ASSESSMENT OF RESIDUAL LIFE OF GIRDERS OF BRIDGE No

1.0 INTRODUCTION:-
Vide Executive Director ( Works) , Railway Board’s DO No. 2004/WI /WR/
Girder dt. 30.04.04, Member Engineering desired that a study may be
conducted to assess the residual life of the girders of the bridge No. 73 &
75 (Abandoned). With a view to use them on new branch line where the
traffic is going to be light in the beginning. The copy of the above letter
alongwith a report prepared by Western Railway on this issue is placed at
Annexure – I.
2.0 OBJECTIVE:-
To assess the residual life of the girders of bridge No. 73 & 75 Mumbai
division of W.R.
3.0 HISTORY OF THE BRIDGES:-
The bridge No. 73 & 75 (abandoned) are located on Basai Creek between
Bhainder and Naigaon stations of Borivali – Virar suburban sections of
Western Railway. The abandoned bridges were open to traffic on
22.01.1927. There are 69 x 2 = 138 nos. of 18.3 m span steel plate
girders on bridge No. 73 and 25 x 2 = 50 nos. of 18.3 m span girders in
bridge No. 75. Thus, there are 188 nos. girders of 18.3 m effective span.
There 8 nos. of 6.1 m span girder in bridge No. 73 & 75. The details of the
girders are as follows:
a) Effective Span - 18.3 m
b) Overall length - 18.95 m
c) Loading Standard - BG standard of 1916
d) Drawing No. - CEN/57728/11-D
e) Manufactured by - M/s P& W Maglellan Ltd., BB & CI. Co. -
1923, Clutha Works Glasgow.
The bridges were abandoned primarily due to Weak foundation and
overstressed sub-structure, where stresses were found to be exceeded
permissible limits, requiring heavy speed restrictions. Many CI piles were
cracked and were continuing in service on clamps. there was heavy
incrustation in the piles due to marine growth and same indicated
extensive loss of section. But the most important and critical reason was
that due to heavy sand dredging in the creek, the bed level gone down by
2.45 m since 1927 and pile grip in rock was reduced to near unsafe limits
in some cases.
In replacements of these bridges, new bridges were constructed on well
foundations at an average depth of 29 m below the mean tidal level and
PSC box type girders of 1.20 m + 28 x 48.5 m spans in bridge No. 73 and
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