Conclusions and Recommendations
The conclusions presented below address the performance offederal motor vehicle size and weight regulations and the adequacy of the information available for guiding regulatory decisions. These conclusions are based on the evaluations in past truck size and weight studies and criticisms of those studies, the comments of interested parties, and the other information sources described in the preceding chapters. The committee’s recommendations involve organizational arrangements designed to promote reform of the federal regulations, as well as changes in the regulations intended to improve the efficiency of truck freight transportation and mitigate the costs of truck traffic to the public.
1. Opportunities exist for improving the efficiency of the highway system through reform of federal truck size and weight regulations. Such reform may entail allowing larger trucks to operate.
Present federal standards are for the most part the outcome of a series of historical accidents instead of a clear definition of objectives and analysis of alternatives. A TRB committee concluded in 1990 that “the result [of past regulation] has been trucks that are not ideal from the standpoint of highway wear, freight productivity, or safety” (TRB 1990b, 15). After another decade of policy deadlock on size and weight, the unsatisfactory performance of these regulations is more acutely evident. The regulations are poorly suited to the demands of international commerce; their effectiveness is being eroded by ever-expanding numbers and types of special exemptions, generally granted without evaluation of consequences; and freight traffic is bypassing Interstate highways, the safest and most efficient roads, to use secondary roads where limits are less restrictive, but the costs generated by that traffic are higher. The greatest deficiency of the present environment may be that it discourages private- and public-sector
innovation aimed at improving highway efficiency and reducing the costs of truck traffic because vehicle regulations are inflexible and because highway users are not accountable for all costs they generate.
2. Appropriate objectives for federal truck size and weight regulations are to facilitate safe and efficient freight transportation and interstate commerce, to establish highway design parameters, and to manage consumption of public infrastructure assets.
The legislative history indicates that these three objectives are consistent with the intentions of Congress in enacting the federal regulations. To fulfill the desire of Congress when it created the Interstate highway system in 1956 that the system be designed to uniform nationwide geometric and construction standards, it was necessary to define standard vehicles so that specifications for pavement and bridge strength and for roadway geometric layout could be developed. The federal responsibility for interstate commerce eventually led, in 1983, to federal legislation establishing minimum vehicle dimensions that all states were required to allow on principal highways, preempting state regulations judged by Congress to be more restrictive than necessary for economy or safety and thus to constitute obstacles to interstate transportation. These objectives are worthwhile, and truck size and weight regulation by the federal government contributes to their attainment, although the regulations ought to be complemented by other policies aimed at achieving the same goals. Evaluation of federal size and weight regulation should take into account how it affects all costs of highway transportation, including environmental, safety, and congestion costs, as well as infrastructure costs and costs to shippers and carriers.
3. Changes in truck size and weight regulations made in coordination with complementary changes in the management of the highway system offer the greatest potential to improve the functioning of the system.
The best way to control all the costs of accommodating existing and future truck traffic is by coordinating practices in each of the following areas of public-sector highway management:
Engineering practices—pavement and bridge design and maintenance, and highway geometric design;
Highway user regulations—size and weight regulation, related areas of vehicle and operator regulation (in particular, vehicular safety regulation and regulation of driver qualifications related to safety), and enforcement of regulations; and
Highway user fees. Imposition of cost-based user fees is a regulatory approach that could usefully supplement or partially replace size and weight regulation to produce more efficient control of the public and private costs of truck transportation.
The federal and state governments should recognize the range of measures at their disposal, including size and weight limits, for meeting highway program goals of cost control and service quality. Whenever Congress contemplates changing policy in any one of these three areas in the federal-aid highway program, it should at the same time consider the need for complementary changes in the other two. It is not possible to change some of these aspects of the highway system quickly to accommodate a change in truck size and weight regulations. For example, systemwide changes in geometric design features occur only over periods of decades. Historically, however, systemwide evolution of standards has been continuous, and it is necessary to plan the direction for these changes.
4. The methods used in past studies have not produced satisfactory estimates of the effect of changes in truck weights on bridge costs.
Bridge costs appear to be the critical impact in past DOT and TRB evaluations of proposed changes in regulations. Bridge costs of introducing larger trucks include the costs of necessary strengthening or replacement of bridges, as well as changes in the useful lives of structures, in the cost to construct new bridges in the future, in maintenance costs, and in the risk of bridge failure. Past studies have not evaluated the changes in the risk of bridge failure or in useful life that would be caused by changes in truck weights. Instead, they have estimated the cost of maintaining the existing relationship of legal loads to bridge design capacity through bridge replacement. The estimated cost of these bridge replacements is the biggest component of the projected costs of accommodating larger trucks; however, many of the projected replacements would, if actually carried out, buy very little risk reduction. Past studies have not included quantitative evaluation of alternative methods of attaining the same or greater risk reduction through much less costly bridge management strategies.
