Parapet Cantilever Strengthening to M25 Bridge

thumb_a2_south_orbitalAs part of the HA’s programme to improve M25 parapets around the network, 175m of parapets on the M25/A2 South Orbital East and West bridges required upgrading to P2 aluminium. To meet proposed increased loadings the design required the cantilever sections to be strengthened by incorporating r/c “ribs” integral with the existing reinforcement. Some of these needed to support lighting columns (and can be seen as being slightly longer in the photos).

Topbond were awarded the work by Carillion for whom they had completed similar work on other HA network structures.

Prior to constructing the reinforced concrete strengthening webs at the proposed 60 No. parapet post locations Topbond carried-out surface preparation and installed a range of anchors and fixings – proof loaded - to support the temporary and permanent works above the A2 carriageways. Working over the carriageways required a high standard of scaffolding stability and protection for the working areas and our experienced, disciplined and attentive workforce.

Prefabricated formwork units were anchored into the cantilever at each of the rib locations following reinforcement installation and then C50/20 concrete pours were made.

All work except deliveries was carried-out during night time lane closures.

To install 4 No lighting column locations hydrodemolition was used to prepare new service channels into the existing edge beam, where each location was protected by a moveable steel plate unit.

All Topbond’s works were completed successfully, meeting our target dates and costs.