Highway Infrastructure
Physical Conditions of the Interstate Highway System Have Improved, but Congestion and Other Pressure Continue Gao ID: GAO-02-1128T September 26, 2002The Interstate Highway System has become central to transportation in the United States. It extends over 46,000 miles in length and includes 210,000 lane miles. The System carries over 24 percent of all vehicle miles traveling in the nation, while making up just 2.5 percent of total lane miles. Funding for the Interstate Highway System has been a major part of total highway funding since 1954 when interstate highway construction began. From 1954 through 2001, federal funding for interstates total over $370 billion (2001 dollars)--46 percent of all apportionments administered by the Federal Highway Administration (FHWA) during this period. Congestion on interstate highways has increased over the last decade; the physical condition of interstate highways has generally improved, and the level of safety has remained steady. Some of the factors states expect to negatively affect the conditions of their interstate highways in the future include increases in passenger and freight traffic, aging infrastructure, and financial constraints. FHWA's estimates of future annual interstate highway investment requirements vary depending on the goal transportation officials have for performance of the interstate system. In 2000, GAO evaluated the model that FHWA uses to forecast interstate and other highways' pavement preservation and highway capacity requirements and found that this model can be useful as a general guide for assessing relative investment requirements over time. However, the model has some limitations; it does not fully account for uncertainties associated with its method, data, and assumptions.
GAO-02-1128T, Highway Infrastructure: Physical Conditions of the Interstate Highway System Have Improved, but Congestion and Other Pressure Continue
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Testimony:
Before the Subcommittee on Highways and Transit, Committee on
Transportation and Infrastructure, House of Representatives:
United States General Accounting Office:
GAO:
For Release on Delivery Expected at 10:00 a.m. EDT Thursday, September
26, 2002:
Highway Infrastructure:
Physical Conditions of the Interstate Highway System Have Improved, but
Congestion and Other Pressures Continue:
Statement of Katherine Siggerud
Acting Director, Physical Infrastructure Issues:
GAO-02-1128T:
Mr. Chairman and Members of the Committee:
I appreciate the opportunity to testify on the conditions of the
Interstate Highway System and estimates of its future needs. My
testimony today is based primarily on our May 2002 report.[Footnote 1]
As you know, the Interstate Highway System, begun nearly half a century
ago, has become central to transportation in the United States. The
Interstate System extends over 46,000 miles in length and includes
about 210,000 lane miles.[Footnote 2] The system carries over 24
percent of all vehicle miles traveled in the nation, while making up
just 2.5 percent of total lane miles. Funding for the Interstate System
has been a major part of total highway funding since 1954, when
Interstate construction began. From 1954 through 2001, federal funding
for Interstates totaled over $370 billion (2001 dollars)--about 46
percent of all apportionments administered by the Federal Highway
Administration (FHWA) during this period.
Given the significance of the Interstate Highway System, our statement
will address the following: (1) How have the operations, physical
conditions, and safety of the Interstate Highway System changed over
time and how do they compare to other classes of roads? (2) What
factors are likely to affect the condition of the Interstate highways
in the future? (3) What are FHWA‘s estimates of the future cost of
maintaining Interstate conditions? and (4) How useful are the estimates
for highway investment requirements in the Department of
Transportation‘s (DOT) Conditions and Performance Report? To obtain
information on Interstate conditions, we conducted a nationwide mail
survey in 2001 of the 50 states, the District of Columbia, and Puerto
Rico[Footnote 3] and visited five states to obtain more detailed
information.[Footnote 4] We also reviewed Federal Highway
Administration data. Finally, to provide information on FHWA‘s estimate
of future investment requirements, I will discuss information on FHWA‘s
highway model based on our June 2000 report to this committee and the
Senate Committee on Environment and Public Works[Footnote 5] and a
review of language for DOT‘s Draft Conditions and Performance Report.
