Mighty masonry

Despite the annoying inconvenience of living amidst a 4-year construction zone, and my belief that the resulting “major improvement” will only ease 35W traffic for a short time, I have found it fascinating to watch the construction.

I live alongside the infamous 35W/Crosstown highway, a problem area almost since it was built. The east/west Crosstown came first, built as a means to enable traffic to the stockyards in St. Paul. The stockyards is gone, but the trouble began when Interstate 35W was planned, coming into Minneapolis from the south. Freeways cross all the time, but a poor decision was made way back when… to use part of the Crosstown as part of the new 35W. The reason was to qualify for more government money. The result was a stretch of maybe half a mile of jams and confusion as one highway merged into the other and then quickly out again. It also meant that 35W had two big curves… to merge into and out of the Crosstown section. The simplest routes, just staying on 35W or just staying on the Crosstown, both became tricky merges. It became “the bottleneck”.

There were other choices back then, but, gradually, those choices have disappeared as people built around it. Solving the problem has since been proposed and abandoned several times,also complicated by it involving Minneapolis, Richfield, the county, the state, the feds, and many other related groups. Nevertheless, a grand new plan IS being implemented, over 4 years, and I live in the heart of it. The building next to mine was taken, and the new freeway wall is at the end of our lawn now. Traffic is raised far off the ground through here, because of a couple of major streets and railroad tracks.

The freeway right here is built up on earth (as it was before), blocking all north/south traffic except for the two major streets, but the area east of Nicollet Avenue is where the construction gets interesting. The new solution doesn’t take up much more space than the old, but it separates the two freeways better, allowing through traffic to flow without merging together.

The design is spaghetti-like, with many long ramps. In spite of the grand design, it will undoubtedly still result in slowdowns for both freeways… any curve does. To the extent that it makes traffic somewhat faster, it will become a choice for even more drivers, and will inevitably again become “the bottleneck”.

All that negativity aside, the construction project is impressive. Coordinating the placement of workmen, heavy equipment, and resources coming in from subcontractors has to be a mammoth task. Many very large cranes are deployed and redeployed as needed. My favorite part of the complexity is the construction of the elevated roadways. These are built of pre-cast cross-sections, each section making up about 8 to 10 feet of 2-lane roadway. If you haven’t seen such construction before, the photos below will make it understandable.

The long elevated sections of roadway are supported by large vertical columns, placed a considerable distance apart. One at a time, a cross-sectional piece is added atop a column… first on one side, then on the other, etc. Each new piece is pulled tight against the previous ones, under what must be enormous tension. They continue to add pieces to either side, seemingly balanced on the columns, until about a dozen are hanging out on either side, where they, amazingly, meet with the roadway stretching out from the next column.

Most impressive to me is that these elevated sections curve, often in elevation, direction, and banking, which means that each cross-section is built precisely and uniquely for its location.

You can click on the photos to see large versions.

Here are several cross-section pieces waiting to be placed over
Nicollet Avenue. These were placed at night because the crane
blocked the street.


This shows a bare column and another with the
first couple of cross-sections in place.

Here is a closeup of two sections about to meet.

Two long ramps coming together over Nicollet Avenue, from
the north and from the east.

Shows the complex curve of the roadway.

When I look at these constructions, I get the same feeling as when I see an airliner flying over… it doesn’t look like it should be able to do that, but it obviously can.