Why the Pierce Elevated backs up.

By now you’ve probably heard about the idea to turn the Downtown Houston freeway loop into a giant traffic circle.

It’s a useful concept, in that it clears the idea space for other radical ideas. I was once on a Value Engineering committee where we were discussing storm drainage design alternatives. I proposed “Amish children with buckets.” Now, there was approximately a 0.0% chance of Amish children being selected. But it made everybody laugh, and it made any other crazy ideas seem just a little bit less crazy. In politics they call this the Overton window.

So now we turn to what might be done with the downtown Houston freeway network. And I think it’s useful, before we get into traffic counts, before we send out origin-destination surveys, before the consultants show up with detailed microsimulations, to just take a step back and look at the big picture.

Coming in on 59, after the Spur peels off you have six lanes. There’s a short weave where traffic comes on from San Jacinto and heads off onto 288, and then you’re once again at six.

Coming in on 288, after the ramps to 59 south peel off you have eight lanes. It gets sort of complicated because the northbound freeway widens out in anticipation of as-yet-unbuilt express lanes, but in the southbound direction it’s a pretty simple setup of two lanes from 59 and two lanes from the C-D from 45. So oversimplify and call it eight lanes for both directions.

Coming in on 45, you lose the C-D to “Downtown Destinations” and pick up a lane from Spur 5, which leaves you with an eight lane cross section going over the Columbia Tap. (I’m not counting the C-D lanes since they don’t interface with the downtown freeway loop).

That’s twenty-two lanes total. How many lanes are available downtown? The Pierce Elevated has six. And a cross-section of 59 at the GRB has eight. Add ’em up and you get fourteen. 22 into 14. 11/7. This is why the Pierce comes to a standstill.

Of course, some traffic is headed from 59/288 to 45, and won’t enter the downtown freeway loop. Presently the ramp from the 59/288 C-D to 45 SB is one lane. So let’s subtract one lane each way from 45 and 59/288. You still have eighteen lanes into fourteen. 9/7. The approaches have 30% more capacity than the loop does. Since the downtown freeway loop already has pretty good geometry, any proposal which doesn’t address this imbalance probably isn’t worth considering.

5 thoughts on “Why the Pierce Elevated backs up.”

  1. Ha, I’m sure some people have entertained a similar radical idea for the 10, the 110, and the 101 in Downtown LA. The real problem on these freeways is that they’re old and the weaves are just too short, e.g. the 10 east to the 110 north followed by a 2-lane downtown C-D, the end of that C-D and the four-level interchange, etc.

    At any rate, if you widen the loop, what does that mean for the approaches on the other (NW/NE) sides?

  2. On the Northeast you have three lanes from 59 and two from IH 10. The Northwest side is trickier to discern because there is a substantial weave where traffic from 10 East and 45 South either stays on 45 South or gets off at McKinney, Allen, or the C-D to Jefferson and Pierce. I’d say it’s about 16 lanes now but it easily becomes 18+ if/when the Hardy Toll Road extension opens.

    Is the 101/110 interchange on the national register? I would think it would be, first stack and all. That would complicate things.

  3. The 101/110 interchange itself does not seem to be on the register but the Arroyo Seco Parkway (the 110 north of the interchange) is. The 110 is also a state scenic highway and national scenic byway, because, you know, the 185,000 people sitting there every day just wanted a nice view. IMHO the interchange is overbulit given the network… it made sense at the time, but today, I don’t see any need to allow any movements to or from the south leg of the 101.

    NIMBYism in Pasadena has pretty much killed any hope of upgrading the 110, as it will probably kill any hope of ever finishing the 710. My personal idea for at least doing something in this area would be to extend the 110 HOV lanes from their current dead end south of downtown north along the 110 and then through a short tunnel under Elysian Park to connect directly to the 2 and allow trucks to use the lanes north of the 10. Also would really help the 110 north if the downtown exit split off to the south of the interchange w/ the 10 to eliminate that weave.

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