In summary:
* Congestion on Interstate highways has increased over the last decade,
while the physical condition of the Interstate has generally improved,
and the level of safety has remained steady. For example, a measure of
traffic density--daily vehicle lane miles traveled--increased over 31
percent from 1990 through 2000. In addition, a measure of how
congestion affects drivers--the travel time index--increased by about
12 percent during the past decade. At the same time, FHWA statistics
show that Interstate pavement condition improved over the past 10
years-8.6 percent of the pavement was in poor condition in 1990,
compared with 3.4 percent in 2000. Although overall physical conditions
have improved, conditions of specific sections of Interstate can vary.
For example, FHWA statistics show 10 states have at least one-third of
their pavement in mediocre or poor condition as compared with 18.3
percent of highways in that condition nationwide. Finally, FHWA data
show that while Interstate highways are generally more congested than
other classes of roads, they are in better physical condition and are
safer than other classes of roads.
* Some of the factors states expect to negatively affect the conditions
of their Interstate highways in the future include increases in
passenger and freight traffic, aging infrastructure, and financial
constraints. States responding to our survey reported that they expect
the overall traffic (passenger and freight) on their Interstate system
to increase over the next decade. The states expect this increase in
traffic to most negatively affect the condition of their pavement and
congestion. For example, 51 states responding to our survey indicated
that traffic volume would negatively affect congestion in their urban
areas. Concerns about increased congestion arise because population,
licensed drivers, and freight all increased over 12 percent over the
past decade, while Interstate lane miles increased only 6 percent. In
addition, the age of the infrastructure is a factor impacting the
future conditions of pavement and bridges. For example, half of the
Interstate bridges are currently over 33 years old.[Footnote 6]
Finally, some states may face an increasing number of large-dollar
projects (such as bridge repairs), state budget shortfalls, and
uncertain funding for federal highway programs, all which may affect
the amount of funds available for Interstate projects.
* FHWA‘s estimates of future annual Interstate highway investment
requirements vary depending on the goal transportation officials have
for performance of the Interstate system. For example, based on
modeling used in DOT‘s 1999 Conditions and Performance Report, the
estimated annual cost to maintain current pavement conditions is $16.4
billion (2000 dollars). The estimated annual cost to achieve another
potential goal, maintaining user costs (including costs to drivers such
as their travel time and costs of operating a vehicle) is $17.3 billion
(2000 dollars). Recent spending on capital investment on Interstates
falls below these estimates at $14.1 billion for 2000. In addition,
FHWA has revised its model used to estimate investment requirements for
use in its next Conditions and Performance Report. According to an FHWA
official, these revisions might be expected to increase the estimated
investment requirements to maintain user costs.
* In 2000, we evaluated the model that FHWA uses to forecast Interstate
and other highways‘ pavement preservation and highway capacity
requirements and found that this model can be useful as a general guide
for assessing relative investment requirements over time. However, the
model has some limitations; namely, it does not fully account for
uncertainties associated with its methods, data, and assumptions. We
recommended that FHWA (1) clarify that there are uncertainties
associated with the estimates and clearly identify sensitivity analyses
that illustrate these uncertainties and (2) explain in its Conditions
and Performance Reports that one portion of the highway investment
requirements is based on benefit-cost analysis and that the other
portion was calculated using less reliable methods. The agency agreed
with these recommendations. FHWA has also taken additional steps to
improve the quality of its highway investment needs forecasts.
Background:
The Federal-Aid Highway Act of 1944 established the Interstate Highway
System but did not provide specific funding for construction. In the
Federal-Aid Highway Act of 1956, Congress declared that the completion
of a ’National System of Interstate and Defense Highways“ was essential
to the national interest. The act stated that the system was to serve
the principal metropolitan areas, cities, and industrial centers;
support the national defense; and connect with routes of continental
importance in Canada and Mexico.
