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3BACKGROUND There are two broad ways in which motor carriers can improve the safety of their operations. One is to improve the safety performance of their individual âassetsââthat is, drivers and vehicles. Improving the safety performance of individ- ual drivers and vehicles almost inevitably involves resource expenditures, such as spending more time and money on driver selection, training, management oversight, or vehicle safety equipment. These are proven ways to enhance safety. Another method is to deploy the same assets in ways that minimize risk and increase opportunities for successful per- formance. This might be considered analogous to the decisions a football coach makes on game day. The potential perfor- mance capabilities of individual âassetsâ (players) are largely established before the game, but the coachâs lineup decisions and plays called during the game greatly affect team success. These methods do not primarily involve increased resource expenditures, but rather resource deployment decisions. Various aspects of motor carrier safety management might be considered risk avoidance as opposed to direct risk reduc- tion through safety performance enhancement (Dewar and Olson 2002; Murray et al. 2003; Knipling 2009). These include strategies such as the following: â¢ Emphasize scheduled, preventive maintenance on trucks, as opposed to reactive repairs; â¢ Minimize deadhead (empty trailer) trips; â¢ Minimize loading, unloading, and related delays; â¢ Optimize routing and navigation; â¢ Maximize travel on divided, limited-access roadways; â¢ Minimize travel on undivided roads; â¢ Avoid work zones; â¢ Avoid peak hours and congested roads; â¢ Avoid adverse weather and slick roads, when possible; â¢ Assign familiar routes to drivers; â¢ Encourage driving at off-peak times, when feasible; â¢ Optimize the mix of vehicle sizes (e.g., in some opera- tions, use larger trucks to reduce the number of trips); â¢ Use onboard computers; â¢ Use mobile communications; â¢ Use driver teams; â¢ Use electronic onboard recorders (EOBRs); â¢ Improve fuel economy; and â¢ Monitor vehicle condition continuously. Some strategies in this list are already in widespread use (Corsi and Barnard 2003; Knipling et al. 2003; Belella et al. 2009). Others are well established by research, yet not neces- sarily appreciated by industry. Still others have clear ratio- nales, but are not firmly based on comparative data. Some risk avoidance strategies require proactive, executive-level strate- gic decisions by carriers. Others are dispatch and routing deci- sions made by operational managers, dispatchers, or drivers themselves. All involve operational efficiency measures with potential safety benefits when implemented intelligently. This synthesis report reviews the rationales and evidence for these risk avoidance strategies, and reports survey findings on their advisability, use, and perceived safety effects. Motor carrier executives and managers are the principal target audi- ence, though government and industry officials involved in highway operations, regulations, or outreach may find some results relevant. Many study topics are more relevant to truck- ing operations than to buses, primarily because trucking opera- tions permit greater flexibility. Nevertheless, the study gathered data from both truck and bus sources, and provides findings relevant to both of these commercial vehicle types. Overview of Crash Risk Avoidance Operational risk can be seen within the context of crash risk in general. Crash risk factors may be distinguished from prox- imal causes. Risk factors exist before the crash event and affect the probability of a crash (Dewar and Olson 2002; Evans 2004; Shinar 2007; Knipling 2009). Much of road safety research seeks to identify crash risk factors and reduce risk. For example, the U.S.DOT Large Truck Crash Causation Study (LTCCS) was done to âidentify associations between various factors and an increased risk of crash involvement in either relative or absolute termsâ (Blower and Campbell 2005). Crash proximal causes, termed Critical Reasons (CRs) in the LTCCS, are the critical driver errors or other failures (vehicle, roadway) immediately preceding and triggering crash events. Figure 1, adapted from Knipling (2009), shows a simple time line of crash risk, cause, and occurrence. Both crash risk fac- tors and causes may be human, vehicle, or environmental. Most proximal crash causes are human errors. In the LTCCS, CR assignments were 89% driver errors, 8% vehicle failures, and 3% roadway and environmental factors (Starnes 2006). The risk time line in Figure 1 is extended to the left to show pre-trip and pre-crash threat periods. The operational practices CHAPTER ONE INTRODUCTION
