Crest-sag-crest sequence a problem?

[Opham]

We have a bridge approach that has settled, creating a crest-sag-crest sequence in the asphalt road profile. The question is whether anyone knows of a standard, "best practice", guideline, etc. that identifies when this situation becomes unacceptable, from either a safety or comfort standpoint. Grateful for any guidance, or even pointing me in the right direction where I can make further inquiries. Thanks!

Margaret Gibbs
Opus Hamilton (Vancouver, B.C., Canada)
margaret.gibbs@opushamilton.ca
tel 604-684-4488

 

[proletariat]

Pg 269 to 283 in the AASHTO green book. These are known as broken back curves. They are undesireable, but if they meet criteria for sight distance, comfort, and drainage, they should be OK as far as I know.

 

[Canadaian]

Hi Opham
this problem happens if approach settlement is not well addressed at advance . Normally there are some requirements regarding eveness of the pavement surface using 3m straight edge in longitudenal and transverse direction.

It may be the bridge owner have a criteria for total post constrcution settlement or post constrcution settlement within say 5 yrs after constrcution that define acceptability.

you need to take the matter very seriously.Investigat if the problem is only related to settlement? how much more to expect? at what rate? How are you going to adress it sometimes top up will induce more settlement and you will end up in a circle ?

I hope this give you the little help you asked for.

thanks
CD