Cross Sections Intersecting Roadway

[mlc3n3]

Hi,

I have a stream in a valley with a bridge crossing perpendicular to flow. Before and after the bridge, the approaching road is parallel to the stream/flow. Think of a harsh “S” shape. Originally I drew x-secs with middle portions perpendicular to flow and parallel to bridge, and outside portions parallel to the road and sometime parallel to stream. At the middle part of x-secs flood events will overtop the road, I have appropriate ineffective flow areas defined here. On the outside parts of the x-secs, I believe flood events don’t cross the road. In this case what do you recommend the cross sections do? Cross the road? Keep original shape but add ineffectively flow areas (temporary or permanent)?

Additionally, the DOT has suggested x-secs that only remain perpendicular to flow and crosses the roadway several times. Where the suggested x-secs intersect the road it’s overtopped during certain flood events. See image.

[Anonymous]

XS should be perpendicular to flow and perpendicular to contours. The XS around and DS of the bridge do not seem perpendicular to contours. If they are, then vary the mannings values but also, if flow should be blocked by these roadways (in real life) then input points on your cross section as levees that only will allow flow to cross them if the WSEL calculated has risen over this elevation of the levee

[Author]

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