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Review of Management Systems for Indian Railways’ Bridges

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MB Bureau

Bridges play a substantial role in the railway transportation infrastructure network of India. The Indian Railways have a total rail-track length of 67,368 kilometers, reaching all corners of the country. Many of these connections, enabling access to even the remotest areas in India is enabled by the construction of bridges. Bridges, therefore, along with tracks, forms the lifeline of rail transport in respect of both passenger and the freight traffic in India. Such structures must, therefore, be accorded the highest standards of safety and maintenance in order to ensure economic growth of the country.

As of April 2018, the total number of bridges across the Indian Railways vast network stands at a total of1,47,523 bridges. This includes only bridges that facilitate the movement of trains. Road over bridges and foot over bridges (ROBs/FOBs) are not considered in this list.

These 1,47,523 bridges are broadly classified into three categories based on their linear waterway into:

1. Important Bridges;
2. Major Bridges; and
3. Minor Bridges.

Important Bridges

Bridges under the important bridge category include linear waterway width of 300 metres or more or a total waterway of 1,000 square metres or more. In certain situations, bridges in India are also classified into ‘important bridges’ based on considerations such as depth of waterway, extent of river training works and maintenance problems.

Major Bridges

Bridges under the major bridge category include linear waterway width of18 meters or more or those which have a clear opening of 12 linear meters or more in any one span.

Minor Bridges

Bridges that do not fall into any of the above two categories are classified as minor bridges and constitute most of the railway bridges in India.

The below chart is a representation of the percentage distribution of the number of bridges in each category.

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Table 1
Table 1

 

 

 

 

 

 

 

India’s Aging Railway Bridges

According to the Railways Ministry, 37,689 (approx. 26% of India’s railway bridges) bridges in India are over 100 years old. This can be expected as India’s rail network has been operational for more than 160 years. This means that regular repair/strengthening/rehabilitation and/ or rebuilding of these bridges will have to be undertaken in order to keep them safe and serviceable. Furthermore, these bridges have been built to sustain much lighter loads. As freight activity and load has increased over the years, these bridges have to also be strengthened or rebuilt.

Railway bridge failures are catastrophic. Apart from disruption of regular activities in the affected area, a railway bridge collapse effects the economy of the region and most importantly, leads to the loss of life. The below table highlights some of the major railway bridge failures in India and their impact.

Bridge Management System

Pursuant to the ‘Track Management System’, the Ministry of Railways recently launched its first consolidated Bridge Management System (IR-BMS)(2). IR-BMS is a web-enabled IT application to store data and provide meaningful assimilation, analysis and dissemination of information related to various activities on the Railways’ 1.4 lakh odd bridges. The web based programme is developed by Centre for Railway Information Systems (CRIS) and shows bridge master data, works data, information regarding inspection/ monitoring and maintenance of the bridges and other essentials.

Table 2
Table 2

 

 

 

 

 

 

Inspection Systems

The Ministry of Railways classifies inspection of bridges into broadly two categories:

1. Routine inspections
2. Special inspections carried out at various levels

According to the Ministry, all bridges (including bridges in sub urban areas) are inspected at least twice a year, one before the onset of monsoon and one detailed inspection after the monsoon by the designated officials. The inspection, according to the Ministry includes the following:

– Flooring & Foundations: To ascertain whether there is any scour around piers/abutments, settlement of foundations etc.
– Masonry in sub-structure: To ascertain whether there is any crack, bulging, tilting, deterioration due to weathering in the masonry etc.
– Protective works and water ways: To ascertain whether protective works such as pitching, guide bunds, approach banks, flooring etc. are in sound condition and whether water way is adequate and clear of obstructions.
– Girder alignment and seatings: To ascertain whether bed blocks and bearings are in sound condition, girder alignment is correct etc.
– Structural condition of girders: To ascertain whether there is any loss of cambers in triangulated girders, distortion of members, incidence of loose rivets / bolts, corrosion in steel members etc.
– Track structure on bridge: To ascertain the condition of rails, sleepers,
fittings etc.

In the case of underwater bridges or for parts of bridges that are permanently submerged under water throughout the year, the Ministry follows an elaborate system of underwater inspections (UWI) once in every five years by the zonal railway through outsourcing.

