Bridges

Cover of Deck Widening Stitch Pours Under Live Traffic
Deck Widening Stitch Pours Under Live Traffic
  • Publication no: ABC-CAS203-14
  • Published: 22 October 2014
With increasing traffic volumes, existing highways are often widened to increase their capacity. Bridges along these highways are typically widened by constructing a new segment of bridge deck and then connecting this to the existing bridge through a stitch pour. In the period immediately after concrete placement the stitch pour is exposed to traffic-induced vibrations and deflections which may be detrimental to the quality of the connection. Traffic restrictions are commonly provided to minimise these vibrations and deflections, but traffic restrictions cause further congestion and the traffic management costs are often very high. The contractor may also be subject to penalties due to a loss of toll revenue. Throughout the construction phase of the M2 Upgrade Project, it was found the traffic restrictions for the concrete stitch pours were very disruptive to the motorway user and the contractor. This paper begins by outlining the issues with constructing stitch pours under live traffic by providing a summary of the past research done on widening bridge decks. Then, with the aim of alleviating the traffic restrictions, without jeopardising the quality of the concrete stitch, it describes the work done by AECOM, Leighton Contractors and Roads and Maritime Services to define a procedure to analyse, monitor and construct the stitch pours with reduced traffic restrictions.