Houston downtown highway project - Why are elevated highways not being proposed? (San Antonio: how much, construction)

[Dopo]

Houston downtown highway project - Why are elevated highways not being proposed?

Seems to me like a very obvious way to fix traffic in downtown Houston.
The exact same way I-10 was done on the NW side of San Antonio where they have about 3-4 miles of highway that is both at ground level (local traffic with several exits) and elevated highway (no exits).



Here's even an article where TXDOT is proposing (today) a 20 mile stretch of elevated highway in NE San Antonio
Plans for I-35 call for elevated lanes through Schertz, Selma - Aug. 2019

The Texas Department of Transportation has unveiled plans for a 20-mile expansion of Interstate 35 that would make part of it a limited-access, non-tolled and double-decked freeway northeast of Loop 410 through Selma and Schertz.

Why the double-decking?
“There’s no option but to go up. There’s really no more right of way,” TxDOT engineer Daniel Worden told a public hearing audience recently.
The idea behind elevated express lanes is to bypass ground traffic. Motorists will, however, be able to enter or exit the elevated lanes at five locations: at the Bexar County line, Loop 1604, Pat Booker Road, Loop 410 North and Loop 410 South.

[chris_ut]

This would be great on 610 west to bypass the mess of people waiting to exit into 59 which kills the through traffic.

[LocalPlanner]

Talk of double-decking Houston freeways has been around for decades. Yet everyone says the upper level lanes in Austin on I-35 are awful. So why would spending untold $ and causing incredible construction disruption (far more than just about any freeway project we've had before) be worth it here? Plus you just amplify the reach of the highway's air and noise pollution and create that much more of an ugly visual barrier.

I'm not saying I'm completely against it, but want to point out some real major negatives that must be addressed before advocating it.

[Dopo]

Originally Posted by LocalPlanner

Talk of double-decking Houston freeways has been around for decades. Yet everyone says the upper level lanes in Austin on I-35 are awful. So why would spending untold $ and causing incredible construction disruption (far more than just about any freeway project we've had before) be worth it here? Plus you just amplify the reach of the highway's air and noise pollution and create that much more of an ugly visual barrier.

I'm not saying I'm completely against it, but want to point out some real major negatives that must be addressed before advocating it.

I don't think the issue in Austin is the elevated section
the issue is the fact that the elevated section doesn't go all the way South past downtown.

[elnina]

Huge and expensive project, but as we already know - congestion just doesn't get better with the addition of lanes. In fact, over the long run, it gets worse, thanks to the principle of induced demand. (it didn't took long with IH10 to Katy)
Sadly, the financial payout for states is based on increasing driving as much as possible. Building wider roads just creates more traffic, and you end up on an endless cycle of building wider roads, seeing them fill up with traffic, making them even wider, and seeing them fill up again.
Take a look at Braess's paradox...

[NTexas2010]

I know the Katy Freeway is the poster child of induced demand theory, but one caveat or limitation of this test case is the growing population of West Houston / Greater Katy area. The widening took place at a time as new development and urban sprawl continued west at a breakneck pace; I have to wonder how much of the increase in traffic on I-10 is due to "induced demand" versus a rapidly growing population this side of town.

A better control case would be studying a major corridor that was expanded in an area with with a zero population net-growth/loss. I would be hard-pressed to believe the outcome would be identical to the traffic situation of I-10 over the last 10 years.

[LocalPlanner]

Originally Posted by NTexas2010

I know the Katy Freeway is the poster child of induced demand theory, but one caveat or limitation of this test case is the growing population of West Houston / Greater Katy area. The widening took place at a time as new development and urban sprawl continued west at a breakneck pace; I have to wonder how much of the increase in traffic on I-10 is due to "induced demand" versus a rapidly growing population this side of town.

A better control case would be studying a major corridor that was expanded in an area with with a zero population net-growth/loss. I would be hard-pressed to believe the outcome would be identical to the traffic situation of I-10 over the last 10 years.

Our local cases are SH 288 - where it took awhile for development to take off (west side Pearland) - but when it did, it was TOTALLY driven by "high speed" access to the TMC and better-reputation schools than were available on the southern side of the city. I'd say that despite the time delay, SH 288 definitely brought induced demand that would not have otherwise occurred.

The other is US 90. Only now is development starting, probably owing to the relative obscurity of that part of the metro with regard to residential activity.

[Dopo]

Originally Posted by NTexas2010

I know the Katy Freeway is the poster child of induced demand theory, but one caveat or limitation of this test case is the growing population of West Houston / Greater Katy area. The widening took place at a time as new development and urban sprawl continued west at a breakneck pace; I have to wonder how much of the increase in traffic on I-10 is due to "induced demand" versus a rapidly growing population this side of town.

A better control case would be studying a major corridor that was expanded in an area with with a zero population net-growth/loss. I would be hard-pressed to believe the outcome would be identical to the traffic situation of I-10 over the last 10 years.

That case ignores that I-10 is a major highway that goes from coast to coast

[NTexas2010]

Originally Posted by LocalPlanner

Our local cases are SH 288 - where it took awhile for development to take off (west side Pearland) - but when it did, it was TOTALLY driven by "high speed" access to the TMC and better-reputation schools than were available on the southern side of the city. I'd say that despite the time delay, SH 288 definitely brought induced demand that would not have otherwise occurred.

The other is US 90. Only now is development starting, probably owing to the relative obscurity of that part of the metro with regard to residential activity.

Fair point on 288 being a better example if true induced demand, although I would argue that may be more of a function of "if you build it (a road), they (developers) will come."

With that said, the textbook definition of induced demand simply states that additional lanes create the incentive for additional drivers to use these added lanes, with no mention as to whether those drivers materialize out of thin air or are the result of new development because of the road itself.

I think there is a degree of nuance needed when considering the concept of induced demand.

I-10, as I mentioned, is a poor example. The Katy area has been booming for a myriad of reasons dating back 25+ years due in part to people's perception and attraction to Katy ISD schools. I would argue the development in Katy was inevitable, freeway expansion or not, similar to what we are seeing in Fulshear now; the population of Fulshear went from less than 800 residents in 2000 to over 10,000 today, despite the lack of expansion of FM 1093 / Westpark Tollway until recently. The fact that FM 1093 traffic counts have steadily increased in the last 20 years has little to do with the fact that it went from 2 lanes to 4 lanes in the last 2 years.

If anything, some examples of induced demand are more of a chicken/egg paradox: Populations boom and roads are expanded; populations continue to grow and use the newly expanded roads and similar congestion occurs despite the added lane space.

[bu2]

Induced demand is nonsense.

Yes, there is some marginal increase in traffic from a few who choose not to use mass transit or who choose the freeway over arterial roads. But the big increases are because the area is growing. When I-10 opened it shaved 20 minutes off the drive from before construction started. All the while, Katy was growing like crazy.

The real question is the one Metro proposed when they did their rail line vote, "What if we didn't build it and they came anyway?" I think the answer is clear. Look at any freeway where we haven't built. They are coming and we need to do what we can. There are limits. I don't know that we can add any lanes to the Katy Freeway and be effective. But most freeways could benefit from expansion.