modified to prevent owner or user changes to the speed-limit setting, and to prevent the feature from being turned off. These changes would be easy for vehicle and engine manufacturers to implement. Making these features sufficiently tamper-proof might prove to be a much greater challenge.

Road-speed governors on new trucks would be easy to implement in a relatively short time frame. Manufacturers will need to modify and validate their existing road-speed-governor features to meet the requirements of the new regulation. It would also be relatively easy to develop calibrations that could be retrofitted to existing vehicles with electronically controlled engines. Getting owners to bring in their vehicles for a retrofit calibration that includes a new road-speed governor might be very difficult, however. Most owners would try to put this off as long as possible, preferably for the life of the truck.

Older vehicles that have mechanical fuel systems could in theory be retrofit with road-speed-governors, but several issues would need to be overcome. First, systems would need to be developed for this market, and they would probably not be low cost. There were road-speed-governor systems for these vehicles many years ago, but they were not low cost or widely used. Second, some way to force implementation by owners would be required. These older vehicles tend to travel few miles per year, so the potential fuel savings is limited. The owners of older trucks often lack the money to pay for an upgrade. On the other hand, if older vehicles were exempt from the speed-governor regulation, this would increase the value of older vehicles and encourage these trucks to be maintained rather than scrapped. Since older trucks have much higher emissions, any incentive to prolong their life would not be desirable. Like many other good-sounding fuel-saving ideas, the unintended consequences of road-speed governing can outweigh the benefits if great care is not taken in implementation.

OTHER COMPLEMENTARY APPROACHES

Intelligent Transportation Systems

Intelligent transportation systems (ITS) encompass a broad range of wireless and wire-line communications-based information, control, and electronics technologies. When integrated into the transportation system infrastructure, and in vehicles themselves, these technologies help monitor and manage traffic flow, reduce congestion, provide alternate routes to travelers, and enhance productivity—all to improve mobility and safety. DOT has developed the National ITS Program Plan for ITS, which provides a new vision for surface transportation in the United States in the following areas:

  • Travel and transportation management

  • Travel demand management

  • Public transportation operations

  • Electronic payment

  • Commercial vehicle operations

  • Emergency management

  • Advanced vehicle control and safety system

The national ITS architecture (see Figure 7-2), provides a common structure for the design of ITS. It is not a system

FIGURE 7-2 U.S. national ITS architecture. SOURCE: FHWA (2008).

FIGURE 7-2 U.S. national ITS architecture. SOURCE: FHWA (2008).



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