Agenda Index City of Vancouver

ADMINISTRATIVE REPORT

TO:

Standing Committee on Transportation and Traffic

FROM:

General Manager of Engineering Services

SUBJECT:

Prospect Point Bridge

 

RECOMMENDATION

CONSIDERATION

GENERAL MANAGER OF ENGINEERING SERVICES' COMMENTS:

GENERAL MANAGER OF PARKS AND RECREATIONS’ COMMENTS:


PURPOSE

The purpose of this report is to recommend the replacement of the Prospect Point Bridge.

BACKGROUND

On March 27, 2000, the Vancouver Heritage Commission proposed that the Prospect Point Bridge is of significance and part of the heritage context of the Causeway and Lions Gate Bridge. On May 1, 2000, at a meeting of the VHC, it was resolved that the Vancouver Heritage Commission believe the Prospect Point Bridge can be retained and meet the design criteria for the widening of the Stanley Park Causeway. Further, the Vancouver Heritage Commission recommended that John Bryson and Partners be retained by BC Transportation Financing Authority (BCTFA) to work with ND Lea to develop conceptual designs and comparative order of magnitude cost estimates for the following two options:

    1. Conservation option: to lower the roadway by as much as 800 mm and leave the Prospect Point Bridge and abutments in place, to tunnel through the abutments to accommodate sidewalks and to install retaining walls as required;

The two options are illustrated in APPENDIX A.

Mr. John Bryson of John Bryson & Partners, Structural Engineers, was retained by BCTFAat the request of the Vancouver Heritage Commission, to investigate the options of conserving and replacing the Bridge. In the abbreviated time frame Mr. Bryson had to review the two options, the following are his cost estimates for the different options:

Mr. Brysons’ estimates indicate that the option to keep the existing structure, lower the road 800 mm and bore tunnels for pedestrians and cyclists would cost approximately twice as much as to replace the entire structure.

On May 16, 2000, Council had before it a memorandum dated May 15, 2000 from the Chair of the Vancouver Heritage Commission providing Council with information on the Commission’s position that the Prospect Point Bridge should be saved. The following motions were resolved by Council:

1. THAT Vancouver City Council support in principle the retention of the Prospect Point Bridge.
2. THAT the City enter into discussions with the Board of Parks and Recreation and with the Province to explore options for retaining the Prospect Point Bridge.
3. THAT the additional cost of approximately $1.5 - 1.9 million to retain the Prospect Point Bridge be borne by the Province.
4. THAT, in the event the Prospect Point Bridge cannot be saved, Council would like the visual impacts of the existing bridge maintained in the design and construction of a new bridge.

The Prospect Point overpass is currently owned and maintained by the Provincial Government. BCTFA staff have indicated that there is no additional money available in the budget to retain this structure and that if desired, the City can fund the additional cost of preserving the bridge.

DISCUSSION

Changes to the Lions Gate Bridge and Stanley Park Causeway necessitate the replacementor revisions to the Prospect Point Bridge. As noted above, the estimated costs of modifying and retaining the existing structure is approximately twice the cost of replacing the Bridge. For this, as well as safety, environmental and construction reasons, both Engineering and Park Board Staff do not recommend retaining the existing Prospect Point Bridge.

With the option of retaining the structure and boring tunnels, staff have concerns regarding the safety of pedestrians and cyclists in the tunnels. This area of the causeway is removed and secluded from other more populated areas of the Park. With tunnels, pedestrians and cyclists would not be visible to the vehicle traffic and the design is not in keeping with CPTED design principles.
Figure 1: Existing Prospect Point Bridge
The addition of the pedestrian and cyclist tunnels on either side of the bridge would result in a number of trees having to be removed. One of the objectives of the Causeway Project related to the Lions Gate Bridge upgrade has been to minimize the changes to the Stanley Park landscape. The approved minimal widening and related loss of trees was a major issue for the Park Board.

The proposal to maintain the overpass would entail bank upgrading and retaining wall placement for approximately 55 metres on both sides of the overpass. This would result in the loss of up to 30 mature trees, nearly double the loss for the Causeway Project to date.

Park Board staff do not feel that the retention of the current overpass, as advocated by the Heritage Commission justifies the resultant damage to the Park and recommend against it.

Finally, from a construction management perspective, retaining the existing structure while either lowering the road or raising the structure, will impact the construction schedule morethan replacing the overpass. One of the greatest challenges of the Lions Gate Project has been to replace the bridge and causeway while limiting the impacts on the approximately 60,000 vehicles that use this route each day. Lowering the roadway or raising the existing structure will impact traffic more than replacing the overpass with a precast structure.

CONCLUSION

While it is recognized that this bridge is an historic object, conditions dictate that a replacement is the most logical option. However a major focus of the replacement design should be to retain the original bridge’s intent to frame the views on the Lions Gate Bridge.

NOTE FROM CLERK: Appendix A and B not available in electronic form - on file in the Office of the City Clerk.

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