IIHS crashworthiness evaluation programs and the U.S. vehicle fleet

Transcription

1 Bulletin Vol. 30, No. 7 : April 2013 IIHS crashworthiness evaluation programs and the U.S. vehicle fleet The Insurance Institute for Highway Safety (IIHS) conducts several different vehicle crashworthiness evaluation programs to assess the risk of serious injury in automobile crashes. The purpose of this analysis is to quantify how the crashworthiness ratings for vehicles in the U.S. fleet have changed over time in order to gauge the impact that these programs have had in reducing the rate of fatal crashes. IIHS has been conducting a moderate overlap front test since In, 65 percent of registered vehicles could be assigned front crash ratings. Good-rated vehicles represent 41 percent of registered vehicles and 64 percent of the rated vehicle population. IIHS began conducting side impact crash tests in 2003 and by ratings could be assigned to 36 percent of the registered fleet. Twenty percent of the fleet and 55 percent of rated vehicles had achieved a rating. In 2009, the IIHS began roof strength testing, and by, 18 percent of the fleet could be assigned ratings. Eight percent of the fleet and 53 percent of the rated vehicle population earned a rating. Good ratings from later test programs increased much faster than from earlier programs. It took 14 years for more than half of registered vehicles rated under the moderate overlap front program to be rated. It took nine years for vehicles rated under the side program and just four years for vehicles rated under the roof strength test. Introduction The Insurance Institute for Highway Safety currently conducts four vehicle crashworthiness evaluation programs aimed at improving occupant protection in severe crashes. The Institute s first crashworthiness program, the moderate overlap front test, began in 1995, followed by side impact testing in 2003, roof strength testing in 2009, and, finally, small overlap front testing in. The crash modes that these tests address represent a large portion of serious injury and fatal crashes. Annual fatal crash rates for automobiles have been dropping steadily since the early 1980s. The purpose of this Highway Loss Data Institute (HLDI) study is to quantify crashworthiness improvements that have been made to the U.S. vehicle fleet as measured by the Institute s testing programs. Methods This study combines information on IIHS crash test ratings and vehicle registration data from R.L. Polk and Company. The test programs studied include the moderate overlap front test, the side impact test, and the roof strength test. The latest crashworthiness evaluation program from IIHS, the small overlap front test, is too recent to evaluate. IIHS crashworthiness evaluation programs In the moderate overlap front test, a vehicle travels at 40 mph toward a barrier with a deformable face made of aluminum honeycomb. A Hybrid III dummy representing an average-size man is positioned in the driver seat. Forty percent of the total width of the vehicle strikes the barrier on the driver side. The forces in the test are similar to those that would result from a frontal offset crash between two vehicles of the same weight, each going just under 40 mph. An analysis of 14 years worth of crash data involving Institute-rated vehicles shows that a driver of a vehicle rated in the moderate overlap front test is 46 percent less likely to die in a frontal crash, compared with a driver of a vehicle rated. A driver of a vehicle rated or is 33 percent less likely to die than a driver of a ly rated one (IIHS, ).

