Improper planning and failure to visualise soil strata behaviour on the part of the railway administration have resulted in an unproductive expenditure of Rs. 890.18 crore on a diverted alignment in the hill section of the ongoing Lumding-Silchar-Jiribam, Badarpur-Kumarghat gauge conversion project (368.46 km) of the Northeast Frontier Railway in Assam.
Earthwork and work on tunnels and bridges may remain fruitless unless the problems caused by unreliable soil strata are solved permanently, reveals an audit report.
This theme based audit report, a copy of which is in the possession of The Hindu , says most of the construction works failed due to unreliable soil strata. For, the construction commenced without adequate geo-technical investigations.
The trial and error method has resulted in an unfruitful expenditure of Rs. 77.5 crore out of a total liability of Rs. 356 crore incurred so far on the construction of tunnels.
Thanks to poor and squeezing strata, the tunnel supports of Tunnel No.10, the longest (3,235 metres) in the section, caved in along a length of 370 metres during the period from January 2007 to August 2007. Construction of this tunnel is critical to the successful completion of the gauge conversion project. Though the soil strata are likely to pose problems in further tunnelling work, the tunnel is targeted to be completed by December 2012.
The audit report includes an extract from the observations made by P.T. Sinha Roy, consultant, Engineering and Geology, on the site condition of Tunnel 10 in the Lumding-Silchar gauge conversion project. It reads: “As per available information, Tunnel No.10 is passing along a thrust sheet, popularly known as the NE-SW tending Disang thrust, which is in continuation of the East-West tending Dauki fault at the southern edge of the Shillong plateau. As a result of this thrust, in the course of a major tectonic movement, the aforesaid Black shale (known as Disang shale) is found sheared/pulverized. It seems that in the course of the investigation of this project, the information available was not known to the railway engineers. Therefore, the alignment of this rail line needs to be modified, particularly between Jatinga Nalla and Dolong Nalla.”
Also the invert level of Tunnel 10 approaches has been pegged lower than the Dolong Nalla bed by about 8 metres, the audit report reveals. This is “a fundamental error at the planning stage which is yet to be resolved to avoid flooding of tunnels during heavy rains in the hilly terrain.”
Due to the failure of the executed works, the scope of various items of work has undergone a change, leading to severe cost escalations, and further delays in the completion of the project. The estimate of Rs. 1,676.76 crore sanctioned by the Railway Board during 1999-2000 has now escalated to Rs. 4,010.70 crore.
In a letter dated November 9, 2009, the board, in its comments on the revised estimate, expressed its reservations: “While it is known that the terrain in this part of the country is difficult and some surprises/uncertainties are expected, the quantum of variations shown in this estimate is drastic. The work under consideration is not a new line work but gauge conversion of an existing line. The terrain is already known. Therefore the only reason for such drastic increase in cost appears to be improper planning, no survey/preliminary activities having been taken up.”
Constructed by the British in the early 1900s, the Lumding-Badarpur-Silchar metre gauge line running through the hilly terrain of southern Assam's North Cachar Hills is considered one of the most challenging engineering accomplishments as the existing rail network has to negotiate severe grade limitations with sharp curves and 36 tunnels.
The gauge conversion project mainly includes land acquisition, earthwork, construction of formation, 358 bridges, a road overbridge, a road underbridge, tunnels, cut and cover, procurement and spread of ballast, and track linking.