5. It is not possible to predict the outcomes of regulatory changes with high confidence.
Development of improved models for analyzing the costs of operating trucks of different designs would be worthwhile. However, models and data will never be adequate for providing more than plausible indications of how institutions, markets, and technology will react to regulatory changes, especially in the long run. More difficult to predict than the physical properties of vehicles and highways are the reactions of institutions: how federal executive agencies, courts, state legislatures, highway administrators, and enforcement officials will interpret and react to changes in federal law; and how carriers and equipment designers will take advantage of new vehicle options to reduce transport costs. The outcome of a regulatory change will depend on numerous dynamic factors in the environment that cannot be controlled or forecast. This inevitable uncertainty is not an argument for inaction, since maintaining the status quo would guarantee the loss of important opportunities for reducing the costs of transportation. Responsible regulation is a process: the regulatory authority should do the best prior analysis possible, but once regulations have been changed, the consequences must be systematically observed and adjustments made where necessary. The chances that a regulatory change will yield a positive outcome will be enhanced if highway users have been given incentives to act in consonance with the public interest through enforcement, user fees, and application of performance standards in regulation. Performance standards are regulations that directly specify required vehicle performance instead of attempting to control performance indirectly through dimensional limits.
6. It is essential to examine the safety consequences of size and weight regulation. Research and monitoring needed to understand the relationship of truck characteristics and truck regulations to safety and other highway costs are not being conducted today.
Understanding of these relationships is needed to design improved highways, vehicles, and safety management and pollution control programs, and to provide a solid basis for truck size and weight regulation. Progress toward resolving uncertainties surrounding the most critical interactions has been nearly nonexistent during the past decade. In particular, little productive safety research has been undertaken. Although the inevitable uncertainties from the sources de-
scribed in the previous conclusion make highly accurate predictions of the consequences of regulatory changes impossible, the present degree of uncertainty about the relationship of truck dimensions to safety and other highway costs is unnecessary. Research can improve predictions. At least as important as the ability to predict the impacts of changes is to have information systems in place that allow observation of the performance of existing regulations and the consequences of changes once they have been made.
Efforts to meet federal goals for reducing truck accidents can be successful only if they are supported by scientific understanding of the relation of safety to truck design and performance, road features, driver characteristics, and other factors influencing risk, and by knowledge of the effectiveness of alternative measures for reducing risk. Because this understanding generally is absent today, we are probably missing important opportunities to reduce accidents on the one hand, and wasting resources on ineffective programs on the other.
Truck safety studies using valid research methods have in the past produced results useful for evaluating regulatory proposals. The kind of research most needed entails the collection of data on accident frequency and factors believed to be related to accident risk, using study designs devised for statistically testing hypotheses about the effectiveness of particular interventions in improving safety. Research involving the analysis of existing general-purpose databases or the collection of anecdotal information will be less valuable guides to policy. Some past analyses of size and weight issues using general-purpose accident and travel databases have been worthwhile; however, improvements in the design of these data programs and research to develop improved analysis methods are required before these sources will be able to contribute much more to the formulation of size and weight policy.
Promising techniques are available for improving the safety of large trucks. These techniques include improved vehicle designs for better control and stability, information technology applications for control and stability and collision avoidance, technology applications designed to improve enforcement, improvements in operator certification and training, and changes in highway design. Some stability-enhancing measures would counteract the mechanisms that are suspected to be sources of differing accident rates among different truck configurations. Some of these approaches may greatly improve truck safety in the future. Past studies have recommended packages comprising changes in size and weight regulations coupled with vehicle design and operating requirements intended to offset any adverse
consequences of the size and weight changes. However, little is known about the effectiveness of the majority of the safety measures recommended by these studies. In particular, there is no empirical evidence for the effectiveness of requiring combination vehicles to meet performance standards regarding stability and controllability. Because such strategies do hold promise, the recommendations provided below involve arrangements for research and for evaluations in trial implementations to develop effective techniques of applying them.
Policy research has also lagged in the area of the relation of truck characteristics to bridge costs. The states are applying new methods of evaluating bridge improvement needs and management practices, but these methods have not been used in assessing size and weight policy.
In addition, data are almost entirely lacking on in-use emissions of diesel-powered large trucks and the relationship of emissions to weight and other vehicle characteristics. Consequently, no highway emissions model is capable of estimating how changes in traffic affect emissions of these vehicles.
Well-defined procedures must be in place for applying the results of research and evaluation to adjust regulations when opportunities to improve performance are discovered. Because of the administrative pattern of size and weight regulation that has evolved in the United States, no federal agency has the direction, authority, or resources needed to conduct this essential regulatory support activity. Moreover, present arrangements weaken incentives for truck operators, manufacturers, and the states to develop improved technologies and management practices because regulation is inflexible, and little opportunity exists to test the effectiveness of alternative approaches.
7. Although violations of size and weight regulations may be an expensive problem, monitoring of compliance with the regulations is too unsystematic to allow the costs involved to be estimated.
There is a need for direct and systematic observation of the frequency and impacts of oversize and overweight vehicles and of the identities of responsible carriers and shippers so that the costs of violations (as well as of legally operated overweight permit vehicles) can be known and the effectiveness of enforcement methods evaluated. The technology needed for low-cost monitoring is now available. The relevant technologies include automatic vehicle identification and weigh-in-motion devices, and the automated vehicle clearance systems that
integrate these devices, as well as systems for on-board monitoring and recording of vehicle characteristics and performance. Extensions of existing applications of these technologies could improve the effectiveness of enforcement, including enforcement of permit schemes that allow differing dimensional limits for different vehicles. Information on the frequency of extreme overloads is essential. The effect of changing federal size and weight limits on the costs of illegal overloads is unknown.
