In: Civil Engineering
A driver is traveling 70 mi/hr on a road with a -2% downgrade. The driver’s vehicle has a braking efficiency of 90% and has anti-lock brakes. There is a stalled car on the road 500 ft ahead of the driver. The road is in good condition and is initially dry, but is wet for a 200 ft stretch just before the stalled car. What is the maximum allowable perception-reaction time of the driver such that she can still stop before hitting the stalled car? (Assume theoretical stopping distance, ignore air resistance, and let frl = 0.013.)
ANSWER;---
PERCEPTION REACTION TIME:--- "perception-reaction time" (PRT), the interval between obstacle appearance and driver response initiation, i.e., the foot just touches the brake pedal and/or the hands just start turning the wheel.