A modeling effort found that forward collision avoidance systems can prevent or mitigate up to 31 percent of all collisions.

A methodology for determining crash and injury reduction from emerging crash prevention systems in the United States using National Highway Traffic Safety Administration (NHTSA) data.

Date Posted
10/18/2017
Identifier
2017-B01183
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Methodology for Determining Crash and Injury Reduction from Emerging Crash Prevention Systems in the U.S.

Summary Information

Forward Collision Avoidance Systems (FCAS) include active safety systems preventing or mitigating frontal crashes. These include Forward Collision Warning (FCW), Dynamic Brake Assist (DBA), and Crash Imminent Braking (CIB). FCW warns the driver of an impending collision. DBA increases the driver brake magnitude once the brakes are applied. CIB autonomously increases braking force, even without driver input. Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) systems rely on dedicated short range communication (DSRC) between vehicles and infrastructure. Information broadcast by these systems can be used in applications like FCAS.



Methodology



Using coded variables from NHTSA’s three nationally representative crash databases, pre-crash scenarios were developed and used to identify the target populations for FCW, Lane Departure Warning (LDW), and Vehicle-to-Vehicle (V2V) or Vehicle-to-Infrastructure (V2I) systems. Three FCAS algorithms were examined: 1) FCW only; 2) FCW and DBA; and 3) FCW, DBA, and CIB. The FCW activated at a time-to-collision (TTC) of 1.7 s. The DBA doubled driver braking effort starting at a TTC of 0.8 s, and CIB increased braking by 0.6 g starting at 0.45 s TTC. Logistic regression is used to evaluate risk of injury in these crash scenarios.

Findings

The modeling effort found that FCAS can prevent or mitigate up to 31 percent of all collisions, including 6 percent of serious injury crashes and 7 percent of fatal crashes.

Individually, the three algorithms are predicted to prevent 3.39 percent (FCW), 3.43 percent (FCW + DBA), and 7.20 percent (FCW + DBA + CIB) of all rear-end collisions. The prevented collisions and reduction in crash severity would reduce the number of injured drivers (MAIS2+) by 32 percent for FCW, 40 percent for FCW and DBS, and 55 percent for FCW, DBS, and CIB for belted drivers in the striking vehicle.

The three algorithms could prevent 1.73 percent, 2.24 percent, and 3.13 percent of all injured drivers (MAIS2+) annually including both striking and struck vehicle injury reductions. They could mitigate 60 percent of seriously injured occupants and 65 percent of fatal crashes.

In total, the three systems could prevent between $184 and $338 million of economic costs associated with crashes per year.

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