2 In the Institute s side test, a 3,300-pound SUV-like barrier hits the driver side of the vehicle at 31 mph. Two SID-II dummies representing small (5th percentile) women or 12-year-old children are positioned in the driver seat and the rear seat behind the driver. In the real world, a driver of a vehicle rated is 70 percent less likely to die in a left-side crash, compared with a driver of a vehicle rated. A driver of a vehicle rated is 64 percent less likely to die, and a driver of a vehicle rated is 49 percent less likely to die. (Teoh and Lund, 2011) In the Institute s roof strength test, a metal plate is pushed against one side of the vehicle s roof at a constant speed. To earn a rating, the roof must have a strength-to-weight ratio of at least 4. In other words, it must be able to withstand a force of 4 times the vehicle s weight before reaching 5 inches of crush. For an rating, the minimum required strength-to-weight ratio is A rating value is 2.5. Anything lower than that is. Real world rollover crashes of 11 midsize SUVs and 12 small cars were studied to establish injury risk given various roof strengths. Results showed that increased vehicle roof strength reduces the risk of occupant injury in a rollover crash (Brumbelow et al., 2009; Brumbelow and Teoh, 2009). The most recent R.L. Polk data available to HLDI goes up to. For each included in the study, a number of recent model years are available, ranging from 23 model years for 1995 to 47 model years for. The number of model years available per has increased over time. In order to have a consistent dataset over all of the s in this study, data were restricted to the 23 most current model years per. In, the most current 23 model years comprise 93.7 percent of available data. In earlier years with fewer than 47 model years, the 23 most recent account for even more of the available data. Because the unused data is comprised entirely of older/unrated vehicles using the most current 23 model years per understates the size of the unrated vehicle population. Some vehicles have multiple ratings for the same model year. This is particularly common for the side impact test program. When side airbags are optional, vehicles are first tested without the optional airbags. Manufacturers can remunerate the IIHS for a second test vehicle so that the vehicle with optional side airbags can be assessed. For example, the model year 2005 Toyota RAV4 had two ratings. The Toyota RAV4 without optional side airbags earned a rating, while the Toyota RAV4 with side airbags earned a rating. Registration data is not available based on side airbag availability. Additionally, take rates for side airbags during the time period that the side impact test was introduced were relatively low. Using data from Ward s Automotive, an audit of 26 vehicles with multiple ratings was conducted. For most of the audited vehicles (20) the take rates for side airbags were lower than 50 percent. For the 2005 Toyota RAV4 mentioned above, Ward s reports that just 34 percent of these vehicles were purchased with side airbags. Consequently, it was decided to use the lowest rating for vehicles that have more than one rating. Using this methodology to handle multiple ratings understates the number of vehicles with favorable ratings. However, given the low take rates, it is likely more accurate than using the highest rating. For each crash test program evaluated, two graphs are presented. The first graph illustrates the percentage of the registered vehicle fleet that has not been rated along with the percentage rated by IIHS rating. The second graph excludes the unrated vehicle population and illustrates just the rated vehicle population. HLDI Bulletin Vol 30, No. 7 : April

3 Results Figure 1 shows the distribution of vehicle ratings for the moderate overlap front test for all registered vehicles. In 1995 more than 97 percent of registered vehicles were unrated and just one percent of the registered vehicle population was rated. By, the unrated percentage was down to 35 percent, and 41 percent of the registered vehicles had attained a rating. 10 Figure 1: Moderate overlap front crash test ratings for all registered vehicles by unrated Figure 2 shows the distribution of vehicle ratings for the moderate overlap front test for rated vehicles. Registration data for unrated vehicles was not included. In 1995 just 39 percent of rated vehicles earned a rating. By vehicles rated represented 64 percent of the rated vehicle population. 10 Figure 2: Moderate overlap front crash test ratings for registered vehicles by, rated vehicles only HLDI Bulletin Vol 30, No. 7 : April

4 Figure 3 shows the distribution of vehicle ratings for the side impact crash test for all registered vehicles. In 2003 when the test program was introduced, more than 96 percent of registered vehicles were unrated and less than 1 percent of the registered vehicle population was rated. By, the unrated percentage was down to 64 percent and 20 percent of the registered vehicles had attained a rating. As previously mentioned, some vehicles have multiple ratings, and when this occurred, the lowest rating was used. 10 Figure 3: Side impact crash test ratings for all registered vehicles by unrated 2004 Figure 4 shows the distribution of vehicle ratings for the side impact crash test for rated vehicles. Registration data for unrated vehicles was not included. In the first year of the program less than 1 percent of rated vehicles earned a rating. Ten years later, in, vehicles rated represented almost 55 percent of the rated vehicle population. In contrast, after 10 years of front testing, less than 35 percent of rated vehicles had achieved a rating. The faster improvement in ratings for the side crash test is particularly impressive given that the methods used in this study understate the number of -performing vehicles due to the large number that have two ratings because they have optional side airbags. Figure 4: Side impact crash test ratings for registered vehicles by, rated vehicles only % 0.6% 0.4% 0.2% HLDI Bulletin Vol 30, No. 7 : April

