Beginning in August, MoDOT will begin work to replace the Union Rd bridges over I-55. The new bridge will be almost exactly the same as the existing one with only some minor changes to meet current highway standards. However, the new bridge does not include any provisions for a transitway underneath the bridge.


The Metro South Study, which looked at extending the Blue Line from its Shrewsbury-Lansdowne I-44 terminus, concluded back in 2005 without a final decision and three MetroLink alternatives still on the table. Two of the three alternatives extend MetroLink past Watson Rd deep into South County all the way to Butler Hill Rd: the Blue Line alternative via the Union Pacific rail right-of-way and the Orange Line alternative via the River des Peres and I-55.

The Northside-Southside Study concluded at the end of 2007 with a single locally preferred alternative. The recommended MetroLink alignment would go south from Downtown via Chouteau Ave, Jefferson Ave, and I-55. The I-55 portion of the alignment south of the River des Peres is nearly identical to the Orange Line alternative from the Metro South Study mentioned above.

As of today, MetroLink has yet to expand beyond its 2006 Cross-County extension. However, a long line of studies have lain the groundwork for where to proceed with expansion. In MetroLink’s long-term future, an alignment along I-55 is all but guaranteed to occur.

MoDOT’s response

In an email I sent to Shirley Norris at MoDOT, I asked whether MoDOT had considered leaving space underneath Union Rd for a potential MetroLink line. Her response:

At this time it is not certain how MetroSouth might be configured in this location in the future. It is also questionable if this alignment will be built—at least not for the foreseeable future[…] Since there is a lot of uncertainty about the future of MetroSouth Extension and the bridge needs replacement, we have moved forward with our current plans. If and when funds become available and that alignment is built, the bridge would have to be looked at, again.

Portland’s model

In the mid 1970s, Portland planners had the foresight to include a “transitway” — land set aside for a future public transit alignment — alongside the newly built I-205. Today, Portland’s MAX light rail makes extensive use of the corridor: the MAX Green line, set to open September 12, will make use of 6.5 miles of transitway set alongside I-205.

In fairness to MoDOT, a small portion of Portland’s I-205 transitway was utilized almost immediately with the construction of the first MAX line at Gateway/NE 99th TC station. And the Red Line to PDX airport began construction a little after 20 years time. However, it has taken more than 30 years for the MAX Green Line to come into being within the transitway; back when the transitway was first planned, it was still unknown whether the portion that became the Green Line would be rail or bus transit.


Replacing the Union Rd bridges over I-55 is an $8 million project for MoDOT which, in end, isn’t that much money for a highway bridge. Adding a transitway underneath Union Rd would only add to the bridge’s cost.

There are repercussions, however, for rebuilding this bridge on the cheap. In order for the MetroLink alignment to get past the obstacle Union Rd presented, planners from the Metro South study shifted the alignment slightly east from I-55 to permit going over Union Rd. Consequently, 3 multi-family properties tucked in between Union Rd and I-55 must be taken. These properties could likely be avoided if the alignment were to remain alongside I-55 at Union Rd.

MoDOT needs to remember that highways and roads are not the only form of transportation in the St. Louis area. What is best option for MoDOT (easiest, cheapest, most efficient) is not necessarily the best for the St. Louis area. The possibility of MetroLink along I-55 should not be ignored.

Posted by Herbie Markwort

I like to write about transportation.


  1. One observation and one thought.Even if the alignment went under the Union Road bridge it would have to cross the ramp. That would require a tunnel since there is no room for the grade change to go under Union and over the ramp. So the proposed alignment is not because of the Union Road Bridge.St. Louis needs to commit to MetroLink. A funding source for expansion is badly needed along with definite route plans.

  2. I don't see why that ramp could not be rebuilt as a bridge structure when MetroLink is constructed in this area. It would be similar to the Laclede Station entrance to I-44 which is squished next to the Burlington Northern railroad tracks.Overall, I am much more concerned with property takings that can easily be avoided with a little foresight.

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