1. Commercial Traffic Effects Institute
Congress should create an independent public organization with a charter to observe and evaluate commercial motor vehicle performance and the effects of size and weight regulation. This organization, referred to here as the Commercial Traffic Effects Institute, would be chartered to develop federal size and weight standards and related highway management practices, recommend regulatory changes, evaluate the results of the implementation of new regulations, and support state implementation of federal regulations. The Institute would be authorized to enter into agreements with private-sector entities to conduct joint programs of data collection, research, and evaluation.
Three considerations demonstrate the need for a new organizational arrangement. First, under present practices, federal size and weight policy has been deadlocked for more than a decade, in spite of general dissatisfaction with the regulations. The current procedure for establishing size and weight regulations is incompatible with the dynamic nature of the size and weight problem. Federal regulations have undergone significant revision just twice in 45 years. Meanwhile, enormous changes have occurred in traffic and highway conditions and technology that call for regulatory responses.
Second, under the present system, regulatory changes that have occurred have been enacted without benefit of objective analysis or full public comment. As a result, some federal regulations have had far-reaching consequences that were not contemplated by their framers, but that might have been foreseeable with adequate prior analysis. DOT has produced a series of comprehensive studies of size and weight issues over the years, but its evaluations have had indirect influence at best. The inherent complexity of regulation in this area, which involves numerous details of motor vehicle and highway technology, argues in favor of a more formal deliberative process to direct necessary reforms.
The present arrangement has not been conducive to serious evaluation of the outcomes of regulation. No new federal size and weight regulation has ever been subjected to a conclusive follow-up evaluation. With the exception of a few nonfederal studies, virtually no new information has been produced in the past decade that would help resolve the question of the safety effects of regulatory changes. Although the deadlock over federal size and weight policy has several sources, one of the important causes has been the inadequacy of information on the impacts of existing regulations and the potential impacts of changes. Information that is perceived as having been produced objectively and openly using scientifically rigorous methods will be required for reform of the regulations.
Third, the committee’s recommendation for a new system for federal supervision of state permitting (Recommendation 3 below) calls for federal oversight functions that are not consistent with the responsibilities and competencies of any existing federal agency. This recommendation involves joint public–private activities that may not be compatible with the organization and functions of existing federal agencies.
The inadequacies of federal truck size and weight regulation are attributable in part to procedural shortcomings. Whereas other spheres of federal regulation are overseen by executive branch agencies with established, ongoing responsibility for regulatory development, federal size and weight regulations have been promulgated almost exclusively by direct legislation. DOT has certain rulemaking responsibilities, but their scope is restricted (for example, to definitional questions). In other areas of regulation, the responsible executive agency routinely carries out evaluations because it has the authority to make adjustments as necessary to respond to emerging problems and changing technology; however, the limited range of executive agency responsibility has discouraged evaluation of size and weight regulations.
Legislation creating the Institute should define the organization’s objective as reducing the public and private costs of truck freight and passenger coach transportation by developing proposals for changes in size and weight regulations, as well as changes in related highway system management and operating practices. Related practices include user fee policy, which is a complementary means of attaining the Institute’s objective. The relevant costs include those borne by carriers and their customers, highway infrastructure costs, accident costs,
and pollution and other environmental costs. The Institute should be charged with promoting innovation by providing a means to evaluate and implement private-sector or state proposals for new motor vehicle or highway operating practices that would require federal regulatory accommodation.
The legislation that creates the Institute should define the scope of its activities by specifying three distinct functions:
The conduct of pilot studies of proposed new vehicles and related operating practices, as well as research addressing fundamental questions about the relationship of vehicle characteristics to highway transport costs, including safety and infrastructure costs. The Institute would solicit proposals for pilot studies and research from the private sector and the states, and would conduct studies jointly with them.
Monitoring and program evaluation on an ongoing basis. Program evaluations would be conducted to measure whether practices intended to control accident risks and to operate highways efficiently (including size and weight regulations) were functioning as intended. Monitoring would consist of systematic observation designed to maintain up-to-date information in three areas: truck and coach traffic volumes and the distributions of vehicle dimensions and configurations; administration of regulations, including enforcement and fees; and costs of commercial motor vehicle traffic to highway agencies and to the public, including accidents and infrastructure costs. The design of data collection systems for monitoring depends on the specific objectives involved, but most needs will require data collection using scientifically designed sampling techniques. Observing the consequences of any changes in federal regulations would be an important monitoring and evaluation task.
Support for state implementation of federal size and weight regulations. Recommendation 3 below calls for giving states new authority to issue permits for truck operations exceeding present federal limits, provided state permitting practices meet certain criteria. The Institute should be responsible for reviewing state permitting practices and determining whether they merit certification as meeting federal requirements. In addition, the Institute would be responsible for developing model regulations and permitting practices as guidance for the states.
