The brilliance of freeway tunnels (part 2 of 2)Part 1 here. Reading the paper sparked a couple of my own variant ideas. All of the conceptual cross-sections show two tunnels, but some tunnel concepts contain as many as 8-9 lanes in each one (stacked 2-3 levels high inside the tunnel cross-section). Might we get away with a single tunnel instead of two, since we're keeping I-45 on the surface? Would that roughly halve the cost?
Another variant: a tunnel allows us to think outside of the 45 corridor itself. Is that really the best place to put the new capacity? If you look at a map of Houston, you can see that big driver of the congestion on 45 is that a large swath of NW Harris County drains into it on local streets. For whatever reason, 249 inside the Beltway never became the spoke freeway it should have been. A tunnel under the 249 corridor may make more sense, connecting to the 249 freeway outside the Beltway and relieving both 290 and 45. 290 could definitely use the relief, and it would provide a more direct trip into town for the people of that heavily populated area around Willowbrook.
Combining the two ideas, it may even make sense to run a single tunnel under 45, and another single tunnel under 249, coming together at some point near 610.
I am really inspired by the potential of tunneling in Houston. If they're successful in this corridor, there are all sorts of other places around town that could certainly use the same solution: (here's a map to help you visualize)
- How about adding capacity to the always-congested West Loop?
- Bring the 225 Pasadena Freeway into the center of town as originally planned? (taking the load off of 45S inside the loop)
- Connect the Ft. Bend Parkway to the southwest corner of the 610 loop?
- Create a missing spoke freeway between 290 and I-10 outside the Beltway?
For a long time I've wondered how we'll connect center-median express lanes (like on the new I-10) with crossing freeways without creating an insane tangle of ramps (or forcing express traffic into the congested general lanes for the exits, defeating their purpose). But if the express lanes are underground - including the connecting exit ramps - then the problem is solved!
TXDoT and HCTRA need to see this as not a one-off project, but building an expertise and capability that can be applied over decades of growth. The cost of that learning curve and that equipment has the potential to be amortized over many projects, not just 45, making the economics even more compelling than it already is.