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Acknowledgments US Department of Transportation - BTS

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NOP<strong>US</strong> was designed as a multistage probability sample to ensure that the results would represent occupantprotection use in the country. In the first stage, counties were grouped by regions (northeast, midwest, south, west),level <strong>of</strong> urbanization (metropolitan or not), and level <strong>of</strong> belt use (high, medium, or low). Fifty counties or groups <strong>of</strong>counties were selected based on vehicle miles <strong>of</strong> travel in those locations. In the next stage, roadways were selectedfrom two categories: major roads and local roads. Of the originally selected sites, some were found to be ineligibleduring mapping and data collection, and at some sites no vehicles were observed. In 2006, a newly designed sample<strong>of</strong> observation sites emerged; subsequent years’ NOP<strong>US</strong> surveys used a combination <strong>of</strong> sites from the old and newsamples. In 2009, a blend <strong>of</strong> 65 percent <strong>of</strong> sites were determined using the new methodology and 35 percent <strong>of</strong> siteswere obtained from the old methodology. In 2009, a total <strong>of</strong> 100,000 passenger vehicles were observed, down from116,000 in 2008. 947 motorcycles were also observed during the 2009 NOP<strong>US</strong>.Each reported estimate has been statistically weighted according to the sample design. Two kinds <strong>of</strong> error can beattributed to all survey research: sampling and nonsampling. A measure, called the standard error, is used to indicatethe magnitude <strong>of</strong> sampling error. The source information provides two standard errors along with each estimate.Nonsampling errors could include problems such as vehicles not counted, incorrect determination <strong>of</strong> restraint use,and data entry mistakes, among others.TABLE 2-31. Estimated Number <strong>of</strong> Lives Saved by Use <strong>of</strong> RestraintsThe U.S. <strong>Department</strong> <strong>of</strong> <strong>Transportation</strong>, National Highway Traffic Safety Administration (NHTSA) uses data obtainedfrom the Fatality Analysis Reporting System to calculate the number <strong>of</strong> lives saved by the use <strong>of</strong> restraints. Themethodology used is outlined in a NHTSA report, Research Note, Estimating Lives Saved by Restraint Use inPotentially Fatal Crashes (Washington, DC: June 1995). The general approach is to adjust the observed number <strong>of</strong>fatalities by a determined effectiveness rate for each type <strong>of</strong> restraint. This equates to subtracting the actual fatalitiesfrom the potential fatalities to determine the number <strong>of</strong> lives saved. This method is more accurate than earlierestimation methods since all calculations are derived from NHTSA's count <strong>of</strong> fatalities in which restraints were used.Reported restraint use is believed to be accurate for fatalities.The key to NHTSA's calculations is the effectiveness estimate for preventing fatalities for each type <strong>of</strong> restraint. Withthe exception <strong>of</strong> an adjustment in the effectiveness estimate for front outboard air bag-only restraint use in passengercars (NHTSA, Fourth Report to Congress, Effectiveness <strong>of</strong> Occupant Protection Systems and Their Use,Washington, DC, May 1999), a list <strong>of</strong> effectiveness estimates can be found in a NHTSA report, Estimating AlcoholInvolvement in Fatal Crashes in Light <strong>of</strong> Increases in Restraint Use, published in March 1998.This report alsoincludes additional references describing the determination <strong>of</strong> these effectiveness estimates.TRANSIT DATATABLE 2-1. <strong>Transportation</strong> Fatalities by ModeTABLE 2-2. <strong>Transportation</strong> Injuries by ModeTABLE 2-3. <strong>Transportation</strong> Accidents by ModeTABLE 2-4. Distribution <strong>of</strong> <strong>Transportation</strong> Fatalities by ModeTABLE 2-32. Transit Safety and Property Damage DataTABLE 2-33. Transit Safety Data by Mode for All Reported AccidentsTABLE 2-34. Transit Safety Data by Mode for All Reported IncidentsTABLE 2-38. Reports <strong>of</strong> Violent Crime, Property Crime, and Arrests by Transit ModeThe data for this report are obtained from the U.S. <strong>Department</strong> <strong>of</strong> <strong>Transportation</strong>, Federal Transit Administration's(FTA's) National Transit Database (NTD) Reporting System. Transit agencies are required to file an NTD report atregular intervals if they are recipients <strong>of</strong> Urbanized Area Formula Funds. In 2008, 692 agencies reported to the NTD.Of that total, 101 transit agencies received exemptions from detailed reporting because they operated 9 or fewer

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