The Institute should be required to use the results of its pilot studies and research to formulate recommendations to Congress and the Secretary of Transportation regarding changes in federal regulations
when there is sound evidence that such changes would further the congressionally defined objective of reducing the public costs of commercial highway transport. The Institute would also recommend adjustments when its monitoring and program evaluations revealed that regulations were not working as intended or when innovations in truck or highway technology created conditions not envisioned when the regulations were enacted. It would not be inconsistent with the functioning of other areas of federal regulation to empower an executive agency to change federal size and weight limits, within boundaries specified by Congress, in response to such events. The Institute should be authorized to make recommendations for harmonizing areas of federal highway policy related to size and weight regulation and to truck costs, including practices and requirements regarding safety regulation, enforcement, infrastructure design and management, and user fees.
The Institute should be governed by an independent board of directors with members drawn from the federal government, the states, and the private sector. The board should be appointed by Congress or by public officials designated by Congress. Funding for core and continuing activities should be from the federal government; authorizing the needed amounts from highway user fees would be appropriate. Private sponsors of proposed new vehicles or regulations should participate in funding the evaluations of their proposals. The board should report periodically on all its activities to the Secretary of Transportation and to Congress, and recommend changes in federal regulations to the Secretary and Congress as warranted by the results of the Institute’s pilot studies, research, and monitoring. A professional staff with diverse expertise would be essential to the Institute’s program.
The board should be required, as its first responsibility, to prepare a business plan and a technical plan for the Institute. These plans would be submitted as a proposal to the Secretary and Congress. The business plan should specify arrangements for joint public and private involvement in research and pilots, arrangements for international liaison, and initial funding and staffing requirements. Arrangements for coordinating activities with the states would be necessary for success because regulation is a joint federal and state activity.
The technical plan should describe the framework the Institute will employ to produce defensible information about the effects of changes in size and weight regulations through pilot studies, research,
and monitoring, and propose initial specific technical activities. The technical plan the committee envisions is not for a single large research project that would finally resolve all questions about the relation of truck size and weight to safety and other highway costs; no such study could be conducted. Instead, the plan would set forth a process that could be relied upon at any time as an essential part of the government’s management of the highway system. As traffic conditions and highway and vehicle technologies change, new regulatory questions will continue to arise.
The technical plan should define how the Institute’s future program of research and evaluation will be determined and revised. This program would include initiatives from four sources: congressional directives; commissions from the Secretary of Transportation for specific research studies or evaluations; proposals from the states, industry, university researchers, safety organizations, or others; and activities identified by the board.
The Institute should be subject to a sunset review by Congress after a specified time, possibly 6 years. The board should be required to report to Congress and the Secretary at the end of the specified time on its past performance and plans for future activities as a basis for Congress’s decision on whether to continue the Institute.
Relation to Existing Agencies
The business plan should also specify relations of the Institute with existing federal agencies. Certain functions proposed for the Institute would be new federal activities, but others would fall within the sphere of present activities of the existing administrations within DOT and possibly of other federal agencies. The proposal for the Institute does not entail transfer of regulatory authority from existing agencies. The Institute should be a resource that allows existing federal agencies to execute their regulatory and administrative responsibilities related to truck size and weight more successfully. To this end, coordination of activities under the direction of the Secretary would be required. At the same time the Institute would need to have a high degree of independence in establishing its program and issuing recommendations.
Development of the Institute’s business plan and technical plan, in consultation with the related agencies and interested parties, would be a substantial undertaking. It would therefore be premature for the committee to make detailed organizational recommendations. However, consideration of two of the Institute’s major activities—the pilot studies proposed under Recommendation 2 and the federally supervised
permitting program detailed under Recommendation 3—indicates some of the areas in which coordination with existing executive agency programs will be necessary.
Pilot studies to evaluate and produce specific recommendations on proposals of states, industry, or others for changes in federal size and weight regulations would constitute a new regulatory support practice. No federal agency now has a permanent charge to conduct such activities. FHWA, NHTSA, and FMCSA have used pilot studies for other purposes and so might be able to contribute expertise. However, practices evaluated in the Institute’s pilot studies and the ensuing recommendations could relate to multiple DOT programs. For example, a pilot study of a new truck configuration might include trucks that were equipped with new braking systems or might involve monitoring of bridge impacts or an evaluation of a bridge retrofit. NHTSA is responsible for truck brake regulations, and FHWA has responsibilities related to bridge design and maintenance on federal-aid roads. Because of these connections, it would be necessary for these agencies to participate in the design of the evaluation. The Institute would remain responsible for recommendations at the conclusion of the pilot study. The recommendations, addressed to the Secretary or to the Congress as appropriate, might call for changes in regulations or practices regarding bridges and brakes, as well as changes in size and weight regulations.
The federally supervised permitting program would also be a new activity. However, the Institute’s oversight functions under the program could overlap with the present responsibilities of other agencies. For example, one function of the Institute’s oversight would be to verify periodically that states participating in the program were enforcing permitting restrictions effectively. At present, FHWA has responsibility for supervising state enforcement of federal size and weight regulations. One possible assignment of responsibilities would be for FHWA to continue with its enforcement oversight responsibilities and for the Institute and FHWA to cooperate in developing the additional procedures needed to verify state enforcement under the permit program. Certainly other arrangements would be possible. The Institute’s business plan would identify such potential overlaps of responsibility and propose resolutions.
