+1 vote
in Irrigation Engineering by (74.4k points)
Calculate the longitudinal braking force (P) for four-lane bridges designed for class 70R loading.

(a) 14 tonnes

(b) 21 tonnes

(c) 17.5 tonnes

(d) 35 tonnes

I had been asked this question in semester exam.

The query is from Small Road Bridges Construction topic in chapter Culverts and Small Road Bridges Construction of Irrigation Engineering

1 Answer

0 votes
by (102k points)
Correct choice is (b) 21 tonnes

Best explanation: The longitudinal braking force is equal to the 20% of the first trainload plus 10% of the load of the succeeding trains in class 70R loading i.e. 70 tonnes.

For four lane bridges- P = 0.3 x 70 = 21 tonnes. (20% + 5% of the loads in lanes in excess of two)

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