INTELLIGENT CRUISE CONTROL FIELD OPERATION TEST

This interim document reports on a cooperative agreement between NHTSA and UMTRI entitled Intelligent Cruise Control (ICC) Field Operational Test (FOT). The overarching goal of the work is to characterize safety and comfort issues that are fundamental to human interactions with an automatic headway keeping system. This report summarizes the status of the FOT and presents preliminary results and findings deriving from the testing activities now in progress. It describes work done to prepare and instrument a fleet of 10 passenger cars with infrared ranging sensors, headway control algorithms, and driver interface units as needed to provide an adaptive cruise control (ACC) functionality. The vehicles have been given to lay drivers to use for two weeks as their personal cars. Based upon data from 35 drivers, objective and subjective results support the following preliminary observations: ACC driving is reported to be comfortable and is perceived as stress relieving. The kinesthetic sensation of ACC-induced deceleration was often cited by drivers as a vigilance-enhancing cue, perhaps implying a safety benefit. Drivers appear to learn how to use ACC quickly and to converge on a strategy that meshes with their driving style. The data contain a natural type of bias by which manual driving appears riskier than ACC driving in part because denser, more conflict-laden, traffic induces drivers to turn the ACC system off. Under virtually all conditions in which ACC is engaged, drivers choose (and the system provides) headway distances that are greater than those seen when the same person drives manually. ACC driving results in fewer near approaches to the preceding vehicle than does manual driving. Headway-keeping behavior differs markedly with driver age. Younger drivers are typically more aggressive, operating at shorter headways. Given the properties of the ACC system being studied, a minimal impact on the accident record would be expected from observations to date. A major element of this expectation derives from the drivers' choice to use ACC only in rather benign traffic environments. When completed, the FOT is expected to present findings based on results from over 100 drivers/participants.