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Author Topic: Texas roadway design question  (Read 3380 times)


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Re: Texas roadway design question
« Reply #50 on: January 08, 2022, 10:47:11 AM »

Fascinating thread, because it reminds me of how Louisiana does it slightly differently with their service/frontage roads.

US 167 between Lafayette and Opelousas and US 90 between Lafayette and Berwick acquired its original ROW under contracts stipulating that the roadway would ultimately be limited access. Because of funding limitations, though, their original ROW acquisition consisted of 300 foot wide corridors, which would be enough to carry the mainline roadways and continuous two-way service roads; along with wider widths of around 450 feet to accommodate bulb-outs of the mainlines to support overpasses at future interchanges. However, unlike Texas and their policy of building the service roads (as one-way) first, Louisiana decided on a different approach: they built the mainlines as at-grade expressways with temporary crossovers and intersections, with the aforementioned bulb outs at intersections where future overpasses could be built to complete the interchanges. Intermittent service roads were then built at strategic spots to control access to the mainlines and to serve businesses and residents along the route.

This was Stage One: ultimately, in the late 70's and 80's when they built the bulk of existing I-49 from Shreveport to Lafayette, they simply upgraded the Opelousas to Lafayette segment of 167 by adding in the remainder of the service roads to make them continuous, added in the mainline overpasses to complete the interchanges, and removed the remaining crossovers and at-grade road intersections. The one exemption was that in order to build the Judson Walsh Drive interchange (Exit 15), they had go to a tighter urban diamond interchange concept due to the local businesses and the preexisting local frontage roads. (That was added on to the project in order to serve Opelousas High School, located about 1/2 mile to the west.)

The same model is now being used for the conversion of US 90 to I-49 South in Iberia and St. Mary parishes. It's now almost complete, save for that dang rail spur crossing serving that sugar mill near Jeanerette. The plan there is to truncate the spur short of the crossing and build a pipeline and service culvert that would pass underneath the mainlines and frontage road that would service a pumping station and storage tanks to deliver the goods from the spur to the processing plant.

I'm assuming that the funding was typical 90/10 Interstate, though there might have been some STiP funds involved as well.

Interesting. For what it's worth, I'm not sure this is directly comparable to the situation on the mainline Interstates in Texas because what Louisiana did in those cases was likely a well-thought-out scheme for phased construction rather than what appears to be a policy preference toward providing frontage roads more generously than in other states. I wouldn't be surprised to find that an evaluation was done of different schemes, likely at the insistence of the FHWA, and maybe the report is still lying around somewhere.


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Re: Texas roadway design question
« Reply #51 on: January 09, 2022, 05:25:51 PM »

Don't like frontage roads closely spaced. I prefer spaced out interchanges and the alternate routes can be used as a frontage road.


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