Signature Bridge:Delhi’s very own London Bridge

Signature Bridge:Delhi’s very own London Bridge

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signature bridge

After missing multiple deadlines due to inadequate funds, the iconic signature bridge is likely to open by October, Delhi Chief Minister Arvind Kejriwal said on. Kejriwal tweeted that the Delhi government had approved the final installment of the signature bridge and that there should “now be no more obstacles”. On July beginning Delhi Tourism and Transportation Development Corporation (DTTDC)which is handling the project  sent a revised cost estimate to Delhi government. The department had earlier set a deadline for October, with senior officials now claiming that it may be shifted to November. However, the tweet from Delhi Chief Minister Arvind Kejriwal cleared out the provision of the deadline.

The signature bridge project was approved in 1997 after an accident on the narrow Wazirabad bridge wherein a school bus fell into the Yamuna, killing 22 children. The completion of the bridge has been delayed by several years due to inadequate funds. Even the project cost has increased from ` 1,100 crore to ` 1,575 crore, becoming a major cause of concern for the Public Works Department. The PWD has released ` 1,244 crore so far. The project was conceptualised in 2004 and got the nod from the Delhi Cabinet in 2007. The first deadline was fixed ahead of the 2010 Commonwealth Games but it was revised to 2013. The project deadline was again pushed to June 2016 and then to July 2017, which was further pushed to December 2017. The 675m long and 35.2m wide bridge will be the first asymmetrical cable-stayed bridge in the country, which will connect Wazirabad across the river Yamuna. The bridge, once completed, will take vehicular pressure off the existing Wazirabad bridge. It will also connect the Outer Ring Road on the western bank of the river with Wazirabad Road on the eastern side.

Significance of the bridge for people

Conceptualised in 2004, the Signature Bridge project was approved by the Delhi cabinet in 2007. Construction was to have started that very year, but it took off only by 2010, the original completion date. Officials explained away this delay saying the project had failed to get an environmental clearance. That nod finally came in 2011 and the deadline was revised to December 2013. The completion date was later pushed to June 2016 and then to July 2017.

In July 2017, the Aam Aadmi government released ` 100 crore for the project and set a new deadline of March 2018, which was further pushed to April 2018, June 2018, and now, to October 2018.

“The construction has resumed, which was stopped due to fund crunch, and reached its last lap and at least 120 working days are needed to complete it. Last November, the work was stopped by the National Green Tribunal owing to severe levels of pollution in the city,” Shishir Bansal, chief project manager, said.

 

 

Cost and other hazzard: PROBLEMS THIS YEAR

  • Work on the iconic bridge came to a complete standstill in April this year
  • Workers abandoned project due to alleged non-payment to contractors
  • Govt ordered a third-party audit of the project as two govt depts were engaged in tussle over funding
  • On May 22, deputy chief minister Manish Sisodia visited the project site for inspection
  • A day after the inspection, Sisodia, in a strongly worded report, criticised Delhi chief secretary Anshu Prakash and other heads of departments involved with the project for not accompanying him to the site
  • On May 23, Sisodia directed chief secy Prakash, principal secretary (PWD) Manoj Parida and principal secretary (finance) Renu Sharma to bring revised estimates of the DTTDC, vetted by CPWD, before the expenditure finance committee (EFC). The EFC meeting is yet to happen
  • On May 29, chief minister Arvind Kejriwal visited the construction site, assured citizens that there would be no problem of funding for the project
  • Kejriwal announced fresh deadline saying the project would be completed by October 2018

Design analysis

is a landmark structure due to its design aesthetics and the bridge will also speed up movement of traffic between the North and East of Delhi over India’s historical Yamuna River, when it opens to traffic in June 2015. The new bridge is being constructed 600m downstream of the existing crossing along the top of a barrage, built in the 1960s and which presently connects North and East Delhi.

