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Small fix, big (we hope) effect

This would be nice.

Take the entrance ramp from Allen Parkway to southbound Interstate 45. Everyone from drivers to transportation officials knows it is a problem.

“At this location there are entrance ramps from both Memorial Drive and from Allen Parkway which merge onto the freeway on the right and left sides, respectively, at the same location,” said Raquelle Lewis, spokeswoman for the Texas Department of Transportation. “This is an unusual arrangement and is unexpected from a driver’s perspective. This configuration is the cause of nearly constant congestion at this location as main lane traffic slows to accommodate merging traffic on both sides of the freeway.”

Entering and exiting freeways to street traffic from the left long ago fell out of favor as a design option, and is largely a holdover only in metro areas. Studies have shown left entrances and exits cause drivers to make hazardous, split-second aggressive moves, for example.

[…]

Toward the end of 2015, work will start to redesign the entrance ramps so Memorial and Allen Parkway both merge from the right side of the southbound lanes. It’s a fix, at $2 million, that is much cheaper than more lanes or some gigantic rehabilitation of the freeway. The effect, however, might be greater than $2 million usually buys.

Like the alterations to I-45 south of downtown, this project is funded by the mechanism created by the adoption of statewide Proposition 1 last year. I presume what they’ll be doing here is rerouting the Allen Parkway ramp to the other side of the freeway, so there will be just one entrance on the right. That will help, but my guess is it won’t make that much difference. In my experience, the vast majority of entering traffic comes from there already, and the often steady flow of vehicles on the short merge lane is a big cause of the bottleneck there. (I would also note that it’s not that long ago there was no merge lane at all – on either side at that juncture, you were pretty much entering from a stop.) The bigger problem is that I-45 narrows down to two lanes at the exit for US59/SH288. The solution to that, if there really is a viable one, isn’t going to be that cheap or that easy.

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