ABSTRACT
Superstructure work commenced immediately after the foundations, as fabrication had been planned to suit the construction schedule.
Most parts of the superstructure were high tensile steel (HTS) with a yield 35% higher than mild steel (BS 153). The use of HTS, a comparatively new material, in Howrah Bridge resulted in a large reduction in cost and made the bridge feasible. After successful testing, HTS specifications were drawn up for rivet bars and structural sections. HTS and MS rivets were given different-shaped heads to avoid a mix-up. Quality site riveting needed special skills and coordination, and the same was achieved resulting in very few rejections of rivets.
Fabrication was subcontracted to a consortium of three companies in Calcutta. Precise fabrication of large pieces (in three shops) and their trial assembly (as pre-stressing was a design requirement) was a challenge that was met successfully. End milling for 50% transfer of loads in compression members was another.
All these were essential requirements as some joints had to be assembled 100 meters above ground. The quality of work came for high praise from senior engineers.
The high quality of fabrication ensured unhindered erection at the site and perfect geometrics of the truss.