Construction of the bridge involves setting up flyovers, loops and ramps comprising 1.8km eastern and 4.2km western approaches on either sides of the river. The approaches will be connected to the main 675m long, unsymmetrical cable-stayed bridge, which has dual carriageways of 14m each (four lanes in either direction) and with 1.2m central verge and maintenance walkways. The other key features are its 251m long span and bow shaped steel pylons measuring some 154m in height, with cable stays on one side and back stays on the other side.

Indian construction major, Gammon, is the contractor for the approaches costing close to US$560 million (INR 350 crore). Work for the main cable bridge valued at $1.01 billion (INR 631.81 crores) is by a joint venture of Gammon India, Cidade Brazil and Tensacciai of Italy. Delhi Tourism and Development Corporation (DTTDC) is the client and project management consultant for the project.

Being constructed in a highly seismic zone-4, executing the megaproject is not without multiple challenges. “The sloping rock profile of the area is the biggest challenge, requiring modification of methodology in foundation works,” said K Prakash, DGM Projects, Gammon, Signature Bridge Project.

Piling and foundation forms the major construction component of the project. Novel foundation solutions were used for the approaches over the river that will connect the main cable bridge. This was important due to the behaviour of the river during peak monsoon months in Delhi, when water flows above the danger zone. Furthermore, the rocky strata of the area posed additional challenges, requiring specific foundation techniques. In addition, the base load and the large dynamic load exerted on the approaches by the high traffic volumes were the other major factors to be considered for the foundation design.

The Signature Bridge project is of note as it is only the second bridge project in India that features a combination of well and pile foundations. The first time this concept was used was in a project carried out by Gammon two years ago; a railway bridge in the North Eastern Indian state of Assam.

Extensive piling and well foundations support the P23 column. This carries the majority of the 6,600tonnes of tensile load exerted by the cable stressed pylon for the main bridge. The method has employed a crane to level the area for the wells. After this any loose material has been removed by the crane using a grab to prepare the well. Meanwhile hydraulic excavators fitted with rock breakers have been used to prepare the surfaces where there is softer rock.

The bridge project requires 18 well foundations in all, with much of this portion now complete. The bridge features nine open foundations, with this portion of the project having been completed.

In addition, Gammon India acquired two new reverse circulation drilling rigs during the second week of December 2014. These have been used for undertaking piling work on the sloping rock terrain at the offshore and onshore level of the river. The rigs were bought from Korean company Buma CE. The reverse circulation (or airlift system) uses compressed air injected into the drill pipe below water level just above the drill bit. This reduces the density of the internal water column and starts the circulation. The mixture of the water, air and cuttings is then flushed out through the drill pipe into settling tanks. This technique is usually used for hard rock drilling and piling in marine conditions. The rigs were brought in for the project to help with the work in areas of sloping terrain.

Work for the approaches has been carried out on prestressed precast concrete sections, which weigh from 68-100.5 tonnes and have been erected on the piers set on open foundation. Bridge girder launchers, mobile telescopic boom cranes and a rail-mounted gantry crane have been used to erect the precast concrete sections. Gammon acquired a new rail-mounted gantry crane with a 40m span and 60tonne lifting capacity, which is being used on the project. The crane is lifting precast concrete sections for the approaches that connect the main bridge on the river and cannot be accessed by the heavy crawler crane.

Precast solutions were selected to cut construction time. In addition this helped the work given the tight space constraints, particularly at the western approach due to the proximity of a carriage depot belonging to Delhi Metro Railway.

The solution was to set up a number of access areas with three intersections on the western approach of the existing road handling heavy vehicle traffic.

Work on the main section of the cable-stayed bridge which is presently underway, involves erection of the pylon structure and deck. This was fabricated at ZTSS China and weighs 6,500tonnes while the deck weighs in at 7,500tonnes. The heavy pylon base itself weighs in at 425tonnes and measures 11.3m x 6.3m x 4.3m. Construction of the main structure also involves the erection of the 154m high steel tower, which carries the head of the cable-stayed bridge. The steel tower features 55 blocks, which weigh from 120-180tonnes. The erection job for the main bridge is being carried out by a Terex Demag CC8800 crane, a 1,250tonne crawler lattice boom machine. Gammon India has hired the crane for a year from heavy lift specialist Sarens for the job.