The Federal-Aid Highway Act of 1956 also established a new method for
apportioning funds among states and set the federal government‘s cost
share for Interstate construction projects at 90 percent.[Footnote 7]
At the same time, the Highway Revenue Act of 1956 introduced a
dedicated source for federal highway expenditures, providing that
revenue from certain federal motor fuel and other motor vehicle related
taxes be credited to the Highway Trust Fund. From 1954 through 2001,
the Federal government invested over $370 billion (2001 dollars) on
Interstates through apportionments to the states, more than on any
other class of road. After 1991, Federal apportionments for Interstate
highways declined from their earlier construction period levels, but
remained substantial. From 1992 through 2001, federal apportionments
for Interstate highways were 17.5 percent of FHWA‘s total highway
apportionments, compared to 18.0 percent for the National Highway
System[Footnote 8] and 21.8 percent for the Surface Transportation
Program.[Footnote 9] FHWA, within DOT, administers a variety of federal
highway programs supported by the trust fund--collectively referred to
as the Federal-Aid Highway Program.
The Interstate System, as of 2000, extends over 46,000 miles in length
and 209,655 lane miles. In 2000, the system accounted for 2.5 percent
of the nation‘s total estimated lane miles, while it carried over 24
percent of total vehicle miles traveled. From 1990 through 2000,
Interstate mileage grew by about 3.1 percent, or 1,405 miles in length,
or 11,491 lane miles during the decade. Additions to the Interstate
system can be made by adding lanes to existing roadways, state requests
for and FHWA approval of new Interstate mileage, and Congressional
designations of new Interstates.
Currently, both the federal government and states fund the construction
and maintenance activities on the Interstate Highway System. Each year,
the federal government provides billions of dollars to the states for
the construction and repair of highways through various highway
programs. Under one such program--the Interstate Maintenance Program
(IM)--federal funds support projects for resurfacing, restoring,
rehabilitating, or reconstructing portions of the Interstate System.
Under certain circumstances, states may transfer funds among various
highway programs. For example, subject to certain limitations, states
may transfer IM funds to other programs and use them on other classes
of roads (with a federal cost share of 80 percent). Similarly, states
may also transfer funds from other funding categories to their IM
program and use them for qualifying projects on Interstate highways.
Other programs that can be used to fund Interstate projects include the
Interstate Maintenance Discretionary Program, the Bridge Discretionary
Program, and the Highway Bridge Replacement and Rehabilitation Program.
Congestion on Interstates Has Grown, but Physical Interstate Conditions
Have Improved:
Congestion on the Interstates has grown and Interstates are generally
more congested than other freeways and principal arterials. However,
the Interstate‘s physical conditions (pavement and bridges) are in good
overall shape, and Interstate highways are also in better physical
condition and are safer than other classes of roads. Finally, although
Interstate conditions are relatively good nationwide, the conditions
are not even across the country.
Interstate Highways Have Become More Congested and Generally More
Congested than Similar Roads:
Whether measured in terms of traffic density or travel time, congestion
has increased over the past decade. We looked at FHWA‘s ’daily vehicle
miles traveled per lane mile“[Footnote 10] to measure traffic
density.[Footnote 11] The overall density of traffic on Interstates has
increased--31.7 percent over the past decade, an average annual
increase of about 3 percent. Also, traffic density is higher on urban
highways than on rural ones.[Footnote 12] Finally, the traffic density
on urban Interstate highways is higher than on other classes of urban
roads. (See fig. 1.):
Figure 1: U.S. Average Urban Daily Vehicle Miles Traveled by Lane Mile,
by Class of Road, 1990 through 2000:
[See PDF for image]
Source: FHWA‘s Highway Statistics.
[End of figure]
Although the density of traffic on urban Interstate highways is higher
than on rural Interstates, traffic on rural Interstate highways is
increasing at a faster rate than on any other class of road. From 1990
through 2000, the daily vehicle lane miles traveled on rural
Interstates increased at an average annual rate of 3.3 percent. By
comparison, the daily vehicle lane miles traveled increased at an
annual rate of 1.9 percent on rural principal arterials[Footnote 13]
and at a rate of 1.7 percent on urban Interstates.
Another measure of congestion--the travel time index--indicates how
much more time it takes to travel during a peak period than at other
times of day.[Footnote 14] During the past decade, the travel time
index on Interstates increased by about 12 percent. This statistic
provides information about drivers‘ experiences as well as the level of
congestion on the road because it accounts for delays due both to the
traffic demand on the road and to roadway incidents, like accidents.
