LG Collapsed in WDFCC Project - CTP 16

Disclaimer: This post intension is showcase the Engineering Lessons we can learn from these kind of Incidents, so that the same incident does not gets repeated in our society, Its does not have any intension to devalue the LG Manufacturer, Contractor. or the Concern Project.

Dedicated Freight Corridor Corporation of India Limited (DFCCIL) is a Public Sector Undertaking (PSU) corporation run by the Government of India's Ministry of Railways to undertake planning, development, and mobilization of financial resources and construction, maintenance and operation of the "Dedicated Freight Corridors" (DFC).

WDFCC CTP -16 was one of the stretch in which the incident happened.

Portal Piers where used as Sub structure & Portal Beams where used for connecting the twin piers. 4 Girder System was used as Super Structure with full span erection methodology. Launching Girder Full Span Erection Video

Contractor : Larsen & Toubro
Launching Girder Manufacture : HLCM Company (China)
Place : SOHNA, Haryana.
Loss of Life: Officially NO
Loss of Machinery: LG setup - 10Cr Around

Date of Incident: 24/11/2020

Brief about the Project:

Its a dedicated line for constructing rail lines of around 130 Km, of which 122 km is on embankments, & 8 km is over the bridge.

In the Elevated portion around 2.8 km is planned to construct by full span erection to speed up the work.

Full Span erection methodology commenced in the alignment for the 4 Girder Span, around 20 Straight Spans are erected smoothly. The Alignment was straight & there is no near curvature ahead and behind the particular location, where the incident happened.

Around 20 Spans where erected before using the same methodology, so we can partially conclude design wise there is less possible to fail, as 20 spans where erected.

Looking in the incident pictures there is evidence of collapsed girders, so we can conclude the LG is not failed in the fully loaded condition or during the Girder hanging condition in other words.

Based on the preliminary Investigation, these where the findings of the reasons behind the collapse listed below.

1. Factor of Safety for Design might be considered lesser in the LG.

2. Operational Mistakes might be also a reason for the collapse.

3. Eccentric Loading of the Launching Girder.

4. Front Leg seated in the Pier Cap might slide from the Pier Cap.

Lets zoom much more closer, at which erection stage the LG has failed.

When it collapsed?

As shown in the above figure, at this erection stage the LG System got collapsed. The Temporary Leg was resting on the n+1 pier, and the Front Leg was moving to seat over the pedestal.

as above shown position it got collapsed.

Its told that the temporary leg got slide from its position that made the complete setup to collapse. But we cant take a final conclusion since the investigation is over.

As the Incident not came out in media and it is covered up, the real root cause may or may not come out.

what we take from the finding is more important, during the course of time there where lot of debates going across, some interesting points which came across.

The same LG model is being used through out the country, as it is cheaper than other models.

One of the Indian Metro years back similar LG was found under designed. Later it was strengthened and used.

and most of the similar incidents are covered up.

LG’s operations requires specialized skill and usually it’s treated as a simple machine leading to the greater risk and accidents.