The rapid urbanisation of Navi Mumbai, coupled with the development of the Navi Mumbai International Airport and the International Corporate Park at Kharghar, has significantly increased transportation demand across the region. To address these growing mobility requirements, CIDCO is developing the Kharghar-Turbhe Tunnel Link Road (KTLR), one of the most significant road tunnel projects currently under construction in Maharashtra.
The project aims to provide a direct east-west connectivity corridor through hill ranges separating the northern and southern nodes of Navi Mumbai. By creating a shorter and faster route between Kharghar and Turbhe, the project is expected to reduce travel distance and time by nearly 50 per cent.
Project overview
The KTLR project is being executed by the Rithwik-Evrascon joint venture (JV) under the supervision of the TCE-Hill JV as the project management consultant. It comprises a total corridor length of approximately 5.96 km, including four-lane twin-tunnels of 1.76 km each, approach viaducts and ramps extending about 3.46 km and a cut-and-cover section of 700 metres. The corridor has been designed for a speed of 80 km per hour and will help in decongesting the Sion-Panvel Highway.
The tunnel system consists of twin independent four-lane tunnels, each having a width of 18.8 metres and a height of 10.23 metres. Five cross passages have been incorporated at intervals of approximately 300 metres, including three pedestrian passages and two vehicular tube cross passages to facilitate emergency evacuation and operational safety. The final reinforced concrete lining thickness is 300 mm.
Excavation methodology and geological considerations
A comprehensive geological investigation programme was undertaken before construction. The tunnel alignment passes predominantly through Deccan basalt formations exhibiting varying degrees of weathering, fracturing and jointing. As with most urban tunnelling projects, understanding ground behaviour has been critical to ensuring excavation stability and construction safety.
The project has adopted the New Austrian Tunnelling Method (NATM), which is based on the principle of mobilising the inherent strength of the surrounding rock mass, through controlled deformation and systematic support installation. The excavation cycle in the project followed the core NATM philosophy of “observe, measure, evaluate and modify”. Activities include profile marking, face drilling, charging and blasting, ventilation and defuming, scaling, survey verification, support installation and instrumentation monitoring.
Ground support and monitoring systems
The project has undertaken rock mass classification using the Rock Mass Rating (RMR) system. Parameters such as uniaxial compressive strength, rock quality designation, joint spacing, joint condition, groundwater conditions and joint orientation are evaluated to determine appropriate support requirements.
Based on observed ground conditions, three support categories – S1, S2 and S3 – have been adopted. These support systems incorporate combinations of self-drilling rock bolts, steel fibre-reinforced shotcrete and polypropylene fibre-reinforced shotcrete. Support intensity increases progressively with decreasing rock quality to ensure stability and control deformation.
The permanent support system built for the tunnel consists of a 500 GSM protective felt layer, a 2 mm PVC waterproofing membrane and a 300 mm reinforced concrete lining. This composite arrangement provides waterproofing, durability and long-term structural performance.
Safety and environmental management
The high level of safety has been a primary focus throughout the tunnel construction in the project. Regular toolbox talks, awareness programmes and training sessions are conducted to reinforce safe working practices. As a result of sustained efforts by project stakeholders, the project has achieved significant safe working milestones without any major accidents.
The environmental monitoring carried out includes continuous assessment of air quality, gas concentration, vibration levels, noise levels and illumination within the tunnel. Parameters are maintained within prescribed limits to ensure worker safety and regulatory compliance.
Operational systems adopted, challenges faced and resolution
Upon completion, the tunnel will be equipped with advanced electromechanical systems, including LED lighting, emergency lighting, CCTV surveillance, fire and smoke detection systems, traffic management systems, emergency communication networks and evacuation signage.
Despite steady progress, the project has faced several challenges. These include the relocation of encroachments near the tunnel portal, disposal of approximately 1.4 million cubic metres of excavated muck, land acquisition and transfer issues, restricted blasting windows in a densely populated urban environment and diversion of natural watercourses. To overcome these challenges, close coordination among contractors, consultants, government authorities and local stakeholders has been instrumental, while maintaining the construction progress. As Navi Mumbai continues to expand, the KTLR corridor will play a critical role in supporting regional connectivity, reducing travel times and facilitating economic development.
Based on a presentation by CIDCO at a recent India Infrastructure conference
