ROB steel fabrication contractor India — plate girder road over bridge steel

A Road Over Bridge in India is built from fabricated plate girders, cross beams, bracing, and bearing seat steelwork — all designed to IRC:24 for highway loading and IRS-B1 where the structure crosses electrified railway lines. Sun Corporation Fabricators & Engineers fabricates that steel at our Hyderabad workshop and erects it at site, including coordinated rail traffic block windows on projects where blocks are issued by the railway authority. We supply ROB steel fabrication for NHAI highway projects, state PWD packages, and railway interface works across South, Central, and West India. Tender documentation is available via our fabricator prequalification documentation.

Source: Ministry of Railways, level crossing elimination programme data. Level crossing elimination remains a priority infrastructure programme — the primary spanning element of most ROB packages is welded steel plate girder superstructure.

Suncorporation has been supplying ROB construction steel — plate girders, cross beams, approach span steel, and bearing seat steelwork — for projects across South, Central, and West India. This page explains what ROB construction involves structurally, how the fabrication process works, what the standards require, and what it costs. If you have a specific project, send us the drawings and span data and we will have a quotation back within 48 hours.

ROB steel fabrication — scope and plate girder capabilities

ROB stands for Road Over Bridge. In the context of Indian railway infrastructure, ROB construction means building an elevated bridge structure that carries road traffic across a railway line, replacing a level crossing where road and rail previously met at grade. The road approaches on either side are ramped up to the bridge deck level, so vehicles can pass over the railway without any interaction with train movements. An ROB is distinct from an RUB — Road Under Bridge — where the road passes beneath the railway embankment through a box structure or underpass. ROB construction is generally preferred when the road approaches can be ramped up economically, which is the case for the majority of level crossing elimination sites in India.

The term ROB Nirman is simply the Hindi description of the same thing — road over bridge nirman meaning road over bridge construction. ROB Nirman projects are jointly funded by the Ministry of Railways and the relevant state government, with Indian Railways providing the land and rail traffic block access for girder launching, and the state government or NHAI funding and constructing the bridge structure. Most ROB Nirman projects in India use steel plate girder superstructures on RCC piers and abutments, which is why structural steel fabrication is the critical procurement item for every ROB programme.

The structure of a typical ROB in India

A typical single-track ROB in India has three spans — a main span crossing the railway track, and approach spans on either side connecting the main span to the abutments on the road embankments. The main span is the critical structural element. It needs to be long enough to clear the railway track and provide the required overhead clearance for electrification equipment on electrified lines, and carry the IRC loading without excessive deflection. Typical main spans run from 24 to 45 metres depending on the track configuration and electrification requirements. The approach spans are shorter — typically 12 to 18 metres — and use lighter structural steel sections than the main span.

Steel plate girder fabrication for ROB construction

The plate girder is the workhorse of ROB construction in India. A welded plate girder is essentially a custom I-section fabricated from flat plates — a top flange, a web plate, and a bottom flange, welded together with full-penetration longitudinal welds, with vertical stiffeners welded at intervals to the web to prevent buckling. For a typical ROB main span of 30 to 40 metres, the plate girder depth runs from 1.5 to 2.2 metres. Two or three girders typically span side by side across the railway, connected by cross beams at intervals to form the composite girder system that carries the bridge deck.

Fabricating a plate girder for ROB construction is a precision exercise. The web and flange plates are cut to size on our CNC plasma cutting machine, checked dimensionally, and then assembled in a jig before welding. The longitudinal flange-to-web welds are the most critical — these need to be full-penetration, double-sided, and inspected by ultrasonic testing before the girder moves to the next stage. Flange splice welds, where individual plates are joined end-to-end to make up the full girder length, are also full-penetration butt welds inspected by UT. Stiffener fillet welds are inspected by magnetic particle inspection. The fabrication standard is IRS B1-2001 — Indian Railways Standard specification for the fabrication and erection of steel girder bridges.

Camber in ROB plate girders

One aspect of plate girder fabrication for ROB construction that often surprises clients unfamiliar with bridge steel is the requirement for pre-set camber. A steel girder loaded with the weight of a concrete deck will deflect downward. To compensate, the girder is fabricated with an upward bow — the camber — so that when the deck is cast and the girder deflects under the dead load, the bottom of the girder is at or near flat. Camber is set during fabrication by assembling the girder with a controlled pre-bow, confirmed by survey. At Suncorporation, camber records are included in the quality dossier that accompanies every ROB girder to site.

ROB Nirman kya hota hai — ROB construction meaning in Hindi

ROB Nirman ka matlab hota hai railway level crossing par ek elevated steel bridge banana jis par road traffic upar se guzarti hai aur train neeche se. ROB Nirman India mein Ministry of Railways aur State Governments ka joint programme hai. Railway department block access deta hai taaki steel girders track ke upar launch ki ja sake. State government ya NHAI bridge ka nirman aur kharcha sambhalta hai. ROB Nirman mein sabse zaroori component steel plate girder hota hai — yahi main railway crossing span carry karta hai. ROB full form construction mein: Road Over Bridge.

IS and IRS standards for ROB construction steel

• IRS B1-2001 — Indian Railways Standard: fabrication and erection of steel girder bridges. The primary code for all ROB plate girder fabrication.
• IS 800:2007 — General construction in steel. Used for approach span design and connection design.
• IS 2062 — Hot-rolled steel — the material standard for all ROB structural steel, with Charpy impact testing for bridge grade steel.
• IRC 6 — Loads and load combinations for road bridges. IRC Class 70R and Class A vehicle loading for ROB design.
• IRC 24 — Standard specifications for road bridges in steel.
• IS 1477 — Painting of structural steel. The shot blasting and painting specification for all ROB construction girders.

ROB construction steel fabrication cost in India — 2026 rates

ROB construction steel fabrication costs in India in 2026 typically fall in the range of Rs 95,000 to Rs 1,20,000 per MT for plate girder fabrication, painting, inspection, and transport to site. A complete ROB steel package for a typical single-track ROB with a 36-metre main span and two 15-metre approach spans involves 250 to 450 MT of structural steel. At current rates, that puts the total steel supply cost in the range of Rs 2.5 crore to Rs 5.5 crore, excluding erection. Erection — launching the main span girders during railway blocks and erecting the approach spans — typically adds Rs 40 to Rs 65 lakh to the total depending on site conditions.

ROB construction enquiries and how to work with Suncorporation

To get a fabrication quotation for an ROB construction project, we need the structural drawings showing the span configuration, the main girder cross-section, and the connection details, plus the material specification and painting specification. If at pre-tender stage, a sketch showing the main span, number of tracks, and electrification requirement gives us enough to provide a budget estimate. We respond to all ROB construction enquiries within 24 hours. For projects in Telangana, Andhra Pradesh, Maharashtra, Karnataka, Madhya Pradesh, and Rajasthan, we have recent project experience that makes our quotations grounded in current local transport costs.

Contact Suncorporation for ROB construction steel. Also see: Pedestrian bridge fabrication | Steel girder fabrication | Structural steel fabricators Hyderabad