RamArch – A487 New Dyfi Bridge Cycleway

PROJECT: A487 New Dyfi Bridge Cycleway
OWNER: Powys Council / Network Rail
DESIGNER: OTB Engineering Limited
CONTRACTOR: Alun Griffiths (Contractors) Ltd / Shotcrete Services Ltd.
PURPOSE: Stabilisation of a masonry arch.
RAMARCH TYPE: Plain steel 8mm RAMARCH mesh, manufactured to BS standard
RAMARCH FINISH: Galvanised.
DATE: 2023

The existing viaduct on the A487 Railway
Bridge in the town of Machynlleth, which carries
the Whitchurch Aberystwyth Railway line,
consists of a steel girder spanning obliquely
over the A487 single carriageway road to the
southwest of Machynlleth Railway Station and
an adjacent masonry arch and embankment.
The masonry arch, which was constructed in the
1860s, was found to be generally deteriorating,
with long-standing cracks at its haunches,
missing masonry, hollow-sounding areas behind
stonework, water seepages and the string
course was sagging at the arch crown.
The arch was blocked-up and infilled in 1977
and the original pedestrian / cycling way through
it interrupted forcing cyclists to use the road
carriageway or the narrow footway. Powys
Council decided that the pedestrian / cycleway
should be reopened and, together with Network
Rail, organised investigations and a detailed
design leading to the reinstatement works.
RAMARCH was selected to provide both
temporary support to the masonry arch during
excavation of the backfill and as structural
reinforcement to the permanent sprayed
concrete lining. The work was successfully
carried out without the need to close either the
road or the operational railway.