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74 SECTION IX Special Vehicles Planning Programs Aimed · Volume 22: A Guide for Reducing Collisions Involving Mo- at Reducing Crashes Involving torcycles (pending) Large Trucks and Motorcycles A link to these downloadable guides can be found at http:// This section of the guide provides the details of choosing safety.transportation.org/guides.aspx. treatment strategies for reducing crashes involving special ve- hicle types, such as large trucks and motorcycles. As indicated earlier, it is assumed at this point that the analyst has chosen Procedure 3 Choosing Treatments his or her emphasis area or areas (e.g., large trucks or motor- and Target Subgroups for Crashes Involving cycles) and has established a stretch goal for crash reduction. Special Vehicle Types When Treatment Four procedures for choosing and targeting treatment strate- Effectiveness in Terms of Crash/Injury gies were described in the Stage 3 text in Section III. Three of Reduction Is Not Known those procedures require that the effectiveness of at least Again, the assumption here is that there is no known level some of the potential treatment strategies be known that the of effectiveness for the treatment strategies of interest no treatments have a known CRF or AMF. However, almost defined CRFs or AMFs. Thus, economic analyses like those none of the strategies in the guides related to these special ve- that are the basis for Procedures 1, 2A, 2B, and 4 are not pos- hicle types have known effectiveness. For that reason, only the sible for these treatments. This Procedure 3 is aimed at help- details of Procedure 3 will be covered in this section. If AMFs ing the analyst make an educated choice of which treatments are developed for treatments for these populations, or if the will be most effective in his or her jurisdiction, and to help the analyst is only interested in examining the few treatments analyst develop a targeting strategy for the treatment in cases with known AMFs, then the economic-based Procedures 1 or where it is not to be applied jurisdiction-wide (e.g., where 2 can be used. If AMFs exist for some of the treatments of po- specific vehicle subpopulations or roadway locations are to be tential interest but not for all (which will likely be the case in targeted). In general, within each user group, the choice the near future), Procedure 4 can be used. While the crash between alternative treatments will be based on the specific types will differ, details of the use of all three of these "known- nature of the population's crash problem, and the choice of effectiveness procedures" are provided in Section IV on target subgroups will be based on the determination of where "Roadway Segment Programs." the crash/injury problem of interest is found. A discussion of Thus, the basic steps in Procedure 3 presented below will be this more general procedure was included under the Proce- appropriate for all four of the special vehicle types covered in dure 3 subheading in Section III, and the reader should this section. The data will differ, but the basic procedure will re- review that section. main the same. The analyst is strongly urged to carefully review the material in each of the pertinent guides before beginning this planning process. These user-population-oriented guides Data Needs are found within the NCHRP Report 500 guide series. The The only required data for Procedure 3 are crash data that specific volumes pertinent to this section are: will allow the analyst to (1) isolate crashes involving the spe- cific vehicle types of interest (e.g., large trucks or motorcy- · Volume 13: A Guide for Reducing Collisions Involving Heavy cles), and (2) define crash types for these vehicle types that Trucks (13) would suggest strategies and target subgroups.
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75 To isolate crashes involving the vehicle types of interest, the a) The many potential treatments judged to be the most ef- analyst will need to examine the data formats/coding in his or fective, even given that effectiveness is unknown her crash file to identify variables that can be used in determin- b) The relative magnitude of the crash types and severity levels ing whether or not a given crash is a "target-population crash." that the treatment will affect Crash databases often categorize data for a given crash into up c) The cost of the potential treatments (either jurisdiction- to three subfiles (1) general accident/crash variables ("crash"), wide or per-mile or per-location) (2) variables for each vehicle in the crash ("vehicle"), and (3) d) Other technical or policy considerations variables for each occupant/person in the crash ("person" or "occupant"). The variable needed to determine whether a crash These factors must be combined in some fashion to decide involves a specific vehicle type is, by definition, found in the ve- which treatment to choose. While there are multiple ways of hicle subfile. Trucks and motorcycles are nearly universally making this choice, the following represents one such procedure. among the vehicle types identified explicitly in the vehicle sub- file data. There are state-to-state variations in the number and 1. Prioritize the specific user-population problem(s) to be nature of truck type categories that are explicitly identified in addressed. crash data. Motorcycles are virtually never categorized into sep- Here, the initial issue is whether to treat large