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15 (RPC) is often an excellent source of traffic data, projections, service call logs, where the type and number of reported con- and other highway design and usage information. With a few cerns can be tracked by location. Customer service data, notable exceptions, court records are almost always obtainable including complaints from the public and their disposition, only at the local level (if at all). These may be used to track may provide useful information on problem locations or safety citations through the court processes, look at recidivism programs that are not functioning as designed. rates, and document the frequency of plea bargaining in traffic- related cases. Time Dimension of Data Some types of data used in safety planning by their nature Other Safety Files cover specific time periods. For example, crash data and cita- A variety of other files that might be useful in safety studies is tion data document events that occurred at a specific time, sometimes available in a jurisdiction. Speed surveys are and data files generally cover a specified time period. collected by both state and local agencies. Note, however, that A second type of data file provides supplementary infor- since statewide speed surveys on Interstate roads were essen- mation gathered subsequent to a crash that, in order to be tially ended in 1995 with the repeal of the National Maximum useful, must be linked to the crash record. Examples include Speed Limit, there are very few jurisdiction-wide speed surveys medical records, which can be linked through the CODES conducted. Instead, speed surveys are usually conducted at spe- database, and trauma registry data. Such data may not cific sites where a change in speed limit is being considered or include the actual time or location of the crash and must, has been recently implemented. The speed data collected at therefore, be linked through the victim's identity. these "special" locations should not be considered good indica- A third type of data represents a snapshot of a population tors of jurisdiction-wide speeds. Thus, safety planning needing at a given point in time, but does not necessarily include the speed data will usually require in-field speed data collection. full history of that population. For example, driver history files Trauma registry data and emergency medical services typically include only drivers with active licenses at a specific (EMS) data can potentially be used to enhance the complete- point in time. The records for drivers who die or move out of ness of crash data in much the same way as medical records state are deleted, so a current driver "history" file does not nec- are used to enhance crash data through the CODES database essarily contain the history for all drivers during a given time (see above). Data on roadway maintenance histories includ- period. Planning based on complete driver history data may ing the types of maintenance actions and their locations and need to consider historical files as well as current files. dates may be useful in the development of safety plans. Because of their effectiveness in reducing fatalities and Closure serious injuries, perhaps the most important of the "other" safety data is occupant restraint (shoulder belt) use data In general, the most basic "Lack of adequate safety collected in each state since 1998 in compliance with TEA-21 safety data the police- data" is almost never a valid requirements. NHTSA developed detailed sampling criteria reported crash report will excuse for not developing a for this data collection, and produces annual reports on be available for use by ana- sound safety program. changes in restraint usage for all states (see, for example, http:// lysts in almost all state and www.nhtsa.gov/people/injury/airbags/809713.pdf). These local jurisdictions. The analyst will sometimes have to locate data are usually collected by the state Highway Safety Office and acquire the data. Procedures are presented in this guide (or Office of the Governor's Highway Safety Representative), that require only basic crash data. Additional non-crash data and data and information can be obtained there. (e.g., roadway inventory and AADT data) that can be used in Finally, public opinion and customer service data can planning safety efforts for roadway-, driver-, and vehicle- provide key inputs in the development of safety plans. Many based treatments are usually available for state-system road- highway agencies conduct or have access to results of surveys ways and sometimes available for local roads. With some of the general public or, more specifically, of motorists. For effort, additional supplemental files that can further enhance example, NHTSA has a requirement for telephone surveys to safety analyses can be located. In summary, "lack of adequate measure the effect of media-based public information pro- data" is almost never a valid excuse for not developing a sound grams. Some state and local agencies may maintain customer safety program.