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.)
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment