Transportation Infrastructure: Better Data Needed to Rate the Nation's
Highway Conditions (Letter Report, 09/27/1999, GAO/RCED-99-264).
Pursuant to a legislative requirement, GAO provided information on
federal and state efforts to assess the conditions of the nation's
highways, focusing on: (1) the uses the Federal Highway Administration
(FHwA), the states, and others make of the International Roughness index
to assess highway conditions; (2) the consistency and accuracy of
state-reported data on highway roughness; and (3) FHwA's efforts to
improve the data across states.
GAO noted that: (1) the International Roughness Index is used widely for
federal and state purposes, as well as for independent analyses; (2) at
the national level, where the index is the only available statistic on
pavement conditions, FHwA uses it to assess changes in the overall
condition of the nation's highways and to forecast future highway
investment needs; (3) actual expenditures for highways by all levels of
government in 1995 were about $29.2 billion, or about $41 billion less
than FHwA had projected as needed to repair the deficiencies; (4) in
addition, FHwA uses the index to measure progress toward a goal for ride
quality in its strategic plan and publishes data from the index for use
by the public; (5) at the state level, where other types of data on
pavement conditions are available, reliance on the index varies; (6)
while some states rely on it to make highway maintenance decisions,
others do not consider it an important decision-making tool; (7) the
states that rely on the index use it to project highway investment needs
and report on pavement performance at the state or district levels; (8)
in addition, some states use the index to set standards for construction
projects; (9) independent analysts have used the data to compare
pavement conditions across states and to develop scorecards of state
performance; (10) critics contend that state comparisons based on the
index are flawed because the pavement roughness data reported to FHwA by
the states are not consistent or accurate; (11) these problems with
consistency and accuracy have occurred for two reasons: (a) the states
use different methods to gather data and compute results; the states
differ in the devices they use to measure the pavement, the part of the
road they measure, and their choice of an appropriate mathematical
simulation; and (b) the type of surface asphalt or concrete influences
the results; concrete roads may produce rougher readings than asphalt
roads, even if the concrete road is of very high quality; (12) features
such as joints between sections can contribute to the roughness of
concrete highways; (13) while FHwA has tried to improve the data, these
efforts have not been completely successful; and (14) the agency
developed detailed guidelines for collecting the data and asked the
states to apply these guidelines before reporting the data.
--------------------------- Indexing Terms -----------------------------
REPORTNUM: RCED-99-264
TITLE: Transportation Infrastructure: Better Data Needed to Rate
the Nation's Highway Conditions
DATE: 09/27/1999
SUBJECT: Highway research
Federal aid for highways
Highway planning
Data integrity
Public roads or highways
Statistical data
Federal/state relations
Evaluation methods
Comparative analysis
Performance measures
IDENTIFIER: FHwA Highway Performance Monitoring System
National Highway System
DOT Highway Economic Requirements System
International Roughness Index
******************************************************************
** This file contains an ASCII representation of the text of a **
** GAO report. This text was extracted from a PDF file. **
** Delineations within the text indicating chapter titles, **
** headings, and bullets have not been preserved, and in some **
** cases heading text has been incorrectly merged into **
** body text in the adjacent column. Graphic images have **
** not been reproduced, but figure captions are included. **
** Tables are included, but column deliniations have not been **
** preserved. **
** **
** Please see the PDF (Portable Document Format) file, when **
** available, for a complete electronic file of the printed **
** document's contents. **
** **
** A printed copy of this report may be obtained from the GAO **
** Document Distribution Center. For further details, please **
** send an e-mail message to: **
** **
** **
** **
** with the message 'info' in the body. **
******************************************************************
United States General Accounting Office GAO Report
to Congressional Committees September 1999 TRANSPORTATION
INFRASTRUCTURE Better Data Needed to Rate the Nation's Highway
Conditions GAO/RCED-99-264 GAO United States
General Accounting Office Washington, D.C. 20548 Resources,
Community, and Economic Development Division B-281731 September
27, 1999 The Honorable John H. Chafee Chairman The Honorable Max
S. Baucus Ranking Minority Member Committee on Environment and
Public Works United States Senate The Honorable Bud Shuster
Chairman The Honorable James L. Oberstar Ranking Democratic Member
