- Report Published -
|Deceleration Lights on Trucks|
|Virginia Transportation Research Council|
|SJR 247 (Regular Session, 1993)|
|History has shown that innovations in motor vehicle safety equipment can significantly improve highway safety. At the same time, the uniformity of signaling systems and the need for appropriate standards to regulate those systems are factors that are critically important to highway safety. The balancing of these two interests is the subject of extensive state and federal regulation. Ideally, the goal of that regulation should be to foster innovation without sacrificing highway safety.|
This, it seems, is the larger issue raised by Senate Joint Resolution No.247, requesting from the Department of Motor Vehicles, the Center for Innovative Technology, the Motor Carrier Division of the State Corporation Commission, and the Department of State Police a study of (1) the desirability of allowing deceleration lights on trucks in the Commonwealth, (2) the types of deceleration lights that currently exist, and (3) the appropriate standards that should govern their use. This study answers the specific questions raised by the General Assembly and in the process offers a solution for the larger issue. It is likely that these questions would never have come before the legislature had a mechanism been in place to resolve the dispute between the proponents of innovation, in this case Mr. Emory Lariscy and his associates, and the state officials charged with protecting highway safety, the State Police. Hopefully, this study will accomplish more than a resolution of the dispute with respect to deceleration lights on trucks. Hopefully, it will initiate the development of a mechanism for dealing with similar disputes in the future.
The steps taken in pursuance of this study included (1) the assembly of a steering committee, (2) an extensive literature survey, (3) a visit to the company that is seeking to market Mr. Lariscy's system in Virginia, (4) analysis of the problem that deceleration warning systems on trucks propose to cure, (5) research into the state and federal law regulating and establishing standards for motor vehicle safety equipment, and (6) analysis of the assembled information in order to answer the three questions posed by the General Assembly.
In answer to the first question, what types of deceleration lights currently exist, it was discovered that a great variety of systems have been developed and tested. The most common type of system, and the category that includes Mr. Lariscy's system, is the accelerator position signal. The principal function of these systems is to signal to the following motorist that the driver of the leading vehicle has lifted his or her foot from the accelerator. A second category of deceleration warning systems includes enhanced brake signaling (EBS) and true deceleration signaling (TDS) systems. These systems use signal lamps to communicate the severity of braking or actual deceleration of the vehicle.
A third category of deceleration warning systems includes systems, including Jake Brake lights, that operate to warn the following motorist of the use by the leading vehicle of a Jake Brake or some other alternative braking system. The final category of deceleration warning systems is the pre-brake signal or advance braking light device (ABLD), a refinement of the accelerator position signal that operates not on the basis of the release of the accelerator but according to the speed at which the accelerator is released.
It was also discovered that there are enhancements available to augment standard signaling and safety systems that may accomplish the same purpose as a deceleration warning system. These enhancements include fast-rise brake lamps, which shorten the time it takes for brake lights to reach effective luminescence, and conspicuity treatments, which use reflectorized materials to make trucks more conspicuous.
Statistical analysis of the extent of the problem that deceleration warning systems on trucks propose to cure (i.e., car-into-truck rear-end collisions) yielded an estimate of the costs to the Commonwealth in terms of crashes and lives lost that amounted to 1,000 crashes and more than 20 deaths each year. This suggests that car-into-truck rear-end collisions are not the most serious highway safety problem in the Commonwealth but are a problem that is certainly worth thinking about.
Motor vehicle safety equipment is heavily regulated under both federal and state law. This is an important consideration for both the question of desirability and the question of appropriate standards. Deceleration warning systems are not explicitly covered by federal regulation, which leaves it to the states to regulate and establish standards for their use. The states are, however, con-strained by the federal requirement that supplementary lighting equipment not impair the effectiveness of federally mandated lighting equipment. The National Highway Traffic Safety Administration (NHTSA) has interpreted that requirement to mean that Virginia could permit the use of deceleration warning systems so long as the signal lamps used are red or amber and operate in a steady burning mode. The Federal Highway Administration (FHWA) has added a prohibition against amber signals on the rear of commercial vehicles.
