New coalition unveils alternative plan for St. Croix River bridge

StillwaterLowSlowNew

Strib reports: New coalition unveils alternative plan for St. Croix River bridge

Competition emerged Tuesday in the debate over a new St. Croix River bridge near Stillwater.

The new Sensible Stillwater Bridge coalition, referring to the longtime $690 million bridge proposal as a "boondoggle," unveiled plans at an afternoon news conference for a lower and slower bridge at less than half that cost. The narrower three-lane bridge would angle from south of Stillwater, at Oak Park Heights, to where the Stillwater Lift Bridge meets the Wisconsin side of the river.

1. Just for the record, despite the presser this afternoon, this is not a new proposal. The image differs only slightly from this 2003 image :
StillwaterLowSlow

We can play one of those kids games, spot the differences. The arch is further east. There is a traffic circle/roundabout control, and some forking of the bridge on the west side, but the angle and the two landing points are the same as was proposed a long time ago judging from my scientific analysis of the watercolor engineering diagrams. That does not make it a bad proposal, and perhaps the coalition is new, but the proposal is not.

2. They are proposing a "3 - lane bridge", which implies 36 feet wide at 12 foot lanes given modern standards for new construction (not including the shoulders that MnDOT will insist on). But at 9 foot lanes, this 36 feet could be almost instantly transformed into four lanes. 9 foot lanes are outrageous you say, but remember, in 10 to 20 years, vehicle lane departure control will be significantly better (we are on the inexorable path towards robot cars), meaning lanes need not be much wider than the vehicles themselves. Even traffic engineers are becoming cool with narrowing lanes today (though not to 9 ft).

At worst, drivers will slow down by 5 miles an hour on their path. So for being slowed down on 2 miles, instead of it taking 2 minutes that bit might take 2 minutes and 10 seconds. Instead of the 20 mile trip taking 20 min, it will take 20 min and 10 sec. Again not a meaningful difference.


We will in the not distant future be able to squeeze more capacity out of all of our roads and bridge (if the pavements and structures will allow us). This means over most of its life (1) it won't do a whole lot to slow growth in Wisconsin compared to the bigger bridge proposal, and (2) you don't need the bigger bridge to have growth in Wisconsin.

This presupposes this bridge comes along with a limited access if not grade separated highway between Wisconsin and Minnesota, which it seems to, depending on what happens to Wisconsin State Highway 64, and from my periodic sojourns through beautiful downtown Houlton, this seems an easily solved problem. The Stillwater side is / can be fully limited access with this design.

Of course the larger bridge proposal could then be easily reconfigured to 6 lanes I suspect, but the demand may not be there. So my view is the capacity reduction on this is largely not meaningful over the relevant timeframe 2015-2065. We need to be planning for a world with narrower lanes, and more capacity in the same footprint.

3. Because it is a smaller bridge, it should save money, but we would need to see the DOT cost estimates before we can be sure we compare apples to apples.

4. This brings more traffic closer to the river than the other plans (e.g. Alt B) (assuming identical traffic levels), as traffic runs next to the river before crossing, and then stays near the river on the Wisconsin side. I am no expert on water pollution, but that bit seems not so good.

5. MnDOT should invest in watercolor artists.

6. This proposal should not simply be brushed aside as Not Invented Here. The objective is maximizing Benefits / Costs. Whatever proposal does that should be selected. I mean, who wants an Insensible Bridge.


David Levinson

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This page contains a single entry by David Levinson published on July 12, 2011 4:34 PM.

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