For example, a travel time index of 1.63, the value on urban
Interstates in 2000, means that a trip that takes 30 minutes in an off-
peak (noncongested) period would, on average, take 63 percent longer,
or almost 19 extra minutes in the peak period--in other words, the trip
would take an average of about 49 minutes when the road is congested,
rather than 30 minutes when it is not congested.[Footnote 15] This
statistic also shows that congestion levels are higher on the urban
Interstate System than on other classes of roads, specifically urban
freeways and expressways and urban principal arterials. (See fig. 2.):
Figure 2: Percent Increase in Urban Travel Time During the Peak Period
by Class of Road, 1990 through 2000:
[See PDF for image]
Note: Interstates show a 3-percentage point decrease in travel time
from 1990 to 1992. According to Texas Transportation Institute
officials, this is partially due to the urban boundary redefinitions
that usually get included in the first and second years after a census.
Source: Texas Transportation Institute data obtained through FHWA.
[End of figure]
Interstate Pavement Conditions Have Improved and Are Generally Better
Than On Other Roads:
FHWA statistics show that Interstate pavement conditions have generally
improved since 1990. According to these statistics, 8.6 percent of
Interstate pavement, or 3,897 miles, was in poor condition in 1990. By
2000, the share of poor Interstate miles[Footnote 16] had dropped to
3.4 percent, or 1,560 miles.[Footnote 17] (See fig. 3):
Figure 3: Percentage of Poor Interstate Pavement--Urban versus Rural,
1990-2000:
[See PDF for image]
Source: FHWA‘s Highway Statistics
[End of figure]
However, the condition of Interstate pavement varies across the
country. State pavement data submitted to FHWA for 2000 showed that for
the nation as a whole, 63.5 percent of pavement was in good or very
good condition, 18.2 percent was in fair condition, and 18.3 percent
was in mediocre or poor condition. However, 10 states have at least
one-third of their pavement in mediocre or poor condition. In addition,
of 51 survey responses, 39 states reported that their Interstate
pavement is currently in good or excellent condition; 9 said that their
pavement is in fair condition; 3 reported poor Interstate pavement
conditions; and none reported very poor conditions. [Footnote 18]
Compared with ’other major arterials,“ Interstates are in better
condition in both rural and urban areas.[Footnote 19] See figure 4
below showing the difference in percent of poor pavement.“:
Figure 4: Percentage of Roads with Poor Pavement--Interstates Versus
Other Major Arterials (2000):
[See PDF for image]
Source: FHWA‘s Highway Statistics.
[End of figure]
Interstate Bridge Conditions Have Improved and Are Generally in Better
Condition than Those on Other Roads:
The number of deficient Interstate bridges has declined over the last 8
years. Specifically, the number of structurally deficient bridges
declined by over 22 percent from 1992 through 2000. [Footnote 20] In
addition, the number of functionally obsolete bridges declined by more
than 10 percent over the same period. [Footnote 21] As of April 2001, 5
percent of the nation‘s Interstate bridges were structurally deficient
and another 16 percent were functionally obsolete. State officials
responding to our survey generally reported that their bridges are
currently in good condition. Of the states responding to our survey, 31
said that the overall condition of their Interstate bridges is good or
excellent; another 19 said it is fair. However, although the number of
bridges with deficiencies is decreasing, the conditions vary by state.
For example, FHWA data shows that in 2001, states varied from having no
structurally deficient Interstate bridges to almost 22 percent
deficient.
