The Mumbai Trans Harbour Link (MTHL) is an ambitious project which aims to improve the connectivity between Mumbai and Navi Mumbai. After being first proposed in 1963, the construction actually took off on 24 April 2018 after a long wait of 55 years.
The traffic studies projected the need for this bridge but for quite long it was considered financially unfeasible. The plans for construction were revived in 2004. But again the bids called in 2005 were rejected for either commercial or technical infeasibility.
In 2008, again bids were called by the state government but the parties backed out. Finally in 2011 Mumbai Metropolitan Region Development Authority (MMRDA) was allowed to get the reins of the project. To test the technical and commercial feasibility new reports were sought from the consulting firms.
When the Maharashtra government approved the project in 2012, the project had lost the environment clearance received in 2005 as the validity of this clearance was five years. But meanwhile, in 2011, new notification was passed a new coastal regulation zone concerning the construction along the mangrove-dominated eastern coastline of Mumbai.
At that time the project had three challenges- environmental, financial and technical. And now we will look at how they were overcome one by one.
With reference to the 2011 notification, the biodiversity and environment activists raised voice to stall the project. The environmental approval was finally received in October 2012 after negotiations with the central Ministry of Environment and Forests.
However, the contract agreement contains various clauses concerning environmental precautions. MMRDA is using vision and noise barriers for a stretch of 6 kilometres. It is to safeguard the secrecy of the sensitive BARC and to avoid disturbing the migratory birds including flamingoes.
While assuring the environmental precautions being taken MMRDA Additional Commissioner Sanjay Khandre told that apart from noise barriers the environment will also be kept warm for migratory birds. Also sensitive lights according to the ecology will be used on the bridge to prevent any effect on migratory birds.
In a span of 10 years, MMRDA will spend Rs. 280 crores for environmental concerns. The affected fishermen will also be compensated from this amount. 47.4 hectares of Mangrove plantation is getting affected by this bridge and to compensate this, mangroves will be planted in a five times larger area.
The other challenge was financial feasibility. The first hurdle was building a consensus around the share of investment between the centre and the state. The next challenge was finding a bidder who was ready to share the financial burden earmarked for the contracting party.
This issue didn’t come to a resolution until January 2014 when the Japan International Cooperation Agency (JICA) agreed to fund part of the project. JICA agreed to fund 80 per cent of the cost at a concessional rate of interest and the remaining 20 per cent came from MMRDA and the state government.
As the bridge is being constructed on the sea, there were obvious technical challenges but one was that the bridge does not affect navigation. For this, care was to be taken to maintain height and distance between piers of the bridge in such a way that it allows ships to pass through.
At some places spans as long as 180 metres were needed without a pillar. This requirement could not be fulfilled by concrete and hence steel spans are being used in some portions. To fulfil the purpose of stiffening and load-bearing behaviour Orthotropic Steel Decks (OSD) will be used.
As far as the height of the bridge is considered, Jawaharlal Nehru Port Trust (JNPT) demanded a height of 51 metres which was not economically viable. After discussions height was fixed to 35 metres to which JNPT issued a no-objection certificate in 2012.
The project is divided into four packages out of which the first three packages concern the construction. The fourth package concerns the traffic management system whose contract is yet to be awarded.