You may have seen the aerial images of the the backed-up traffic on limited-access highways in the Houston area as people attempt to evacuate in advance of Hurricane Rita. The lanes (carriageway) heading toward Houston are largely empty. Why don’t they block the entrance ramps on those empty lanes, reverse the direction of traffic, and effectively double the highway capacity? Those few who need to go toward the city can use other primary roads.
That’s the big question that has to be answered. It seems that while the governor, mayor of Houston, and top county official for the area (Harris County) wanted to do that, it still takes a lot of coordination to pull off. You need a lot of people to patrol all the entrances. The Houston freeway system is pretty extensive. Much more so than that of New Orleans.
This is being done. From http://www.news8austin.com/content/your_news/default.asp?ArID=146147
Buffalo is about halfway from Houston to Dallas. Seguin is only about 30 miles shy of San Antonio.
And it doesn’t seem to be an unqualified success From http://www.zwire.com/site/news.cfm?newsid=15263054&BRD=1574&PAG=461&dept_id=532215&rfi=6
One-way in both directions? My brain hurts.
The officials were slow on the up beat. But the difficulties are understandable. The highway was not designed to be able to reverse the traffic flow, and as much as humanly possible it was likely designed to prevent traffic from going the wrong way.
Another issue is that even if there had been twenty lanes available from Houston, that doesn’t change the lanes available further North and further North was in gridlock as well. Would it have improved things much, adding thousands of additional vehilcles to the morass to the North?
Here in the part of the South that’s more used to hurricanes, we reverse lanes all the time when there’s an evacuation order. It’s never a problem, although of course you’ll still have to wait in traffic for ages, and there’s no gas, etc… (And before you say it, sometime we’re reversing in big cities too.) We probably have more practice, though.
It takes a bit of work to contraflow traffic as you have to make sure what you want to get in has gotten in, and you have to clear out the lanes for the entire length of the contraflow. You can’t simply say “OK, you can drive the wrong way now”, if there’s traffic coming at you head on 100 miles up the road.
Another point is there are many routes out of Houston but only 2, I-10 and I-45, can really be set up for contraflow traffic. The other routes are US and state highways that look like nice wide freeways in and near Houston, but become 4-lane roads once you get 50 miles or so out of town. Contraflow would not really improve the situation at all on these roads. So while you see empty lanes on TV, they might not be much use.
That would be a good point if South Carolina had a city that even approached the population of Houston.
I’m in Dallas, and there was some crazy footage on the local news of folks who were going north on the southbound lanes prior to the change. Actually, it didn’t turn out so bad, the southbound traffic was staying to right lanes, while the northbound stayed on their right lanes (the southbound left lanes).
I don’t think the difference in population really accounts for the enormous time difference in shifting lanes, do you? Besides, I’ve seen them contraflow I-95 in Florida often in the past, and I assure you there are a lot of people who evacuate via 95.
Shouldn’t matter that much concerning the time needed to implement contra flow. For example, within two hours or less of the time the governor gives the order, I-65 from Mobile to Montgomery can be contra flowed. Some newer interstates in Georgia (near Augusta or Savannah?) were constructed with evacuation contra flow in mind.
As Zsofia pointed out, plans to evacuate the Miami area have been carried out a number of times, and quickly. Maybe it’s a matter of experience.
I’ll bet the next time this is needed in Texas, it gets done much faster.
From a highway engineering perspective, you need to be wary of doing this since the guard rails are designed for one direction of traffic. When you put traffic in the opposite way, you are risking having errant motorists colliding with the departure end of guard rails, which often are just blunt ends and not appropriate for approach ends.
Heh, actually, from what I’ve noticed, the end of the guard rails that you’d hit first on Texas highways are the blunt end. A friend of mine who later got a job working for TexDOT said that this was because they found if you hit the end that tapered down towards the ground, your car could get launched into the air by it.