New Pamban rail bridge: Commissioner of Railway Safety permits operation of trains but flags ‘glaring lapses’

The new bridge sets a bad example for constructing important structures, A.M. Chowdhary says 

The Commissioner of Railway Safety (CRS), Southern Circle, A.M. Chowdhary, has pointed out “glaring lapses” right from the planning stage to the execution of the new Pamban rail bridge, even as he gave the go-ahead for operating trains on the structure.

Mr. Chowdhary authorised the opening of the reconstructed bridge between Mandapam and Pamban (halt) stations in the Madurai Division of Southern Railway for public carriage of passengers and goods traffic, with a maximum speed of 75 kmph.

In his authorisation report, dated November 26, made available to The Hindu, he has imposed a speed restriction of 50 kmph over the lift girder of the bridge, which, he said, could be further relaxed by the Chief Bridge Engineer of Southern Railway.

The CRS on November 13 and 14 inspected the bridge consisting of 99 spans, two auxiliary girders, one vertical life span of 72 m, and a single line broad gauge track on the diverted alignment between Mandapam and Pamban railway stations over the Pamban sea channel.

The new rail bridge has been constructed to replace the old Pamban rail bridge built in 1914 with a double-leaf bascule section and a Scherzer rolling type lift span that could be raised to let ships pass.

The CRS was appreciative of the construction of the old bridge more than 100 years ago, which is widely regarded as a technical marvel, considering the lack of availability of technology in those days and the corrosive environment the bridge had withstood.

Lapses in planning

The Railway Board normally takes technical advice from the Research Designs and Standards Organization (RDSO), a research and development organisation under the Ministry of Railways, which functions as a consultant to the Railway Board, in respect of design and standardisation of railway equipment and problems related to railway construction, operation, and maintenance.

The 72-m-long lift span girder was a non-RDSO standard and designed using foreign codes, which entailed the association of the RDSO in the project. “However, from the perusal of records, it is evident that with the support of the Railway Board, the RDSO shunned its responsibility in the design of the girder,” the CRS stated.

Similarly, the standard practice of formation of a Technical Advisory Group (TAG) for planning such important bridges was also not followed “as a fallout of the decision taken to disassociate the RDSO from the project. It is unfortunate that the Railway Board has been flouting its own guidelines,” the CRS lamented in his report.

As for the plate girders, constructed using non-RDSO standard design, the approval of Principle Chief Engineer, Southern Railway, was taken only after the Commission pointed it out, he said.

Stress carrying capacity reduced by 36%

Primary stressed members like the bottom chord and top chord have been welded at the site in deviation of the Welded Bridge Code. It was done without specific approval from the Railway Board, the CRS pointed out. Even the overhead field welding was permitted for the primary stressed members at the site. These two factors have resulted in 36% reduction in the stress carrying capacity of the primary members, he complained.

The fabrication inspection unit of Southern Railway could not supervise and test-check 20% of the welds done at the site. “To meet the criteria of the 20% test checks as per approved quality assurance plan, the inspection unit has done tests of the welds done in the workshop and deliberately avoided the field welds,” the report said.

Corrosion issue not addressed

Stating that adequate measures had not been taken to address the issue of corrosion of the bridge, even when the structure is said to be in the second-worst corrosive environment in the world, Mr. Chowdhary said that some of its components have already begun corroding.

“This was highlighted by Member Infrastructure of the Railway Board in his inspection notes of July 11. However, no solution has been found for the problem yet,” the CRS stated.

The CRS, after his statutory inspection, sought a report from General Manager, Southern Railway, on critical deviations. The report had stated that there were no infringements to the provision of Schedule of Dimension.

‘Lift span first of its kind’

A senior railway engineer, however, said the lift span girder of the bridge was the first of its kind for Indian Railways. “It is a non-standard design because the RDSO did not have a design for it per se. Hence, with the approval of the Railway Board, the design was studied by IIT Bombay. The design approved by IIT Bombay has been executed,” he added.

The bridge was designed for 80 kmph and now, it has been approved for 75 kmph. “After the approval of Chief Bridge Engineer, the speed limit of 50 kmph on the lift span could be raised to 75 kmph,” he added.

Train operations can be started anytime now, the official added.

Published - November 27, 2024 06:20 pm IST