This study examines the incidence rates of pedestrian and bicyclist crashes that involved hybrid electric vehicles (HEV) and to compare the results to internal combustion engine (ICE) vehicles under similar circumstances. State crash files from NHTSA’s State Data System were used to measure the incidence rates of pedestrian and bicyclist crashes by HEVs and to compare the incidence rate with their peer ICE vehicles. The purpose of the study is to compare the crash experience of two different types of vehicles; it is not to make national estimates of problem size. The small sample size used in this study remains as a limitation towards conducting further analysis. Incidence rates provided in this report should be interpreted with caution due to the small sample size. Future analysis using larger sample size would provide better estimate of the problem size. This analysis was conducted on a total of 8,387 HEVs and 559,703 ICE vehicles that met the selection criteria. A total of 77 and 3,578 pedestrians were involved in crashes with HEVs and ICE vehicles, respectively. A total of 48 and 1,862 bicyclists were involved in crashes with HEVs and ICE vehicles, respectively. This study found that pedestrian and bicyclist crashes involving both HEVs and ICE vehicles commonly occurred on roadways, in zones with low speed limits, during daytime and in clear weather, with higher incidence rates for HEVs when compared to ICE vehicles. A variety of crash factors were examined to determine the relative incidence rates of HEVs versus ICE vehicles in a range of crash scenarios. For one group of scenarios, those in which a vehicle is slowing or stopping, backing up, or entering or leaving a parking space, a statistically significant effect was found due to engine type. The HEV was two times more likely to be involved in a pedestrian crash in these situations than was an ICE vehicle. Vehicle maneuvers such as slowing or stopping, backing up, or entering or leaving a parking space, were grouped in one category based on that these maneuvers are potentially have occurred at very low speeds where the difference between the sound levels produced by the hybrid versus ICE vehicle is the greatest. In future analysis with a larger sample size, it would be ideal to investigate each of these maneuvers individually. Incidence rate of pedestrian crashes in scenarios when vehicles make a turn was significantly higher for HEVs when compared to ICE vehicles. There was no statistically significant difference in incidence rate of pedestrian crashes involving HEVs when compared to ICE vehicles when both type of vehicles were going straight. Similar to pedestrians, in crashes that potentially have occurred at very low speed such as when vehicles are turning, slowing, or stopping, backing up, or entering or leaving a parking space, the incidence rate of bicyclist crashes involving HEVs was significantly higher when compared to ICE vehicles. On a roadway was the most common location of bicyclist crashes involving both HEVs and ICE vehicles with no statistically significant difference. On the other hand, bicyclist crashes involving HEVs at intersections or interchanges were significantly higher when compared to ICE vehicles. In conclusion, this study found that HEVs have a higher incidence rate of pedestrian and bicyclist crashes than do ICE vehicles in certain vehicle maneuvers. These results should serve as a guide when designing future HEVs pedestrian and bicyclist crash prevention programs. NHTSA will continue monitoring the incidence of pedestrian and bicyclist crashes involving HEVs. In future, a larger sample size would allow us to perform a more detailed analysis such as limiting the entire analysis to low-speed crashes, analyzing different vehicle maneuvers individually, etc. Data findings on this study will be updated when more recent State Data System and other data sources are available. (Author/publisher)
Samenvatting