Committee on Transportation and Infrastructure House of
Representatives The International Roughness Index is used
throughout the world to measure whether travelers experience a
rough or a smooth ride while driving on a highway. The index is a
quantitative measure of a vehicle's up-and-down movement while
traveling. In the United States, the states use specially equipped
vehicles to collect data for the index and report the data to the
Department of Transportation (DOT). The Department uses the index
to describe the condition of pavement across the nation, to set a
performance goal for the quality of the nation's highways, and to
project pavement investment needs through a computer model called
the Highway Economic Requirements System. The Secretary has
delegated responsibility for collecting data on pavement
conditions to the Federal Highway Administration (FHWA). The
Transportation Equity Act for the 21st Century (TEA-21) (P.L. 105-
178) directed GAO to evaluate how the index is used and how
reliable the data are and report the results to the Congress no
later than June 9, 2000. Accordingly, this report describes (1)
the uses FHWA, the states, and others make of the index to assess
highway conditions, (2) the consistency and accuracy of state-
reported data on highway roughness, and (3) FHWA's efforts to
improve the data across states. Results in Brief The
International Roughness Index is used widely for federal and state
purposes, as well as for independent analyses. At the national
level, where the index is the only available statistic on pavement
conditions, FHWA uses it to assess changes in the overall
condition of the nation's highways and Page 1
GAO/RCED-99-264 International Roughness Index Data B-281731 to
forecast future highway investment needs. For example, in 1997,
FHWA projected that repairing deficiencies on the nation's
highways would cost $70.3 billion annually. Actual expenditures
for highways by all levels of government in 1995 were about $29.2
billion, or about $41 billion less than FHWA had projected as
needed to repair the deficiencies. In addition, FHWA uses the
index to measure progress toward a goal for ride quality in its
strategic plan and publishes data from the index for use by the
public. At the state level, where other types of data on pavement
conditions are available, reliance on the index varies. While some
states rely on it to make highway maintenance decisions, others do
not consider it an important decision-making tool. The states that
rely on the index use it to project highway investment needs and
report on pavement performance at the state or district levels. In
addition, some states use the index to set standards for
construction projects. Independent analysts have used the data to
compare pavement conditions across states and to develop "report
cards" of state performance. Critics contend that state
comparisons based on the index are flawed because the pavement
roughness data reported to FHWA by the states are not consistent
or accurate. These problems with consistency and accuracy have
occurred for two reasons. First, the states use different methods
to gather data and compute the results. The states differ in the
devices they use to measure the pavement, the part of the road
they measure, and their choice of an appropriate mathematical
simulation. As a result, state-to-state comparisons are not valid.
Second, the type of surface-asphalt or concrete-influences the
results. Concrete roads may produce rougher readings than asphalt
roads, even if the concrete road is of very high quality. Features
such as joints between sections can contribute to the roughness of
concrete highways. While FHWA has tried to improve the data, these
efforts have not been completely successful. The agency developed
detailed guidelines for collecting the data and asked the states
to apply these guidelines before reporting the data. However, FHWA
accepts any data that the states submit, even if they do not meet
its data collection guidelines. Accordingly, we are recommending
that FHWA revise its data collection guidelines to limit the
technology and procedures the states may use in collecting
International Roughness Index data and work with the states to
seek compliance with these guidelines. Such action will help to
ensure the reliability of the index data that the Department uses
for several critical activities, including the estimation of the
nation's highway investment needs. Page 2
GAO/RCED-99-264 International Roughness Index Data B-281731
Background In 1993, FHWA adopted the International Roughness
Index as a measure for the states to use in assessing and
reporting highway conditions in the United States. FHWA viewed the
index as an improvement over an earlier, more subjective method
that permitted ride and visual evaluations of highways by state
inspectors. In adopting the index, FHWA believed it would improve
the reliability of national data on pavement conditions. In
addition, the index was accepted worldwide and was used by foreign
countries and the World Bank as a measure of pavement conditions.