5 For vehicles with multiple ratings in the same model year using the lowest rating understates the improvements in side crashworthiness over time. The alternative is to use the highest rating, but given low side airbag take rates that would considerably overestimate the improvements in side crashworthiness. The true measure of improvements in side crashworthiness lies somewhere between the two approaches. Figure 5 illustrates how the percentage of vehicles with ratings would be different if the highest ratings for vehicles with multiple ratings were used instead of the lowest. It should be noted that the graph shows ratings for all vehicles rated and not just the ones with multiple ratings. The differences in the results of the two methodologies decrease over time primarily because the number of vehicles with multiple ratings has decreased, with side airbags becoming standard in the vast majority of models. Figure 5: Registered vehicles with side crash test ratings by, rated vehicles only using highest rating for any given vehicle using lowest rating for any given vehicle 2004 Figure 6 illustrates how the percentage of vehicles rated would be different if the highest ratings for vehicles with multiple ratings were used instead of the lowest. It should be noted that the graph shows ratings for all vehicles rated not just the ones with multiple ratings. As with Figure 5, the differences between the two methodologies decrease over time primarily because the number of vehicles with multiple ratings has decreased over time. Figure 6: Registered vehicles with side crash test ratings by, rated vehicles only using lowest rating for any given vehicle using highest rating for any given vehicle 2004 HLDI Bulletin Vol 30, No. 7 : April

6 Figure 7 shows the distribution of vehicle ratings for the roof strength test for all registered vehicles. In 2009, just over 92 percent of registered vehicles were unrated, while about 3 percent of the registered vehicle population was rated. By, the unrated percentage was down to 82 percent and more than 8 percent of the registered vehicles had attained a rating. In contrast, it took eight years for a comparable percentage of vehicles to achieve a rating in the moderate overlap front test. Figure 7: Roof strength ratings for all registered vehicles by % 0.6% unrated 0.4% 0.2% Figure 8 shows the distribution of vehicle ratings for the roof strength test for rated vehicles. Registration data for unrated vehicles was not included. In 2009, over 35 percent of rated vehicles earned a rating. By, vehicles rated represented almost 53 percent of the rated vehicle population. Figure 8: Roof strength ratings for registered vehicles by, rated vehicles only % 0.6% 0.4% 0.2% HLDI Bulletin Vol 30, No. 7 : April

7 Figure 9 shows the number of s required for half the registered vehicles to be rated under each of the testing programs. It took 14 years for half the vehicles rated under the moderate overlap front program to be rated. It took nine years for vehicles rated under the side program and just four years for vehicles rated under the roof strength test. 16 Figure 9: Years required for 50 percent of rated, registered vehicles to be rated frontal side roof Figure 10 shows rated versus unrated vehicles in the frontal test by size and class groups for model year vehicles in. In some size and class groups, such as midsize four-door cars and midsize SUVs, 100 percent of registered vehicles have been rated. In other size and class groups, such as small sports cars and very large pickups, no vehicles have been evaluated. In total, 83 percent of model year vehicles in have been rated. 10 Figure 10: Rated versus unrated vehicles in frontal test for model year in, by vehicle size and class rated registrations unrated registrations Micro Micro 2-door 4-door station wagon/ minivans Very sports luxury cars Very Very Very pickups SUVs luxury SUVs Very passenger vans HLDI Bulletin Vol 30, No. 7 : April

