KOCHI WATER METRO: A technical overview of project .....................

The water metro is one of the most ambitious infrastructure developments of Kochi and expected to benefit more than 100,000 islanders. The proposed project envisages sixteen identified routes connecting thirty eight jetties across ten island communities across a 76 km route network. It is for the first time in India that a significant level of investment is being brought in for improving water transport, also proposed to integrate with the newly completed metro rail service. Eighteen jetties proposed to be developed as major jetties or main boat hubs while the remaining twenty jetties will be developed as minor jetties.

Implementation of the project would provide many advantages such as better connectivity of the islands around Kochi with mainland; reduce the road traffic by diverting the passengers to water transport thereby reducing the road congestion and air pollution from vehicles, Impetus to tourism in and around Kochi providing easy access to the scenic islands around.

Each boat station is unique in terms of its wave tranquility, geotechnical, design vessels, tide conditions, berth requirements and turning basin area. A boat station and its basin is a miniature form of seaport including the turning area and channel alignment. Proper planning and design of boat basin, berths and channel width, depths are vital for its safe and efficient operation.

Local and international standards are to be followed for the planning and design. Hydrographic, topographic and geotechnical surveys, tides, current, wind and waves data, potential water level rise due to greenhouse effect, seismic activity etc are required to be gathered prior to final design of each jetty.

Indian maritime standards are not updated since 1980; research and developments in this area are significantly advanced for the last two decades particularly in the Europe. Therefore it is recommended to adopt BS 6349 part 1 to 7, CIRIA manual and PIANC publications for the planning, design and construction of these jetties and associated maritime structures. Planning of basin and channel can be also based on Australian standard AS 3962 as this is the only international standards for the planning of small craft harbors. A design life of 50 years and a return period of 100 years for the environmental loads would be appropriate for this facility.

In the design of small craft harbors, it is necessary to limit the wave heights, which can impinge on the vessels berthed in the jetty. If the facility is to be sited in large exposed waterways where excessive wave height will occur during strong winds, then wave height should be limited using an attenuator or fixed breakwater.

The following are the type of jetty construction generally adopted, the final selection of which is based upon a number factors including environmental conditions, availability of materials, time for construction, contractors knowledge and skills, design life, durability and maintenance and of course geotechnical conditions.

•  Pile (steel or concrete) supported platform.
•  Mass concrete gravity block work wall.
•  Steel sheet piled embedded wall.
•  Cast in place reinforced concrete diaphragm wall.

The maritime environment can be very aggressive to concrete in terms of physical weathering, abrasion and chemical attack. Corrosion can be chloride-induced, sulphate-induced or microbiologically-induced and has the capability to damage embedded metal or reinforcement. Reinforced concrete elements and steel elements in the marine environments particularly in the tidal zone require a maintenance plan and management to be set out throughout the design life of the structure. However corrosion can be managed at the design stage, such as for reinforced concrete structures, through the use of high density concrete and adequate cover to reinforcement. In steel structures the use of coatings and/ or cathodic protection systems can control corrosion and help extend the design life of steel structures.

Ancillary facilities such as boat lift or slipway, maintenance and repair yard, workshop with suitable lifting equipments, fueling stations etc are to be planned at an early stage of developments. Adequate and suitable navigation lights, markers and buoys are also to be planned/designed in accordance with IALA regulations and to be deployed throughout the channel lengths and jetties for the safe and efficient operation of the boats. Further for the maintenance of jetties a management plan shall be set out prior to the operation of these long awaited public facilities.