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51 CHAPTER FIVE CONCLUSIONS AND FURTHER RESEARCH This report has gathered research, vendor, survey, and inter- sure to crash threats rather than improve direct responses to view data on commercial motor vehicle (CMV) transport risk crash threats. Many of the individual strategies may appear avoidance strategies; that is, ways in which motor carriers can to have the potential to reduce carrier crash rates by just a few conduct their operations and deploy their assets to minimize percentage points. Concurrently adopting multiple strategies, crash risk. In this context, risk avoidance can be distinguished, however, could result in significant carrier crash reductions. at least conceptually, from conventional risk reduction. Risk Considering these strategies is an attempt to broaden the scope reduction, constituting the majority of carrier safety efforts, of commercial vehicle crash analysis and prevention. This improves the safety performance of individual "assets"-- expanded perspective seeks to expand motor carrier safety that is, drivers and vehicles. Risk reduction usually involves management to include safety-proactive operational planning. making company investments in proven interventions, such as improved driver selection, training, management oversight, or vehicle safety equipment. These actions are often evaluated SAFETY-RELEVANT CARRIER EFFICIENCIES based on their benefits per unit of cost. Chapter two of this report presented the 15 categories of carrier efficiencies, along with a general conceptualization of As defined here, risk avoidance strategies may also be conceptualized as carrier efficiencies with potential benefits how these strategies work in crash reduction. The Haddon to safety. This is an easier and more inclusive way to define Matrix provides a general conceptual structure for identifying these approaches; hence the report title Safety Effects of Car- factors that influence crashes and outcomes. It divides the rier Efficiencies. The following specific carrier practices and crash scenario in terms of time frame (i.e., pre-crash, crash, operational issues were discussed: and post-crash) and in terms of the primary "actors" affecting the event (human, vehicle, and roadway and environment). Employing preventive maintenance (PM); For motor carrier safety, expansion of the Haddon Matrix is Reducing empty ("deadhead") trips; warranted to allow for both a broader time frame and more Minimizing loading, unloading, and related delays; prominent "actors." Expansion of the pre-crash time frame Optimizing routing and navigation: into pre-trip, pre-threat, and pre-crash impact facilitates con- Providing navigational and routing aids; sideration of carrier efficiencies and other strategies that Assigning familiar routes to drivers; avoid risk before that risk is confronted directly. Selecting road type: divided versus undivided roads; Avoiding work zones; Vehicle mechanical deficiencies are not among the top Avoiding traffic; proximal causes of commercial vehicle crashes, but they are Emphasizing efficient scheduling: optimal times for safe strongly associated with crash risk. Vehicle PM is reliably travel; practiced and strongly supported by safety-conscious carriers Avoiding adverse weather; and managers. Of practices presented in the current safety- Using higher-productivity vehicles (HPVs); manager survey, PM was both the most frequently used and Using onboard computers and mobile communications; the most strongly supported for safety. Most respondents also Maximizing team driving; used maintenance management software and supported its use. Using electronic onboard recorders (EOBRs); These products provide many specific useful applications. Optimizing fuel economy and safety: Using speed limiters; One of the simplest ways to improve safety through Monitoring driver fuel economy; and improved efficiency is to reduce empty backhaul trips ("dead- Monitoring vehicle condition. heads"). Reducing empty miles is primarily motivated by its financial benefits, but there is also a proportional safety These practices have in common that they are potentially time- benefit. Every empty mile avoided reduces crash risk without or cost-saving practices with concurrent safety effects, mostly reducing productivity and revenues. For-hire carrier empty benefits, of interest. Secondly, they are pre-trip or pre-crash miles have averaged about 20% of their total travel in recent threat interventions. They are deployment, operational, or years, but many efficient carriers are using web-based load driving-route selection practices that potentially affect expo- boards and other means to reduce their empty miles to as low

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52 as 10%. Reducing empty miles does not necessarily reduce exposure points, suggests an almost tenfold increase in risk carrier crash rate per vehicle-miles traveled, but does reduce in work zones. Thirteen percent of all truck crash involve- crash rate per unit of productivity, ultimately a more com- ments in the Large-Truck Crash Causation Study (LTCC) pelling metric. occurred in work zones, a percentage far above mileage expo- sure in work zones. Avoiding work zones was recognized by As with empty miles, lost time owing to truck loading and survey respondents as an important safety strategy. unloading delays is a form of asset underutilization. Such time delays are more insidious, however, as they are more In recent decades, all across the United States, traffic likely to affect driving performance. Drivers are generally delay has increased in urban areas, whether relatively small, unable to use waiting times for sleep or other restorative rest. medium-sized, or large. The recession of recent years has