FHWA wanted the nation's system of measuring pavement conditions
to be consistent with international guidelines. The index is a
quantitative measure of a vehicle's up-and-down motion while the
vehicle is traveling at a specific speed. Most states collect and
measure the data with specially equipped vans, called profilers
(see fig. 1). The vans can operate at highway speeds and can cost
from $75,000 to $1,500,000.1 However, these costs are dropping as
the costs of computers and sensors decline. A profiler has sensors
attached underneath the van that quickly gauge the surface, or
"profile," of the road as the van travels at normal speeds in
traffic. The vehicle typically has a computer and three types of
sensing equipment: a height sensor,2 an acceleration sensor, and a
speed/distance device connected to the profiler's speedometer or
to a wheel. Height sensors measure the up-and-down movement of the
van, acceleration sensors detect changes in the speed of the van's
up-and-down movement, and speed/distance sensors measure how fast
the van is traveling and how far it has traveled. All of these
measurements are needed to compute an International Roughness
Index statistic. On a smooth road, the up-and-down movements are
small and the road's index is low, but on a rough road with large
cracks and potholes, up-and-down movements are more noticeable and
the index is higher. The index is measured in inches per mile;
smooth roads have an index of up to 60 inches per mile, while
rough roads have an index of about 170 inches per mile or greater.
1Most profilers cost under $200,000. The more expensive devices
cited here often perform additional functions, such as videotaping
and measuring the depth of ruts. 2Height sensors use a wide
variety of technologies, including laser, infrared, optical, and
ultrasonic types. Page 3
GAO/RCED-99-264 International Roughness Index Data B-281731 Figure
1: Profiler Vehicle Engineering Information Number of units owned
by Pennsylvania Department of Transportation - 3 Months of
operation - March to November Height sensors mounted in the front
bumper of this Pennsylvania Department of Transportation road
Personnel needed for operation - 2 profiler send pavement data to
an onboard computer for calculating the International Roughness
(operator and driver) Index.
Number of test miles measured in 1997 - 14,744 Source:
Pennsylvania Department of Transportation. DOT, the States, and
DOT uses International Roughness Index data in reports describing
the Others Have Various overall
condition of the nation's roads and forecasting future highway
investment needs. FHWA publishes the data annually in its
publication, Uses for the Index
Highway Statistics, and uses the data to support conclusions in
the Department's Conditions and Performance Report, a biennial
report to congressional authorizing committees on the state of the
nation's roads. (App. I contains an example of the roughness data
published in FHWA's Highway Statistics.) The 1997 Conditions and
Performance Report contains estimates of the nation's highway
investment needs for the next 20 years. For example, in 1997, FHWA
projected that repairing deficiencies on the nation's highways,
when the repairs were economically justifiable, would cost $70.3
billion annually. In comparison, all levels of government spent
$29.2 billion for highways in 1995-a shortfall of about $41
billion. FHWA's computer model, using roughness index and other
data, projects this needs estimate.3 3FHWA also projects pavement
investment needs with another computer model, known as the
Analytic Process model. Page 4
GAO/RCED-99-264 International Roughness Index Data B-281731 FHWA
also uses the data as a performance indicator for the nation's
highways. Under the Government Performance and Results Act of
1993, FHWA and the Department use the data to set a goal for ride
quality in their performance plans. The performance plans call for
93 percent of the National Highway System4 to have an index of
below 170 inches per mile by 2008. Using 1997 data (the most
recent data available), FHWA reported in 1999 that 91.7 percent of
the National Highway System had already achieved this goal, and
therefore officials believe the goal is achievable. However, FHWA
noted that since the index measures only pavement roughness, other
measurements of pavement distress would be needed to fully assess
the overall condition of the nation's highways. The states we
reviewed vary in the extent to which they rely on the index to
make maintenance decisions or manage their construction schedules.
For example, three of the seven states we reviewed-Ohio,
Pennsylvania, and South Dakota-believe the index is helpful in
managing the condition of their pavement and use the data in
determining their pavement investment needs. These states use the
data as an indicator of pavement performance statewide or at the
highway district level. Four of the seven states-Georgia,
Pennsylvania, South Dakota, and Texas-currently use or plan to use
the index as a construction specification for new pavement
construction. For example, in Georgia, contractors must construct
new highways with an index reading below 47 inches per mile.