In addition, Interstate bridges are generally in better condition than
those on other classes of roads. According to 1998 FWHA data, about 27
percent of urban Interstate bridges were deficient,[Footnote 22]
compared with a range from over 27 percent for ’urban other freeways
and expressways“ to over 38 percent for both ’urban minor arterials“
and ’urban collectors.“ In addition, 16 percent of rural Interstate
bridges were deficient, compared with a range from 17 percent for
’rural other principal arterials“ to over 36 percent for ’rural local
roads.“:
Interstate Safety Has Been Mainly Stable and Better Than on Other
Roads:
The fatality rate on the Interstate System has been relatively steady
after falling early in the 1990s. The number of fatalities on
Interstate highways has increased over the past decade, but so has the
level of traffic, as indicated by the number of vehicle miles traveled
(VMT).[Footnote 23]
Relatively speaking, Interstate highways are the safest of all
highways. We recently reported[Footnote 24] that among urban road
types, ’other principal arterial“ roads had the highest 1999 fatality
rate[Footnote 25] at 1.27--compared with 0.61, the lowest fatality
rate, on urban Interstate roads. Similarly, we reported that among the
rural road types, ’rural local roads“ had the highest 1999 fatality
rate at 3.79--compared with 1.24, the lowest fatality rate, on rural
Interstate roads. In addition, 45 states we surveyed said that the
current level of safety on their Interstates was good or excellent.
Future Condition of Interstates Could be Affected by Increases in
Traffic, the Age of the Interstates, and Financial Uncertainty:
State department of transportation officials expect the performance of
their Interstates to fall behind over the next 10 years, especially in
terms of congestion. (See fig. 5). These officials pointed to certain
factors, including increasing passenger and truck traffic, age of their
infrastructure, and financial constraints that could negatively affect
the condition of their Interstates, not only in terms of congestion,
but also in terms of pavement conditions and safety.
Figure 5: Number of States Expecting Performance on Their Interstate
Systems to Fall Behind in the Next Decade:
[See PDF for image]
Source: GAO survey.
[End of figure]
Increasing Traffic Expected to Have the Greatest Negative Effect on
Interstate Conditions:
Passenger traffic is expected to increase and states expect the total
traffic volume to negatively affect many Interstate conditions,
especially urban congestion. Estimates that FHWA uses show that
passenger traffic will increase by 17 percent from the end of 2001
through 2010--an increase from 2.7 trillion vehicle miles traveled to
3.1 trillion. Although 39 states reported that their Interstate system
played a great or very great role in providing efficient travel within
urban areas, they are still concerned that increases in traffic volume
will negatively affect urban congestion. Specifically, 51 states said
that traffic volume would negatively affect congestion in their urban
areas.
In addition, states and FHWA data indicate that truck traffic is
expected to increase in the future. Specifically, all of the states
expect truck traffic to increase over the next 10 years. In addition,
estimates used by FHWA show freight movement by truck increasing by 28
percent from the end of 2001 through the end of 2010. Finally, an
alliance of primarily southern and southeastern states released a 2001
study that estimates a 6.9 percent annual increase in Latin American
truck traffic in the United States (resulting in almost a doubling over
the 10-year period). Ninety-six percent of this truck traffic will be
on Interstates. Forty-nine of the states said that they expect this
increase in truck traffic to negatively affect the condition of their
pavement. In addition, 49 states expect truck traffic to increase urban
congestion.
States‘ concerns about increases in passenger and freight traffic and
their relation to Interstate congestion are illustrated below. As
figure 6 shows, increases in overall population and the number of
licensed drivers are factors that could each cause more cars to be on
the road during peak hours. These, along with other factors, resulted
in a 39 percent increase in the number of miles traveled in the United
States in the past decade. Freight movement by truck also increased by
40 percent over the first 8 years of the decade. However, Interstate
capacity in terms of lane miles increased by only 6 percent over the
past decade.
Figure 6: Percent Change of Variables Related to Congestion, 1990
through 2000:
[See PDF for image]
[A] Freight data were available only for 1990 to 1998.
Source: Prepared by GAO using data from FHWA Highway Statistics, U.S.
Census Bureau Census 2000 Brief, and Bureau of Transportation
Statistics National Transportation Statistics 2000.
