North Texas managed lanes data reported

[MaxConcrete]

The managed lanes on IH-635 in North Dallas and IH-820/SH 183 in the Fort Worth area have been open for more than a year and the first data is now being reported. Segment 2 of NTE is the SH 183/121 section through Huless, Hurst and Bedford. Segment 3 of the LBJ Express is between US 75 and the Dallas North Tollway.
For the data-wonk types out there....

http://www.nctcog.org/trans/committees/sttc/documents/Item_7.sttc062416.pdf

The results are quite impressive. On both those sections, afternoon and evening delays on the general purpose lanes have been entirely eliminated, even with 7% more traffic on the general purpose lanes than before the managed lanes project began. The data almost seems too good to be true, and I'm wondering if they cherry-picked the sections and directions to get those amazing results. I'm also inclined to wonder if the good results can be sustained as traffic increases.

[Chris]

Did they add auxiliary lanes between exits? That may explain the improved traffic flow on the GP lanes despite the addition of no new lanes and higher traffic volumes. Less weaving. I find it hard to believe that geometry alone could have such a big effect, it's not like it was a 1930s New York style parkway before construction.

DFW is still growing very fast so traffic volumes will continue to grow strongly as well. The whole business case of managed lanes is that they rely on congestion on the general purpose lanes to be profitable. Few people will use the managed lanes if the GP lanes are free-flowing.

[wxfree]

There are some improvements aside from the GP lanes.  There's at least one area with new frontage roads, and some frontage roads now have bypass lanes, which break off of the frontage road and go over or under the intersecting roads before rejoining the frontage road.  This lets short-distance drivers avoid traffic signals without getting on the freeway.  It's basically a new limited-purpose freeway lane that doesn't cause merging when it ends.  Another improvement I noticed looking at old aerial photographs is one place where traffic going to the freeway from two separate roads converges onto a single entrance ramp, whereas before each had its own ramp, causing two consecutive merge points close together.  These operational improvements seem to add together to make a difference.  I'm sure there are others I didn't notice.

[Bobby5280]

The frontage roads along the rebuilt LBJ Freeway are definitely improved. Although I would have preferred seeing some of the numerous driveways dumping traffic directly on/off them eliminated. I think a major cause of traffic jams are tie-ups down at the surface level between the combinations of traffic light cycles and traffic entering & leaving the frontage roads via driveways. The back-ups end up growing onto freeway exit ramps and then onto the freeway itself. Throw in a fender bender either on a frontage road or major crossing street and the same thing can happen.

On I-635 the frontage roads have portions that can leap frog Josey Ln, Webb Chapel, Welch, Hillcrest & Park Central. The downside is some of those movements can create weaving issues with traffic entering or leaving the general purpose lanes of I-635.

The frontage roads are now traveling "through the box" at all but a couple or so freeway interchanges rather than unexpectedly merging onto the freeway. Most of the intersections have Texas style U-turns built into them. It's not as big a problem if you miss your exit or get forced past it; it's easier to double back.

I think the tolled express lanes are getting quite a bit of use due to the time they can potentially save. Traffic jams on the LBJ can be a major time vampire. The toll on the express lanes can pay for itself in return for time saved not burning up a bunch of fuel while stuck or crawling along slowly.