2. Evaluation of the Consequences of Changes in Truck Size and Weight Regulations Through Pilot Studies
Congress should authorize the Secretary of Transportation to approve pilot studies involving temporary exemptions from federal motor vehi-
cle size and weight regulations for vehicles operating within alternative limits, operated by motor carriers that agree to participate in evaluation of the safety and other impacts of the alternative limits. DOT should approve pilot studies upon the recommendation of the Institute, which should be responsible for planning the studies, carrying out the evaluations, observing that carriers comply with the conditions of the studies, and recommending to DOT and Congress on the basis of the results of each study whether changes in federal regulations are warranted.
It would be necessary for vehicles participating in a pilot to be in compliance with the laws of the states in which they were operated or receive approval from the states through established permitting processes or other state action. Congress should require that as a policy, Institute programs promote cooperative, regional, multistate solutions to size and weight problems.
In this recommendation, a pilot study is defined as a controlled experiment designed to measure the consequences of changes in vehicle dimensions, weights, or operating practices; following a scientific design; involving the collection of data under actual operating conditions; and entailing direct observation of the primary impact of interest (e.g., frequency and severity of accidents) rather than proxies (e.g., vehicle stability or driver performance) alone. The design of pilot studies should not place primary reliance on existing government-maintained accident and travel data programs for the evaluation of outcomes.
The most successful past studies of the relative accident rates of trucks of differing dimensions have used data obtained from truck operators that include records of large numbers of trips made by different kinds of trucks operating between the same origins and destinations. Pilot studies should encompass this general methodological approach whenever it is feasible and appropriate. A carrier wishing to operate a new vehicle configuration (or a vehicle not complying with existing weight or dimensional regulations) would receive temporary approval to do so as part of the pilot study on the condition that it provide data to be used in the evaluation.
The most appropriate organizational arrangements and the best study design in each case would depend on the specific potential regulatory change being evaluated and on the participants. However, the following would be one possible set of procedures:
A proposal for a pilot study would be presented to the Institute by states or private parties or would be originated by the Institute.
The Institute would make an initial determination, based on all available information, as to whether the proposed pilot study could be conducted without harm to public safety. If the study were judged to be acceptable on this basis, the Institute would develop a plan specifying the objectives of the study (i.e., what impacts were to be measured and for what purposes), the methods to be used for collecting and analyzing data, and criteria for carrier participation.
The Institute would make a recommendation to the Secretary on the conduct of the pilot study and on necessary exemptions from federal regulations.
If the pilot were approved, the Institute would solicit participation from states and from motor vehicle operators, consistent with its study plan. Carrier participants would be responsible for all or part of the direct costs of conducting the pilot study. Carriers might have to agree to some departures from their normal procedures regarding dispatching, routing, and equipment and driver assignments as required by the evaluation protocol.
During the course of the pilot study, the Institute would ensure that participants were complying with the study’s data reporting and operating requirements and watch for indications that the pilot was compromising safety. The Institute could terminate the pilot or remove participants at any time if it determined that the pilot was unlikely to meet its objectives.
The Institute would report pilot study results, regulatory recommendations, and the justification for its recommendations to the Secretary and Congress.
The Institute could recommend to the Secretary any general limitations it believed were advisable for reasons of safety or practicality with regard to the kinds of vehicles that would be eligible for pilot studies and the numbers of carriers or vehicles that could participate.
The proposed course of action poses certain risks and difficulties. Challenges include the uncertain transferability of the results of pilot studies to the whole population of truck operators, the inherent difficulty of designing and applying truck accident rate measures, the potential competitive inequity of allowing only certain carriers to operate more productive trucks, and concerns about liability. It may be argued that a temporary exemption would be used as a foot in the door and would inevitably become permanent; however, the committee believes that with information available about the actual consequences of the exemptions, making necessary adjustments to the regulations over time would be feasible.
In pilot studies involving a small number of vehicles, it would not be possible within a reasonable time span to measure small differences in relative accident risks. In these cases, it should be acceptable for the Institute to recommend continued operation of vehicles provided the pilot study results were sufficiently accurate to rule out serious deficiencies, and procedures were in place for continued close observation of the performance of the new vehicles.
The legislation authorizing the pilot program should specify the general criteria that temporary exemptions would have to satisfy to be considered for permanent status. These criteria should include demonstration in the pilot study that an exemption is consistent with public safety and the requirement that any increases in highway agency costs be covered by user fees paid by operators of the vehicles involved.
The committee anticipates that the primary objective of most pilot studies would be to estimate the effect of changing regulations on accident risk. However, the pilot study approach could also provide information of value in estimating the infrastructure cost impacts of new regulations.
3. Immediate Changes in Federal Regulations
Federal law should allow any state to participate in a federally supervised permit program for the operation of vehicles heavier than the present federal gross weight limit, provided the state satisfies the requirements outlined below. DOT should be authorized to certify, on the advice of the Institute, that a state meets these requirements and to review certifications periodically. The Institute should be given permanent oversight responsibility for monitoring the performance and consequences of the federally supervised permit program.
