The proposal suggests suspending two diaphragm beams under the main arch section in order to support the "clip-on" lanes that run along both sides of the structure. A load-sharing mechanism would enable the main bridge to support part of the peak loads on the clip-ons.

The addition of walking and cycling lanes was rejected last year by New Zealand's Transport Agency for fears of reducing the life of the clip-ons, which are about 30 years old. Strengthening of the box girders that support them began a year ago.