Construction and closures Roads: Loop 1604 SH 151 superstreet
UPDATE (11/1/11) - The changeover has been postponed until Wednesday.
Just back from vacay and have some local news to report. The final element of the package of improvements along Loop 1604 West that included two superstreet intersections will come online tomorrow. Namely, the left turn from southbound 1604 to SH 151 will be eliminated. Motorists wanting to go to SH 151 will now exit at a new exit ramp just south of Culebra, follow the access road, then cross 1604 at a perpendicular signalized intersection. The existing entrance ramp from Culebra will be closed and replaced by an improved entrance ramp at the SH 151 intersection. (For a schematic of these changes, see the link under “Additional information” below.)
Like the superstreet intersections, this change will most likely seem completely unintuitive for many folks. After all, southbound Loop 1604 traffic will now have to stop to allow traffic to enter SH 151 whereas before they didn’t ever have to stop. But this new arrangement will actually be safer overall and will help reduce congestion in the area. The reason is that most of the traffic coming from Culebra moves over to the left to make the turn onto 151. This causes lots of conflicts with through traffic on 1604, thus creating an unsafe free-for-all and lots of resulting congestion, not to mention the resulting driver angst. Moving all that traffic onto the access road (which has been improved to handle it) will eliminate that mess. Yes, southbound 1604 traffic will now be stopped periodically to allow traffic to cross over to 151, but it will be better controlled now, which will improve safety. And there are some things that will mitigate the delay to southbound 1604 traffic: 151-bound traffic will now be moving straight, so it can move a little faster than it did when turning left; there will be three lanes crossing 1604, thus improving throughput by 50%; and the signal can be synchronized to minimize the disruption to southbound platoons of vehicles coming from Shaenfield. Computer modeling of these changes showed an astounding 85% reduction in morning peak period delays and a 47% reduction in the afternoon over current levels.
The change is also considered a necessary preparatory change for the upcoming SH 151 underpass at Loop 1604. That left-turning traffic will need to be moved out of the way to facilitate that anyway, so doing it now will help expedite that project when it starts next year.
Finally, the changes will have some ancillary benefits including allowing traffic from Alamo Ranch Parkway to reach SH 151 and allowing traffic headed to Alamo Ranch from southbound 1604 to bypass the congested Culebra intersection, both of which should reduce the congestion in that intersection a bit.
The previous improvements along Loop 1604 have already resulted in a dramatic reduction in congestion. As I have previously reported, the simple addition of an auxiliary through lane at Braun virtually eliminated the peak period backups there. Since then, the superstreet intersections at New Gilbeau and at Shaenfield have turned a chronically-congested stretch of 1604 into free-flowing, even in peak periods.