Once inspected, the bridges’ structural reliability is rated based on a condition rating system followed by the Government of India.According to the rating system, every bridge is assigned a numerical rating of 1 to 5 based on its physical condition at the time of inspection. The system helps in identifying progressive deterioration, if any, in the condition of the bridge. Lower the overall rating number (ORN), more attention is required to the bridge. Bridges with ORN-1 rating indicates that bridge require immediate rehabilitation/ rebuilding of the whole bridge or one or more of its components whereas bridges with ORN-2 rating require rehabilitation/ rebuilding of the whole bridge or one or more of its components on programmed basis. Thus, bridges with ORN-2 rating do not require immediate rehabilitation/ rebuilding and/or imposition of speed restriction.

As per available data, there are 233 bridges assigned with ORN-2 rating, out of which 190 bridges have been approved for required rehabilitation/rebuilding. Out of these, 90 bridges were planned for rehabilitation during 2018-19.

Strengthening / Rehabilitation / Rebuilding of bridges:

Repair, rehabilitation, rebuilding and/or strengthening of Indian Railways’ bridges is proposed by the Zonal Railways online on IRPSM (Indian Railways Projects Sanctions &Management) portal about one to four months before the Annual Budget and is sanctioned by Railway Board in the concerned Budget Year. According to available data, bridge works of more than Rs. 2.5 Crore each are sanctioned by Railway Board and works of less than Rs. 2.5Crore are sanctioned by zonal railways themselves at Headquarter & Divisional Level.

The Ministry follows the underlying points for proposing a bridge for repair, rehabilitation, rebuilding and/or strengthening:

1. Physical condition ascertained during the regular inspections.
2. Design considerations for enhanced loading due to higher axle load trains, high powered locomotives etc.
3. Elimination of obsolete materials (cast iron screw piles, early steel girders etc.)
4. Additional openings based on hydrological considerations to provide adequate waterway.
5. Replacement of small span steel girders to maintain more uniformity in track structure and to reduce maintenance efforts.

Over the last three years(2015-16 to 2017-18), 8611 new railway bridges have been commissioned on account of commissioning of new lines, doubling etc., and 2347 existing bridges have been rehabilitated / rebuilt by the Ministry during the same period. According to data by the Ministry, presently, 3017 railway bridges have been sanctioned for rehabilitation/rebuilding.

Bogibeel_bridge_over_the_Brahmaputra_river_in_the_north_eastern_Indian_state_of_Assam

 

 

 

 

The progress of rebuilding rehabilitation strengthening of bridges in Indian Railways during the last five years since 2012 13
The progress of rebuilding rehabilitation strengthening of bridges in Indian Railways during the last five years since 2012 13

 

 

 

 

 

Technologies for Bridge Construction &Maintenance

The Indian Railways is using the following technologies for the construction and maintenance of its bridges:

1. Use of Modern Spherical & Cylindrical Bearings on Bridges:

With the introduction of higher axle load trains and powerful locomotives, the bridges designs need to accordingly updated and/or changed. Bearings are also to be designed to transmit higher axle load and longitudinal forces safely with required translational and rotational movement. Conventional bearings being used on Indian Railways are not able to transmit higher forces. In this regard, modern spherical / cylindrical bearings are able to transmit higher loads with required translational and rotational movements. In addition, these bearings match the life of the bridge thereby avoiding the need for replacement during service life of bridge. According to the Railways Ministry, this type of bearings is being used world wide and it has been used for the first time on Indian railways on recently commissioned new Jubilee Bridge across Hooghly River, Jhajjar Bridge in J&K Project and under construction Bogibeel bridge across Brahmaputra River near Dibrugarh. Spherical bearings are also being used in several mega bridges under construction in J&K Project. Keeping in view the benefits associated with the spherical bearings, the Ministry decided to use them for bridges of longer spans of 61.0 m. The Ministry is also no planning to permit the use of spherical bearing for lesser spans also.

2. Girder launching using Cable cranes:

Launching of steel girders for tall and long span bridges is a herculean task. Now a days cable cranes are being used worldwide for launching of such type of girders. On Indian railways, this technology is being used for the first time in under construction Chenab Bridge in J&K project. Cable crane assembly including pylons at span of 915 meters for launching of arch segments of the bridge is the longest in the world. The height of the pylons is a staggering 127m. The Ministry is planning the use of this technology for construction of many more bridges in hilly terrains across India.

3. Continuous Water Level Monitoring system at bridges:

Flood Water level at identified railway bridges are required to be regularly monitored so as to take appropriate action as and when the water level reaches/crosses the threshold limit for safe movement of rail traffic as suggested in the Kakodkar Committee Report, chaired by Dr. Anil Kakodkar in 2012. Presently, at some places, water level is still being monitored by stationary watchman. Unfortunately, this system requires lot of manpower and is also prone to human errors. In order to remotely monitor the water level, a pilot project on Continuous Water Level Measuring Instrument (WLMI) was successfully completed in 2015. In this system, water level can be monitored from anywhere through SMS alerts. It eliminates the need of posting stationary watchman. It has been decided to install the system on all important/vulnerable bridges. In the first phase, Railways have identified 151 bridges, out of which system has been installed and commissioned on 117 bridges.

