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Thread: Gated communities and driveway stacking distance

  1. #1
    Cyburbian hilldweller's avatar
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    Gated communities and driveway stacking distance

    Gated communities are bad enough for most planners, but especially deplorable if designed poorly. One unfortunate trend I have witnessed is poor driveway access off higher capacity two-lane roadways and arterials. The distance between the ROW and the gates is often limited since the developer has crammed in as many units as possible. Meanwhile, there is usually not a deceleration lane and thus a significant speed differential is created that is likely to cause accidents. Has anybody dealt with this issue? Does your code have anything to say about it?

  2. #2
    Cyburbian Jeff's avatar
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    PADOT will not give a highway occupanct permit to age-restricted w/o decels. Most of the gated communitites are age-restricted, so I guess we got most of our bases covered.

    How many people you got coming into these things?

  3. #3
    Cyburbian hilldweller's avatar
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    Quote Originally posted by Jeff View post
    PADOT will not give a highway occupanct permit to age-restricted w/o decels. Most of the gated communitites are age-restricted, so I guess we got most of our bases covered.

    How many people you got coming into these things?
    We're not talking just age-restricted; here in south Florida gated communities are for all ages . The average I've seen is about 250 units, so quite a bit of trips.

  4. #4
         
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    We don't have a standard in our code but we have them place the gate far enough back from the public road to allow cars to stack or a large moving van to pull off and operate the gate without blocking the public road. If they needed a decel lane we would treat them like any other access point.

  5. #5
    Cyburbian Flying Monkeys's avatar
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    I think this is better handled through your access management rules. If it is a state road, then the access class will dictate the spacing.... The other way do this may be requiring turn lane analysis. With the right threshold a right turn lane (decel lane/turn lane) could be required.

    There are two issues; safety and capacity.

    You can do this from a safety point of view.... look at other entrance/exits off of two-lane roads and the crash record for these.

    From a capacity side, you can do alternative capacity analysis (think ARTplan, Freeplan, HCS arterials...) to show that the capacity is degraded by the spacing of these entrance/exits on two-lane roads.... thereby requiring decal/turn lanes to improve capacity, which can also be proven via alternative capacity analysis.
    What’s in a name? – Your reputation….:)

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    Cyburbian Jeff's avatar
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    I've designed several of these, some in FL as well, and I always design these w/ 2 entrance lanes. 1 w/ a crd reader so residents get right in, the other to the guard shack for visitors. I dont think I've ever placed the gates coser than 250' or so from the road, for no particular reason of course, other than to beef up the entrance features and landscaping.

  7. #7
    Cyburbian Flying Monkeys's avatar
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    ohhhhh... I may have read this wrong...although what I said still applies. Reading Jeffs reply I realized you were more interested in the distance of the Gate from the roadway. I guess you would handle this in you Land Development Codes, no?

    But you know, you could determine the rate of traffic expected to use the gate via PM peak trip generation (to determine stacking). And that would determine how far from the road the gate should be located, and it would differ depending on the size of the development. Just an Idea.

    Also, no mater how far back the gate is.... a two lane road is affected by slowing and turning traffic. So what I wrote above applies to turn lane analysis (left and right) that should be required by the developer.
    What’s in a name? – Your reputation….:)

  8. #8
    Cyburbian solarstar's avatar
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    We have nothing here to stop this other than typical access management standards which may or may not apply to the internal roadway. Fortunately, most (but not all) of our gated communities have to come through the PUD process and we can regulate that kind of thing up front. We usually have a condition requiring no direct residential access onto the main collector road, which eliminates the cramming by the front gates.

  9. #9
    Cyburbian Random Traffic Guy's avatar
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    To add to the good comments above, the specific gate equipment plays a big role. Swinging, sliding, or raising can take surprisingly different amounts of time, along with whether they are activated by card, bar code on car, or garage-door-style remote. Plus the issue if it lets one vehicle through, or if once open other vehicles can slip through. If you get the trip generation and the service time (gate opening time), you can run a queuing analysis on the gate to see, statistically at least, what the probabilities of having 1, 2 , 3 etc vehicles lined up. Typically only the slower gates which are also strictly one vehicle per operation have any queuing problems. Just make sure to get the visitors out of the entering stream as well. For 250 units, you are looking at approx 125 inbound vehicles in PM peak if this is your only entrance. Given average gate operations, I'd probably end up at 3-4 vehicles storage, tending towards more as the adjacent road gets bigger and faster.

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