Analysis of the demand for parking may indicate that there are periods during the day in which a large number of vehicles want to enter the parking facility at roughly the same time. The entrance to the parking lot must be able to handle the entering traffic without forcing vehicles to wait in the street, because stagnant vehicles will reduce the capacity of the adjacent street. To avoid conflicts with other traffic, entrances should be located as far from intersections and conflict points as possible. Multiple entrances may ease access and reduce restriction on the adjacent roadways.
Years of experience have produced general entrance dimensions that seem to work. The basic nominal design width for a two-way driveway serving commercial land use is 30 ft., with 15 feet radii. With greater volumes such as at a shopping center, a 36-ft driveway may be appropriate. It should be marked with two exit lanes (each 10 or 11 ft wide) and a single entry lane (14-16 ft wide) to accommodate the off-tracking path of entering vehicles. Larger commercial facilities such as regional shopping centers may require twin entry and exit lanes separated by a 4-12 foot median.
Many areas of the country have specific regulations or guidelines for the design of access facilities. It is important that the local and state regulations concerning access management are followed when designing access to off-street parking facilities.