4. Stainless steel reinforcement for corrosion protection:

Prevention of corrosion in reinforcement is essential for overall durability of RCC /PSC structures and also to enhance the life of the structure. In order to enhance the life of concrete bridges, decision has been taken to use stainless steel reinforcement bars for new bridges and other structures in corrosion prone areas.

5. Use of Completely Welded Steel Girders:

Presently, the steel girders being used in the Indian Railways are welded cum riveted / bolted. In this design, the built-up members are welded but the connections/joints are bolted. The current trend is to use completely welded girders in advanced and developed nations. The fully welded girders are not only aesthetically pleasing but are also lighter in weight as compared to conventional welded girders having riveted/bolted joints. These girders require less maintenance also. For the first time in India, completely welded steel girders are being used in construction of Bogibeel rail cum Road Bridge across mighty Brahmaputra River at Dibrugarh, Assam. The Ministry is now contemplating the use of completely welded girders in big way on Indian Railways.

6. Under Water Inspection of Bridges:

Presently, the detailed under water inspection is carried out by trained divers by visual inspections, with NDT equipment and with video cameras which have lot of subjectivity. In order to minimize human intervention, advanced technology of using robotic remote operated vehicle (ROV) has been adopted on trial basis at one bridge each in Southern Railway and Northern Railway. Using this technique, dependency on diver is eliminated and all the submerged parts of the bridge can be inspected and monitored remotely from the Bridge/Bank.

According to the Ministry, the Indian Railways is also currently using the Indian Space Research Organisation’s(ISRO) satellite based system to prevent accidents and for also for track surveillance. However, ISRO’s satellites are not being used for monitoring bridges, but the Ministry is instead considering the use of drones for the inspection of bridges. The Ministry is of the view that the highly inaccessible parts of the bridges can be reached with great ease without the need of costly vehicles, ladders etc., with the help of drones. The details (photographs, videos etc.) captured by drones can be analyzed to assess the condition of the components. Further, with the data captured by drones, 3D modelling is possible which in turn would be a highly beneficial and cost effective alternative to conventional methods of inspection and maintenance currently in practice. The zonal railways have been issued instructions to carry out trials for taking further decision in this regard.

Conclusions

The Indian Railways houses a staggering 1,47,523 number of bridges across its immense network. Maintaining these assets has good social as well as economic implications. As seen above, India has 37,689 bridges that are over 100 years old. Many of these bridges have deep rooted historical significances to their areas and to the country as well. In fact, it is fortune, if not luck, that in-spite of the axel load variations, weathering, corrosion, and more, that these bridges are subjected too, they are still able to serve their intended functions.
The Indian Railways is also gradually upgrading its tracking, management, surveying and digital tools and solutions. Drone surveying, 3d mapping and other such advanced tools will without a doubt enhance the effectiveness, reduce disasters and aid in accelerating the growth of the railways and the country as well. §

Reference

– http://164.100.47.193/lsscommittee/Railways /16_Railways_23.pdf
– (2) (13 Jul 2018) Bridge Management System (Web-based platform) developed by Railways to help in meaningful assimilation of bridge data, Available at: http://www.railnews.in/ bridge-management-system-web-based-platform-developed-by-railways-to-help-in-meaningful-assimilation-of-bridge-data/ (Accessed: 30 September 2019).
– (3) RAILWAY BRIDGE COLLAPSES, Available at: https://trove.nla.gov.au/newspaper/article/ 138628408 (Accessed: 30 September 2019).
– (4) Kadalundi train derailment, Available at: https://en.wikipedia.org/wiki/Kadalundi_train_derailment (Accessed: 30 September 2019).
– (5) Flyover mishap: What went wrong?, Available at: https://timesofindia.indiatimes.com/city/hyderabad/Flyover-mishap-What-went-wrong/articleshow/2354115.cms (Accessed: 30 September 2019).
– ASSOCHAM (2019) Indian Railways: Moving the Future of India on Right Track, Available at: https://www.resurgentindia.com/pro_bfloors/services_img/pdf_teders/1323252203RAILWAY%20REPORT.pdf (Accessed: 30 September 2019).

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