Georgia Department of Transportation officials claim that this
requirement explains the low roughness of their roads. These
officials also stated that contractors in Georgia rarely deliver
new pavement that fails to meet this requirement. On the other
hand, New York does not use the index for any state purpose; it
collects the data only to fulfill FHWA's requirement that the
states report index measurements. Outside analysts also use
roughness index data for studies of pavement conditions and
performance. Nonprofit organizations and academic institutions
occasionally publish "report cards" comparing pavement conditions
among the states. For example, the Surface Transportation Policy
Project issued reports in 1997 and 1998 based, in part, on FHWA's
index data. (App. II contains an example of a Surface
Transportation Policy Project report card.) These reports ranked
the states on the condition of their roads and estimated how much
the condition of the roads cost drivers in repair bills. The
Surface Transportation Policy Project report uses FHWA's data to
categorize a state's roads as good, fair, 4The National Highway
System is a federally designated portion of the nation's roads
consisting mainly of interstate highways and other arterial roads.
Page 5 GAO/RCED-99-264
International Roughness Index Data B-281731 mediocre, or poor.
Similarly, the Center for Interdisciplinary Transportation Studies
at the University of North Carolina-Charlotte has issued annual
reports since 1993 ranking state transportation departments on the
cost-effectiveness of their expenditures. The Center's reports use
index data and other indicators, such as how much a state highway
department spends for administration, to determine how effectively
a state spends its transportation dollars. These reports and
others like them can be controversial, especially among those
states that do not appear high in the reports' rankings. For
example, officials from the Maryland State Highway Administration
expressed concern over the controversy generated by one such
report that the officials felt erroneously portrayed the condition
of their highway system. Similar controversies arose in Illinois
and Iowa. These reports contrast with those that FHWA publishes.
FHWA's Highway Statistics contains an annual listing of state
index data but makes no attempt to rank the states according to
the condition of their roads. FHWA officials noted that Highway
Statistics includes a notice that users need to account for
variability in the index data reported by the states. The notice
explains that sources of variability include differences in the
type of pavement material, in measuring equipment, and in
measurement protocols. Differing State The states' roughness
index data are not comparable because the states Procedures
Produce differ in the devices and procedures they use to
measure the roughness of their highways, as well as in the
mathematical simulation they use to Inconsistent Data
calculate the index. Any one of these factors can bias the
results, producing inaccurate and inconsistent data. However, the
cumulative effect of these differences among states is unknown-
some state practices tend to reduce values in the data, while
others overstate the values. These known sources of variability
reduce the accuracy of the data disseminated by FHWA and limit the
comparability of the data from state to state. Furthermore,
different types of pavement-concrete and asphalt-may differ in
roughness, according to state highway officials. As a result, the
states with more concrete pavement may have higher index readings
than the states that primarily use asphalt. The states use laser,
optical, infrared, and ultrasonic profilers to assess a road's
roughness and determine its index. According to a 1998 survey by
the Florida Department of Transportation to which 38 states
responded, 28 states used laser devices, 9 used ultrasonic
devices, 4 used infrared devices, and 2 used optical devices.5 The
technology used by the profiler 5Some states collect index data
with more than one type of height sensor. Page 6
GAO/RCED-99-264 International Roughness Index Data B-281731 can
affect the measurement of roughness. Laser, optical, and infrared
devices all measure roughness by emitting beams of light and
measuring the distance between the vehicle body and the road.
Ultrasonic sensors measure roughness by emitting a sound wave and
measuring how long it takes for the sound wave to travel back to
the sensor to compute the distance between the vehicle and the
road. Ultrasonic sensors do not sample as much of the pavement as
other types of sensors. This limits their ability to measure
roughness reliably. For example, a 1998 study for the Florida
Department of Transportation showed that a low-cost ultrasonic
sensor still in use by some states produced measurements about 25
percent higher than profilers using laser technology. The results
were particularly dramatic on certain rough surfaces. States
switching from ultrasonic sensors to laser sensors could show a
marked "improvement" in their roads, even if pavement conditions
stayed exactly the same. None of the states we contacted were
using ultrasonic sensors, and four of the seven had replaced old
ultrasonic sensors with other types. The states also differ in
their procedures for operating profiler vans, and these
differences can affect the data. For example, most states use two
technicians to measure roughness. A 1999 study by the University
of Michigan Transportation Research Institute recommended the use
of at least two people, one to drive and the other to take the
readings.6 The driver can then focus on the van's lane position,
speed, and safety while the operator finds landmarks, triggers the
system, and conducts quality control steps during measurements.
However, according to a Georgia Department of Transportation
official, Georgia uses only one person to perform both functions.
Of the other states we contacted, Illinois, Ohio, Pennsylvania,
South Dakota, and Texas use two people to gather the data. New
York officials could not tell us how many people take the readings
in their state because private contractors perform that task. FHWA
officials said a definitive study has not been done on the effect
of a profiler's crew size on roughness index data, but they
thought a larger crew might be a good safety factor. The location
of the profiler equipment can also affect the measurement of
roughness. Some states measure a highway's roughness over the path
of the right wheel, while other states measure the left wheel path
or take readings over the paths of both wheels and average the two
results. Generally the right wheel path is the roughest part of
the highway lane, and thus readings are higher from the right
wheel than from the left wheel 6This study also addresses other
data quality issues, such as standardizing the profiler's design
and other system operating practices. Page 7
GAO/RCED-99-264 International Roughness Index Data B-281731 or the
average of both wheels. FHWA recommends that the states collect
data over the right wheel but allows them to average measurements
collected over both wheels.7 A Florida Department of
Transportation study found that 4 states gathered data over the
left wheel, 13 gathered data over the right wheel, and 14 averaged
the measurements gathered over both wheels. In addition, under
FHWA's guidelines, the states are to exclude readings taken when
their profilers cross bridges and railroad tracks. However, some
states include these readings in their data. For example,
Illinois, which has more rail-highway crossings than any other
state except Texas, includes readings over bridges and railroad
crossings in its data. FHWA's guidelines contain specific
procedures for calculating a roughness index from the raw data
collected by the profiler. The guidelines call for the states to
use a method known as a quarter-car simulation.8 However some
states have not always used this method. For example, two of the
states we contacted, Georgia and Ohio, computed their index using
a method known as a half-car simulation.9 A 1998 University of
Michigan report compared the two methods and found that half-car
measurements were 11 percent smoother than quarter-car
measurements on the same roads. In addition, before 1997, Texas
gathered data for a different pavement condition statistic-the
Pavement Suitability Index-converted it to an International
Roughness Index value, and reported the converted statistic to
FHWA. FHWA found that this approach produced unrealistic
measurements of roughness for certain pavements. For example,
Texas Department of Transportation officials stated that the
conversion produced index measurements of zero (a glass highway)
for about 40 percent of the state's highways. In response to these
results and FHWA's concerns, Texas changed its methods and began
to measure the International Roughness Index directly as of 1997.
Finally, the type of pavement can also affect measurements of
roughness. Officials from Georgia, Illinois, and New York all
stated that concrete pavements generally have higher index
readings than asphalt pavements, even when the two types of
pavements are in comparable physical condition. For example, a New
York official said that past measurements had shown new concrete
pavement with index values 30 inches per mile 7In early 1999, FHWA
announced it would accept index data averaged from the left and
right wheels, as authorized by new protocols approved by the
American Association of State Highway and Transportation
Officials. These protocols differ somewhat from FHWA's current
guidelines. 8The quarter-car simulation involves modeling the
movement of one corner of a passenger car's suspension over the
road being profiled. 9The half-car simulation involves modeling
the movement of half a passenger car's suspension over the road
being profiled. Page 8
GAO/RCED-99-264 International Roughness Index Data B-281731
rougher than new asphalt pavement. This difference may have
occurred, in part, because some concrete pavement, unlike asphalt,
has joints between the concrete sections, and each concrete
section has a slight natural curve in it. FHWA does not
distinguish between pavement types when it publishes its data, so
direct comparisons cannot be made between states that mainly use
asphalt and states that mainly use concrete. FHWA officials noted
that pavement contractors have developed ways of building concrete
highways that can match asphalt highways in terms of roughness.