4FIGURE 1 Risk-cause crash timeline with extended pre-crash risk segments. Adapted from Knipling (2009). FIGURE 2 Relative risk by vehicle speed. 84% %36%61 â¤ 50 mph 37% Exposure Incidents 51+ mph discussed in this report all fall into one or both of these periods. Pre-trip practices that affect risk include preventive maintenance, trip scheduling, pre-trip route optimization, and use of driver teams. Pre-crash threat practices include route selection to avoid undivided highways, traffic conges- tion, and work zones. The dotted lines between the risk zones denote that many risk avoidance practices operate across the zones. The next chapter will extend this conception into a two-dimensional framework for commercial motor vehicle (CMV) risk avoidance strategies based on the Haddon Matrix of road safety (Haddon 1980) and subsequent elaborations by CMV safety researchers (Faulks and Irwin 2002; Murray et al. 2003, 2009). Efficiency and Safety Example: The Speed Paradox Are trucks safer when traveling fast or slowly? The answer provides a prologue to several of the operational efficiencies discussed in this report. On one hand, driving too fast for existing conditions is the leading proximal cause of large- truck crashes. In the LTCCS, âtoo fast for traffic or road con- ditionsâ was the âCritical Reasonâ for 21% of truck at-fault crashes, versus 17% for inattention or distraction, 12% for inadequate surveillance (âlooked but did not seeâ), 10% for all vehicle causes combined, and 7% for asleep-at-the-wheel (Starnes 2006). On the other hand, when one considers the entire fleet of vehicles operating at any time and the normal ranges of truck speeds (i.e., not traveling over the posted speed limits), fast travel appears to be dramatically safer than slow travel. This is demonstrated in naturalistic driving studies comparing exposure (based on a random sample of normal driving) to crash-relevant driving incidents (crashes, near-crashes, other traffic conflicts) captured in onboard recorders. Figure 2, based on data from an FMCSA-sponsored naturalistic driving study (Hickman et al. 2005), compares the vehicle speed pro- file of a random sample of driving (representing exposure) to vehicle speeds when incidents occurred. The first bar is the profile for exposure, the second the profile for incidents. For simplicity, just two travel conditions are shown: â¤50 mph and 51+ mph. Comparing the two bars, we see that slow travel is far riskier than fast travel, at least in regard to the kind of close traffic interactions captured in naturalistic driving. Trucks in the study were traveling at 50 mph or less only 16% of the time, but 63% of the incidents occurred at these slow speeds. The risk odds ratio is a statistical measure of the relative risk of two situations. In these data, slow travel was 8.9 times riskier than fast travel. The risk odds ratio was derived as follows: (63%/16%)/(37%/84%) = 3.94/0.44 = 8.9. This counterintuitive finding may be termed the speed paradox (Knipling 2009). Though excessive speed is a major cause of serious crashes, most safety incidents occur when commercial vehicles are traveling relatively slowly. To under- stand this, consider the situations in which commercial vehi- cles must drive slower than regular highway speeds. Slow travel is associated with heavier traffic, undivided roads, closer
5proximity to other vehicles, traffic signals, crossing traffic, and geometric constrictions such as narrow lanes, curves, and ramps. All of these road situations increase risk. Most of these especially elevate the risk of crashes with other vehicles, which constitute about 80% of large-truck fatal and injury crashes (FMCSA Analysis Division 2010). In contrast, fast travel usually means smooth and efficient flow. It follows that efforts to make commercial vehicle travel more efficient by avoiding potential delays are also likely to make that travel safer. This is a major theme of this report. National Significance and Future Trends This synthesis report focuses on carrier practices and the impacts of these practices measured from within carriers. Worth noting, however, is the aggregate national impact of carrier transport efficiencies. AASHTO (2010) recently pub- lished a report on freight mobility concerns in the present and, especially, for the future. The following excerpt from this Unlocking Freight report highlights the current and future national significance of CMV transport efficiency: â¢ By 2020, the U.S. trucking industry will move three bil- lion more tons of freight than we haul today. To meet this demand, the industry will put another 1.8 million trucks on the road. â¢ In 20 years, for