An international team that includes some world-leading companies has been involved in this project. Apart from the main contractors, design work on the main bridge has been carried out by German company SBP while design for the temporary structure and methodology has been carried out by Italian firm DMA. Proof checking of the structure has been handled by leading French firm Systra Virlogeux, while the erection stage analysis has been handled by Italian company De Miranda Associate. Geometry control support has been carried out by Len Gower Canada and third party quality assurance has been provided by Lloyds Register UK. Indian structural engineering specialist Tandon Consultants is the principal consultant for the projects.  In addition, there are 10 other partners involved in the project involving the project consultants and managers, Maurer Sohne of Germany, the bearing supplier.

Because of the complexity of the project and to ensure appropriate project management coordination of all the stake-holders, DTTDC has set up dedicated File Transfer Protocol software (FTP). Contractors and stakeholders have been able to upload queries on required design changes or execution methodologies. This has then been examined by DTTC senior engineers followed by solutions. Contractors, consultants and other stakeholders in the project have been given access to FTP to carry out required design, structural or project execution modifications suggested by DTTDC.

Advantages of Cable Stayed Type Bridge

Cable-stayed bridges may appear to be similar to suspension bridges, but in fact, they are quite different in principle and in their construction.

In suspension bridges, large main cables (normally two) hang between the towers and are anchored at each end to the ground. This can be difficult to implement when ground conditions are poor. The main cables, which are free to move on bearings in the towers, bear the load of the bridge deck. Before the deck is installed, the cables are under tension from their own weight. Along the main cables smaller cables or rods connect to the bridge deck, which is lifted in sections. As this is done, the tension in the cables increases, as it does with the live load of traffic crossing the bridge. The tension on the main cables is transferred to the ground at the anchorages and by downwards tug on the towers.

In the cable-stayed bridge, the towers are the primary load-bearing structures which transmit the bridge loads to the ground. A cantilever approach is often used to support the bridge deck near the towers, but lengths further from them are supported by cables running directly to the towers. This has the disadvantage, compared to the suspension bridge, that the cables pull to the sides as opposed to directly up, requiring the bridge deck to be stronger to resist the resulting horizontal compression loads; but has the advantage of not requiring firm anchorages to resist the horizontal pull of the main cables of the suspension bridge. By design all static horizontal forces of the cable-stayed bridge are balanced so that the supporting towers do not tend to tilt or slide, needing only to resist horizontal forces from the live loads.

Key advantages of the cable-stayed form are as follows:

  • much greater stiffness than the suspension bridge, so that deformations of the deck under live loads are reduced
  • can be constructed by cantilevering out from the tower – the cables act both as temporary and permanent supports to the bridge deck
  • for a symmetrical bridge (i.e. spans on either side of the tower are the same), the horizontal forces balance and large ground anchorages are not required

Cost escalation

Conceptualised in 2004, the Signature Bridge project was approved by the Delhi cabinet in 2007. Construction was to have started that very year, but it took off only by 2010, the original completion date. Officials explained away this delay saying the project had failed to get an environmental clearance. That nod finally came in 2011 and the deadline was revised to December 2013. The completion date was later pushed to June 2016 and then to July 2017.

In July 2017, the Aam Aadmi government released ` 100 crore for the project and set a new deadline of March 2018, which was further pushed to April 2018, June 2018, and now, to October 2018.

“The construction has resumed, which was stopped due to fund crunch, and reached its last lap and at least 120 working days are needed to complete it. Last November, the work was stopped by the National Green Tribunal owing to severe levels of pollution in the city,” Shishir Bansal, chief project manager, said.

