• Bridge structures
  • Cranes & Gantries
  • Plate girders
  • Box girders
  • Cellular beams
  • Fabrication
  • Additional services
Bridge structures

With in-house capability to produce Plate Girders and the additional expertise to include additional fabrication it has been a natural step for Jamestown to establish itself in the Bridge market. Bridges can be constructed principally from plate girders, trusswork or even complex platework in ‘U’ Decks, box girder and arch structures.

With fabrication bays up to 180m long and a facility large enough to accommodate trial assembly of bridge structures up to 1000 Tonnes, units can be supplied in weathering steel or painted to the customers specific requirements. With shotblast and paint halls built to accommodate these larger structures, units up to 50m in length can be painted prior to delivery direct to site using our specialist transport network saving the customer time and money.

Cranes & Gantries

Alongside the Plate Girders, Bridges, and other Heavy Structures you will often see Crane Gantries, Crane Rails and Lifting Beams under construction on Jamestown’s busy shop floor. Experience in producing large Plate Girders and more specifically Box Girders has led to the growing number of Crane Projects currently in manufacture and with the capability to shotblast and paint in-house, gantries up to 56 metres in length can easily be accommodated.

Continued investment in the specific skills needed to carry out final assembly, both mechanical and electrical plus final testing now enables Jamestown to deliver the completed Crane Project direct to the customer saving both time and money in the final stages of the project. The final testing and inspection processes are often carried out working hand in hand with our customer thus ensuring complete satisfaction and repeat work for the future.

Plate girders

With two Corimpex automated beam lines plate girders can be produced up to 3.2m high a 1.2m wide and up to 2.5 Tonnes per metre. This presents endless
possibilities for both the design and construction of plate girders enabling beams to be constructed in material thicknesses up to 150mm, with simple fillet welds or more complex partial or full penetration welds.

Constructing plate girders in this manner allows cambers to be profiled into the web plate prior to assembly and any number of configuration variables including both symmetrical and asymmetrical beams with top and bottom flanges of differing thicknesses. Tapered plate girders are easily produced in addition to several fabricated extensions including haunched beams, cranked beams and if required as carcass only or fully fabricated. Fabricated plate girders produced in this manner can be supplied in unit weights up to 80 Tonnes and up to 40 metres in length.

Box girders

Box girders, double web and even triple web plate girders are becoming more widely used in the construction industry, not only for their increased torsional strength properties but for their aesthetic value also. In recent years Jamestown have produced all manner of box girders and multiple web plate girders in a variety of cross-sectional shapes often comprising heavy plate thicknesses up to and including 100mm and requiring corner welds to be partial penetration or full penetration.

Often used as supporting columns in building structures or main component parts of truss assemblies, bridge structures and crane gantries, rectangular box girder fabrication is a regular feature in Jamestown’s everyday production. Like their plate girder counterparts box girders can be produced in almost any section size and lengths can be up to 40 metres subject to the unit weight no exceeding 100 Tonnes.

Cellular beams

Cellular beams are commonly fabricated from plate. In these plate girder type
sections the flange and web sizes, thicknesses and overall depth can be selected to be the most efficient for the applied loading, form of construction and opening requirements. The fabrication process using automated equipment suits the production of both cellular beams/ plate girders with a series of regular openings, and beams with bespoke openings in terms of size, shape, and position.Fabricated beams/plate girders provide an efficient solution for both long span secondary cellular beams and more heavily loaded primary beams, as the web thickness can be increased relatively easily.

Again, for composite construction the top flange may be significantly reduced in size relative to the bottom flange to maximise structural efficiency. The web plate can be profile-cut with a pre-determined camber prior to welding to suit any eventual pre-camber requirements. The ability to shape the web plate prior to welding the three components into a beam configuration also means that beams with holes need not be of a constant depth, opening up all sorts of architectural possibilities with haunched or tapered girders.


With a highly skilled workforce regularly supplying fabrications to Exec. Class 3 and 4 many customers take advantage of this skillset and request Jamestown to supply our Plate Girders, Box Girders and Cellular Beams fully fabricated including all connections, stiffeners and endplates where required plus drilled holes and machined bearing surfaces or end plate connections.

With a highly skilled workforce regularly supplying fabrications to Exec. Class 3 and 4 many customers take advantage of this skillset and request Jamestown to supply our Plate Girders, Box Girders and Cellular Beams fully fabricated including all connections, stiffeners and endplates where required plus drilled holes and machined bearing surfaces or end plate connections.

Additional services

Abrasive Blasting & Painting

Jamestown commenced painting operations in 2021 after installing and commissioning two self-contained environmentally controlled units for abrasive blasting and painting. The two units are controlled by mechanical heat recover systems which keep a constant temperature while extracting stale air, dust and fumes and pumping in fresh temperature-controlled air in a constant cycle.


The blast hall measures 36m x 7m and the paint hall measures 42m x 7m. It is with this investment into the business that we were able and are still able to work in multiple industries which include structural steel in Buildings, Bridges for Network Rail, Irish Rail, Transport Infrastructure Ireland, Highways England, and Offshore wind energy, Maritime and Craneage projects.


We can work to the most stringent of specifications with high life expectancy before major maintenance and in very high-risk corrosive environments with high salinity i.e. (C5 Corrosive category) We have been certified for many years under welding quality management systems along with ISO standards and we added the abrasive blasting and painting into the scope of our HSQE certification to ISO9001:2015, ISO14001:2015, ISO45001:2018 and FPC.

Machining & Drilling

To complement Jamestown’s extensive fabrication facilities, we have invested in the latest CNC Milling and Drilling machines enabling us to machine bearing surfaces and end plates and carry out a range of drilling and tapping of heavy plates as part of a composite structure. These machines enable us to provide our customers with a complete package in house thus removing the need to subcontract these additional processes. Jamestown can now offer the following processes:


Beam Machining Centre – drilling, tapping and milling beams with a 3-axis moving head. Lengths up to 16m and overall beam dept of 1.05m can be accommodated. Drilled holes of 42mm diameter and milling finish to a +/-0.5mm tolerance can be achieved.


Plate Machining Centre – drilling, tapping, and milling of plates. Max plate thickness is 100mm. Max size plate is 4500x 2080mm. Drilling complete with high-speed carbide drills.


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