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Effectiveness of Behavioral Highway Safety Countermeasures (2008)

Chapter: Chapter 4 - Estimation of Highway Loss

« Previous: Chapter 3 - Countermeasure Classification
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Suggested Citation:"Chapter 4 - Estimation of Highway Loss." National Academies of Sciences, Engineering, and Medicine. 2008. Effectiveness of Behavioral Highway Safety Countermeasures. Washington, DC: The National Academies Press. doi: 10.17226/14195.
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Suggested Citation:"Chapter 4 - Estimation of Highway Loss." National Academies of Sciences, Engineering, and Medicine. 2008. Effectiveness of Behavioral Highway Safety Countermeasures. Washington, DC: The National Academies Press. doi: 10.17226/14195.
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Suggested Citation:"Chapter 4 - Estimation of Highway Loss." National Academies of Sciences, Engineering, and Medicine. 2008. Effectiveness of Behavioral Highway Safety Countermeasures. Washington, DC: The National Academies Press. doi: 10.17226/14195.
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10 This chapter presents the estimated highway loss associ- ated with the target groups for which countermeasures have been developed. Highway loss can arise from both fatal and nonfatal injury. Property damage is not considered here because it is a relatively small proportion of all loss and is not consistently reported across the states. Target Group Size—Fatal Injury The countermeasures reviewed cover differing groups of road users and differing numbers of fatal and injury victims. For instance, some involve nonmotorists (pedestrians and cyclists), others involve alcohol, speed, motorcycles, belt use, teen drivers, etc. The size of each of these target groups varies substantially. Table 1 indicates the number of fatalities asso- ciated with each of the target groups and the percentage of all fatalities that each group represents. Note that the groups are not mutually exclusive. For in- stance, a single crash could involve a 16-year-old driver, dis- tracted, at night, who had been drinking. Target Group Size—Nonfatal Injury Fatalities are only part, and typically not even the major part, of overall highway loss. We estimate, based on Blincoe, Seay, Zaloshnja et al. (2002), that for every motor-vehicle- related fatality, there are 126 associated injuries (of any sever- ity). This figure refers to the overall injury-to-fatality ratio (i.e., 126/1). There is substantial variance in this ratio as a function of the target population. For instance, motorcyclists and pedestrians have different injury-to-fatality (i.e., injury/ death) ratios than do occupants of passenger vehicles. To estimate the injury/death ratio for each target group and then use such ratios to determine target group costs based on the Blincoe et al. report, this ratio was first calculated for each target population based on General Estimates System (GES) data for 2004–2006. The ratio for each subgroup was then divided by the ratio for all persons to provide an adjust- ment factor. For example, if the GES injury/death ratio for pedestrians was 21/1 and the ratio for all groups combined was 85/1, then the relative size of the injury/death ratio for pedestrians was 0.25 that of the overall group (i.e., 21/1 ÷ 85/1 = 0.25). This proportion (0.25) was then used to adjust the overall injury/death ratio calculated from the Blincoe et al. report (2002). Thus, if the pedestrian injury/death ratio was 0.25 of the overall injury/death ratio in the GES data set, then it was assumed to be 0.25 the overall injury/death ratio in the data used by Blincoe (126/1). Therefore, multiplying 0.25 by 126/1, the overall injury/death ratio from the Blincoe dataset resulted in an adjusted 31/1 ratio, which was used to estimate costs associated with both deaths and injuries. Adjusted ratios for various target groups are shown in Table 2. Taking pedestrians as an example, the final column in the table for adjusted ratios was obtained by determining what proportion of the all persons ratio is comprised of the pedes- trian ratio shown in the column for GES ratio relative to all persons (hence: 21/85 = 0.25), and adjusting the Blincoe et al. ratio by that factor to provide the data in the last column (125.95 × 0.25 = 31.49). The last column of Table 2 indicates the injury/fatality ratio used to estimate the benefits for each Proven counter- measure. Rounding, the first ratio shown is 126/1, which rep- resents the overall ratio calculated across all target groups. The next ratio is 31/1 for pedestrians (used in the previous example). Based on this procedure, motorcyclists have an injury/fatality ratio of 35/1. Both pedestrians and motor- cyclists are “unprotected” road users. The result is that these persons are far more likely to sustain fatal injury, as compared with a nonfatal injury, given that a crash has occurred. At the opposite end of the range are child occupants of passenger vehicles. They are highly protected by the car and by the fact that they are often in the back seat, sometimes in a child re- straint device. Their injury/fatality ratio is 656/1, indicating that fatal injury in the event of a crash is far less likely than C H A P T E R 4 Estimation of Highway Loss

