Chenab Bridge is an under-construction rail bridge, located between Bakkal and Kauri in the Reasi district of Jammu and Kashmir (J&K), India. The 1,315m-long bridge is being built at a height of 359m. Once completed, it will be the tallest rail bridge in the world.
The Rs5.12bn ($92m) bridge is a part of Jammu-Udhampur-Srinagar-Baramulla Rail Line (JUSBRL) project being undertaken by the Ministry of Indian Railways. The bridge will include a 14m-wide dual carriageway and a 1.2m-wide central verge.
The project is expected to be finished by December 2021 and will have a lifespan of 120 years. It will contribute to the economic development of the state and help in providing better transportation accessibility within the state and the country.
Need for the Chenab rail bridge
Travelling in and around the mountainous terrain of Jammu and Kashmir has been a great difficulty for locals. An urgent need to provide better transportation facilities was recognised by the Government of India. Construction of a national railway project that will connect J&K with the rest of India was therefore proposed.
The JUSBRL project was launched in 2003 as part of this proposal. The 345km-long railway line between the Jammu and Baramulla regions will enhance mobility within the state and across India. The railway line will traverse along Jammu-Udhampur-Katra-Quazigund-Baramulla. Construction of the Jammu to Udhampur section was completed and opened in April 2005. Work is progressing on the Udhampur to Baramulla section.
The project includes construction of several bridges and tunnels along the route, of which Chenab Bridge is one. It is will span across the deep Chenab river and provide access to the Kashmir valley from Udhampur.
The project was suspended in 2008 due to construction challenges. The alignment of the entire JUSBRL project was reviewed to propose solutions for the challenges faced. The review work was submitted to the Railway Board and approved in 2009. The design of the bridge, however, was approved in July 2012.
Chenab Bridge design details
Chenab Bridge forms a massive steel arch, the first of its kind in India. The country has no codes or design guidance for such massive structures. Based on experiences drawn from similar projects worldwide, the design practices for the bridge are being followed.
BS: 5400 is being used as the basic guideline for the design and construction of the bridge. The deep Chenab river valley under the bridge is prone to high wind pressure risking the stability of the bridge.
Norway-based Force Technology Laboratory conducted several wind tunnel tests to understand the effects of wind speed, static force coefficients and gust buffeting. The bridge is designed to resist wind speeds of up to 260km/h. The seismic nature of the project zone was also considered during its design.
The bridge will include 17 spans, as well as the 469m main arch span across the Chenab River, and viaducts on either side. The main span of the bridge will include two 36m-long approach spans. It will be built as a two ribbed arch with steel trusses made of concrete-filled sealed steel boxes. The structure will be supported by two 130m-long, 100m-high pylons on either end through cables.
Steel was chosen to construct the bridge as it will be more economical and able to resist temperatures of -20°C and wind speeds of above 200km/h. The Jammu and Kashmir region witnesses frequent terrorist attacks. To enhance safety and security, the bridge will be made of 63mm-thick special blast-proof steel. The concrete pillars of the bridge are designed to withstand explosions. It is expected that the structure will be able to withstand earthquakes of magnitude eight on Richter Scale and up to 40kg of TNT blasts.
A ring of aerial security will be provided to safeguard the bridge. An online monitoring and warning system will be installed on the bridge to protect the passengers and train in critical conditions. Footpaths and cycle trails will be provided adjacent to it. The bridge will be painted with a special corrosion-resistant paint, which lasts for 15 years.
Bridge construction and challenges faced
The bridge is being constructed in one of the most complicated and isolated terrains. One of the biggest challenges involved was construction of the bridge without obstructing the flow of the river. Approach roads, five kilometres in length, were constructed to reach the foundations of the bridge.
The deck of the bridge is partly in straight horizon and partly in curves. It is located on a transition curve with changing radius. Construction is therefore being carried out in stages following the gradual change in the alignment. This is the first time a bridge is being constructed incrementally on a transition curve.
Cable cranes and derrick will be used to construct the bridge. The cable cranes used for the project will be the largest in the world.
Construction of the bridge is expected to require 25,000MT of steel, 4,000mt of reinforced steel, 46,000m³ of concrete and eight million cubic metres of excavation. The construction of the bridge was discontinued in 2008 due to alignment and safety issues. It was resumed in 2010, with estimated completion in 2015, which was subsequently pushed to 2019. The erection of 5,462MT of the 9,010MT of steel was completed as of January 2020, which marked the completion of 83% of the construction work.
Contractors involved in constructing the Indian bridge
Amberg Engineering was appointed to carry out review work of the alignments. Konkan Railway Corporation is executing the project. Design and construction of the bridge was awarded to a joint venture of Afcons Infrastructure, Ultra Construction & Engineering Company of South Korea and VSL India in 2004.
Finland-based WSP Group and Germany-based Leonhardt Andra and Partners are the consultants for the project. VCE Consult ZT-GmbH designed the pylons of the bridge. Jochum Andreas Seiltransporte installed the cables for the pylon. AkzoNobel was awarded the painting services contract for the bridge.
AECOM was awarded a contract to provide technical guidance and monitoring services for design and construction works. The scope includes engineering services, proof-checking the project drawings and design, ground engineering, planning and consulting.