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27 generates a "Driver Report Card" for each trip. The com- onboard electronic data recorders. Wireless transmission of pany's safety director reported that driver acceptance of the vehicle condition data to roadside enforcement is an emerging monitoring was good and that the drivers even "make it a capability, with potential efficiency benefits to commercial competition" to see who can earn the best scores. transport and safety benefits to everyone. Such monitoring can potentially include brake adjustment and condition (the most Zuckerman (2009) described various fleet efforts to train common vehicle-based problem in inspections and crashes), drivers to decrease their fuel consumption, with associated tires, lighting, and vehicle weight. safety benefits. One fleet owner interviewed identified "high acceleration and jack-rabbit starts-and-stops" as the principal Tire pressure monitoring exemplifies truck vehicle condi- targets for remediation. Minimizing speeds per se is less impor- tion monitoring, and is relevant to both safety and efficiency. tant than minimizing rapid accelerations and decelerations. In the LTCCS, 1.1% of at-fault truck crashes were caused Training and other practices suggested included: primarily by tire failure. The percentage was much higher for STs (2.2%) than for CTs (0.7%; Knipling and Bocanegra Use of speed limiters to eliminate the highest speeds; 2008). Poor tire condition is the second most common vehi- Instrument panelmounted fuel-use displays to give cle source (behind brakes) of violations in truck roadside drivers feedback on fuel use; inspections. Many of these crashes and violations could be Training drivers to resist the urge to speed up for yellow avoided by proper tire care and regular inspection. The most lights, but rather to anticipate light changes and coast common cause of tire failure is underinflated tires, which can slowly to stops; become overheated and have excessive sidewall flexing Use of cruise control; (Freund et al. 2006; Knipling 2009). A 2003 study of large- Monthly analysis of individual driver fuel use and driving truck tire inflation (Kreeb et al. 2003) found that many fleet patterns; operators do not perform the regular tire pressure maintenance Rather than discipline, emphasis on rewards and recog- recommended by tire manufacturers. The study reported that: nition for best performers; and For large fleets, extending the training and rewards up Approximately 7% of CMV tires tested were under- the line to fleet managers and supervisors. inflated by 20 psi or more. Only 44% of tires were within 5 psi of their specified No item addressing fuel economy monitoring was on the target pressure. safety-manager survey form, but one was added to the other- Tire-related costs were the single largest maintenance expert form. Respondents rated the item, "Monitor fuel econ- expense for CMV fleets, averaging about 2 per mile or omy for individual drivers and provide feedback" on a -3-to-+3 about $2,500 for an annual 125,000-mile operation. Likert scale. The mean rating assigned by 31 respondents was Improper inflation raised total tire-related costs by $600 +0.7, near the grand mean rating for the 16 items rated. to $800 annually per tractor-trailer combination. Improper tire inflation increased annual procurement MONITORING VEHICLE CONDITION costs for new and retreaded tires by 10% to 13%. Larger fleets are generally more systematic and rigor- Automatic monitoring of vehicle condition was not included ous than smaller fleets with regard to tire pressure and in the project survey but was cited by several case study inter- other tire maintenance. viewees as a growing application with both safety and effi- ciency benefits. Mechanical maintenance deficiencies are far An FMCSA safety technology product guide, available on more common in large trucks than in light vehicles because of its website, describes various types of tire pressure monitoring their larger number of components and their more continuous systems (TPMS) available from nearly 20 vendors (FMCSA use. In the LTCCS, 40% of crash-involved trucks had some Technology Division 2010b). These devices also save pre-trip vehicle-related deficiency or malfunction, and the presence inspection time, improving operational efficiency. Flanigan of such deficiencies was strongly associated with fault in (2010) reported that approximately 5% of fleets use TPMS. crashes. Mechanical failures were much less frequently a prin- The small system penetration was said to be the result of fleet cipal cause, however. Overall, about 4% of LTCCS truck concerns about system reliability, maintenance costs, and ini- crash involvements were assigned a CR of vehicle mechani- tial costs. This situation may be changing rapidly, however. In cal failure, with another 2% as a result of cargo shifts. Transport Topics, Reiskin (2010) reported a survey of man- agers of large U.S. fleets finding that 43% use TPMS. Wide- As discussed in the section on preventive maintenance ear- spread use of TPMS by large fleets may portend greater lier in this chapter, almost all successful motor carriers prac- penetration across all fleets. tice systematic PM. By regulation, drivers are required to make pre-trip vehicle inspections each day. To supplement these Challenges associated with the use of TPMS include proper measures, numerous automatic vehicle condition monitoring training for maintenance staff, consistent and correct use of technologies are penetrating the fleet. These can provide con- data from the systems, and disciplined inspections and track- tinuous monitoring and feedback to drivers and recordings to ing of the sensor systems themselves to ensure that they do not