nonfatal injury. All of the remaining target groups fall some- where between these two extreme values. Cost of Fatal and Nonfatal Injury The Blincoe et al. (2002) report estimates the cost of fatal- ities and injuries of varying severity. Nichols and Ledingham (2008) use Blincoe’s 1994 and 2000 base-year figures and in- terpolate estimates for other years. For the year 2007, Nichols estimates the cost of each fatality at $1,115,820 and the aver- age cost of Maximum Abbreviated Injury Scale (MAIS) 2 to 5 injuries at $2,686,417 (cost of total MAIS 2 to 5 injuries per unit fatality). Using Nichols’ method and figures, the average cost of 126 MAIS 1 to 5 injuries per unit fatality was estimated to be $3,780,038 in 2007. This overall cost was then converted to an average cost-per-injury estimate that, combined with the (adjusted) injury/death ratios for the various crash cate- gories, was used to estimate total costs for MAIS 1 to 5 injuries 11 Fatality Analysis Reporting System (FARS) 2006 Crashes involving No. of fatalities Percentage of all fatalities Description All persons 42,642 100.00 All motor-vehicle-related fatalities Pedestrians 4,784 11.22 All pedestrian fatalities Distracted 4,246 9.96 Fatalities involving distracted drivers (drowsy excluded) Drowsy 1,344 3.15 Fatalities involving drowsy drivers Speed 11,518 27.01 Speed related, speed violation, or excessive speed fatalities Aggressive 11,684 27.40 Fatalities involving speeding, reckless driving, road rage, aggressive driving Alcohol related 17,602 41.28 Fatalities involving drivers with BAC .01 Teen drivers 2,291 5.37 Fatalities involving 16- and 17-year-old drivers in passenger vehicles 16-year-old drivers 880 2.06 Fatalities involving 16-year-old drivers in passenger vehicles Elderly drivers 3,135 7.35 Fatalities involving drivers age 75 and over in passenger vehicles Motorcycles 4,654 10.91 All motorcyclist fatalities Nighttime 15,194 35.63 All fatalities occurring between 9 P.M. and 6 A.M. Child in car 993 2.33 Children 0-12 in passenger vehicles Front seat occupants 26,715 62.65 Outboard front seat occupant of passenger vehicles ages 13 and up Bicycles 770 1.81 All bicyclist fatalities Table 1. Percentage of fatalities associated with various types of crashes. GES 2004–2006 Crashes inv olv ing No. of Injuries No. of Fatalitie s Injury - to- fatality rati o GES ratio relativ e to all persons Adjusted ratios All persons 7,719,076 90,612 85 Blincoe’s ratio: 125.95 Pedestrians 183,659 8,640 21 0.25 31.49 Distracted 1,951,355 12,315 158 1.86 234.28 Drowsy 276,000 5,464 51 0.59 74.68 Speed 1,812,245 30,628 59 0.69 87.48 Aggressive 1,867,291 30,731 61 0.71 89.84 Alcohol related 600,415 19,008 32 0.37 46.70 Teen drivers 787,101 4,884 161 1.89 238.28 16-year-old drivers 334,031 1,843 181 2.13 267.96 Elderly drivers (75+) 468,402 7218 65 0.76 95.95 Motorcycles 229,522 9,827 23 0.27 34.53 Nighttime 1,290,607 28,915 45 0.52 65.99 Child in car 413,146 931 444 5.21 656.15 Front seat occupants 5,886,027 55,710 106 1.24 156.21 Bicycles 125,599 1,745 72 0.84 106.41 Table 2. Adjusted fatality-to-injury ratio by crash type.

