Repairs amongst archaeological treasures

York Street in Bath runs parallel and next to the Roman Baths museum. During Victorian times the level of the street, as with many other roads in Bath, was raised by approximately 4m above the old Roman pavement. The street is supported on a series of composite steel and concrete beams (with concrete jack arches between) which were found to be corroding mainly at the bearings ends. The street then had to be shut to heavy goods vehicles until a solution was found. Stress UK were called in to try and find a practical method of achieving the replacement or strengthening of the existing beams.

Working in an archeologically sensitive area

The void beneath the road has highly restricted to access due to it being directly next to the Roman Baths and the area being the site of Roman ruins. No suitable route through the museum was practical and so all plant and materials had to be lowered from York Street via a manhole. Being above and beside a historic monument meant that no dust, noise or vibration could be tolerated during the works. Agreement with the archaeologist had to be made to be able to install a working platform over the Roman pavement.

Steel and concrete – assessing the damage

Careful breaking out of the concrete casing at the ends of the beams revealed corrosion of the main steels around the bearing areas. Our team were required to work in a confined, difficult space in a location that features some of the UK’s most prized Roman ruins.

Careful planning

Planning a safe system of work with no noise, dust or vibration and being able to lower into and use heavy steel beams in a highly restricted area was our first major task. The existing Victorian composite beams comprising two parallel steel I-beams side-by-side and surrounded in concrete had to be diamond drilled for the installation of bolts. The location of the holes was marked out using templates which were identical to the templates used by the steel fabricators for the new galvanised C-section beams.

Using prefabricated C-section galvanised steels meant that each segmented beam could come in three lengths, lowered beneath the road and bolted together on site beside the original Victorian composite beams.

The benefits of our chosen strengthening method

Lengths and weights of new steel which could be handled down through the manhole and lifted easily into position beside the old beams. Leaving the existing beams in position and fitting new full capacity steels meant the noise, dust and general disturbance was kept to the absolute minimum.

The outcome

The engineering collaboration, innovation of the system adopted, support of the client and team spirit of the project crew resulted in a difficult problem being solved efficiently, quietly, to programme and budget and resulting in a highly successful outcome for the museum and a road re-opened to traffic for the client.