By introducing a degree of flexibility together with stronger federal oversight, this change in law would reinforce an essential federal regulatory function that is in the process of eroding. Through grandfather rights or special statutory exemptions, 31 states allow vehicles weighing more than 80,000 lb to operate on the Interstates under divisible-load permits or with no permit required. (Divisible loads are cargoes that practicably could be divided and carried in more than one vehicle.) Of these 31 states, 15 are east of the Mississippi. Most states make extensive use of their grandfather rights, increasingly through issuance of multiple trip permits. According to DOT, “multitrip permits essentially allow unlimited operation with no accounting for mileage or routes for a greater length of time, generally one year” (DOT 2000, Vol. II, II-19–II-20). In addition, 22 states allow operation
of multitrailer combinations of more than 80,000 lb. Actual legal operation of trucks over 80,000 lb remains limited; vehicles that usually operate with a loaded weight of more than 80,000 lb accounted for 3.3 percent of all combination-VMT reported in a 1997 survey of truck operators (U.S. Bureau of the Census 1999, 70).
The federally supervised permit program provided for under this recommendation would be a step toward rationalization of the present, largely uncontrolled and unmonitored system of exemptions. The recommended federal oversight functions would create a mechanism whereby the performance of the regulations could be evaluated, and adjustments made when warranted by the evaluations and by changes in external conditions. For the first time, Congress would know the consequences of changes in regulations and would be able to modify practices in response. Improved information, together with greater facility to adjust regulations when necessary, ultimately would lead to regulations that more effectively promoted safety and controlled highway transport costs, including costs to shippers, other highway users, and the public.
The permit program, implemented with effective federal oversight of safety, fees, and enforcement, would constitute a redefinition of the federal role in truck size and weight regulation. The federal government would have diminished involvement in defining numerical dimensional limits on the Interstates and other federal-aid highways, but greater responsibility for ensuring that state regulations governing the use of vehicles on federal-aid highways were contributing to the attainment of national objectives. In effect, federal oversight would tend toward performance standards: states could propose solutions to problems, and the federal government would have to assess whether the proposals met qualitative objectives. Federal regulation, by requiring states to justify their proposals on performance grounds, would continue to provide a buffer protecting state highway programs from local, short-term economic pressures to depart from best management practices.
The opportunities created by the permit program would be expected to stimulate new multistate agreements on truck size and weight. Federal administration of the program should promote or require consultation among neighboring states. Expansion of regional agreements would constitute further evolution toward more rational standards and away from arbitrary state-to-state variations.
This recommendation incorporates the core elements of the permit program recommendation in TRB’s report to Congress entitled Truck Weight Limits: Issues and Options (TRB 1990a): a federally
supervised, state-implemented permit program, adopted at state option, to allow operation of certain trucks larger than those currently allowed under federal law on the Interstates and other roads where some federal restrictions now apply, with permit fees covering all administrative and infrastructure costs of the program. The differences between the present proposal and that of the earlier committee are intended to address objections raised to the Truck Weight Limits proposal on grounds of practicality: first, the 1990 study’s recommended change in the bridge formula is forgone; second, only a limited set of vehicles of certain specified configurations and dimensional limits would be eligible for permit operation; and third, more concrete actions are proposed to ensure that implementation would be effective in furthering the objectives of the regulations.
Size and Weight Provisions
Recommended size and weight provisions of the permit program are as follows:
The states should be allowed to issue permits for operation, on any road where the use of such vehicles is now prevented by federal law, of
Six-axle tractor-semitrailers with maximum weight of 90,000 lb; and
Double-trailer configurations with each trailer up to 33 ft long; seven, eight, or nine axles; and a weight limit governed by the present federal bridge formula.
After a specified transition period, all trucks operating under grandfather exemptions or state-specific exemptions from federal regulations (when operating on roads where they could not be legally operated without such exemptions) should be made subject to the requirements for monitoring and evaluation that would apply to trucks in the proposed new federally supervised permit program. Reliable information obtained in this way on the impacts of grandfather operation would allow Congress to decide whether the grandfather provisions should be altered or additional permitting flexibility should be extended to all states.
Trucks of the dimensions specified above should be allowed to operate through the mechanism of special permits, rather than through a change in the federal gross vehicle weight limit, in order to avoid possible undesirable impacts of weight increases for configurations other than those specified.
The recommended permit vehicle specifications are not presented as the optimum regulation. The definitions of the vehicles eligible for permitting would be subject to revision over time. Federal review of the performance of the permitting program would be permanent and ongoing, and as the program’s effectiveness was strengthened through experience, the results of the review process would provide the needed guidance on revision of the limits. Revisions would most suitably be instigated by recommendation of the Institute, following the procedures outlined in the preceding recommendation.
The recommended actions outlined below are designed to ensure successful implementation of the permit program through federal oversight of enforcement, fees, safety measures, and bridge management.
Enforcement A joint federal–state enforcement effort under the permit program should include the following four elements. The legislation creating the permit program should contain specific requirements regarding each of these elements:
Formal and effective performance monitoring of enforcement functions.
Application of new enforcement tools, which may include imposition of federal penalties for violation of federal limits. Congress should consider requiring, as a precondition for state participation in the permit program, that the state enact enforcement provisions to effectively hold accountable the parties responsible for placing overweight loads on the highways and to target repeat violators. Such provisions might include information systems that would make possible identification of responsible parties and repeat offenders, as well as “relevant evidence” statutes.
Adequate and stable funding for enforcement, including federal contributions derived from user fee revenues.
A program to substantially advance the application of information technology as an enforcement tool. Information technology applications available today could, with the proper institutional support, dramatically improve the effectiveness of enforcement.