[End of figure]
Age of Infrastructure also Negatively Affecting Physical Condition of
the Interstate System:
Another factor negatively affecting the condition of Interstate
pavement and bridges is the age of the infrastructure. For example,
half of the Interstate bridges are currently over 33 years old. (See
fig. 7.) Officials from one state we visited explained that many of
their state‘s Interstate bridges were built about 40 years ago and are
reaching the end of their estimated 50-year design life.[Footnote 26]
In addition, officials in 45 states believe age may jeopardize their
bridge conditions: officials in 38 states expect age to negatively
affect their pavement conditions 10 years from now.
Figure 7: Year Interstate Bridges Were Built:
[See PDF for image]
Note: When the Interstate System was built, it incorporated some
portions of already existing roadways; therefore, some Interstate
bridges were built before the official establishment of the program.
Source: FHWA data.
[End of figure]
Cost of Large-Dollar Projects and Other Economic Conditions Could
Negatively Affect States‘ Highway Programs:
Transportation officials are concerned that some states may face an
increasing number of large-dollar projects, such as work on bridges or
interchanges, which may constrain spending for those states‘ other
projects for a number of years. For example, Missouri is looking at
reconstructing the 200-mile I-70 corridor at a cost of $2.5 billion to
$3.0 billion. In addition, the Woodrow Wilson Bridge, which moves
north-south traffic on I-95 around Washington, D.C., is expected to
cost over $2 billion and is being funded by two states and FHWA.
According to a Maryland official, over the 6-year project, funding for
the bridge accounts for 45 percent of expenditures on major projects in
the state‘s capital budget.
In May we reported that 40 states were facing budget shortfalls for
2002. Currently, the National Association of State Budget Officers
reports that 45 states either currently face a budget shortfall or had
one at some point during fiscal year 2002. Furthermore, the amount of
funds available for federal highway programs in fiscal year 2003 is
uncertain,[Footnote 27] depending on congressional action. Potential
reductions in state funds and the uncertainty of federal funding levels
could reduce the funds available for maintaining the Interstates.
Estimates of Costs to Maintain Interstates Vary:
FHWA‘s estimate of future annual Interstate highway investment
requirements to maintain current conditions is $16.4 billion and its
estimate to maintain user costs is $17.3 billion based on modeling used
in the 1999 Conditions and Performance Report (2000 dollars).[Footnote
28] The maintain current conditions scenario estimates the investment
requirements needed to maintain average pavement condition. The
maintain user costs scenario focuses on benefits to highway users such
as reductions in travel time costs, crashes, and vehicle operating
costs. Under the maintain user cost scenario, FHWA would expect the
effect on individual user costs to vary. For example, the 1999
Conditions and Performance Report explains that if about $60 billion
(2000 dollars) was spent on all highways, travel times should rise by
1.5 percent while vehicle operating costs would fall by 1.2 percent.
Spending on Interstates in 2000 fell below these estimates at $14.1
billion. This amount reflects investment by all levels of government--
federal, state, and local. According to an FHWA official, however,
enhancements of the model used to estimate investment requirements
might be expected to increase the estimate to maintain user costs in
the next Conditions and Performance Report. For example, the model has
been modified to consider the effects of delay due to incidents such as
crashes, making potential benefits from capacity improvements more cost
effective. This may raise the estimated cost to maintain current user
costs and current expenditures may be farther behind cost to maintain
current user costs.
FHWA‘s Model for Estimating Highway Needs Is Generally Reasonable,
Despite Limitations:
In 2000, we reported on FHWA‘s approach for estimating future
Interstate and other highway investment requirements and evaluated the
model that FHWA used to forecast investment requirements for pavement
preservation and capacity. We found that this model can be useful as a
general guide for assessing the relative investment requirements over
time. Furthermore, we found no other transportation model that could
assess the benefits and costs of alternative improvement options at the
national level. However, we found that the model does not fully account
for uncertainties associated with its methods, data, and assumptions.
To help users understand the potential impact of these uncertainties,
FHWA provided sensitivity analyses to demonstrate how much model
estimates could change if the value of key inputs or assumptions were
changed.