Virginia law states that unless a lighting device is required by federal law or required or permitted in the Code of Virginia it must be approved before use by the Superintendent of State Police. The Superintendent is required, before approving the use of a lighting device, to see that the device complies with recognized testing standards. No recognized standard for deceleration warning lights exists, which forces the developers of deceleration warning systems either to go outside the Commonwealth to develop their systems and generate information that could serve as a basis for appropriate, recognized standards or to seek tacit approval for their systems in the Code of Virginia. There is little doubt that highway safety in Virginia is benefited by the requirement that all lighting devices on motor vehicles comply with recognized standards. Unfortunately, Virginia loses inasmuch as there is currently no mechanism providing for the Commonwealth's involvement in the development and revision of those standards.
Seven other states make reference to deceleration warning systems in their regulations or codes. California and Washington are the states that have gone to the greatest effort, including in their regulations technical standards for the systems they have allowed. Even though allowable under the laws of these states, deceleration warning systems have failed to achieve even nominal use. And, at this point, many of the state regulations are in conflict with positions recently adopted by NHTSA and FHWA.
The second question posed by the General Assembly, whether it would be desirable to allow the use of deceleration lights on trucks, is more tenuous than the first. Relying on past studies and the observations of motor vehicle safety researchers and administrators, a compilation of the factors weighing in the consideration of desirability has been constructed. These factors include the need for signaling systems to deliver a familiar, consistent message and to do so without generating ambiguous or false signals. Systems must also comply with legal barriers intended to protect the effectiveness of required lighting and signaling systems. Systems should not be prone to problems in installation and adjustment that would alter the nature of the signals they deliver. And finally, systems should be uniform in the message they deliver, which emphasizes the need for recognized standards and suggests the need to avoid having a great variety of systems in use.
Because this study specifically addresses the desirability of allowing deceleration lights on trucks, as opposed to all vehicles, it was important to consider the ways in which trucks are particularly desirable or undesirable vehicles for the use of such lights. It is apparent that trucks are more likely than a passenger vehicle to obstruct the view of a following motorist of the traffic ahead. Trucks give fewer cues of the severity of their braking than a passenger vehicle. And the lighting systems on the rear of trucks, in particular straight trucks, are in many cases substantially inferior to what is typical on passenger vehicles. These factors argue that trucks are a relatively desirable platform for deceleration lights.
Alternatively, performance differences between trucks and passenger vehicles suggest that car-into-truck rear-end collisions are principally a product of human error and may not be solved by additional signals on trucks. Trucks are also working vehicles, and the wide-ranging differences in configuration among trucks may complicate the need for uniformity in mounting and placement of signal lamps. A great number of trucks are engaged in interstate commerce, and systems approved for use in Virginia may be illegal in other states. Finally, the FHWA position on amber- lamps on the rear of commercial vehicles limits most trucks to using red lamps as deceleration warning signals. These considerations undermine the desirability of allowing deceleration lights specifically on trucks to a great extent.
Accelerator position signals (APS), including the Lariscy system, were analyzed according to the factors noted above and were found, despite their intuitive merit, to be undesirable. Prior studies have shown that APSs will not consistently convey useful information to a following motorist and that, in fact, when they do convey useful information the following motorist is likely to be unresponsive to that information as a result of the false or meaningless signals that have previously been given. One study suggested that APSs tend to create visual noise that could lead to disturbances in traffic flow. The APSs may also pull the concentration of the following motorist away from the leading vehicle's brake lights. Refinements have been made to APS systems to reduce their propensity to generate false signals, but in certain cases these refinements eliminate a greater part of the systems' usefulness. In the end, APSs are not a desirable type of deceleration warning light to allow for use on trucks in the Commonwealth.
