimal. Existing rail systems would be maintained in the current conditions with no major improvements. Investments on existing rail systems would occur at the rate needed to ensure that equipment and facilities are replaced as they wear out. New rail systems would be constructed at a rate sufficient to accommodate the present rate of transit patronage growth. Table 5 summarizes 1992-2011 transit investment requirements.
Table 5 - Summary of annualized transit investment requirements, 1992-2011
All estimates are expressed in billions of 1991 dollars and do not reflect inflation)
*Americans With Disabilities Act.
Page Owner: Office of Corporate Research, Technology, and Innovation Management
Scheduled Update: Archive - No Update
Technical Issues: TFHRC.WebMaster@dot.gov