We did not evaluate the tools that FHWA used to forecast Interstate
needs for bridges, new construction, or transportation enhancements
like safety, traffic operations, and environmental improvements. These
methods were not based on benefit-cost analysis, and FHWA viewed them
as less reliable than the pavement preservation and highway capacity
model. Forecasts of highway costs not estimated by FHWA‘s pavement
preservation and capacity model accounted for less than half of FHWA‘s
20-year Interstate needs forecasts in its 1999 Conditions and
Performance Report.
We recommended that FHWA clarify, when presenting estimates from its
pavement preservation and highway capacity model, that there are
uncertainties associated with the estimates and refer readers to the
sensitivity analyses that illustrate these uncertainties. We also
recommended that FHWA explain in its Conditions and Performance Reports
that one portion of each highway investment requirement is from the
pavement preservation and highway capacity model and is based on
benefit-cost analyses and that the other portion was calculated using
less reliable methods, as well as the percentage that each of these
portions constitutes of the overall estimate. The agency agreed with
these recommendations and, provided draft language they plan to include
in the 2002 Conditions and Performance Report, which addresses our
recommendations.
In addition to the revisions to the highway preservation and capacity
model discussed earlier, FHWA took other steps to improve the quality
of its highway investment needs forecasts. For example:
* FHWA is using a new model as the primary tool for estimating future
bridge preservation needs. According to FHWA, compared to its previous
model, this model has three advantages. It filters out improvements
that are not cost-beneficial; it is more accurate in determining the
value of routine bridge repair and rehabilitation; and, its estimates
more closely reflect state and local bridge management strategies.
* FHWA is directly modeling new highway and bridge construction needs
by using the highway preservation and capacity model. FHWA had
previously estimated new construction costs based on a fixed percentage
of existing highway needs forecast by the highway and bridge models.
Concluding Observations:
Although Interstate highways as a whole are in good physical condition
and are relatively safe when compared to other classes of roads,
Interstates will likely move an increasing amount of people and freight
in urban areas and throughout the country. The Interstate highways will
face increasing traffic and congestion, given the comparatively small
growth in lane miles. Therefore, federal, state, and local government
officials will face many challenges as they work to assure that the
Interstate component of the nation‘s transportation system continues to
provide efficient travel and remain in relatively good condition, given
uncertain economic conditions. In particular, these challenges include:
* finding effective methods of easing traffic congestion, particularly
in urban areas;
* providing for efficient freight movement given increases in both
passenger and freight traffic; and
* responding to the effect of traffic on roads and bridges given the
continued aging of these structures and the potential shortfall of
funds to meet needs.
Mr. Chairman, this concludes my prepared remarks. I would be happy to
answer any questions you or other Members of the Committee may have at
this time.
Contact and Acknowledgements:
For questions regarding this testimony please contact Katherine
Siggerud on (202) 512-2834 or at siggerudk@gao.gov. Individuals making
key contributions to this testimony included Richard Calhoon, Catherine
Colwell, and Josephine Perez.
FOOTNOTES
[1] U.S. General Accounting Office, Highway Infrastructure: Interstate
Physical Conditions Have Improved, but Congestion and Other Pressures
Continue, GAO-02-571 (Washington, D.C.: May 2002).
[2] Lane miles are the number of lanes in a mile of road. For example,
a four-lane road, 2 miles long would equal 8 lane miles.
[3] I will refer to this group as states throughout my statement.
[4] We selected Arizona, Florida, Missouri, North Dakota, and
Pennsylvania to obtain perspectives from a variety of regions with
various types of weather, population differences, and other factors
that affect Interstate planning.
[5] U.S. General Accounting Office, Highway Infrastructure: FHWA‘s
Model for Estimating Highway Needs Is Generally Reasonable, Despite
Limitations, GAO-00-133 (Washington, D.C.: June 2000).
[6] Officials from one state we visited explained that many of their
bridges are reaching the end of their estimated 50-year design life.
However, maintenance can extend the life of the bridges.
[7] The federal share of Interstate project costs was set at 90
percent; but in states with large areas of federal public land, the
federal share is increased proportionately up to a 95-percent limit.
