This work was for a concept design of a pedestrian bridge crossing over the Whakatane River. The pedestrian bridge was proposed for connecting to the southern bank immediately adjacent to the existing Whakatane Gardens and Outdoor Amphitheater (both on the southern bank).
The Whakatane River Pedestrian Bridge consists of a main span cable stayed bridge crossing over the river channel and a low-level crossing (e.g. boardwalk or bund) through the existing southern wetland. In attempting to connect Bunyan Road with the route, the scheme also included a small crossing over Orini Stream.
The bridge is intended to link the Coastland Peninsular with the central business district (CBD) of Whakatane (to the southeast of the image below). The client is particularly interested in connecting the future residential, rest-home, and marina developments planned along Bunyan Road with the CBD. On the CBD side of the crossing, the route will connect with the existing Warren Cole shared path in the south. This route is consistent with routes considered in a Business Case being prepared by WSP Opus on behalf of NZTA which considers cycle routes in and around the wider Bay of Plenty region.
The Whakatane River crossing consists of a main structure crossing over the river channel and a low-level crossing (e.g. boardwalk or bund) through the existing southern wetland. In attempting to connect Bunyan Road with the route, the scheme will also need to traverse the Orini Stream.
Below is a summary of some of the workshops used in reaching a consensus on concepts. This is intended to provide the reading some insight into “how” bridge options are considered and selected.
Pedestrian Bridge Concept Workshop (May 2018)
A small concept study for the bridge crossing was carried out in May 2018. The study considered two potential routes and three bridge forms.
Bridge forms considered were:
- Medium (60m) cable-stay bridge in combination with back-spans;
- Long span (125m) suspension bridge;
Routes considered were:
- A route perpendicular to the existing amphitheater on the southern bank (this is the route confirmed on site with the client);
- An alternative route 400m further west that would enable the use of the existing grass banks instead of needing the boardwalk structure. Less direct but potentially cheaper.
The cable stayed option along a route perpendicular to the amphitheatre was selected as the preferred solution.
Pedestrian Bridge Concept Workshop (July 2018)
Following on from the initial concept workshop, the options were slightly modified. Two competing options were progressed in parallel to concept development and costing. Both options followed the route perpendicular to the amphitheater selected in the concept workshop. The updated options were developed on the basis that a temporary bund/causeway can only be used to a depth of circa 1m and hence the use of a back-span to the cable stay bridge would be limited to a single 18m back-span with the remainder requiring a longer span cable stay structure built in situ. The other construction approach would be to use barge access for all construction and this would enable a more conventional multi-span bridge option.
The two options were presented to Whakatane District council (WDC) and Bay of Plenty Regional Council (BoPRC) in July 2018. These concepts were discussed in detail and were as follows:
- Option 1: Multi-span glulam beam bridge (7No. 18m spans) all built using barges circa $4.0M build cost;
- Option 2: Long-span architectural Cable Stay bridge that can be built from the northern bank. A small bund to a maximum depth of 1m has been used on the south for a small 18m back-span circa $4.8M build cost.
Preferred Pedestrian Bridge Concept
During the July 2018 concept workshop is was agreed by all that the cable stay concept was the preferred approach for the following reasons:
- Less impact on the riverbed;
- Less river obstructions that lead to flood debris accumulation and flood level rise;
- More architectural merit for encouraging cycling and tourism for Whakatane;
Recommendations were made for increased flood envelopes, increased boardwalk width, single mast design, and sinuous rip-rap to northern bank during the workshop.
Next Steps
Cost of Pedestrian Bridge
The overall cost of the pedestrian bridge project was estimated to cost $3.5M (in 2018). This was based on pricing provided by a respected bridge building contractor familiar to building pedestrian bridges in the Bay of Plenty region.
Project Status
The Whakatane River Pedestrian Bridge was put forward for provincial growth funding (PGF) in late 2018. It was unsuccessful in qualifying/receiving PGF allocations and instead will become part of the longer-term cycleway plans likely to be considered further in 2022.