Constant delays have escalated the cost of the project. Initially, it was estimated to cost ` 887 crore, which rose to ` 1,131 crore in 2013. The DTTDC in 2016 sent a revised estimate of ` 1,575 crore to the government for approval and the government released ` 1,414 crore. The public works department (PWD) sought an expert opinion by the Central Public Works Department (CPWD) on its demand for an additional ` 161 crore.

Unique factors of the bridge

It is quite known to everyone that people in metropolitan cities experience huge traffic problem. Even reaching 5km distance destination takes several hours. To share the burden of traffic, the government always come up with new bridge constructions, local trains etc. Delhi CM Arvind Kejriwal assured that the construction of the much-awaited Signature Bridge on the Yamuna River will be completed by October this year. He also said that the residents of Delhi have been eagerly waiting for the opening of the city’s iconic Signature Bridge.

  1. It Is The FIRST Asymmetrical Cable-Stayed Bridge In India. In addition, It is around double the height of the Qutub Minar. Yes, the bridge is 675 meters long, and the bow-shaped steel pylon is 154 meters tall.
  2. It Shares The Traffic Burden Of Wazirabad Bridge. Futhermore, The new signature bridge will share the burden of traffic that the Wazirabad Bridge is bearing alone. As people travel to and from Delhi and Ghaziabad, there is the severe traffic problem. Once the signature bridge is ready, it will reduce the travel time by at least 30 minutes for commuters going towards the Ghaziabad and Bhopura Border. The bridge connects the Outer Ring Road on the Western Bank, with the Wazirabad Road on the Eastern Bank of the Yamuna.
  3. This Project Will Develop Business And Tourism
  4. Perched at a height of 150 feet, which is double the height of Qutub Minar, the gallery will provide a panoramic view of the city to the public.
  5. Situated at the top of the main entrance of the Signature Bridge, the gallery will be constructed by an expert agency appointed by the Delhi Tourism and Transportation Development Corporation (DTTDC).
  6. Developed by the Delhi Tourism and Transportation Development Corporation over the river Yamuna in Wazirabad, the upcoming Signature Bridge itself will be a global architectural marvel.
  7. Assisted by thick iron cables, the bridge will hang like a swing on both sides of a 151 feet tall tower, on top of which this gallery will be constructed.
  8. The bridge will be constructed in two parts, whereby the first part will be inclined at an angle of 80 degrees while the second part will make the same angle in the opposite direction.
    1. Due to this, the tower will appear to be in the shape of a bow, due to which the tourists will have to change the lift to ascend to the gallery perched above. Due to the inclination of the tower in opposite directions, the motion of the lifts will also be inclined,” he added.
  9. It is considered to be an engineering challenge to construct the lifts ascending in inclined motion. Each of the lifts will weigh 500 kilograms and will carry four people at a time.
  10. 10 As per the design, it will have a single bow-shaped polygon uniquely placed in the river, inclining towards the east and supporting the deck on the stay cables placed in harp format.
  11. It will reduce the time travel by at least half an hour for commuters going to Ghaziabad and Bhopura Border via Khajuri Khas, from Wazirabad, Timarpur, Mukherjee Nagar and Burari.
  12. Modelled on the ‘London Bridge,’ Signature Bridge is envisaged as a symbol of the city. The unique ‘cable suspended’ bridge, located in Wazirabad, connects north and east Delhi.

Info and image source

  • https://www.financialexpress.com
  • https://timesofindia.indiatimes.com
  • https://www.hindustantimes.com
  • https://structurae.net
  • https://m.dailyhunt.in/
  • https://so.city/delhi/article/
  • http://ompropmart.com/news-and-future-plans/
  • http://www.bharatestates.com/blog/signature-bridge-linking-to-unconventional-future/
  • http://www.worldhighways.com
  • https://www.indiatoday.in
  • https://www.dailypioneer.com
  • http://www.dailymail.co.uk

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