[8] The National Highway System is a system of interconnected principal
arterial routes which serve major population centers, international
border crossings, ports, and other intermodal transportation facilities
and major travel destinations; meets national defense requirements; and
serves interstate and interregional travel. It contains all Interstate
routes.
[9] Surface Transportation Program includes funding for most types of
highway projects such as construction and resurfacing on most classes
of roads, except for roads classified as local or rural minor
collectors.
[10] Daily vehicle miles of travel per lane mile is a basic measure of
how much travel is being accommodated on our highway systems since it
is a count-based metric. Daily vehicle miles traveled is the average
daily traffic on a section of roadway multiplied by the length (in
miles) of that section of roadway.
[11] FHWA used this indicator in its Fiscal Year 1999 Federal Highway
Administration Performance Plan and the biennial Conditions and
Performance Report.
[12] The five classes of roads that we compared were (1) urban
Interstates, (2) urban freeways and expressways, (3) urban other
principal arterial streets, (4) rural Interstates, and (5) rural other
principal arterial streets.
[13] Arterials are roads that allow the highest traffic speeds and
often have multiple lanes and a degree of access control.
[14] The Texas Transportation Institute has developed measures that
address a central concern of urban drivers--how travel time is affected
by congestion.
[15] The Texas Transportation Institute data also show that delay from
incidents is greater than recurring delay from traffic. Specifically,
their Mobility Report 2001 states that delay from incidents accounts
for 54 percent of total delay.
[16] Since 1995, FHWA‘s Highway Statistics reports have portrayed
pavement conditions in International Roughness Index unit categories
without quality descriptions. Thus, FHWA reported that 1,560 miles of
Interstate pavement in 2000 had a roughness index over 170 inches per
mile. We use the term ’poor“ to describe this pavement, following the
descriptive approach used in DOT‘s Condition and Performance Reports.
[17] The improvement pattern was not continuous partly because FHWA
required the states to adopt a new condition measure, International
Roughness Index.
[18] Our survey asked states to rate their pavement quality on a scale
of very poor to excellent. This scale was not necessarily designed to
match FHWA‘s pavement condition categories, which are based on
International Roughness Index data.
[19] Unlike our analysis in fig. 4, FHWA generally uses lower condition
standards to rate classes of roads that are not Interstates. FHWA‘s
criteria for the best road categories (very good and good) are the same
no matter which class of roads is being considered. But the ranges of
fair, mediocre, and poor roads are more stringent for Interstates than
for other roads. For example, non-Interstate highways are considered to
be in poor condition once their roughness index exceeds 220 inches per
mile.
[20] Structurally deficient bridges can have restrictions on the weight
of vehicles using them or may need to be closed and repaired before
they can be used again.
[21] Functionally obsolete bridges are not up to design standards and
generally face less serious problems than structurally deficient
bridges--for example, shoulders that are not as wide as the roadway
leading to the bridge.
[22] Includes both structurally deficient and functionally obsolete
bridges.
[23] VMT is a measure of the level of travel on roads: 1 VMT is equal
to one vehicle traveling 1 mile on a road.
[24] U.S. General Accounting Office, Federal Highway Funding by Program
and Type of Roadway, With Related Safety Data, GAO-01-836R (Washington,
D.C.: July 16, 2001).
[25] The fatality rate here is measured as the number of deaths per 100
million VMTs. DOT uses fatality rate rather than crash rate because the
data are more reliable.
[26] Pavement has a shorter life expectancy than bridges, usually
ranging from 15 to 40 years depending on such factors as the type of
material used. Routine and preventive maintenance can extend the life
of the bridges.
[27] U.S. General Accounting Office, Highway Financing: Factors
Affecting Highway Funding Fluctuations and Revenue Trends, GAO-02-527T
(Washington, D.C.: Mar. 20, 2002).
[28] These estimates are for 1998 through 2017. The cost of these
scenarios has been converted to 2000 dollars using FHWA‘s Composite Bid
Price Index.
