The Revised Arch Ground Plans

If there is one good thing that comes out of this project, it will be the flipping the half diamond interchange on I-70 near the Eads Bridge. Currently the first exit available for those traveling westbound after Memorial Drive is up at Madison Street, 1.69 miles later (slightly less for those coming from I-70 off the PSB, slightly more for those coming from I-55. The new ramps will reduce the distance to around 0.6 miles. Better than the current design, especially for cross river traffic, but ideally it seems there should be another exit before Madison Street - which doesn't seem like the best place for an exit anyway; Cole Street or Broadway seem like superior locations.

In the past there used to be a full interchange for the MLK Bridge, but the westbound exit and eastbound entrance seem to have been removed sometime before 1988. I am guessing these ramps were removed due to weaving issues with the current ramps to/from Memorial Drive at the north end of the depressed section.

One advantage of the revised interchange is the Eads Bridge finally gets decent interstate access on at least one side, making it a somewhat better alternative to the PSB, although it could use some access improvements on the Illinois side. The current design can make exiting or entering I-55/64/70 somewhat tricky for destined for or coming from I-55/70 due to weaving with I-64 traffic. This could be fixed however with a new half diamond on the Illinois side right at Broadway.

As for possibly changing the Eads Bridge from 2x2 to 1+reversible+1, I would like to see more traffic data before fulling endorsing this idea. The Eads Bridge is currently underutilized, but the improved interstate access on the west side could change this.

Depending upon the alignment of the modified Third Street between the Eads Bridge and Laclede Landing Boulevard/Convention Plaza, access could get easier or harder for northbound traffic wanting to access the MLK Bridge. The most recent presentation document (see http://www.cityarchrivercompetition.org/wp-content/uploads/2011/01/MVV_Public_Presentation_1_26_11.pdf) does not give a detailed view of the area to see if there will be any changes to the intersection with the MLK Bridge. If there are not, given the current intersection design and the diagram of changes on Page 24/36 of the presentation, MLK Bridge access will require cutting west to Fourth Street, since the provided drawing does show the connector between Morgan and Convention Plaza being removed.

This is one area that could use some changes, both now and in the proposed plan. One option would be to go with the proposed plan, but leave the Morgan - Convention connector, and even make it two way. Another, maybe less optimal option would be to realign Convention Plaza to directly align with Morgan Street, align Third Street so it has access to the MLK Bridge, and shift Southbound Memorial Drive to create a four-way intersection at Morgan Street. The whole MLK Bridge area would be best revisited though after the new I-70 bridge opens, when it can be confirmed how much traffic will shift to the new bridge.

One area of the new plan that is disagreeable is narrowing Chestnut and Market Streets. Chestnut is already two through lanes plus two parking lanes (and without a median, despite what the drawing on Page 9/36 says), with a curb to curb width around 36 feet around Seventh Street (estimated from Google Earth). It does seem to widen to around 42 feet elsewhere however. Narrowing Chestnut by 15 feet by removing the south lane could easily get one trapped behind someone trying to parallel park. Depending on the design for Market, the same issue could arise for westbound traffic.

Another area that may be lacking is not revising the I-55 interchange around Seventh Street. The PWP proposal would have made it easier for traffic to divert around a reduced Memorial Drive with better access to/from I-55 around Seventh Street. The current design does not seem to compensate for removing/downsizing Memorial Drive between Market and Pine. Maybe if the traffic study would be made freely available online I would be more convinced that the adjusted I-55 access is not needed.

As for the gondolas? I would rather see a new pedestrian bridge parallel to the PSB, or a new pedestrian walkway on a replacement of the PSB.

Design changes for I-270 interchange with Page Avenue (MO 364/Route D)

MoDOT is announcing a major design change for the interchange between I-270 and Page Avenue (MO 364/Rte D). The NB I-270 to WB MO 364 ramp will be changed from a semi-direct flyover (like the ones at the I-255/I-270/I-55 cloverstack) to a more looping, turbine ramp with separate bridges for crossing the mainlines of Page Avenue and MO 364 like the NB I-465 to WB I-70 ramp on the west side of Indianapolis). The new design also changes access from WB Page to Bennington Place; instead of a braided design, traffic from WB Page will have to weave with traffic from SB I-270 desiring to access WB Page. The official site for the I-270 projects at Page and Dorset has a map showing the new deisgn while the older project site still has a map with the old design.

The new design for this interchange will lessen impacts on I-270 and Page Avenue in the short term - pier construction for the original flyover design would probably require closing the left lanes on both routes - and saves more than $1.4 million. Long term, however, I have concerns that the new design will repeat the weaving failures experienced on the WB I-44 ramp to I-270.

In addition, the future second phase project for this interchange has been changed. The original second phase was to add a flyover for the SB to EB movement. Now the future second phase will be adding a similar turbine ramp for the WB to SB movement. As seen in the animation MoDOT has posted, this design requires construction an underpass to get this ramp under MO 364. Such a design will require a temporary shoo-fly for MO 364 to enable this bridge to be constructed. Without more design information, it is my opinion that an overpass for the new ramp would be better. In addition, this new design is not weave free; EB MO 364 traffic wanting to access NB I-270 will have weave with SB I-270 traffic wanting access to EB Route D. This design is less safe, and may have congestion issues depending upon future volumes. Unless there is a hope to eventually remove another loop from this interchange (in a perfect world with more funding, I'd make this interchange loop free), the second phase should stick with replacing the SB to EB loop.

(Disclaimer for the heck of it: I have no current affiliation with MoDOT or anyone involved with this project.)

Business Loop 55 to be four laned between I-55 and US 61-67

MoDOT held a joint meeting today with Herculaneum to display preliminary plans to widen Business Loop 55 (McNutt Road) and build a new intersection with a relocated Scenic Drive

Aerial photo (5.57 MB pdf) showing the planned configuration of BL 55

Due to lack of funding, the bridges carrying I-55 will not be replaced for this project. Leaving the existing bridges necessitates dividing BL 55 under the interstate, similar to how Rte Z is divided under I-55 at Pevely. However, the through lanes will not be divided as on Rte Z, rather the through and left turn lanes will be divided.

It was mentioned at this meeting that this interchange will likely be reconfigured to a SPUI once MoDOT widens I-55 in this area.

The design of the relocated Scenic Drive is not set in stone yet; feedback from the meeting will determine if there will be a right in/right out with the existing road north of BL 55.

Other items of interest learned from this meeting:

* There will likely be traffic signals installed at the Rte Z/Metropolitan Road intersection in Pevely. There is talk of using a roundabout there instead of signals, but funding may be an issue.

* There was construction underway to extend Riverview Plaza Drive across Joachim Creek. I was told this was to provide a route that is still usable in event of a 100-year flood, and to be a new route for trucks to/from the lead smelter in the area.