L&T Builds India’s First Steel Railway Underpass at Udhna Station in Just Eight Hours

India has marked a significant engineering milestone with the installation of the country’s first prefabricated steel pedestrian underpass beneath active railway tracks at Udhna railway station in Surat, Gujarat.

Executed by Larsen & Toubro, the critical structure was installed and the railway line restored within an eight-hour traffic block. The operation combined detailed advance planning, prefabrication, heavy lifting, excavation and continuous coordination among construction teams and railway authorities.

The project demonstrates how modern modular construction can substantially reduce the disruption normally associated with building infrastructure beneath busy railway corridors.

A Critical Facility for Udhna’s Commuters

Udhna is an important railway station serving Surat’s industrial areas and a large population of migrant workers employed in the city’s textile and manufacturing sectors.

The station ordinarily handles around 10,000 passengers a day, while footfall can rise to nearly 30,000 during holidays and other peak travel periods. Congestion frequently creates difficulties for passengers moving between platforms, particularly when travellers attempt to cross railway tracks instead of using safer designated routes.

The new pedestrian underpass is intended to provide a secure passage beneath the tracks, reducing unsafe track crossings and improving movement between platforms.

Unlike a road underpass, the structure has primarily been designed for commuters and porters moving within the railway station.

India’s First Prefabricated Steel Railway Subway

The Udhna structure has been described as India’s first steel pedestrian subway installed beneath railway tracks.

It is an arch-shaped prefabricated tunnel measuring approximately 12 metres in length, 4.8 metres in width and 2.7 metres in height. The structure was manufactured away from the installation site and brought to the station in a condition ready for placement.

Prefabrication allowed much of the cutting, welding, inspection and finishing work to be completed in a controlled manufacturing environment before railway operations were interrupted.

This approach improves construction quality while reducing the amount of work that must be performed beside active railway lines.

The Track Cut-and-Cover Method

The project used a technique known as the track cut-and-cover method.

Under this approach, railway services are suspended for a carefully scheduled period and the track above the proposed underpass is temporarily removed. The ground beneath the line is then excavated to create a pit large enough to receive the prefabricated structure.

Once the steel arch is lowered into position, the surrounding space is filled and compacted. The railway formation, ballast and track are subsequently reconstructed above the underpass.

The method used at Udhna involved several carefully sequenced stages:

1. Isolating and securing the work zone
2. Removing the rails, sleepers and ballast
3. Excavating beneath the railway alignment
4. Preparing the base for the steel structure
5. Lifting and positioning the prefabricated arch
6. Filling and compacting the surrounding ground
7. Reconstructing the railway formation
8. Reinstalling and aligning the track
9. Conducting safety inspections before reopening the line

All these activities had to be completed within the approved block because the railway corridor was required to return to normal service immediately afterward.

Completed Within an Eight-Hour Window

L&T’s rapid-execution team completed the main installation and railway-restoration work within eight hours.

The company said the operation required meticulous planning, multidisciplinary coordination, heavy lifting equipment and round-the-clock execution. The objective was to restore the railway line safely within the stipulated period while minimising disruption to train movements.

During the block, the tracks connecting Udhna in Gujarat with Jalgaon in Maharashtra were temporarily removed. Excavation was carried out beneath the alignment, after which the steel arch was placed inside the prepared pit.

The excavated area was then refilled, the track structure reconstructed and the railway line restored. Railway officials reported that the operation was completed without significantly affecting scheduled train services.

Heavy Lifting at the Centre of the Operation

One of the most challenging stages involved lifting and lowering the large steel structure into a confined excavation beside railway infrastructure.

Heavy-duty cranes and specialised lifting arrangements were required to move the arch while maintaining accurate control over its orientation and position.

Even minor misalignment could have delayed backfilling and track restoration. Surveyors, equipment operators and engineers therefore had to coordinate continuously during the lifting process.

The structure also had to be placed without damaging its steel sections, foundations or surrounding railway assets.

Why Prefabricated Steel Was Chosen

Traditional railway underpasses are commonly built using reinforced cement concrete. Such structures may involve extensive on-site reinforcement, formwork, concreting, curing and waterproofing.

These processes can take considerably longer and may require repeated railway blocks or prolonged restrictions near the tracks.

The prefabricated steel design adopted at Udhna offered several advantages:

Faster Installation

Most of the structure was produced before the railway block began. On-site work was therefore concentrated on excavation, placement and restoration.

Reduced Railway Disruption

The eight-hour installation period limited the impact on passenger and freight services using the corridor.