Hours spent waiting but awake contribute to driver fatigue caused only a slight and temporary dip in urban traffic. In later, on the road. Schedule pressure or frustration may cause larger urban areas, free traffic flow occurs reliably only drivers to speed or otherwise hasten their work unwisely. between 9:00 p.m. and 5:00 a.m. Predictable and signifi- Whereas system-wide technological changes may reduce the cant congestion lasts for about 3 hours during both morn- problem, the principal carrier countermeasure is to charge ing and evening peak hours. Increases in traffic density and detention fees to customers for excessive delays (usually those travel times generate disproportionate increases in interac- more than 2 hours). Charging detention fees appears to help, tions among vehicles and associated crash risk. Large-truck but does not eliminate the problem. naturalistic driving data suggest that driving in heavy traffic involves six times more risk than driving in lighter traffic. Smoother routing and navigation improve the efficiency About 45% of combination-unit truck (CT) driving and 57% of CMV operations. Each time a truck accrues unnecessary of single-unit truck (ST) driving takes place in urban areas, miles (or unnecessarily risks miles) because of poor routing, and trucks in the LTCCS were more likely to be at-fault in its equipment is not being utilized efficiently and risk has not multivehicle crashes in urban than in rural areas. Both safety- been minimized. Drivers also perform more safely when they manager and other-expert survey respondents recognized the know or can easily follow their routes. A distinction can be safety value of avoiding urban traffic. A new Freight Perfor- made between routing and navigation in CMV operations. mance Measures service available from the American Trans- Routing optimization generally refers to improvements in the portation Research Institute and FHWA provides extensive efficiency of the overall delivery operation. Navigation aids and detailed travel time data to allow carriers to adjust their are devices to help drivers make a particular point-A-to- operations toward faster Interstate highway freight lanes and point-B trip. Most responding carriers used or encourage use faster times for travel. Routing and navigation software ven- of global positioning system navigation systems by drivers. dors are making progress in incorporating traffic avoidance The use of truck-specific routing and navigation systems was into their programs. recommended by many. These systems help truck drivers avoid low underpasses and other large-truck hazards and Given the strong effects of traffic density on crash risk, one restrictions. These systems offer many more features in sup- would think that off-peak driving, particularly night driving port of trip management. A simple, non-technological way to when traffic densities are lowest, would always be safest. improve both efficiency and safety is to assign drivers familiar Opposing this idea is the concept that driver fatigue is great- routes when possible. est in overnight hours, particularly in early morning, between 3:00 a.m. and 6:00 a.m. The overall time-of-day distribution The safety advantages of divided over undivided highways of large truck crashes, available exposure data, and naturalis- are well known to highway engineers and safety researchers. tic driving studies suggest that day driving is more risky than Depending on the metric and study, undivided roads have night driving because of the presence of other vehicles. How- two to five times the risk of divided roads. Survey results ever, overnight driving clearly is more risky from the stand- indicate that responding safety managers also appreciated the point of driver alertness and asleep-at-the-wheel risk. In this safety of Interstates and other divided, limited-access roads project's surveys, both groups of respondents generally over undivided roads. Most responding companies encouraged considered day driving to be safer than night driving. One the use of toll roads by providing drivers with toll transponders conclusion consistent with all research reviewed is that the (e.g., EZ Pass) or fully reimbursing tolls. This prevents driver evening hours between 6:00 p.m. and 2:00 a.m. are probably diversion from toll roads onto smaller, higher-risk roads. among the lowest-risk travel times for large trucks. Given the disparity of research findings and opinions regarding other Highway work zones are very-high-risk areas for all times of the day, however, conclusive research on the issue is vehicles, especially large trucks. Crash threats in work needed. Reliable guidance on the question likely could reduce zones include constricted lanes, narrow or absent shoul- significantly the risk exposures of companies with time-of- ders, makeshift signs, and traffic backups where light vehi- day flexibility in their operations. cles may dart in front of trucks to move up in the queue. Large-truck naturalistic driving research, whereby the loca- Adverse weather is an obvious source of risk in driving and, tions of incidents can be compared with randomly selected when extreme, can be a direct crash cause. In the LTCCS, 14%

