In what could be termed as a major achievement, the Mumbai Rail Vikas Corporation (MRVC) has announced the successful breakthrough of Tunnel-2 (Wavarle Tunnel), the longest tunnel in the Mumbai Suburban Railway Network, as part of the Panvel-Karjat railway project under the Mumbai Urban Transport Project 3 (MUTP-3).
The underground excavation of the Wavarle Tunnel commenced on February 22, 2023 and the breakthrough was achieved on June 7 in the presence of the Chairman and Managing Director of MRVC, Subhash Chand Gupta. This significant achievement marks a major step towards project's execution despite logistical challenges and complex geological conditions.
The Panvel-Karjat railway project encompasses the construction of three tunnels, totalling 3,164 meters in length. Tunnel 1 (Nadhal) is 219 meter-long, tunnel 2 at Wavarle is 2,625 meter-long while tunnel 3 at Kirawali is 320-meter long, an official release from MRVC said.
The Wavarle Tunnel's construction adhered to the New Austrian Tunnelling Method (NATM), which involved a cyclic sequence of excavation followed by the installation of a primary support and a delayed secondary lining. The key aspects include primary lining which consists of shotcrete reinforced by wire mesh and rock bolts for immediate support and stability. The other is excavation technique which comprises drill and blast with observation methodology using instrumentation and 3D monitoring.
The Wavarle Tunnel features a ballast-less track and includes public refuge areas, a tunnel control system (SCADA), lighting system, fire fighting system, and ventilation systems meeting contemporary international standards. The height of the tunnel is 7.323 meters while the width at rail level is 13.282 meters, the release said.
During the excavation, significant challenges were encountered, including fractured rock masses with water seepage and minimal cover (as low as 12 meters) and two water streams that cross the tunnel alignment at the low cover zone. Despite these challenges, an average underground excavation output of 175 meters per month was achieved through meticulous planning, with two rounds of blasting per day during the daytime since the blasting is not allowed during night time, the release added.
The successful breakthrough of Tunnel-2 represents a major milestone in the Panvel-Karjat railway project, paving the way for enhanced connectivity and transportation efficiency in the Mumbai suburban region. The cost of this rail corridor is approximately Rs 812 Crore and two rail flyovers, 44 major and minor bridges, 15 road-under bridges, and 7 road-over bridges besides three tunnels.
The new corridor will connect Navi Mumbai with Raigad district of the Mumbai Metropolitan Region (MMR), and would aid the development of Panvel, Karjat and the proposed Navi Mumbai Airport Influence Notified Area (NAINA). Moreover, it will allow local trains to run between Mumbai and Karjat via Panvel.
