Quote:
Originally Posted by Repatriot
Thanks, good to know.
I have another question vaguely related, concerning a condition I've seen in a couple of spots:
- The left turn at E Chatham Street onto Maynard where there is a gas stand on the right immediately after that left turn
- The corner of Six Forks and Wake Forest Road where the entrance to the Vitamin Shoppe is
If a car is turning into theses places while another car is turning onto those roads, there is dangerously little space and reaction time for turning traffic, and could cause a chain reaction with the rest of the cars turning.
Are these know problem areas?
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Oh yes. Any time you have a driveway in what's considered the "intersection influence area", it's a problem. The intersection influence area is the part of the road network where vehicle free-flow movements are affected by an intersection, either up- or downstream. For instance, if it's in the area for deceleration, or acceleration (completing a movement) that's a problem.
An example would be an egress driveway that's within the turning lane of an intersection. If it's a right-lane, they might creep out and block it because the thru traffic is queued up past it and they can't get out to that lane. With a left-lane, they dart across three or four lanes trying to get to it, a rather risky move.
Back in the '50s or '60s, gas stations and the like were right up against a corner. "Best visibility" and most expensive site for land, I'd guess. We know now that these driveway locations are the worst, and that we want to get driveways 400'+ from corners of important intersections. The sites you mention are likely grandfathered in, or knew somebody that overruled the engineering and allowed the driveway. Now, unless it has access to other properties, the corner properties might be the worst pieces of land.
The type of driveway matters in terms of how significant the problem is. A full-movement driveway (lefts in and out) will be a much bigger problem than a right-in and (usually) right-out. I'm not too worried about a right-turn into a driveway off a turn, depending on the volume. But, even with better spacing, a right-in driveway like the one into the WalMart shopping center in Brier Creek is going to be a bigger problem, since it's high volume, and the turns are platooned (vehicles clustered together by the signal at US 70.) The Vitamin Shoppe is a lesser problem, even though it's closer, because it's lower volume. (Not that it can't create a problem.)
It's the continual research and data that pushes the access further away from a corner, and also limits the types of movements. Retailers hate it (to them, any restriction will "kill our business", which doesn't work with engineers, but sure influences politicians.)
To me, a traffic engineer, the retailers are still acting as if it's the '60s and '70s. "MUST HAVE" this driveway right at their door (in the worst spot possible for traffic safety), if it's a couple hundred feet down the road, nobody will come to our site. I'd love for most of the retail developers to act like Chick-Fil-A or Cracker Barrel (and WalMart, for the most part.) They know where we are, and they'll find us. (Not that these business types haven't complained in the past.)
Access Management (the control of driveways in the manner I've been describing) rarely hurt businesses, from our research. The ones it does affect are those that are "impulse" decisions, such as gas stations or coffee shops. (If there's a Starbucks on the afternoon peak side of the road instead of the morning, it's a bad location.) What hurts business more is too many traffic jams. (Yogi - Nobody goes there anymore, it's too crowded.)
You can probably tell I get worn down from having to deal with this part of our business. I would say that if you see a problem with a driveway, it was likely forced on the public by the developer going political. Or, as I mentioned, it's a legacy of a different mindset from 40+ years ago. We've had a few clunkers, for sure, but the majority of access issues I come across were thanks to the developer. (And thanks for tolerating a rather long response here to your short question!)
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