truck arate motorcycle types in crash data. Example variables used to crashes, motorcycle crashes or both. This prioritization will identify these two vehicle types are shown in Exhibit IX-1 below. be based on the frequency and severity of the specific types Defining crashes that will guide the choice of treatment strat- of crashes by vehicle type occurring in an analyst's jurisdic- egy and the targeting of these strategies will require crash data tion. For each vehicle type, the analyst could begin the that includes specific variables and codes on such items as process by analyzing 3 to 5 years of crash data to determine location of crash (intersection vs. non-intersection, ramp vs. the frequency of each population. However, since some mainline); condition of driver (e.g., impaired, fatigued); driver crashes for specific vehicle types may vary in severity, total action prior to crash; driver license status (e.g., motorcycle crash frequency alone does not provide the complete an- license or endorsement); condition of vehicle, etc. Again, the swer. While an alternative is to restrict the analysis to only names of variables and the specific codes needed to conduct fatal and serious-injury crashes, this will severely limit the these analyses will vary from jurisdiction to jurisdiction. Ex- crash sample, and will also omit a large component of the hibit IX-2 provides some guidance concerning where example crash problem non-serious injury and no-injury crashes. variables related to some treatment strategies might be found. A better solution is to weight each crash for a given user population by an economic cost based on its severity, and then accumulate the total crash cost for each population. In Procedure the preceding sections of this guide, information on eco- As described in Section III, Procedure 3 has two basic steps. nomic cost per crash severity level was extracted from Crash First, choose the "best treatments" for the user population of Cost Estimates by Maximum Police-Reported Injury Severity interest (e.g., the large truck or motorcycle treatments most Within Selected Crash Geometries (22). Exhibit IX-3 presents likely to be applicable in a given jurisdiction) from among the those costs per crash. Costs for combinations of crash sever- set of all treatments presented in the applicable NCHRP Report ity levels (e.g., K+A crashes) are presented in that report 500 guides. Second, choose the subgroups of highway locations (22). This analysis of total crash costs per year will provide to which the selected treatments should be applied. As the analyst with overall information on which vehicle types described earlier in more detail, the choice of the "best treat- are most important in his/her jurisdiction. ments" from the listing of many potential user-population Note that the total crash cost calculated using these treatments can be based on the following factors: severity-based figures may not be as accurate for motorcycle Population Type Variable Crash Database Subfile Drivers of Heavy Trucks Vehicle Type Vehicle Motor Vehicle Body Type Vehicle Category Commercial Motor Vehicle Vehicle Configuration Commercial Cargo Body Type Vehicle Motorcycle Operators Vehicle Type Vehicle Motor Vehicle Body Type Vehicle Category Exhibit IX-1. Crash variables and subfile location by population type.
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76 Crash Type/Issue Variable Crash Database Subfile Intersection vs. Non- Relation to Junction Crash intersection; Ramp-related Type of Intersection Crash Traffic Control Device Type Crash or Vehicle Lane Departure (Potentially Accident/Crash Type Crash Related To Pavement Manner of Collision Crash Markings) Sequence of Events Vehicle First Harmful Event Crash Most Harmful Event Vehicle Crash Location (Off-road) Crash Vehicle Equipment Vehicle Defect Vehicle Problems Contributing Circumstances, Vehicle Motor Vehicle Fatigue-related Crashes Fatigue Involvement Captured under Person/Vehicle "Driver Condition" (If Available) Alcohol-involved Crashes Alcohol Involvement Crash Law Enforcement Suspect Person/Vehicle Alcohol Use Alcohol Test Person/Vehicle Violation Codes Person/Vehicle Speed-related Crashes Driver Action Prior to Crash Person (or Vehicle) Violation Indicated Person (or Vehicle) Contributing Circumstances Person (or Vehicle) Work Zone Crashes Work Zone Related Crash Roadway Condition Crash Driver Age Driver Age Person (or Vehicle) Occupant Age Person Seating Position Person Motorcycle Helmet Use Occupant Protection System Person (or Vehicle for Used Driver) Driver License Status/ Driver License Class Person (or Vehicle) Motorcycle Endorsement Driver License Status Person (or Vehicle) Violation Codes Crash or Vehicle Driver Clothing Driver Protective Equipment (maybe) Person or Vehicle Crash Location (for County Crash Targeting Treatments) City Crash Route Crash Milepost Crash Longitude/Latitude Crash Block Address Crash Speed Limit (for Use in Speed Limit Crash Developing Cost per Crash) Exhibit IX-2. Crash variables and subfile location by crash type/issue. Crash Severity Speed Limit Comprehensive Category Cost/Crash* < 45 mph $3,622,200 Fatal (K) > 50 mph $4,107,600 < 45 mph $195,700 Serious Injury (A) > 50 mph $222,300 < 45 mph $62,200 Moderate Injury (B) > 50 mph $91,600 < 45 mph $40,100 Minor Injury (C) > 50 mph $49,500 < 45 mph $7,000 No Injury (O) > 50 mph $7,800 * Crash Cost in 2001 dollars (22) Exhibit IX-3. Crash cost by crash severity and posted speed limit.
