North County traffic studyhttp://www.co.st-louis.mo.us/hwyweb/Publications/NW_Pkwy_Study/I-270_I-70_MO370_MoDOT_Report_2006-11.pdf
(30 MB PDF)
* The study is dated since it lacks the now under construction diverging diamond as an alternative for the I-270/Dorsett interchange, plus the new design for the I-270/Page interchange (the new turbine plan with a NB-WB and future WB-SB semi-direct ramps, versus the older NB-WB flyover with a future SB-EB flyover as shown in this study), and the now under construction completion of the MO 141/Earth City corridor.
* The study briefly notes that MoDOT developed conceptual alternatives to grade separate the Page/Schuetz intersection, but funding constraints and a lack of priority are hampering the project (Page 63 or 77/129).
* A MO 370 to Lambert Airport connection was once considered (a “fourth leg” of I-270/MO 370 interchange), possible new terminal and access via MO 370. Alternate 3 later in the study has the complete I-270/MO 370 interchange with the fourth leg as a stack variant with six levels, but I only count five from the diagram (NB-WB on the bottom, I-270 mainlanes, EB MO 370 + EB-NB, SB-EB, and WB-SB on top)(Page 79, 93/120)
* Alternate 4 looks at one-way outer roads for I-270 between Missouri Bottom Road and I-70.
* I-270 half diamond south of the McKelvey Road overpass briefly looked at, dropped due to weaving issues (Page 99, 113/129). So traffic wanting to use such ramps would have to cross traffic exiting to I-70 instead of simply merging over sooner with the rest of the traffic exiting in the area?
* The study leans towards conversion of the I-70/Earth City Expressway interchange to a SPUI over using a flyover for the SB-EB or WB-SB movements due to the presence of other traffic lights on the Earth City Expressway, and some study members thinking of flyovers as overkill (wonder if any of them have seen I-80/I-94 in the Gary area with semi-direct ramps for surface street movements?). For some reason a six ramp partial cloverleaf option is neglected yet again around St. Louis (other area I know for sure this happened was the I-64/Kingshighway interchange).
* The study notes many drivers using McDonald Blvd to bypass I-270 congestion, and states "widening of I-270 between I-170 and IL 3 and reconstruction of the Lindbergh Boulevard interchange may alleviate some of the need for improvements to the I-270/McDonnell Boulevard interchange." (Page 108 or 122/129).
* The study ultimately recommends a SPUI for I-270/MO 180, adding one- way outer roads for I-270 between I-70 and Missouri Bottom Road, and possible conversion of the I-270/McDonnell interchange to a diverging diamond, and to wait on final decisions for the I-270/MO 370 interchange, widening the NB I-270 to WB I-70 flyover, and the I-70/ Earth City Expressway interchange.NorthWest Parkway
Main website: http://www.co.st-louis.mo.us/hwyweb/Publications/NW_Pkwy_Study/NW_Pkwy_Study.html
* Pretty much a northern extension of the MO 141/Maryland Heights Speedtrap/Earth City Expressway corridor, the RFQ indicates the route is one day intending to extend eastward to MO 367
* The environmentalist are going probably be a problem for this route.