FHWA Has Not FHWA has developed guidelines for
the states to use in collecting, analyzing, Required the States to
and reporting data on pavement roughness. However, some elements
of these guidelines allow for inconsistencies in the way the
states collect the Comply With Its data. In
addition, while FHWA has emphasized the importance of these
Guidelines for guidelines, it does not require the
states to follow them. FHWA instead relies on persuasion to get
the states to collect data as specified in the Collecting
guidelines. International Roughness Index Data In 1993, FHWA
developed guidelines on measuring roughness and provided the
states with detailed instructions for collecting and reporting the
data. FHWA issued its guidelines as an appendix to its Highway
Performance Monitoring System field manual. This appendix provides
detailed instructions on measuring roughness-where on a roadway
the state agencies should measure the pavement, what types of
measuring devices are acceptable, how the index is computed, and
other technical issues. The appendix also instructs the states to
exclude roughness measurements taken at bridges, railroad tracks,
and other obstacles designed as part of the roadway. At the same
time, the guidelines allow for inconsistencies in collecting the
data. For example, the states are allowed to use mechanical
roughness meters10 instead of the more accurate profilers. Also,
under the guidelines, the states are allowed to measure roughness
in the left wheel path if measuring the preferred right wheel path
is not practical. However, FHWA's instructions do not otherwise
address deviations from the guidelines. FHWA expressed its desire
for consistency in the states' application of its guidelines in
1994, when it directed its field staff to review the equipment the
states used to collect roughness data, the frequency with which
they collected data, and the reasonableness of the data they
reported. FHWA 10Mechanical roughness meters would collect index
data by measuring the response of a mechanical device-like a fifth
tire riding behind a car-in contact with the roadway as the device
traveled on a road. In contrast, the profilers most commonly used
today rely on sensors, such as lasers, that are not in contact
with the road. Page 9 GAO/RCED-
99-264 International Roughness Index Data B-281731 field office
staff at one of the states we visited found large-scale errors in
their state's reports of roughness data. The state subsequently
revised its data collection process to satisfy FHWA. When the
states deviated from FHWA's guidelines, they generally had an
engineering reason for doing so. For example, Georgia and Ohio
preferred measurements based on half-car simulations rather than
quarter-car simulations because they had been collecting pavement
roughness data before FHWA introduced its guidelines and the data
from half-car simulations better matched their data from prior
years. Pennsylvania and South Dakota left the measurements taken
over bridges and railroad grade crossings in their data because
they considered the information potentially useful in identifying
trouble spots. In general, FHWA has not strictly imposed its data
collection guidelines on the states, and it accepts the data the
states submit. FHWA has legal authority to impose and enforce
requirements for accurate data. FHWA officials stated that the
sanction for noncompliance could be for the agency to withhold
planning and research funds. However, officials noted that the
states use these funds to pay for many other data elements they
report for FHWA's Highway Performance Monitoring System field
manual, as well as for other planning and research activities,
including metropolitan planning, statewide planning, and clean air
requirements. FHWA officials also told us that persuasion was
their preferred tool for encouraging the states to report
roughness index data as specified in the agency's guidelines. New
protocols on measuring pavement roughness issued in early 1999 by
the American Association of State Highway and Transportation
Officials (AASHTO) could help address the problem of
inconsistencies in the states' application of FHWA's guidelines.
FHWA supported the development of AASHTO's protocols,11 believing
they would help standardize state data collection practices. FHWA
officials told us they plan to issue a new Highway Performance
Monitoring System field manual by the end of 1999 that
incorporates AASHTO's new protocols, called provisional standards.
In addition, to obtain closer compliance with its reporting
requirements, 11AASHTO's protocols differ from FHWA's guidelines
in that they call for the states to measure pavement roughness in
both the right and left wheel paths and average the measurement to
calculate a roughness index statistic. While FHWA recently agreed
to accept data averaged according to AASHTO's protocols, FHWA's
current guidelines call for taking measurements from only one
wheel path, preferably the right wheel path. Furthermore, AASHTO's
protocols do not address what types of profilers the states should
use to collect data, whether the states should exclude data
collected over bridges and railroad crossings, or how many
technicians the states should use to collect index data. Page 10
GAO/RCED-99-264 International Roughness Index Data B-281731 FHWA
will include revised instructions on gathering roughness data in
the appendix to its new field manual. Finally, recognizing the
importance of consistent roughness data as a performance indicator
for FHWA's strategic planning process and as a factor in
estimating highway investment requirements for the Congress, FHWA
officials said they plan to examine several issues related to
collecting more consistent roughness data. Specifically, FHWA
plans to * evaluate the effects of different data collection and
analysis protocols on the roughness data, * assess current
practices to identify where changes could significantly improve
roughness data, and * work with its field offices and the state
highway agencies to implement changes that would make roughness
data more consistent. Conclusions The International Roughness
Index is a more consistent tool for measuring pavement conditions
than the subjective system FHWA previously used. However, the data
on pavement roughness that FHWA receives from the states need to
be more consistent and accurate. Differences in the states' data
collection methods and the resulting lack of comparable data
become important when FHWA aggregates the data to the national
level, such as when the data are used in the Department's model
for projecting the nation's highway investment needs. Unreliable
statistics result from aggregating data that are not comparable.
