We are seeking feedback on the three options for the replacement of the Sutton-Mount Ross Road bridge.
The replacement bridge will be designed to meet local needs and we are aiming to have it built by mid-2019.
All options feature a single-lane bridge of pre-cast concrete (66m long), with a 65 tonne weight limit. Standard guardrails will be installed, with a higher rail along the bridge and approaches to safely contain livestock. The bridge will be 4.7m wide to allow for agricultural equipment and will include a 1.5m wide foot/cycle path.
The approaches to the bridge will be sealed and it will be higher than the original to provide better flood protection. The piers, abutments and foundations will also be designed to withstand floodwaters and minimise debris build-up. The piers will be put close to the bank to minimise disruption to the riverbed and protect fish.
Many bridges of similar design have been built throughout New Zealand. They are economic, low maintenance, safe and relatively straightforward to build.
The first design option leaves remnants of the historic bridge in place and the other two options include rebuilding the historic pillars. Any historic materials not included in the replacement may be used elsewhere in the Middlemarch area. Following initial feedback, we have not considered a replica arch or suspension bridge. This option would be more expensive, take longer to build and restrict future use of the bridge due to maximum weight limits.
Option 1 –bridge in current location, no pillars
The first option is to build the new bridge on the same alignment as the old bridge. The old abutments will be left in place, but the pillars will not be rebuilt in this option.
Option 2 –bridge in current location, pillars rebuilt in new positions
In option 2, the bridge will be built in the current location, with the pillars from the historic bridge rebuilt by a stonemason to match the original. The pillars will be rebuilt with a reinforced concrete core and foundation and will meet seismic standards. They will be placed on either side of the approaches to the bridge, which will set them further apart than in the original bridge. The braid will be put back on the pillars and connected to new anchors.
Option 3 –bridge downstream, pillars rebuilt in original place
This option shifts the new bridge downstream of the historic bridge alignment and allows for the pillars to be restored in their original location.
The costs are similar for all options, but it will cost more to rebuild the pillars. Option 3 will be the most expensive as it’s likely we will need to purchase land and more work is needed to construct the bridge approaches and connect them to the road.
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