rough railroad bridge cost 1

[sdciviltech]

I am currently working on an at-grade railroad crossing in the state of south dakota. We are running into many horizontal and vertical constraints and it looks like it will be expsensive to purchase properties to get the project complete. I would like to figure out how much a 100' span single track railroad bridge would cost to design and build. there are many advantages to building the bridge, but I need to do a quick analysis of the cost of an at-grade crossing plus property purchases and utility borings against the bridge cost. are there any rules of thumb for quickly costing out a railroad bridge of this size?

 

[HgTX]

If your DOT has done a railroad underpass before, they should have that kind of information. So would a railroad, but the DOT is a government agency so it has open records.

If you're talking a pair of through-girders, it's probably a couple times the cost a similar span highway bridge would be.

But that's just the bridge itself. That's not including the cost of raising the grade of the approaches (my guess is they need a shallower grade than a highway bridge does) and/or lowering the grade of the highway.

I think I'm misunderstanding something about your post, though. Why would the at-grade crossing involve more property purchase and utility borings than a bridge? Why would it have more vertical constraints?

Hg

Eng-Tips policies: faq731-376

 

[sdciviltech]

HgTX - Thank you for the quick multiplier for the cost.

I think you are reading the post correctly, but I have not properly explained the horizontal and vertical limitations.

As far as the limitations are.

Horizontal - The current roadway resides entirely on the north side of the railroad. I order to improve intersection spacing at a crossing roadway, a portion of the roadway is being moved the the south side of the railroad. Horizontally, the roadway is parallel to the railroad on each side of the crossing. the railroad and the roadway run east-west. The roadway is 100' north of the railroad on the west side of the crossing and 250' south of the railroad on the east side of the crossing. We are limited to a maximum 30 degree skew from 90 degres at the crossing and hence we have to divert the roadway to the north to gain adequate spacing to place a 300' curve to head the roadway across the railroad and maintain the horizontal skew requirement. this diversion costs two property purchases lying on the north side of the roadway.

Vertical - the railroad is 18' higher than the roadway and there are two intersections that need to be maintained in the diversion area. To raise the roadway to cross the railroad, we are ending up reconstruction about 1200' of asphalt roadway on these two streets. This reconstruction also includes three business entrances from these two streets. If the railroad was above the roadway, we would only be reconstructing 200' of roadway and one entrance.

 

[HgTX]

So either way, it's not an at-grade crossing.

By a "couple" times more, I mean "couple" in its most vague sense, not 2.0.

Hg

Eng-Tips policies: faq731-376

 

[sdciviltech]

In the current design, as the road diverts to the north to prepare for the crossing, we put in a vertical curve to get up to the existing railroad grade to make an at-grade crossing.

If we were to build the bridge so the railroad would pass over the roadway, we would not have to divert to the north and could cross the railroad at a 70 degree skew to perperdicular. This would avoid the property purchases, the adjoining roadway reconstruction costs, and make a safer crossing.

I will go with a factor of 3 for the sake of arguement and be on the safe side if the numbers work out.