Frost Protection for Bridge Abutment

[andy383]

Hi All,
Here is the situation. A client has asked us to look into roadway widening for a development and the widened section of roadway goes under a bridge. Additionally they need a sidewalk to be added. Unfortunately, as we widen the road way we start to encroach on the bridge abutment. To solve part of that problem we've looked into retaining walls to hold back the soil on the toe of the abutment. However, we're still faced with a situation where on one of the abutments we no longer have adequate frost protection. Incidentally, it is a stub abutment on spread footings. I'm still trying to wrap my head around the project, used to be someone elses job then got plopped onto my desk. What I'm looking for is any resources or suggesting in addressing the frost protection issue. I've read about styrofoam insulation but I'm not convinced this is a good solution. Any suggestions would be greatly appreciated. Also, I've checked out several cold weather state's bridge manual but I can't find any alternatives to frost protection other than making the foundation deep.
Thanks,
Andy

 

[jdonville]

andy383,

Can you raise the sidewalk grade up to maintain the frost protection over the abutment footing? You may need to provide a grade separation (berm, retaining wall?) between the underpass road and the sidewalk.

If the bridge has a spillthrough abutment, you could probably run the sidewalk up on the spillthrough slope a bit.

Hope this helps,

Jeff


Jeffrey T. Donville, PE
TTL Associates, Inc.

http://www.ttlassoc.com

 

[jheidt2543]

There is nothing wrong with using the insulation solution. The rigid insulation board comes in various thicknesses and has pretty high compressive strength. But, you must remember that insulation only slows down the frost penetration. If you have extended periods of extreamly cold weather, frost could still penetrate a thinly insulated section. So, you will have to actually calculate the amount of protection you need based on weather records for the duration of freezing tempertures.