User Fees The federal legislation creating the permit program should specify a quantitative test for the revenue adequacy of the permit fees imposed by states that wish to participate. As far as possible, fees
should be structured to avoid giving truck operators incentives to use truck configurations whose public costs exceed their private benefits. Fees should at least cover estimated administrative and infrastructure costs for the program when it is at its steady-state level, but proposals from states for fees that reflect other external costs or benefits, supported by well-reasoned arguments, would be acceptable. States that decide to participate in the program should be required to provide DOT with the data necessary to verify revenue adequacy.
The committee recognizes that administration of this requirement will be challenging. Costs and demand for permits will be imperfectly known at the outset of the program. Fees should be set initially according to the best available information, and the appropriateness of fees should be subject to ongoing review by the Institute. It is possible that some permit vehicles on some road systems would generate costs lower than those of the trucks they replaced. User fees should reflect the cost savings in such cases.
Safety Requirements As a temporary measure, equipment requirements developed in the most rigorous existing state permit programs should be imposed on permit recipients. These should include the requirement that truck components carry manufacturers’ ratings consistent with the loads they are permitted to carry. Requirements should be proposed by the states that apply to participate in the federally supervised permit program, and should be reviewed by the Institute and subject to approval by the Secretary. The requirements proposed could be more stringent than any existing requirements if the state provided a rationale for them. As noted earlier in this chapter, evidence is lacking to demonstrate that any particular vehicle performance requirements, equipment specifications, or operating practices would reduce overall accident risk. Implementation of such requirements should be coordinated with the program of research on the effectiveness of these measures to be undertaken by the Institute.
Bridge Management A state where larger trucks come into use through the permit program will need a plan for cost-effectively alleviating constraints on the vehicles’ use due to deficient bridges. The DOT responsibility for certifying that permit fees cover program costs implies the need to evaluate each participating state’s management of the bridge costs of the larger trucks. A state that wishes to participate in the permit program should be expected to submit its plan for managing bridge impacts as part of its application. Specification of the contents
of an adequate plan should be a matter for mutual agreement between the federal and state governments. An adequate plan would be likely to include the following elements:
A priority ranking of truck routes in need of bridge upgrades based on the expected volume of permit truck traffic and the presence of bridges that are inadequate for larger vehicles.
A program of bridge capital improvements and noncapital measures necessary to accommodate the larger trucks.
A program of bridge inspection and evaluation. There are opportunities for reducing the costs of bridge replacements or upgrades by undertaking more intensive inspection. Also, the cooperation of states in supplying data will be required for federal monitoring of the effect of larger trucks on bridge costs.
A cost estimate and finance plan. Required bridge improvements and added costs of bridge management and maintenance should be financed with permit fee proceeds. In addition, states should be encouraged to seek arrangements for direct private-sector financial support of specific projects aimed at correcting deficiencies in order to open routes to larger trucks. Such arrangements would be suitable on routes where only a small number of shippers or carriers would take advantage of the larger permissible truck loads.
4. Longer Combination Vehicles
Federal law should allow operation of longer combination vehicles under the provisions of the federally supervised permit program outlined in Recommendation 3 and participation of these vehicles in pilot studies according to the procedures outlined in Recommendation 2.
Specifically, federal vehicle weight limitations should not prevent the double-trailer configuration described in Recommendation 3 above from operating in any state under the rules of the proposed federally supervised permit program and should not prevent the conduct of pilot studies involving operation of any longer combination vehicle according to the procedures described in Recommendation 2. “Longer combination vehicle” is defined here as in federal law: “any combination of a truck tractor and 2 or more trailers or semitrailers which operates on the Interstate System at a gross vehicle weight greater than 80,000 lb” [23 USC Section 127(d)(4)].
5. Routes and Roads to Which Federal Standards Should Apply
The committee does not see justification at this time for any general revision of the specifications in federal laws and regulations regarding
the networks of roads to which the various federal dimensional regulations are applicable. In particular, there does not appear to be justification for extending federal weight regulation to the non-Interstate portion of the National Highway System (that is, the system of principal arterial roads designated by federal law), where state regulations now govern most aspects of truck operations.
New enforcement mechanisms must be instituted and a plan for evaluating the safety effectiveness of route restrictions developed before any new federal regulations regarding truck operations on restricted networks of roads are enacted. However, the designated network concept, as it has been applied in past federal size and weight laws, is a reasonable regulatory approach in principle. If restrictions are effective and enforceable and if user fees are in line with costs, it makes good economic and safety sense to have more liberal standards that apply to the best roads. The principle of federalism underlying the highway program dictates that states have a role in such designations.
The preceding recommendations call for three general kinds of activities involving data analysis and research: systematic monitoring of truck traffic and truck costs to evaluate regulatory effectiveness, basic research on the relationship of truck characteristics to highway costs, and pilot studies to test new vehicles. The following are specific topics requiring research. Research on these topics should be conducted at congressional direction by the Institute. If a study topic is essentially related to an established responsibility of an existing DOT agency, the study should be conducted cooperatively by the Institute and that agency.