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53 of truck crash involvements had weather as an associated fac- for the case studies. The four topics are team driving, EOBRs, tor, but less than 1% of truck at-fault crashes were assigned a fuel economy and safety, and vehicle condition monitoring. weather-related Critical Reason (proximal cause). In other Brief discussions of each were provided. Team driving is an words, bad weather contributes to many truck crashes, but is efficiency practice because a long-haul, team-driven truck can the proximal cause of only a few. In this project's surveys, the legally be moving almost continuously during an extended factor "weather and roadway surface conditions" was consid- trip. Team driving has several important safety advantages. ered less important than enduring driver traits, temporary Most notably, the presence of another person in a vehicle driver states, and roadway characteristics and traffic condi- reduces unsafe driver practices, including the tendency to tions (e.g., road type). Only the factor "vehicle characteristics" continue to drive even when excessively drowsy. The major was rated as less important. These survey results are consistent disadvantage of team driving is that sleep in a moving vehi- with research findings. cle is usually lighter and less restorative. Still, a naturalistic driving comparison of team and solo driving found the inci- The question of truck size and crash risk is much like the dent rate among team drivers to be less than one-half that question of time-of-day and crash risk. Differences of opin- of solo drivers. ion abound, but it is difficult to draw reliable conclusions based on available research. Larger trucks might be safer if This report did not address regulatory or hours-of-service using them results in fewer trucks on the road and, therefore, (HOS) compliance issues relating to EOBRs, but did touch less exposure to risk. Smaller trucks might be safer if they are on their safety management applications. EOBRs are used individually less likely to figure in crashes or if their crashes voluntarily by a growing number of CMV fleets, and they are less severe because of their smaller size. In a current were cited as aids to both efficiency and safety by several analysis based on several data sources, CTs and STs were interviewees. By automating driver log-keeping, EOBRs found to have about the same total crash costs per mile trav- save drivers' time, streamline records and compliance man- eled. This replicates a finding of a previous study by Wang in agement, and provide a means for safety oversight of drivers 1999. However, one cannot base operational decisions on through quick identification of noncompliant drivers. EOBRs this finding, because the uses and road type exposures of CTs facilitate load assignments in larger fleets by identifying drivers and STs are different. Two major Canadian studies suggest with sufficient time available for the loads. Shackelford that HPVs can be operated with equal or lower crash rates and Murray (2006) found other EOBR benefits to include than one-trailer CTs. However, average crash severity of improved fuel consumption monitoring and fuel tax compli- HPVs may be much higher than that of CTs, which perhaps ance, quicker tabulation of driver mileage and loads, easier cancels out their potential safety benefits. Project survey tracking of vehicle and engine wear, and better communica- findings somewhat favor the use of larger trucks, but there tions and dispatching. are many contrary views as well. The link between fuel economy and safety was noted by Commercial vehicle onboard computers and mobile com- several interviewees, and is well established by research. munications (also known as telematics) cover a wide range Improved fuel economy is achieved in large part by changes in of potential applications for operations and safety. Many of vehicle speed and driving style. These changes in turn produce these applications are beyond the scope of this report. The safety benefits such as reduced driver stress, crash likelihood, report discussion focused on those specific telematic appli- and crash severity. Two primary approaches to improving cations mentioned by motor carriers in project surveys and fuel economy with concomitant safety benefits are speed- interviews that relate to both operational efficiency and limiting vehicles and monitoring individual driver fuel con- safety. These were discussed primarily with regard to safety sumption. CTBSSP Synthesis Report 16 examined the safety benefits, though some concerns were expressed about safety impact of large-truck speed limiters. In its project survey, losses owing to driver distraction. Onboard computer and most carrier respondents indicated that speed limiters were communications suites are becoming complex and compre- either "successful" or "very successful" in reducing crashes. hensive fleet monitoring and management tools. Systems Almost all of them believed that speed limiters had no nega- allow central, real-time viewing of a vehicle's map location, tive effects on their company's safety and productivity. A moving speed, engine speed, battery and fuel status, and trip more direct method for improving fuel economy is to monitor history. Vehicle component (e.g., brake, tire) condition mon- fuel use of individual drivers and trips. A capability for onboard itoring is also available. Systems can be programmed to flag fuel consumption monitoring is commonplace in today's any trouble indicator, whether it relates to vehicle function- trucks. Almost all of the project case study companies mon- ing or driver behavior. A safety concern arises, though, with itor individual driver fuel use and component behaviors, regard to driver use of onboard systems during driving. Some such as hard braking and speeding. For example, Carrier J, carriers program their onboard systems to withhold visual a small charter bus company, uses onboard safety monitor- displays from drivers when vehicles are moving. ing of driving behaviors and fuel use. The system generates a "Driver Report Card" for each trip. Driver acceptance of Four topics were added to the study based on comments the monitoring has been good; they "make it a competition" by carrier safety managers on project surveys and interviews to see who can earn the best scores.