Evaluating the Associations between Forward Collision Warning Severity and Driving Context

Sean Seaman,Pnina Gershon,Linda Angell,Bryan Reimer,Bruce Mehler

doi:10.3390/safety8010005

Abstract

Forward collision warning (FCW) systems typically employ forward sensing technologies to identify possible forward collisions and provide an alert to the driver in the event they have not recognized a threat. These systems have demonstrated safety benefits. However, because the base rate of collisions is low, sensitive FCW systems can provide a high rate of alarms in situations with no or low probability of collision, which may negatively impact driver responsiveness and satisfaction. We examined over 2000 naturally occurring FCWs in two modern vehicles as a part of a naturalistic driving study investigation into advanced vehicle technologies. Analysts used cabin and forward camera footage, as well as environmental characteristics, to judge the likelihood of a crash during each alert, which were used to model the likelihood of an alert representing a possible collision. Only nine FCWs were considered “crash possible and imminent”. Road-type, speed, traffic density, and deceleration profiles distinguished between alert severity. Modeling outcomes provide clues for reducing nuisance and false alerts, and the method of using subjective video annotation combined with vehicle kinematics shows promise for investigating FCW alerts in the real world.

Highlights

Unlike automatic emergency braking (AEB) or emergency steering function (ESF), both of which were developed and deployed more recently (FCW systems were made widely available on passenger cars and trucks in the mid-2000s), Forward collision warning (FCW) alerts alone do not provide any control input into the vehicle’s steering, throttle, or brakes, but depend upon the driver to respond appropriately to a hazard [3]
In which a driver follows a moving lead vehicle that unexpectedly departs the lane, revealing a stopped lead vehicle, an FCW alert is used with a time-to-collision (TTC) of 2.1 s, to which the driver, who is engaged in a non-driving-related task (NDRT), should respond and avoid or mitigate a collision
Alerts to imminent hazards occurred in high traffic density, and always in response to a slowing or stopped lead vehicle

Summary

Introduction

FCW alerts are issued much earlier than those CAS components (such as AEB) that are designed to respond later in the collision-possible sequence, after the driver has failed to respond to help mitigate or prevent crashes [4]. For many of the scenarios in which an FCW can be effective, such as the scenario used in the NHTSA FCW performance test procedure [5], AEB may be ill-suited In this scenario, in which a driver follows a moving lead vehicle that unexpectedly departs the lane, revealing a stopped lead vehicle, an FCW alert is used with a time-to-collision (TTC) of 2.1 s, to which the driver, who is engaged in a non-driving-related task (NDRT), should respond and avoid or mitigate a collision. Despite the developments of other advanced technologies, FCWs remain an important tool in crash avoidance and mitigation

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