Evaluation of Enforcement Effectiveness
The TRB Truck Weight Limits committee recommended that Congress direct DOT to conduct research on methods of improving the enforcement of truck weight laws. The recommended study was to “identify specific techniques for improved enforcement and assess these techniques in terms of their impact on the … frequency of overweight trucks, … costs to enforcement agencies, and possible burdens on the trucking industry” (TRB 1990a, 24–25). This recommendation was not acted upon. Today, little more is known about enforcement effectiveness than at the time of the earlier TRB report. The study should be conducted and should include evaluation of the effectiveness of applications of automatic electronic vehicle identification and screening technology for enforcement.
Air Quality Impacts of Changes in Truck Characteristics
Basic data on in-use emissions of heavy trucks are extremely limited. Research is needed to develop and apply methods of measuring the in-use emissions of trucks as a function of vehicle dimensions and other relevant characteristics. Of equal importance, research is needed on how truck traffic volume, the performance characteristics of trucks, and the effect of trucks on the behavior of other drivers affect emissions of all vehicles on a road. The Institute should coordinate with the Environmental Protection Agency, state environmental agencies, and engine and truck manufacturers to develop a program that will provide the data needed to evaluate the effect of changes in size and weight regulations on emissions.
Relation of Truck Performance to Crash Involvement
A data collection and research program should be conducted to establish the links between crash involvement rates and the physical and dynamic characteristics of trucks, such as weight, braking, offtracking, and rearward amplification in double-trailer combinations. Truck manufacturers and carriers have a stake in the results of such research. Since only a well-funded effort with access to industry data would have a good chance of succeeding, a government–industry consortium should undertake the initiative and underwrite its cost.
Risk-Based Bridge Costs
Correct methods should be developed for estimating the highway agency and user costs of impacts on bridges and structures caused by changes in the size and weight composition of the truck traffic stream. The methods developed should be based directly on risk assessment instead of on cost to comply with previously established engineering standards. The methods should incorporate estimates of changes in fatigue costs and in the useful lives of structures, derived from survey data collected according to a scientifically valid sampling plan. The methods should be capable of comparing the cost-effectiveness of alternative mitigation measures, including bridge replacement, bridge strengthening, and changes in bridge monitoring and weight enforcement practices. Congress should specify that the pilot studies and program evaluations conducted by the Institute include monitoring of bridge impacts.
Freight Transportation Market Research
A program of research should be carried out to develop predictive models of the effects of changes in truck costs on the volume of truck
traffic in the short and long run. To be successful, the research program will need to develop new databases on freight market transactions and shippers’ logistical decisions. As stated above, attempting to use truck size and weight regulation to manipulate truck traffic volumes or shippers’ industrial location decisions is not practical or desirable. However, better understanding of freight markets would be useful in evaluating proposed changes in regulations or in highway user fees.
Costs of Mixed Automobile and Truck Traffic Arising from Nuisance and Stress
Some costs of truck traffic have been overlooked in past studies. Motorists evidently often regard large trucks as a nuisance or a cause of stress. This reaction, one apparent source of public antipathy toward large trucks, may be independent of the effect of large trucks on accident risk and may constitute a cost of trucks that should be taken into account in policy evaluations, analogous to the environmental cost of highway noise.
The test to determine whether these possible effects are real costs that should be considered in evaluations of highway regulations is whether they lead to observable changes in travelers’ behavior. Therefore, research should be conducted to determine whether changes in the volume and characteristics of truck traffic on particular roads affect highway users’ route selection, time of travel, and frequency of trips, and to quantify the costs to travelers of any such impacts on behavior. If it is documented that such costs are significant, the research should investigate how their magnitude is affected by changes in truck size and weight regulations. Finally, the research should examine alternative measures for reducing these costs of car–truck conflicts through demand management, expansion of highway capacity, and applications of vehicle and road technology.
New Infrastructure Development and Truck-Only Facilities
Size and weight regulation is one aspect of the long-run problem of provision of adequate freight system capacity. Present trends in the growth of freight demand relative to capacity expansion, especially in certain high-density corridors, are not sustainable. Other modes will be part of the solution to this problem, but substantial expansion of truck capacity and better management of capacity will be needed.
One potentially important form of new infrastructure development is exclusive truck facilities. Such facilities are already being planned in
a few locations, but experience and analysis have been insufficient to indicate the scope of their practical application. A planning and research program should be conducted to determine what conditions would render exclusive truck facilities economically feasible. The research should include examination of alternative forms of private-sector participation in the development of such facilities and of how their feasibility would be affected by changes in user fee policy for the highway system as a whole.
A related and more general problem is provision of infrastructure required for goods movement in the urban environment, especially in older cities. Research is needed to identify the full range of best practices and innovative techniques available for retrofitting and upgrading facilities and to understand the costs and benefits of the growth of urban freight traffic.
U.S. Department of Transportation
Transportation Research Board
Bureau of the Census. 1999. 1997 Economic Census: Vehicle Inventory and Use Survey: United States. Oct.
DOT. 2000. Comprehensive Truck Size and Weight Study. Aug.
TRB. 1990a. Special Report 225: Truck Weight Limits: Issues and Options. National Research Council, Washington, D.C.
TRB. 1990b. Special Report 227: New Trucks for Greater Productivity and Less Road Wear: An Evaluation of the Turner Proposal. National Research Council, Washington, D.C.