associated with a given number of deaths. For 2007, the esti- mated cost of each fatality is $1,115,820 and the average unit cost of MAIS 1 to 5 injuries was $30,238, as indicated in Table 3. The sources of the costs differ depending on whether in- juries are fatal. For fatal injuries, 82% of the $1,115,820 is lost productivity, 2% is from medical and emergency service costs, and 15% is from other costs (e.g., legal fees, insurance). For nonfatal injuries (MAIS 1 to 5), 45% of the costs ($30,238) is due to lost productivity, 35% is associated with medical and emergency services, and 20% represents other costs. For any given countermeasure, the percentage of cost savings falling into each category is dependent on the injury-to-fatality ratio. For example, the savings from a pedestrian countermeasure would have lower medical savings because a higher propor- tion of the victims were fatally injured. Whereas a counter- measure focusing on teens would be expected to have a higher proportion of the savings coming from medical costs as a higher proportion of the victims being “saved” were non- fatally injured. Note that costs for fatalities after year 2000 were extrapo- lated from the rate of change from 1994 to 2000 (Blincoe, Seay, Zaloshnja et al., 2002). An alternative method for mak- ing this estimation would have been to use changes in the consumer product index from the Bureau of Labor Statistics (www.bls.gov). Using that approach, the estimated cost of a death in 2007 would have been 1.03 times the estimated cost shown in Table 3 (i.e., it would be $1,149.344, rather than the $1,115,820 shown). This latter number would, of course, pro- vide a higher estimate of costs. In the “typical” state with 600 deaths, the costs associated with deaths (alone) would be about $689.7 million, rather than $669.5 million, or an addi- tional $20 million. In this scenario, total costs (deaths and injuries) associated with 600 deaths in the “typical” state would be $2.975 billion, rather than $2.955 billion as esti- mated in Chapter 5. None of these costs include grief, pain, and suffering. Al- though enormous, the latter costs are difficult to quantify. Thus, the estimated costs used in this report focus on more direct and measurable costs associated with fatalities and nonfatal injuries. Also, as mentioned previously, property damage (a relatively small portion of overall highway loss) is not included. In summary, the societal cost of each fatality in 2007 is (conservatively) estimated to be $1,115,820, and the average cost of each MAIS 1 to 5 injury is estimated to be $30,238. These unit estimates are used to determine the total costs of deaths and associated injuries for each subgroup examined in this report. Again, these estimates are likely to be very con- servative. The costs of pain, grief, and suffering, for example, are not included. If included, it is likely that they would in- crease these estimates by approximately 300%. 12 * Blincoe et al. base years Cost Year Average MAIS 1-5 Per unit fatality 1994* $10,721 $822,330 1995 $12,223 $844,906 1996 $13,724 $867,482 1997 $15,225 $890,059 1998 $16,726 $912,635 1999 $18,228 $935,211 2000* $19,729 $957,787 2001 $21,230 $980,363 2002 $22,731 $1,002,939 2003 $24,233 $1,025,516 2004 $25,734 $1,048,092 2005 $27,235 $1,070,668 2006 $28,737 $1,093,244 2007 $30,238 $1,115,820 Table 3. Estimated costs associated with each death and MAIS 1-5 injury by year.

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TRB’s National Cooperative Highway Research Program (NCHRP) Report 622: Effectiveness of Behavioral Highway Safety Countermeasures explores a framework and guidance for estimating the costs and benefits of emerging, experimental, untried, or unproven behavioral highway safety countermeasures.

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