|This article needs to be updated. (December 2010)|
|Crosses||Chenab River between Bakkal and Kauri.|
|Material||Steel and Concrete|
|Total length||1,315 m (4,314 ft)|
|Height||(river bed to formation) 359 m (1,178 ft)|
|Longest span||467 m (1,532 ft)|
|Number of spans||17|
|Kashmir Railway route map|
The Chenab Bridge is a railway steel arch bridge under construction between Bakkal and Kauri in the Reasi district of Jammu and Kashmir in India. When finished, the bridge will span the Chenab River at a height of 359 m (1,178 ft) above the river, making it the world's highest rail bridge.
Key technical data of the bridge include:
- Deck height (height above river): 359 m (1,178 ft)
- Bridge length: 1,315 m (4,314 ft), including the 650 m (2,130 ft) long viaduct on the northern side
- Arch span: 467 m (1,532 ft)
- Arch length: 480 m (1,570 ft)
This makes the Chenab Bridge
- the world's highest railway bridge
- the bridge with the widest span in the Indian broad gauge railway network
Introduction and topography
Indian Railways has undertaken the mega-project of constructing a new railway line across the Indian state of Jammu and Kashmir between the towns of Udhampur near Jammu and Baramulla on the northwestern edge of the Kashmir Valley. This project has been declared a national project in 2002. It is directed by the Konkan Railway Corporation Ltd..
The extraordinary challenge lies in a large number of tunnels (totalling 63 km in length) and bridges (7.5 km) to be implemented in highly rugged and mountainous terrain, with the difficult Himalayan geology. The most difficult part is believed to be the crossing of the deep gorge of the Chenab River, near Salal Hydro Power Dam, by the Chenab Bridge.
After many deliberations, taking into account aesthetics, economy, and availability of local expertise and construction materials, the Chenab Bridge was designed as a large span single arch steel bridge with approach viaducts on either side. The arch is two-ribbed, fabricated from large steel trusses. The chords of the trusses are sealed steel boxes, internally stiffened and filled with concrete to assist in controlling wind-induced forces on the bridge. Another advantage of concrete filling is that internal painting will not be required.
The numbers of bearings have been minimized, particularly on the approach viaduct, through the use of continuous construction. This is advantageous, as it reduces the maintenance and inspection efforts, and improves the riding quality. The viaduct piers are of concrete, while the piers near the arch are in steel.
The design of major arch rail bridges requires considerations of a number of additional parameters, such as fatigue, global stability, second order effects, composite action, etc. It also requires that such a bridge is designed to achieve a consistent level of reliability for all load cases, and that the design standards match the construction standards. Indian construction standards such as the Indian Railway Standards (IRS), the Indian Road Congress (IRC) and the Indian Standards (IS) were found inadequate for the large spans of the Chenab Bridge. For example, the Indian Railway Standards (IRS) is primarily intended for simply supported bridges with spans up to 100m (although these have been successfully used for higher spans up to 154m). The spans for the Chenab Bridge greatly exceed this limit, and are continuous. Therefore, to assure a safe design, Indian national standards have been supplemented with International standards such as British Standards (BS), International Union of Railways (UIC) and Euro. Also, many experts throughout the globe, based on their versatile and relevant experience, have been involved in order to make the building project a success Following are some of the design considerations taken into account:
- Limit state philosophy of design has been decided to be followed as per BS codes
- Computation of wind load effects as per Wind tunnel tests
- Site specific seismic spectra developed by Indian Institute of Technology (IIT) Roorkee
- Provision of Euro code 8 for ductility detailing of very tall and hollow rectangular RCC piers
- Provision of long welded rail (LWR) over the bridges and resulting force calculation as per UIC – 774-3R guidelines
- Blast resistant design has been used
- Design checking for fatigue as per BS codes
- Deformation limits as per comfort criteria of UIC – 776-2R and UIC 776 -3R guidelines
- Redundancy provided in the structures, for lower level of operation during mishaps and against collapse in extreme cases of one pier failure
The Quality aspect has been emphasized, as the quantum of fabrication and welding is colossal. Mostly indigenous material compliant to IS codes has been planned to be used, whereas for the design, international codes have been referred, which means the Quality Control work is still difficult.
The erection scheme for the bridge is a project in itself. Two pylons (about 130 m and 100 m high) were erected on either side of the river, and two auxiliary self-propelled cable cranes (capacity of 80t each) were used to tow temporary auxiliary ropes across these pylons. The ropes were used to support the partly finished arch parts. After arch completion, the trusses will be added, finally the girder will be constructed as a horizontal sliding type platform.
Regular painting of such bridges is an intimidating task; hence, a painting scheme has been developed, having life over 15 years, compared to approx. 5 to 7 years of life in most of the Indian railway bridges.
Anji Khad Bridge
||It has been suggested that this section be split out into another article. (Discuss) (December 2013)|
About 8,5 km southeast of the Chenab Bridge, near Reasi, the alignment of the new railway line crosses the deep gorges of Anji-Khad via the new Anji Khad Bridge. It is also designed as a long steel arches span bridge. Its main arch span is 265 m, deck height 189 m.
Regarding quality aspects, construction standards, indigenous materials and the painting scheme the facts from the Chenab Bridge equally apply.
- "Salient Features of the Chenab and Anji Khad Bridges" (PDF). Official Webpage of the Konkan Railway Corporation Limited. Retrieved 2008-08-14.
- "World's highest rail bridge to come up across Chenab river". Hindustan Times. 2013-02-17. Retrieved 2013-02-17.
- Narayan, Laxmi (March 2006). "TECHNICAL PAPER ON ANJI KHAD AND CHENAB BRIDGES" (pdf). Advances in Bridge Engineering: 101–114. Retrieved 2008-01-14.[dead link]
- "Chenab Bridge". Trimble Solutions Corporation. 25 June 2016.
- "Indian Railways makes history;Awards largest bridge contract in J&K". Project Monitor. Retrieved 2008-08-14.
- "J&K Rail Link Project". Northern Railway Website: Official Page on the Kashmir Railway Project. Archived from the original on May 6, 2008. Retrieved 2008-05-08.
- "At 359 metres, rail bridge over Chenab will be world's highest". Times of India. Retrieved 2011-05-31.
- "Chenab bridge will be highest in the world". Online edition of The Hindu, dated 2008-01-17. Chennai, India. 2008-01-17. Retrieved 2008-08-14.
- "J&K to have world's tallest bridge". TOI News. 2007-11-05. Retrieved 2008-01-14.
- Reasons for cancellation, reinstatement against security concerns
- "Highest railway bridge in J&K to be ready by 2015". The Times Of India. 18 June 2012.
- "India joins the superlative club, we now have the world's highest rail bridge". India Today. Retrieved 2013-07-04.
- Narayan, Laxmi (March 2006). "TECHNICAL PAPER ON ANJI KHAD AND CHENAB BRIDGES" (pdf). Advances in Bridge Engineering: 101–114. Retrieved 2008-01-14.
Type of Bridge : Trussed Steel Arch (Arch Span = 480m)[dead link]