An alert driver $($with a reaction time $0\mathrm{.}5$ seconds$)$ is driving downhill on a $4\%$ grade at $35$ mph when a person steps from behind a parked car in the path of the driver, at a distance of $125$ feet. a$.$ Can the driver stop in time with emergency braking? b$.$ Can the driver stop in time on a rainy day with comfortable braking? A driver takes $3\mathrm{.}0$ seconds to react to a complex situation while traveling at a speed of $55$ mph$.$ How far does the vehicle travel before the driver initiates a physical response? How does this compare to a standard reaction time of $2\mathrm{.}5$ seconds and compared to an attentive younger driver with a reaction time of $1\mathrm{.}25$ seconds? Assume a driver is traveling on a road at a speed of $40$ mph and a deer run into the street $300$ feet in front of him. a$.$ Will he be able to stop in time if the road is level? b$.$ Will he be able to stop in time if he is driving on a hilly part of the road with i$.$ a positive $3\%$ grade? ii$.$ a negative $2\%$ grade? If an existing section of rural $2-$lane road with speed limit of $55$ mph has a sight distance of $1200$ feet, should passing be allowed? Provide numerical values to support your answer. Use the AASHTO Green Book PSDs$.$ A car collided with a telephone pole and left $20-$ft skid marks on dry asphalt pavement, and then traveled another $10$ feet on a gravel shoulder before hitting the pole. Based on the damage sustained, an engineer estimated that the speed at collision was $15$ mph$.$ If the roadway had a $+3\%$ grade, calculate the speed of the car at the onset of skidding. A large rock became visible to a driver at a distance of $175$ feet. Assuming a perception$-$reaction time of $0\mathrm{.}8$ seconds, an initial speed of $34$ mph and a level roadway, determine whether or not a collision occurred. The design speed of a rural highway is $60$ mph with a grade of $4\%.$ What is the minimum decision sight distance that should be provided if a$.$ A stop is required? b$.$ A speed or path change$$is$$required$?$