As a city planner, you receive complaints from local residentsabout the safety of nearby roads and streets. One complaintconcerns a stop sign at the corner of Pine Street and 1st Street.Residents complain that the speed limit in the area (55 mph) is toohigh to allow vehicles to stop in time. Under normal conditionsthis is not a problem, but when fog rolls in visibility can reduceto only 155 ft. Since fog is a common occurrence in this region,you decide to investigate.
The state highway department states that the effectivecoefficient of friction between a rolling wheel and asphalt rangesbetween 0.689 and 0.770, whereas the effective coefficient offriction between a skidding (locked) wheel and asphalt rangesbetween 0.450 and 0.617.Vehicles of all types travel on the road,from small VW bugs weighing 1430 lb to large trucks weighing 9180lb.
Considering that some drivers will brake properly when slowingdown and others will skid to stop, calculate the minimum andmaximum braking distance needed to ensure that all vehiclestraveling at the posted speed limit can stop before reaching theintersection.
minimum braking distance: ft
maximum braking distance: ft
Given that the goal is to allow all vehicles to come safely to astop before reaching the intersection, calculate the maximumdesired speed limit.
maximum speed limit: mph
Which factors affect the soundness of yourdecision?
Drivers cannot be expected to obey the posted speed limit.
Reaction time of the drivers is not taken into account.
Precipitation from the fog can lower the coefficients offriction.
Newton's second law does not apply to this situation.
