One vehicle is following another on a 2 lane highway at night. According to the rule of right thumb, one car length of clearance per 10mph speed exists between cars. If both vehicles are traveling at 60mph and the lead car crashed into the rear of an unlighted parked truck, at what speed will the rear car hit the wreckage? (Assume a reaction time of 2.5 seconds, car length= 18ft and a coefficient of friction of 0.65. Is the rule of thumb safe? Under the prevailing conditions in this example what is the minimum space in terms of car length between cars for every 10mph speed to avoid the crash?

. The design speed on a road is 60 kmph. Assuming the driver reaction time of 2.5 seconds and coefficient of friction of pavement surface as 0.35, the required slopping distance for two-way traffic on a single lane road is

Two cars,on a level surface, are approaching each other from the opposite directions at a speed of 120 kph and 90 kph respectively. The reaction time is 2.0 seconds. Compute the minimum sight distance required to avoid a head-on collision of the two cars. Use 2011 AASHTO formula.

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