— April 2019
Independent design check (CAT 3) of phase 2B refurbishment of the Whiteball tunnel that comprises SCL lining protecting the existing brick lining.
1km rail tunnel named after the nearby village of White Ball built by Brunel (opened 1844 on the Great Western Main Line). Victorian brick-arch lining, which has deteriorated over the years including weathering and chemical reaction from the sulphurous steam trains. A refurbishment scheme was required to make it fit for purpose which was planned through various phases. The early phases of the project involved installation of the RAM Arch System and wire mesh to prevent loose bricks from falling on to the tracks. In latter phases of the refurb - the subject of the CAT3 check - sprayed concrete was applied to cover the RAM Arch system coupled with rock bolts with butterfly plates were used to hold the concrete lining.
The ground was not exposed in this refurbishment effort.