Question

What is the tolerable differential settlement at bridge approach as per designed speed is deemed to be safe for road users?

Answer 1

Sir,

The allowable differential settlement at bridge approach at the point of connecting the structure and embankment is zero. The allowable settlement at approach bridge embankment is however is at the rate of 1:500. Which means that the allowable maximum settlement is of 100mm within the 50m range from bridge abutment.

Thank you.

fairul

Comments

Thank you. But a settlement depth of 100mm will be a big impact to the motorist in term of the kink effect, in this case the safety of the road users will eventually at risk.

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Sir,

No such kink effect will occur. It is a gradual settlement and 100mm is max settlement at the point between toe of embankment and incoming road. Settlement on road has greater rate value with maximum total settlement of 250mm after 5 years post-construction.

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Sir,

But many occasion the settlement happened at the bridge approaches will have the kink effect especially right after the ballast wall. In this situation impact from the kink effect will be a risk to all motorist if the the drop is >100mm.

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During many of my road trips, I'm quite sure I've encountered with bridge's approaches which do not satisfy to this settlement requirements, especially to newly constructed bridges. Is it due to problems in design, material or construction.?

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Most of the cases were of construction issue caused by poor compaction.