What is the intersection departure sight distance for a STOP-controlled minor road if the AASHTO recommended time gap is 7.5 seconds and the major road design speed is 60 mph?

To determine the intersection departure sight distance for a STOP-controlled minor road given a time gap and the design speed of the major road, it's important to understand the concepts of sight distance and the relationship between speed, time, and distance.

AASHTO (American Association of State Highway and Transportation Officials) guidelines provide a way to calculate the necessary sight distance using the formula:

[ \text{Sight Distance} = \text{Speed} \times \text{Time} ]

First, it's important to convert the major road design speed from miles per hour to feet per second. Since there are 5280 feet in a mile and 3600 seconds in an hour, the conversion factor is:

[ 60 \text{ mph} = 60 \times \frac{5280}{3600} \text{ feet per second} \approx 88 \text{ feet per second} ]

Now, multiplying this speed by the AASHTO recommended time gap of 7.5 seconds gives the sight distance:

[ \text{Sight Distance} = 88 \text{ feet/second} \times 7.5 \text{ seconds} = 660 \text{ feet} ]

This value represents the minimum