Vehicular Use Area
Technical Standards for Vehicular Use Area 
General- shading of parking lots is a landscape code standard in many southern and western communities as a means of moderating the harsh climate caused by excessive hard surface paving. Shading, spacing and quantity requirements may vary slightly from latitude to latitude but the general purpose is to design the tree plantings in relationship to the movement of the sun to cast shade over the parking during the longest period of a day.
Minimum Spacing- the distance between shade trees is dependent upon Class, size of tree and extent of tree canopy as well as time of day or year and angle and azimuth of the sun. Class A trees are discouraged within the interior but may be used on the perimeter. Minimum spacing for Class A trees used for shading should be forty (40) feet on center. Class B trees, especially those with a small root system are better used on the interior of a parking lot to produce a shade canopy. Class B trees should have a minimum spacing of twenty (20) feet on center and a maximum of thirty (30) feet on center. Class C trees may be effectively used within parking lot interiors but will not cast sufficient shade so should not be used for shading.
General Planting Standard for parking lot shading- tree planting pattern shall be such that seventy-five (75) percent of the parking lot interior shall be covered after fifteen (15) years of growth with dense shade pattern between the hours of ten (10) am and four (4) pm during summer months. In northern climates, parking lot shading is not desirable in winter months so deciduous trees are preferred. Parking lots should be sited on a north south axis for maximum shade coverage during the day if possible. Rows of shade tree trending north and south or east and west will provide better shade coverage patterns.
Planting Configuration- usually will be geometrically and formal in compliance with parking lot movement geometry. Plantings for shading can be installed within parking lot interior islands, peninsulas, curbed cut-outs and medians as well as within perimeter parking lot screens. Parking lot tree plantings may be spaced throughout the paved area in small planters or spaced in very large grove type planters that may occupy several hundred square feet and by used to give a stronger green character to the to the VUA than might be found in a parking lot with small evenly spaced tree planters.
Plant Spacing- Trees shall be planted within the interior of the VUA parking areas at the rate of one Class A or two Class B trees at the following rate. Lots under 12 spaces----no interior trees required
Lots 12-25 spaces--------one class A or 2 class B per twelve (12) spaces
Lots 26-100 spaces-------one class A or 2 class B per ten (10) spaces
Lots 100+ spaced---------one class A or 2 class B per eight (8) spaces
Minimum Interior Planting Space - Interior planting and or storm water management spaces within the parking lots shall total a minimum of twelve (12) percent of the area of paving. If storm water management is provided within the interior this percentage shall be increased to fifteen (15) percent.
Distance to shade trees- All parking spaces must be within fifty-four (54) feet of a shade tree planted in island, peninsulas. medians or parking lot edges.
Planting Islands, Peninsulas and Medians- Planting islands, peninsulas and medians must be matched to tree class. The size of the planting space must be matched to the potential critical root zone (CRZ) of the tree species to be planted. Therefore there are created four allowable classes of parking lot planting spaces as seen below.
Class A space shall be twenty (20) feet in width in order to be planted with Class A trees
Class B space shall be fifteen (15) feet in width in order to be planted with Class B trees.
Class C space shall be eight (8) feet in width in order to be planted with Class C tree
Class P spaces shall be a minimum of forty (40) feet in width around all trees to be preserved within VUA.
Class A medians shall be twenty (20) feet in width and may be planted with any class tree.
Class B medians shall be fifteen (15) feet in width and may be planted with any class B and Class C trees.
Class C medians shall be eight (8) feet in width and may be planted with only class C tree.
Ground Cover Planting- Ground cover for all interior planting spaces must be planted with three (3) gallon bedding shrubs planted twenty-four (24) inches or center or one (1) gallon ground over plants spaced twelve (12) inches on center to fill completely each island, peninsula or median.
Any islands created within VUA for mass plantings or groves of trees must use Class P (preservation) planting areas as a minimum size.
All planting spaces for each class of tree shall be length of a standard parking space and protected with a six (6) inch vertical curb.
Structural soils consisting of a prescribed mix of loamy soil and crushed stone to a minimum depth of eight (8) inches shall be used under all parking lots in the general area where trees are to be planted.