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77 and truck crashes as for crashes covered in other sections. maintenance problems (e.g., minimize roadway irregulari- The costs per crash in Council, et al. (22) were based on the ties such as potholes and lower manhole covers, reduce full distribution of crashes and vehicles in crashes, and thus roadway debris, reduce or eliminate use of low traction are predominately weighted by passenger vehicles. They materials in roadway markings). It does not appear that are not based exclusively on truck or motorcycle crashes. examining only crashes related to poor road condition Thus, they are based to some extent on the expected num- would capture all applicable motorcycle crashes. However, ber of occupants in all crash-involved vehicles who might one could examine motorcycle crashes occurring in work be injured or killed in a crash of a given severity. Since zones to determine the possible problem size for the strate- heavy truck and motorcycle crashes involve a different mix gies related to those zones. It would also be possible to of "occupants" than passenger cars, these figures may not identify alcohol-related motorcycle crashes and crashes be totally accurate. In the absence of other crash-cost fig- involving motorcycle operators who are either unlicensed ures, it is suggested that these be used for motorcycle or not licensed to operate a motorcycle. With respect to crashes. They could also be used for truck crashes for con- strategies related to protective equipment, it will be difficult sistency with other vehicle types. However, a second study to identify crashes where more protective or more reflective by Zaloshnja and Miller (28) presented costs specific to clothing might be needed, but will be much easier to truck-involved crashes. Exhibit IX-4 presents cost- identify crashes in which the motorcycle operator was not per-crash by crash-severity level for "all large trucks" from wearing a protective helmet. that report. The Zaloshnja and Miller report (28) does not In order to analyze the possible benefit of those truck or categorize the cost by crash types or speed limits, but does motorcycle strategies targeted to specific crash types or categorize them by different large truck types (e.g., straight user subpopulations, crashes involving only the applicable trucks, bobtail, truck-tractor with one trailer). Note also subpopulations can be identified using variables in the that crash costs shown here are converted from Year 2000 table above (e.g., motorcycle operators not licensed to costs in Zaloshnja and Miller to Year 2001 costs to be operate a motorcycle) and can be analyzed. Here, just as consistent with other costs in this guide. The conversion in Step 1, the prioritization of subpopulations can be was based on changes in the Consumer Price Index and based on the frequency and severity of the specific types of followed procedures recommended in that report. user-subpopulation crashes occurring in an analyst's 2. Prioritize the specific subpopulations to be addressed. jurisdiction. For each user subpopulation or crash type, Once one or more populations are identified, the second the analyst could analyze 3 to 5 years of crash data to step involves the identification of subgroups in most need of determine the frequency of each crash population. Again, treatment. Most of the strategies in the heavy truck guide are either total crashes or some subset (e.g., fatal and serious- applicable to all truck crashes. Thus all crashes involving injury crashes) could be used, but the economic cost of heavy trucks are treatable with these strategies. However, crashes is a better measure since crash severity may differ. there are three truck strategies that appear to be more appli- The cost figures presented above could be used. cable to only selected crash types. The strategy related to 3. Identify possible treatments for use for each high-priority truck rollover on interchange ramps is focused on this type crash type. of crash at this type of location. Strategies related to truck The analyst will then review the pertinent NCHRP Re- mechanical failure might be targeted to crashes involving port 500 guides and list treatments that would be most ap- truck defects, and the parking-related strategies might be propriate for each of the high-priority crash types identi- considered applicable to fatigue-related truck crashes. fied in the above step. The choice should be limited to Many of the strategies in the motorcycle guide are also those treatment strategies that are classified as proven or applicable to all motorcycle crashes. In the cases of the road- tried in the guides. way-related strategies presented there, it is difficult to define 4. Rate the possible treatments based on "estimated specific crash types that might be analyzed since many of effectiveness." these are suggestions for changing roadway design and Since this procedure deals with treatment strategies with unknown effectiveness, this appears to be impossible. Crash Severity Comprehensive Cost/Truck Crash* However, for a given set of possible treatments for a par- ticular vehicle type, it may be possible to make a judgment Fatal (K) $3,370,648 Serious Injury (A) $138,841 concerning which treatment strategy would be expected to Moderate Injury (B) $62,779 be most effective. For example, strategies related to chang- Minor Injury (C) $52,412 ing the roadway may be more effective, in general, than No Injury (O) $10,713 strategies related to education (but, of course, will affect * Converted to 2001 dollars (28) only those users at the treated locations). At times, this will Exhibit IX-4. Truck crash cost by crash severity. clearly be a very difficult judgment to make.