Related Experiment Video
Updated: Aug 6, 2026

Driving Simulation in the Clinic: Testing Visual Exploratory Behavior in Daily Life Activities in Patients with Visual Field Defects
Published on: September 18, 2012
Time-to-collision judgments under realistic driving conditions
Raymond J Kiefer1, Carol A Flannagan, Christian J Jerome
1General Motors Structure and Safety Integration Center, 30200 Mound Rd., Mail Code 480-111-E18, Warren, MI 48090-9010, USA. raymond.j.kiefer@gm.com
Objective:
This study examined perceived time to collision (TTC) with automobile drivers under realistic approach, rear-end crash scenario conditions.
Background:
TTC refers to the time before impact if prevailing conditions continue.
Method:
In this test track study involving 51 drivers ranging from 20 to 70 years old, the driver's vision was occluded at either 3.6 or 5.6 s TTC during an in-lane approach to a lead vehicle. Drivers provided TTC estimates by pressing a button the instant they felt that they would have collided with the vehicle ahead.
Results:
Results indicated that TTC was consistently underestimated. The TTC ratio (perceived TTC/actual TTC) increased as driver speed decreased and as relative speed increased. These ratios were largely unaffected by age, gender, actual TTC, viewing time (1 s vs. continuous), and the presence of an eyes-forward, mental addition distraction task.
Conclusion:
Overall, these results suggest that under these low TTC conditions drivers estimate TTC in a relatively uniform fashion and that they are capable of providing this estimate based on a brief glimpse to the vehicle ahead.
Application:
These results are being used to develop an alert timing approach for a forward collision warning system intended to assist drivers in avoiding rear-end crashes with the vehicle ahead.
Related Concept Videos
Elastic Collisions: Case Study
Types of Collisions - II
Types Of Collisions - I
Collisions in Multiple Dimensions: Problem Solving
A small car of mass 1,200 kg traveling east at 60 km/h collides at an intersection with a truck of mass 3,000 kg traveling due north at 40 km/h. The two vehicles are locked together. What is the...
Elastic Collisions: Introduction
Real-World Applications of Space Curves

