Design of Parking Facilities Chapter 16 Dr. TALEB M. AL-ROUSAN

Introduction  The geometric design of parking facilities involves: Dimensioning of parking bays Arrangement of parking bays  Goal: to provide safe and easy access without seriously restricting the flow of traffic on adjacent lanes.

Design of On-Street Parking Facilities  May be designed with parking bays being: parallel to the curb Inclined to the curb  See Figure (most common angles of inclinations used for curb parking and associated dimensions for automobile parking).  As angle of inclination increase (up to 90 o ) the number of parking bays that can be fitted a long a given length of curb increase.  But, The higher the inclination angles, the greater the encroachment of the parking bays on the traveling pavement of the highway.

Design of On-Street Parking Facilities  Parking bays inclined at angles to the curb severely interfere with the movement of traffic which would increase crash rates compared to streets with parallel parking.  Dimensions in the figure are for automobile, but when parking bays are to be provided for trucks and other types of vehicles, the dimensions should be determined on the basis of the dimensions of the specific vehicle being considered.

Design of On-Street Parking Facilities

Design Of Off-Street Parking Facilities/ Surface Car Parks  Primary Goal: to obtain the max. possible number of spaces.  See Figure (different types of layouts that can be used in a surface lot).  Its important to have the layout such that parking a vehicle involves only the one distinct maneuver without the necessity of reverse.  Parking space is most efficiently used when the parking bays are inclined (90 o ) to the direction of traffic flow.

Design Of Off- Street Parking Facilities / Surface Car Parks

 The use of herringbone layout (Figure ) facilitates traffic circulation since it provides for one- way flow of traffic on each aisle.

Design Of Off- Street Parking Facilities / Surface Car Parks

Design Of Off-Street Parking Facilities/ Garages  Consist of several platforms, supported by columns, which are placed in such a way to facilitate the efficient arrangement of parking bays and aisles.  Access ramps connect each level to the one above: gradient of straight ramps not more than 1:10. gradient of curved ramps not more than 1:12. Radius of curved ramp not less than 70 ft. Max. superelevation (0.15 ft/ft). Width of curved ramps >= 16 ft. Width of straight ramps = 9 ft. Can be one-way (more preferable) or two-way. For two-way ramps: lanes must be clearly marked and (preferable) physically divided specially at curves and turning points to help avoiding head-on collisions.

Design Of Off-Street Parking Facilities/ Garages Cont.  In some cases, platforms are connected by elevators into which cars are driven or mechanically placed. These elevators left the car to the appropriate level for parking. Then the vehicle removed either by an attendant who parks it or by mechanical means and then parked by the attendant.  Size of receiving area is an important factor in garage design and depends on whether the cars are owner- parked (self-parking) or attendant parked.  In self-parking, very little or no reservoir space is required (drivers need pause only for a short time to pick up a ticket from a machine or to be given one by the attendant.

Design Of Off-Street Parking Facilities/ Garages Cont.  When cars are parked by attendants, the driver must stop and leave the vehicle so that the attendant will drive the car to the parking bay.  Attendants parking require a reservoir space to accommodate temporary storage for entering vehicles.  Size of reservoir space depends on the ratio between rate of storage of the vehicles and rate of arrival of the vehicle.  Rate of storage must take into consideration the time required to transfer the vehicle from its driver to the attendant.  The number of temporary storage bays can be determined by applying the queuing theory.  Figure shows size of reservoir space required for different ratios of storage rate to arrival rate with overloading occurring only 1% of time.