Mumbai Metro Line-2B’s Mithi River Bridge Redesigned

Spannovation has announced it has been awarded a sub-contract by NCC Ltd. to redesign 23.6 km Mumbai Metro Line-2B (Yellow Line)’s bridge over Mithi River between MTNL and SG Barve metro stations.

Mithi River Bridge’s new segmental balanced-cantilever design replaces the original cable-stayed tied-arch bridge design which the Mumbai Metropolitan Region Development Authority (MMRDA) termed as “iconic” when announced with two other bridges at BKC Entry & Vakola Nalla Crossing (see designs) in July 2019.

The roughly 270m long bridge will span between Line-2B’s piers P569 to P578. Its construction under 5.868 km Package CA-06 (MTNL – Chembur) was originally awarded to RCC Infra Ventures – MBZ JV in 2017, but terminated in January 2020 due to poor progress on key performance indicators.

NCC was awarded its contract in 2022 under Package C102 for remaining construction works after four rounds of bidding between February 2020 – August 2021.

Old Design (Arch Bridge)

Mithi River Bridge was originally designed by Designfrakt Architects with Tony Gee as its structural designer.

Per Designfrakt Architects, the concept of this bridge, the ‘Arch’, simplistic yet dynamic in its form, derives its inspiration from ‘Akash’, meaning―the sky. The bridge is an elegant, sophisticated expression that, much like its name, reaches for the sky as it draws one’s gaze along its curve. The large-span arch form embraces a soft compression towards its centre, in turn resolving forces into compressive stresses and eliminating the tensile stresses.

New Design (Segmental Bridge)

Per Spannovation’s press release, the new 270-meter-long bridge, featuring a curved alignment with a span arrangement of 75m – 125m – 70m, has a radius of 210m. The new design features an innovative cast-in-place segmental design on a “fast-tracked” schedule.

Spannovation mentions that although the foundations and portions of the substructure have been constructed in accordance with the original design, progress on the superstructure has been delayed due to unresolved technical challenges.

Spannovation has been retained as a sub-consultant to NCC Limited to expedite the design process and secure the necessary approvals from the client (MMRDA). Their scope of work includes redesigning the bridge superstructure, conducting an independent verification of the existing substructure and foundation designs, and proposing any required remedial measures. The redesigned superstructure will feature a cast-in-place segmental construction, utilizing the balanced cantilever method with double-bladed piers.

Line-2B like all other metro lines in Mumbai is running terribly behind schedule due to a host of reasons, so at this point I’ll take any design as long as it doesn’t affect operational performance.

MMRDA is targeting to first open Line-2B’s Mandale – Diamond Garden section with 5 stations on the east-side, which at this time I see happening no sooner than Q1 2026 with the rest of the line opening up no sooner than Q4 2027.

While civil construction challenges remain throughout the line’s alignment, MMRDA just can’t catch a break from rolling stock bidding and contractual issues. While most of it is self-inflicted, in Line-2’s case I hear BEML & MMRDA are currently stuck in negotiating their 126 & 72 coach follow-up orders’ value due to supplier cost escalation issues by Hitachi on BEML’s side of the house which MMRDA has refused to entertain.

That doesn’t affect things at this point as BEML has 378 other coaches on order, but if not addressed soon it’s something that will impact train frequency when operations on the entire line begins.

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– TMRG