For example, FHWA will not be able to determine with confidence
that it has met the Department's performance goal for pavement
condition set under the Results Act-that 93 percent of the
National Highway System have an index below 170 inches per mile by
2008. Without accurate data on pavement roughness, FHWA cannot
reliably assess the current condition of the highways relative to
the goal or determine whether progress is being made toward the
goal. In addition, meaningful comparisons among the states cannot
be drawn using the data because the states use different
procedures and calculation methods. While FHWA has given the
states wide latitude in how they report pavement roughness data,
FHWA also has the authority to require that they use accurate
equipment and consistent techniques to collect the data. Page 11
GAO/RCED-99-264 International Roughness Index Data B-281731
Recommendations to To enable the Federal Highway Administration
to reliably report on the the Secretary of condition of the
nation's highways and accurately estimate the nation's highway
investment needs, we recommend that the Secretary of
Transportation Transportation direct the Administrator,
Federal Highway Administration, to revise the agency's guidelines
to exclude profiling technologies known to produce significant
errors and achieve consistency with the American Association of
State Highway and Transportation Officials' protocols. We further
recommend that the Administrator work with the states to implement
the revised guidelines. Agency Comments We provided a copy
of a draft of this report to the Department of and Our Response
Transportation for review and comment. We discussed the draft
report with Department officials, including the Federal Highway
Administration's Director, Office of Highway Policy Information,
and Acting Director, Office of Pavement Technology. FHWA generally
agreed with the findings and our conclusion that the roughness
data reported by the states could be more consistent. However,
FHWA disagreed with part of the recommendation in our draft
report, which said that FHWA should direct the states to comply
with its own and AASHTO's guidelines on reporting data. FHWA
believed that it could obtain more consistent roughness index data
by working cooperatively with the states rather than by requiring
them to comply with a federal mandate. According to FHWA, such a
mandate was unwarranted. FHWA further stated that because the
Congress in the National Highway System Designation Act of 1995
overturned earlier legislation that mandated state Pavement
Management System requirements, FHWA did not believe it was
appropriate to impose criteria for measuring roughness. FHWA
believes it has worked effectively with the states to obtain
better roughness data and that the states have already made great
strides in improving their collection and reporting of the data.
FHWA also noted that it has planned several actions to obtain more
consistent roughness data from the states. First, it said it plans
to adopt AASHTO's recently developed roughness standards as its
own. FHWA believes that these new standards will substantially
address our concern about the quality of the data. In addition, to
obtain closer compliance with its reporting requirements, FHWA
said it will include revised instructions on gathering roughness
data in the appendix to its new Highway Performance Monitoring
System field manual. This appendix contains the guidelines that
states use. Finally, FHWA said it plans to evaluate the effects of
different data collection and analysis protocols on the roughness
data, assess current practices to identify where changes could
significantly Page 12 GAO/RCED-99-264
International Roughness Index Data B-281731 improve the data, and
work with its field offices and the state highway agencies to
implement changes that will improve the consistency of reported
roughness data. FHWA believes that adopting AASHTO's protocols,
along with taking the actions it has planned, will address our
concerns without imposing a federal mandate. We are encouraged by
FHWA's recently stated commitment to work with the states on these
issues and agree that a federal mandate may not be necessary.
Nevertheless, we believe that following through on plans such as
this is often just as difficult as developing them. Accordingly,
we have revised our recommendation to reflect FHWA's new plan and
this continuing need. FHWA made a number of additional technical
comments on the report, which we incorporated as appropriate.
Scope and We contacted FHWA and state transportation
department officials to Methodology determine how they use
International Roughness Index data. We examined state and federal
reports based on these data and documentation concerning FHWA's
Highway Performance Monitoring System database and the related
models for projecting future highway investment needs.