Controlled Manufacturing Quality

Factory fabrication permits closer control over welding, dimensions, protective coatings and structural tolerances.

Lower On-Site Congestion

Fewer construction activities were required inside the restricted railway environment.

Potential for Replication

Standardised steel modules could be adapted for other stations where rapid underpass construction is required.

Precision Planning Before the Block

Completing the underpass in eight hours was possible only because the operation was planned in detail before the track was closed.

Construction teams would have needed to establish the exact sequence of activities, allocate machinery, calculate lifting requirements and prepare materials in advance.

Excavators, cranes, ballast, track equipment, compaction machinery and emergency resources had to be positioned close to the work zone before the block commenced.

Separate teams were assigned to excavation, lifting, civil work, track reconstruction, signalling safety and final inspection. The transition between each stage had to occur immediately because delays in one operation would affect every activity that followed.

Contingency arrangements were also essential. Backup machinery, lighting, personnel and materials would be required to address equipment failure, unexpected soil conditions or alignment problems.

Restoring the Track Safely

Speed alone could not determine the success of the project. The railway line had to be returned in a condition suitable for safe train operation.

After the underpass was installed, the surrounding soil and filling material had to be properly compacted to prevent settlement beneath the tracks.

Ballast was then placed and the rails and sleepers restored to their correct alignment. Railway engineers were required to inspect track geometry, levels, fastening systems and structural clearances before permitting train movements.

The transition zones on either side of the steel structure are particularly important. Differences in stiffness between the underpass and the surrounding soil can create uneven settlement or additional track stresses if the formation is not carefully designed and compacted.

Improving Passenger Safety

The most important benefit of the underpass is the safer movement it provides for passengers.

Busy railway stations often experience dangerous track crossings when passengers move between platforms through unauthorised routes. This risk can become greater during periods of heavy crowding or when travellers are carrying luggage.

The Udhna underpass creates a permanent grade-separated crossing, allowing passengers to move below the tracks without entering areas used by trains.

It can also reduce pressure on existing foot overbridges and help distribute passenger movement more evenly across the station.

An Alternative to Foot Overbridges

Foot overbridges remain an essential feature at railway stations, but they may present difficulties for elderly passengers, people carrying heavy luggage and travellers with limited mobility.

A pedestrian subway can offer a more direct route with smaller changes in elevation, depending on its access design.

Subways can also be useful where platform conditions, overhead electrical equipment or space constraints make the construction of a new bridge difficult.

However, their long-term success depends on proper lighting, drainage, ventilation, surveillance and maintenance.

Drainage and Waterproofing Requirements

Structures built beneath railway tracks must be protected against water infiltration and flooding.

Rainwater entering the underpass could affect pedestrian access and, over time, cause corrosion or deterioration if drainage systems are inadequate.

The Udhna structure will therefore require effective surface-water diversion, internal drainage and regular inspection of joints and protective coatings.

Because steel can corrode when repeatedly exposed to moisture, the condition of its coatings and drainage arrangements will be important throughout the structure’s service life.

A Model for Rapid Railway Construction

The project offers a possible construction model for other high-traffic stations where railway authorities need to improve passenger circulation without imposing lengthy operational blocks.

Prefabricated steel structures could potentially be used for pedestrian subways, service passages, drainage crossings and selected road-under-bridge applications.

The method may be especially valuable on busy routes where even a short suspension of railway traffic affects large numbers of passengers and freight services.

Every location would nevertheless require a separate engineering assessment covering soil conditions, axle loads, drainage, available working space and long-term durability.

Engineering Beyond the Eight-Hour Record

The speed of installation is the project’s most visible achievement, but the larger innovation lies in transferring much of the construction process away from the railway line.

By manufacturing the structure in advance, L&T converted a complex under-track construction project into a tightly controlled installation exercise.

This approach reflects a broader shift in infrastructure development toward modular engineering, digital planning, prefabrication and mechanised execution.

Such methods can help Indian Railways modernise stations while reducing disruptions on an increasingly busy network.

A Milestone in Indian Railway Infrastructure

The successful installation of the steel pedestrian underpass at Udhna demonstrates how careful engineering and coordinated execution can compress a complicated railway project into a short operational window.

Within eight hours, teams removed an active railway track, excavated the formation, positioned a large prefabricated steel arch, restored the ground and rebuilt the line for safe operation.

The project has provided Udhna station with an important commuter facility while establishing a new benchmark for rapid railway construction in India.

More importantly, it shows how prefabricated infrastructure can improve passenger safety and station capacity without requiring extended disruption to one of the country’s busiest public transport systems.

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