Tuesday, November 29, 2011

The new I-70 river bridge: Not the best project that could be

The new Mississippi River bridge currently being built north of downtown St. Louis is supposed to relieve congestion on the PSB. However, for many reasons, it may have not been the best project that could have been pursued. Consider:

* Westbound I-70 traffic already has a non-stop alternative to the PSB via the MLK Bridge. Eastbound I-70 traffic only has to face one light before entering the MLK Bridge. Using the MLK Bridge for through movements to WB I-44 or SB I-55 requires a long trip through downtown to return to the interstate. EB I-44 or NB I-55 through movements have a slightly easier time accessing the MLK - except when special events close Memorial Drive - but it still requires a mile long drive through downtown. This route also includes a sometimes difficult right turn onto Convention Plaza to access the MLK Bridge.

* The I-55 PSB ramps seem to back up regularly outside of rush hour, while the I-70 ramps are almost always free flowing outside of rush hour, excluding ball games.

* Sure, MoDOT says they will fix the access issues if a companion bridge is built in the future. However, there is no guarantee that the companion bridge will ever be built. In addition, what happens should the PSB become unusable for a long period due to a barge collision, severe hazmat accident, or increasing maintenance issues?

Driving Distances
For traffic heading to I-70 or I-55 beyond Troy:
  • From the I-70/I-270 interchange:
- 30.8 miles via I-270
- 38.9 miles via the PSB
- 37.23 via the new bridge (initial build)
  • From the I-55/I-270/I-255 interchange:
- 34.7 miles via I-255
- 32.7 miles via the PSB
- 34.3 miles via the new bridge had access been provided in the initial phase
  • From the I-44/I-270 interchange:
- 40.5 miles via I-270 and I-255
- 35.4 miles via the PSB
- 45.1 miles via I-270
- 37.0 miles via the new bridge had access been provided in the initial phase

For traffic heading to I-64 east of St. Louis, using the point where the I-255 ramps merge onto I-64 as the eastern end:
  • From I-44 at I-270:
- 26.5 miles via I-270 and I-255
- 23.2 miles via the PSB
- 24.66 via the new bridge had access been provided in the initial phase
  • From I-55 at the I-255/I-270 interchange:
- 20.6 miles via I-255
- 21.9 miles via the PSB
- 23.36 miles via the new bridge had access been provided in the initial phase
  • From the I-70/I-64/US 61 interchange at Wentzville:
- 48.2 miles via I-64 and the PSB
- 47.2 miles via I-70 and the PSB
- 58.5 miles via I-64, I-270 south, and I-255
- 56.3 miles via I-70, I-270 east, and I-255
- 52.7 miles via I-70, I-170, I-64 and the PSB
- 45.45 miles via I-70 and the new bridge

What Could Be Done
Since it is too late now to abort the project and instead look again at a new bridge south of the PSB, there are a couple of changes to the new bridge project that could make this project much more useful to all.

* Add a new WB I-70 exit and a new EB I-70 entrance between Memorial Drive and the new bridge. While not an ideal solution, this would at least make it easier to access the new bridge from the south without as much time sitting at stoplights. The best location would be at Cass Avenue, but new ramps here would require closing the existing EB exit/WB entrance to/from Broadway or using a more costly braided design.

* Replace the current entrance to WB I-70 south of St. Louis Avenue with a new WB exit. This would at least allow a somewhat indirect U-turn option that might aid in any closure of the PSB

* Simply add the ramps to the south. Supposedly adding those ramps now would be incompatible with a future companion span, but the current design is not entirely compatible with the companion either. The connection between EB I-70 and the first bridge will be unneeded and require modification and removal, so why not modify it in the initial build to allow a more useful product?