I walked over the southbound clip on in 1970-something?........the Maori land march was an opportunity at the time for many to cross. My intermediate school teacher took the opportunity and our class did the walk.
My recollection of that day was the walk being stopped at the top of the bridge as the clip-on swayed visually, accompanied by loud creaking. As a lad I was very scared.
The bridge was built in the UK by Dorman Longs, assembled on a field, then broken down and shipped to NZ-my grandfather helped in its construction! Originally the bridge was designed as having an extra four lanes but the NZ government in its stupidity decided to cut costs and remove four lanes. As a result the centre section of the bridge is arguably overbuilt and certainly solidly. The clip-ons are another story. Not long after, realising the bridge could not cope with traffic volumes the Japanese built the 'nippon clip-ons'. Cleverly designed and executed the clip-ons used a higher tensile steel to provide extra lanes without excessive weight. Unfortunately for at least the last 20 years the surface of the clip-ons have buckled and cracked. Ongoing maintenance has seen many efforts to fix the problem with limited results.
The centre span is safe, could last a very long time given maintenance and technological modifications. The clip-ons are questionable at best. The authorities are aware of the clip-ons short comings hence the various attempts to limit vehicle weight and flow.
In regards to pedestrian access: slinging a lane under the main span is the best and only 'real' option. Placing pedestrian access on, in, or attached to a clip-on is never going to happen. 'Marching' [as I found out on the Maori land march] results in the creation of harmonic frequencies that destroy bridges-this is widely known!.......and while having a few people cycle or walk the bridge everyday, the creation of a 'bridge run' [like round the bays] would be a real danger to the bridges destruction.
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