Ottawa, Ontario: Will ground conditions thwart grade-separation plans?

30 Sep

In the aftermath of the level crossing accident that saw six people lose their lives on Ottawa’s Woodroffe Avenue level crossing, the decision to abort a grade-separated solution is again in focus. A decade ago the costs of grade-separating this level crossing were deemed unaffordable because of “bad rock” and groundwater issues.

Now, while the extent to which the same issues will prevail at the nearby Greenbank Road level crossing, it has been decided to press-on with the CAD 43.5 million grade-separation project pending a better understanding of the sub-surface ground conditions to be determined through detailed site condition surveys. So, there remains a possibility that the Greenbank Road grade-separation may not be possible, at least in terms of a highway underpass. Also, it is possible that the costs will rise substantially when the geotechnical surveys are complete. Potentially, the same ground condition issues will in due course be found to exist at nearby Strandherd Drive which in the longer-term remains a candidate for grade separation. However, the preferred solution here is a road-over-rail bridge.

Recent census information for the Greenbank Road level crossings has shown the number of road vehicles each day to be running at about 15.5 thousand giving a traffic moment of just under 0.25 million compared with one about 50% higher at Woodroffe Avenue when the busway and highway traffic are both considered.

One Response to “Ottawa, Ontario: Will ground conditions thwart grade-separation plans?”

  1. Dave H (@BCCletts) October 1, 2013 at 06:28 #

    Pretty certain that the Dutch will have done quite a few underpasses where the local water level will be well above the surface of the path or road. I’m collecting details of such ‘impossible’ crossings and know that one of the main walking and cycling routes in Utrecht goes across under the main station sharing the underpass with a substantial drainage channel with the water level at least 1 metre above the path.

    It was frustrating to have such limited resources at one inquiry when trying to press for such a solution, which would have avoided a 200 metre increase in the distance walked to cross the railway, not to have strong enough technical resources to show this could be done – again sharing the crossing span with a small stream, and the drainage of the low point taken away downstream, but avoiding the use of pumping wherever possible. I suspect that issues with water table level and drainage fall were similar to the challenges facing the Ottawa sites.

    Up in Scotland we had a neat solution to the regular trespassing short cut before the Strathspey line station moved, a concrete cill cast down one side of a large melt water sized culvert provided a crossing of the main line and heritage line in one simple solution. At several points along the A95, several newer storm culverts have been built specifically with this use in mind and a similar option of building a submersible route under a flood arch at the level of the 100 year flood or a seasonal surge that blocks the route for a day or two at most, and emerging from the water fit for a return to use, as soon as the flood subsides, after all we have some routes where the road closes for several hours with every high tide

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