Rail Engineer – July 2019

B

arnard’s Lock is a rail underbridge structure spanning

the river Kennet, located 3.7km west of the centre of

Newbury, West Berkshire. The underbridge carries the

Berks and Hants Line (BHL) between Hungerford and

Newbury, a section of the Reading to Taunton line, which is a

major branch of the Great Western Main Line.

Barnard’s Lock underbridge

is located in a saturated,

wooded area with the nearest

road access about 2km away.

The area is a Site of Special

Scientific Interest, often referred

to as a “triple SI”. The location

would attract the attention

of the Environment Agency if

any form of engineering work

were to be proposed due to

special concerns for the local

population of otters, water

voles and other forms of wild

life in the area.

The bridge comprises three

wrought-iron half-through

girders with intermediate

wrought-iron cross girders

supporting a timber decking.

It has two spans, is 40 metres

in length and is skewed at an

angle of 57 degrees to the

channel of the river Kennet,

so the brick bridge abutments

are aligned with the direction

of the river flow. The clearance

between the bridge deck and

the river is very small, so the

bridge has the capacity to

become a barrier to the river

flow after heavy rainfall.

Significant deterioration

Well over fifteen years

ago, structural inspections

and assessment of the

underbridge, carried out by

JBA Consulting, identified

significant deterioration of the

timber deck and section loss

of the main and cross girders

throughout the structure. As a

consequence, the structure was

considered to be life expired

and required renewal.

However, subsequent load

monitoring of the structure

has enabled Network Rail to

Barnards Lock Underbridge

A SPONGY AND SUCCESSFUL LIFT

COLLIN

CARR

PHOTOS: JBA CONSULTING

68 FE ATURE