A developer has requested permission to build a large retail store at a location adjacent to the intersection of an undivided four-lane major road and a two-lane minor road. Traffic on the minor road is controlled by a stop sign. The speed limits are 35 and 50 mi/hr on the minor and major roads, respectively. The building is to be located at a distance of 65 ft from the near lane of one of the approaches of the minor road. Determine where the building should be located relative to the centerline of the outside lane of the major road in order to provide adequate sight distance for a driver on the minor road to turn right onto the major road after stopping at the stop line. Design vehicle is a single-unit truck. Lanes on the both roadways are 12 ft wide. Grades are approximately level.

Question

What will be an ideal response?

Answer 1

Use Equation 7.5:



From Table 7.8, tg = (9.5 – 1.0) = 8.5 sec for a single-unit truck. No

adjustment can be made for grade on the minor road since it is approximately

level.



This question asks for the location of the building relative to the centerline of the

outside lane of the major road. An answer is not provided for this value.

Calculating dISD is just the first part of the solution.

Calculating location of building:

Use Eqn. 7.4 with ????a = ????ISD = 624.75 ????????, ???? = 65 ????????, and ????b = 14.5 + 6 =

20.5 ???????? (14.5 feet is for offset between edge of roadway and stop sign and 6 feet

is for distance from edge of roadway to centerline of inside lane) and solve for ????:



This is the building location relative to the inside lane. Add 36 ft (3 lane widths)

to get location relative to the outside lane. ???????????????????????????????? ???? 18.36 ???? 36 ???? 54.36 ????????.

So the building must be located at least 54.36 feet from the centerline of the

outside lane.