every two trucks now on the road, there will be an additional one . . . carrying the expected growth in food deliveries, goods, and manufacturing equipment. â¢ In 40 years, overall freight demand will double, from 15 billion tons today to 30 billion tons by 2050. Freight carried by trucks will increase 41 percent . . . The num- ber of trucks on the road compared with today will also double. â¢ Between 1980 and 2006, traffic on the Interstate Highway System increased by 150%, whereas Interstate capacity increased by only 15%. â¢ On average, 10,500 trucks a day travel some segments of the Interstate Highway System. By 2035, this will increase to 22,700 trucks for these portions of the Interstate, with the most heavily used segments seeing upwards of 50,000 trucks a day. â¢ The amount of traffic experiencing congested condi- tions at peak hours in the nationâs most urban areas on the Interstate System [has] doubled from 32 percent to over 67 percent. â¢ Major highway bottlenecks at urban Interstate inter- changes cause tens of thousands of hours of delay each day, week, and year for truckers, business travelers, and commuters. Strings of bottlenecks are emerging along regional and transcontinental freight routes, creating corridors of congestion instead of corridors of commerce. â¢ Estimates of the truck hours of delay for the worst freight-truck bottlenecks show that each of the top 10 highway interchange bottlenecks cause over a million truck-hours of delay per year, costing $19 billion overall. â¢ Delays and idling trucks at bottlenecks and chokepoints exacerbate negative air quality impacts on the surround- ing communities. Unlocking Freight did not address safety concerns related to freight congestion. The speed paradox described previously, along with other evidence to be presented in this report, tes- tify to the adverse safety impacts of traffic congestion and other sources of travel inefficiency. PROJECT OBJECTIVES, METHODS, AND SCOPE This report on Safety Effects of Carrier Efficiencies synthe- sizes current information on carrier operational efficiencies, which may also provide safety benefits by decreasing expo- sure to risk. It provides information that may assist motor carriers in deploying their trucks and buses in ways that min- imize crash risk. The project has involved the following information-gathering activities: â¢ Research evidence and product review: â Research literature and trade press; â Crash and naturalistic driving statistics; and â Vendor products and services. â¢ Surveys: â Carrier safety-manager questionnaire; and â Other-expert (e.g., research, government, trade asso- ciation) questionnaire. â¢ Carrier safety-manager interviews (for case studies). The survey and interview methodologies are described in chapters focusing on those efforts. The research literature and vendor product review methodology is described here. Searches were done using websites, academic databases, books, trade press publications, and articles. The following databases were used to conduct the reviews: â¢ Transportation Research Information Database (TRID): Offers the largest online bibliographic database of trans- portation research, with more than 650,000 records of published research. â¢ Business Source Premier: Features the full texts of more than 2,200 journals. Full texts from as early as 1965 are provided, and searchable cited references, from as early as 1998. â¢ Lexis Nexis: Provides access to a multitude of popu- lar articles as well as some scholarly works. There is also access to congressional records, court decisions, and government statistical reports. â¢ EconLit: From the American Economic Associationâs electronic database, covers economic literature, with more than 735,000 records. These databases were searched using a variety of topic- related keywords and phrases, often in combinations to
improve focus. Keywords included: trucking, safety, crash risk avoidance, motor transport efficiency, truck routing software, preventive maintenance, traffic, road risk, safety strategies, construction, work zones, reversing safety, and efficiency benefits. The remaining chapters of this report present this informa- tion and draw conclusions regarding carrier efficiencies with 6 safety benefits or other effects. Chapter two presents evidence and product information relating to strategies potentially affect- ing efficiency and safety. Chapter three describes the methods and results of the project surveys. Chapter four presents several carrier case studies. Chapter five summarizes findings regard- ing current and emerging carrier practices, as well as needs and opportunities for further research. An appendix to the report provides the project survey forms.