|Re: Paving for pedestrian streets||<– Date –> <– Thread –>|
|From: Kay Argyle (argylemines.utah.edu)|
|Date: Wed, 16 Feb 2000 11:10:08 -0700 (MST)|
At Wasatch Commons (Salt Lake City), the area between the houses also serves as an emergency vehicle access, so it was required to be an all-weather drivable surface twenty feet in width. I don't know if our solution would be suitable for your needs, since it sounds like the gravel is your primary walking surface. The contractor installed a twenty-foot-wide roadbed (roadbase about six inches deep, a dark grey gravelly stuff) with a five-foot concrete sidewalk winding down the center. The sidewalk was about two inches higher than the roadbase surface. The original plan called for putting gravel on top of the roadbase. Permeability was an important consideration in the sections of the path where the houses are closest (maybe 25 feet), since the engineer who designed the drainage put the central path HIGHER than the doorsills of the houses on either side, and there's really no place for the water to go. It would be nice if the kids had a hard surface to play on other than the parking lots. Heat mitigation was important to some members. We (the landscape committee) did research on various materials, distributed a summary to the group showing benefits, drawbacks, and costs, and then did a survey to ask what people preferred in front of their own house. With a little jiggering, that worked out so that the path is broken into four segments of about 125 feet each, brick, grass pavers, brick, grass pavers again. Where the houses are set back further is brick, and where the houses are closest to the path are grass pavers. The areas of brick provide a surface for the kids to skate, ride bikes in circles, or play two-square and other games. By "grass pavers" I mean plastic honeycombs that are laid on a packed gravel and sand substrate, filled with soil, and planted (seed, sod, or plugs). The walls of the cells take the weight of vehicles or pedestrians and protect the plant roots from compaction -- which is what actually kills grass, not so much the wear-and-tear on its tops. The vegetation hides the top edges of the paver (unlike open-celled concrete pavers). We sent for samples from a couple of companies, and ended up choosing Bartron: http://www.landscapeonline.com/-bartron/bartron.htm. I think it cost about $2 per square foot, not including installation (a much bigger expense). This application is meant for moderate foot traffic and VERY occasional vehicular traffic. Bartron gave us a couple of nearby locations where their product was installed, one of which is a park that hosts a weekly farmer's market. In a few spots the grass is worn down to the point that the tops of the paver show. However, even if we were using the pavers (rather than the sidewalk) as the primary footpath, it still wouldn't get the wear it gets in the park, so the fact that most of the grass there was flourishing despite its weekly trampling by thousands of people was very encouraging. While our site is flat, the company indicates it also works for erosion control on slopes, and it can be used for wheelchair access areas or even dirtbike trails. A friend and I visited a fire station one evening and talked to the chief, who had never heard of the stuff, despite it being advertised for use in fire lanes, with photos in the brochures showing a pumper truck parked on the grass. We hired a landscape company to install it. They said they had installed it before and knew what they were doing. Fortunately we had done enough research we knew how it was supposed to be installed and, when they did it wrong, spotted the mistake, stopped them, and got them to do it over correctly. The difficulty was that the pavers are designed to be installed on reasonably large areas (the panels are about 4x4 ft), and our central path is an S-curve with a sidewalk winding from side to side in the middle and cement-block paths branching off to each porch, so they had to do a lot of cutting, which they hadn't anticipated. If your path is straight, this won't be a problem. A couple of households decided to lay sod on the pavers. Most of the pavers we planted with starts of woolley thyme, which is a low-growing evergreen drought-tolerant groundcover that will survive some foot traffic (although "evergreen" is a misnomer -- the leaves have turned a soft purple this winter). We got a discount from the nursery because we were buying 80 flats of it. We mixed in a few flats of lemon thyme and Thymus minus for variety. We planted it in late fall, so it hasn't had a chance to fill in. On a sloping site or one with more foot traffic, something faster growing would probably be more suitable. I and a couple of others used the leftover paver panels underneath sod against the edges of our playground and the common house patio. It was hard physical work (dig the dirt out, put down sand, lay the pavers, lock them together, fill them with a mix of soil, sand, and compost, lay the sod, roll ...) but not at all complicated. It is possible to lay sprinklers underneath where the pavers will be and feed the risers up through the openings during installation of the pavers. The five-foot-wide sidewalk was not quite wide enough -- we frequently had a couple of people walking along together, and in order to pass another pedestrian or cyclist it was necessary for someone to step off the sidewalk. In the areas of grassy pave, we had the contractor lay a line of bricks three bricks wide (one foot) on either side of the sidewalk, for a total width of seven feet, and this is proving more satisfactory. We shredded a couple of panels when a tractor-tiller got too close to the path and the tiller blades caught the edge, but that's the only problem so far. We've had a lost car drive the length of the path and kids straying off the sidewalk with their bikes, without leaving any visible marks. Kay Argyle Wasatch Commons Salt Lake City
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