Concession 3 Bridge Rehabilitation

Client: Township of Uxbridge
Services: Detailed Design, Site Inspection and Construction Administration

Key Features:
  • Design of a new timber-concrete composite deck
  • Partial replacement of one abutment pile due to rot

The Township of Uxbridge retained Chisholm, Fleming and Associates (CFA) to complete a timber investigation on the Concession Road 3 Bridge. The timber investigation included testing of the exposed portions of the timber piles, pile caps and the timber elements of the composite deck for decay. The timber elements were inspected using a combination of visual inspection, sounding, coring and boring.

The results of the timber investigation indicated that the timber piles, caps and deck timbers were in generally good condition. With the exception of one pile at the north abutment which exhibited a decay pocket in the centre of the pile extending from the waterline to the top of the pile. It was also noted that the deck appeared to sag between supports and that the spacing of the butt joints in the timber portion of the deck did not meet the requirements of the Canadian Highway Bridge Design Code (CHBDC). It was recommended that the decayed pile be repaired and that the deck be replaced.

A preliminary life-cycle cost analysis was completed to compare the net present value of rehabilitating the existing structure, or constructing a new bridge on the same alignment. It was determined that rehabilitation of the structure is the preferred alternative.

In order to correct the deficiencies found during the timber investigation of the bridge a new timber/concrete composite deck was designed that meets the requirements of the CHBDC, a portion of the deteriorated pile at the north abutment was replaced and new thrie beam guide rail was installed across the structure.