Turf Protection System

Masterpiece – posted 24 September 2002 18:57

Can anyone point me in the right direction? I’m planting Bermuda grass in a shopping center parking lot near the Beach in North Fla. I’m looking for a plastic type underlayment to keep cars from leaving ruts, etc. with they park on it. I’d like something fairly economical that comes on a roll that is easy to put down. Also, do you know if it needs compacted stone underneath?

seed – posted 26 September 2002 16:37

Masterpiece, I have reported some successes of grass parking lots here:http://floridaturf.com/vehicle.htm

In my opinion, the best foundation for vehicular turf is something heavy, stable, and well drained. Shallow sand over crushed rock can accomplish all three goals, if it is properly maintained.

You might look at some of the geotextile fibers or mats, but there are reasons they may not necessarily be that appropriate.

Heaviness is necessary to provide inertia, that is, vehicles turning and stopping must impart their kinetic energy somewhere, and the higher the bulk density of the substrate, the more readily that energy can be absorbed and dissipated. Plastic and light mats don’t accomplish that. Sand, crushed rock, and concrete pavers are heavy and do have inertia.

Stability is necessary so the driving surface can maintain its shape. Plastic can only offer minimal structural support, in my opinion, by bridging across areas being compressed by tires, and dissipating that compressional energy by stretching much like a trampoline, but at the expense of causing a sheer interface where all the wear and tear will be directed. It is likely that the surface soil will slip around on the plastic. Properly maintained, a dense knitted turf root system will provide considerable stability for all but the largest vehicles, but if that grass has to grow on plastic, the root system will probably stop at the plastic.

Drainage is necessary to prevent the lubricating effects of water from combining with compression to cause compaction. Almost any layer of material, even a porous material if it is thin and flat, such as a perforated plastic, will impede water movement, worsening drainage. A woven or loose fiber may allow drainage, but not still provide inertia. Loose fibers have been used for turf stabilization, provided the fibers are rough, not smooth.

Over the years I have seen a number of plastic devices designed to assist turf withstand traffic. So far I have not seen one which is better than natural materials such as stone and rock.

Phil