8 Figure 11 illustrates the unrated vehicle population for model year vehicles in by vehicle size/class group. Very large pickups represent the largest group of vehicles without frontal ratings, followed by large pickup trucks. The third-largest unrated population came from the small two-door car group. However, the number of registered vehicles in this group is much smaller than the number of registered unrated pickups. 250,000 Figure 11: Registered vehicles without frontal ratings by size and class group for model year in 200, , ,000 50,000 0 Micro Micro 2-door 4-door station wagon/ minivan Very sports luxury cars Very Very Very pickups SUVs luxury SUVs Very passenger vans Table 1 provides additional information about the unrated vehicle population for each of the three programs in this study. The denominator for each cell in the table was the number of unrated registered vehicles. The numerator for each cell was the number of registered vehicles from rated size/classes that were too old to have been tested. To be considered too old to test, the model year that a vehicle design was introduced had to be older than the first year of a test program. The remainder of the unrated vehicles are in size/classes that were not regularly tested by IIHS. For the frontal program in more than 37 percent of the registered vehicles were too old to have been tested. This suggests that when the old vehicles age out of the fleet, 87 percent of the fleet will be rated for the front test assuming the testing program continues to operate in its current form and there is not a shift in the vehicle population to untested size/class groups. HLDI Bulletin Vol 30, No. 7 : April

9 Table 1: Unrated, out-of-scope vehicles by crashworthiness program Calendar year Front Side Roof % % % % % % % % 98.4% % 96.9% 66.2% 95.2% % % 90.6% % 88.5% 99.8% 49.6% 85.9% 99.2% % 82.8% 98.3% 37.4% % Discussion Vehicle ratings are steadily improving. In all three test programs evaluated, there were dramatic increases in the percentage of -rated vehicles. The frontal program went from having 39 percent of vehicles rated in the first year to having 64 percent in the most current year. This is an annual average increase of 1.5 percentage points per year. For the later test programs improvements came much faster. For the side impact and roof strength programs, the annual average increase was about 6 percentage points per year. It took 14 years for more than half of registered vehicles rated under the moderate overlap front program to be rated. It took nine years for vehicles rated under the side program to achieve the same level and just four years for vehicles rated under the roof strength test. Given the number of older vehicles in the registered vehicle fleet, it takes a long time for changes to new vehicles to impact the fleet. Although 64 percent of vehicles rated in the moderate overlap frontal offset crash test are rated, these vehicles only represent 41 percent of the registered fleet. For the side impact crash test program, just 20 percent of the registered fleet is rated and for the roof strength program just 8 percent of the registered fleet is rated. Given that studies conducted by IIHS of the moderate overlap front crash test and the side impact crash test indicate that occupants of -rated vehicles are much safer than those in -rated vehicles, fatal crash risk should decrease as the percentage of -rated vehicles in the registered fleet grows. HLDI Bulletin Vol 30, No. 7 : April

10 References Brumbelow, M.L. and Teoh, E.R Roof strength and injury risk in rollover crashes of passenger cars. Traffic Injury Prevention 10: Brumbelow, M.L., Teoh, E.R., Zuby, D.S. and McCartt, A.T Roof strength and injury risk in rollover crashes. Traffic Injury Prevention, 10: Insurance Institute for Highway Safety.. Status Report: Special issue: frontal crash test verifications. Vol. 41, No. 3. Teoh, E.R. and Lund, A.K IIHS side crash ratings and occupant death risk in real-world crashes. Traffic Injury Prevention, 12: The Highway Loss Data Institute is a nonprofit public service organization that gathers, processes, and publishes insurance data on the human and economic losses associated with owning and operating motor vehicles N. Glebe Road, Suite 700 Arlington, VA USA tel 703/ fax 703/ iihs-hldi.org COPYRIGHTED DOCUMENT, DISTRIBUTION RESTRICTED 2013 by the Highway Loss Data Institute. All rights reserved. Distribution of this report is restricted. No part of this publication may be reproduced, or stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the copyright owner. Possession of this publication does not confer the right to print, reprint, publish, copy, sell, file, or use this material in any manner without the written permission of the copyright owner. Permission is hereby granted to companies that are supporters of the Highway Loss Data Institute to reprint, copy, or otherwise use this material for their own business purposes, provided that the copyright notice is clearly visible on the material.