Enhanced brake signaling (EBS) systems and true deceleration signaling (TDS) systems, although they avoid the false signals given by APSS, are similarly undesirable. These systems communicate the severity of a vehicle's deceleration based on one of two reliable indicators: braking force or actual deceleration. These systems were tested, with what appeared to be great success, in a study conducted in California in the early 1970s using a fleet of taxicabs. The results of this study are called into question, however, by concerns on the part of the California Highway Patrol that the reduction in collisions may not in fact have been due to the enhanced signal on the cabs but instead to the excessive brightness of the signal, and by a later study that showed identical results for vehicles using enhanced signals and vehicles using standard signals. The evidence in favor of EBS and TDS systems, therefore, is not convincing. The usefulness of EBS and TDS systems is further called into doubt by the evidence from prior studies that most car-into-truck rear-end collisions occur not in emergency braking situations, where an enhanced signal might be useful, but in situations where a truck is moving slowly or is stopped in traffic. And flashing signals, on which many of these systems rely, are not allowable under NHTSA's recent interpretation of the relevant federal regulations.
Jake Brake lights and other deceleration warning systems that indicate to the following motorist that an alternative form of braking is being employed by the leading vehicle are desirable. Jake Brakes are widely used by operators of large diesel trucks and may in some instances supplant friction brakes as the primary means of braking used by truck drivers. These types of systems are allowable under NHTSA's recent interpretation of the relevant federal regulations and suggest few problems in terms of false signals or inconsistent messages. Instead, they would provide a useful signal that a braking device is engaged and the driver intends to decelerate the vehicle.
ABLDs face both the false signal problems of the APS systems, and the limited usefulness of EBS and TDS systems, and are therefore undesirable. The study that was conducted of an ABLD suggested that the system was susceptible to adjustment problems, and these devices may, in any case, be prohibited by NHTSA's position on flashing lights.
Fast-rise brake lamps are in themselves not a deceleration warning system, but a potential enhancement to existing brake light systems. As such, they seem desirable. In shortening the time it takes for brake lamps to reach effective luminescence, they would not alter the existing signal but instead would get it there faster. The value of that improvement in terms of crashes prevented and lives saved is unknown. But fast-rise brake lamps certainly deserve further investigation.
NHTSA has been active in adopting or revising federal regulations over the last 10 to 15 years in ways that bear directly on the desirability of any action Virginia might take with respect to deceleration lights on trucks. The agency has addressed the same problem addressed by this study in three important ways: (1) by revising the regulations concerning rear underride guards on truck trailers, (2) by adopting new rules relating to conspicuity treatments on trucks, and (3) by requiring the use of center high-mounted stop lamps (CHMSL) on passenger vehicles and light trucks. Each of these actions suggests that as a result there is less for the states to do, and over time there should be less of a problem. With particular regard to the CHMSL, NHTSA's success with that device has lessened the chances that deceleration warning signals will ever be allowable on passenger vehicles or light trucks.
The one implication that arises from this that encourages state action is the fact that it takes an immense amount of time, and often the support of the states, to accommodate innovation in motor vehicle safety equipment at the federal level. It is for that reason that this study, in answering the General Assembly's third question, what are the appropriate standards that should govern the use of deceleration warning lights, has developed two proposals that would go hand-in-hand in creating a mechanism for state involvement in standard set-ting and innovation for motor vehicle safety equipment. The first of those proposals suggests that Virginia should work together with other states to reestablish and fund the Vehicle Equipment Safety Commission (VESC) as a standard-setting organization for items of motor vehicle safety equipment that fall into the 'no-man's land' outside of the federal motor vehicle safety standards. The second proposal suggests that Virginia should consider adding a provision to the Code of Virginia that would allow for experimental testing of motor vehicle safety equipment on the highways of the Commonwealth through a permit system administered by the State Police.
These recommendations are intended both to answer the questions put by the General Assembly and to suggest means by which the Commonwealth might accomplish the dual goals of providing for innovation in the future while maintaining highway safety today.