Furthermore, to assess independent uses of roughness index data,
we reviewed reports by the Surface Transportation Policy Project
and the Center for Interdisciplinary Transportation Studies at the
University of North Carolina-Charlotte. To obtain information
about the reliability of the data, we interviewed FHWA and state
transportation department officials about data collection
practices and reliability. In particular, we interviewed state
transportation department officials from seven states about their
experience and concerns with the reliability of the roughness
data. The seven states-Georgia, Illinois, New York, Ohio,
Pennsylvania, South Dakota, and Texas-were selected to give us a
broad cross section of opinions about the reliability and
collection of the data. We also spoke with officials from Maryland
about applications of the data. In addition, we interviewed
experts in the field of pavement monitoring from the University of
Michigan, the University of North Carolina-Charlotte, and a
profiler manufacturer. We also analyzed pavement data from the
Highway Performance Monitoring System database and reviewed
reports on the reliability of roughness index data that were
presented before the Road Profiler Users Group and the
Transportation Research Board. We performed our review from Page
13 GAO/RCED-99-264 International Roughness
Index Data B-281731 August 1998 through September 1999 in
accordance with generally accepted government auditing standards.
We will make copies of this report available to cognizant
congressional committees; the Honorable Rodney E. Slater,
Secretary of Transportation, the Honorable Kenneth R. Wykle,
Administrator, Federal Highway Administration; and other
interested parties. We will make copies available to others on
request. Please call me at (202) 512-2834 if you or your staff
have any questions. Major contributors to this report were Richard
Calhoon, Joseph Christoff, Robert Ciszewski, and Raymond Sendejas.
Sincerely yours, Phyllis F. Scheinberg Associate Director,
Transportation Issues Page 14 GAO/RCED-99-
264 International Roughness Index Data Page 15 GAO/RCED-99-
264 International Roughness Index Data Contents Letter
1 Appendix I
18 Pavement Data Published by the Federal Highway Administration
Appendix II
20 Pavement Data Published by the Surface Transportation Policy
Project Figure Figure 1: Profiler Vehicle
4 Abbreviations AASHTO American Association of State Highway
and Transportation Officials DOT Department of
Transportation FHWA Federal Highway Administration TEA-21
Transportation Equity Act for the 21st Century Page 16
GAO/RCED-99-264 International Roughness Index Data Page 17
GAO/RCED-99-264 International Roughness Index Data Appendix I
Pavement Data Published by the Federal Highway Administration Page
18 GAO/RCED-99-264 International Roughness Index Data
Appendix I Pavement Data Published by the Federal Highway
Administration Note: In this Federal Highway Administration table
on the roughness of rural pavement, the states are listed
alphabetically. Source: Highway Statistics 1997, Federal Highway
Administration. Page 19 GAO/RCED-
99-264 International Roughness Index Data Appendix II Pavement
Data Published by the Surface Transportation Policy Project Note:
In this Surface Transportation Policy Project chart, the states
are listed by the percentage of pavement not in good condition.
Source: Potholes & Politics 1998, Surface Transportation Policy
Project. (348119) Page 20
GAO/RCED-99-264 International Roughness Index Data Ordering
Information The first copy of each GAO report and testimony is
free. Additional copies are $2 each. Orders should be sent to the
following address, accompanied by a check or money order made out
to the Superintendent of Documents, when necessary. VISA and
MasterCard credit cards are accepted, also. Orders for 100 or more
copies to be mailed to a single address are discounted 25 percent.
Orders by mail: U.S. General Accounting Office P.O. Box 37050
Washington, DC 20013 or visit: Room 1100 700 4th St. NW (corner
of 4th and G Sts. NW) U.S. General Accounting Office Washington,
DC Orders may also be placed by calling (202) 512-6000 or by using
fax number (202) 512-6061, or TDD (202) 512-2537. Each day, GAO
issues a list of newly available reports and testimony. To
receive facsimile copies of the daily list or any list from the
past 30 days, please call (202) 512-6000 using a touchtone phone.
A recorded menu will provide information on how to obtain these
lists. For information on how to access GAO reports on the
INTERNET, send an e-mail message with "info" in the body to:
[email protected] or visit GAO's World Wide Web Home Page at:
http://www.gao.gov PRINTED ON RECYCLED PAPER United States
General Accounting Office Bulk Rate Washington, D.C.
20548-0001 Postage & Fees Paid GAO Permit No. G100 Official
Business Penalty for Private Use $300 Address Correction Requested
*** End of document. ***