Main benefits

Cheaper to build and operate

Estimated construction costs are between $2.5 billion and $3.0 billion, compared with the estimated cost of between $3.7 and $4.1 billion for the tunnel option.

Once constructed, operating costs are three to five times less for bridges than tunnels, due to savings on ventilation, lighting, drainage, and maintenance.

Greater carrying capacity

The bridge would respond to increased demand for carrying capacity in the future through scalable design, meaning the bridge would be constructed with space for further lanes to be added, should they be needed.

The configuration of the bridge would be flexible. A movable median barrier, similar to that used on the existing bridge, could be installed to manage tidal flows in peak direction.

Wider economic benefits

The bridge would produce a number of other wider benefits that are not evident with a tunnel:

• Tourism – an extra $325 million per year in revenue
• Real estate – approximately 350,000 square metres of prime waterfront real estate would be released along the St Mary’s Bay and Northcote Point foreshores. That land could be used for the development of recreational, residential, or commercial spaces
• Transport savings – the bridge’s more direct cross-harbour route would result in travel time and distance savings of around $30 million per year (in comparison with a tunnel). A tunnel would also provide a shorter route, but less traffic would enjoy the benefits. Trucks may be required to travel on the old bridge, due to restrictions on transportation of hazardous goods in tunnels

Environmental and social benefits

The bridge’s shorter cross-harbour route would reduce airborne vehicle emissions by 10,000 tonnes annually; a tunnel would reduce emissions by less than one-third that amount. Removing redundant motorway stretches would significantly reduce the aquatic contamination caused by copper, zinc, oil, and other vehicle run-off.

While a tunnel would concentrate its air pollutants in waterfront areas – in particular, the Wynyard Quarter – the new bridge would disperse vehicle emissions evenly and away from the waterfront and populated areas.

The bridge would offer a number of health and wellness benefits, providing the population with resources for exercise and recreation, and providing a means to engage with the city’s cultural and natural environment.