This photo is not a fake, although several people on Facebook seem desperate to believe it is. In 1974, the Government responded to a bus strike in Auckland by closing to cars one of the harbour bridge clip-ons. On July 4, many people on the North Shore walked to their jobs in town and some rode their bicycles. Even though it rained, as the photo shows.
Could we do that again? Transport analyst Richard Young says he's looked at hourly traffic data on the bridge for the last nine years and he thinks we could. This is for two reasons.
The first is that, despite massive population growth on the Shore, there has not been a massive growth in the number of vehicles on the bridge. In fact, since 2008 it's hardly grown at all. The reason is mass transit: the Northern Busway. About 1000 buses cross the bridge every week day and, in normal non-Covid times, they carry about 40 per cent of morning peak commuters. The dedicated busway has just been extended to Albany, which means that number will rise.
The second reason concerns a phenomenon that occurs when you increase or reduce the road capacity. If you increase it, you get "induced demand": having more motorway lanes encourages more driving. This is the reason those extra lanes near Papakura are already full. The reverse is also true: when you reduce the available road space, demand reduces too. Some of the traffic disappears. People catch the bus, take another route, drive at a different time of day or just stay home.
Induced and reduced demand were first identified in America in the 1930s and have been repeatedly measured all over the world ever since. Including on bridges that used to carry only vehicles and now allow bikes and walking too.
We've known it for close on 100 years, although the "more roads" dinosaurs deny it to this day. Just last month, in a story headlined "Gridlock nightmare", the AA called for more roads because the focus on public transport "wasn't working". It's working very well, as that Northern Busway data shows. And when the City Rail Link opens, it will double the city's rail capacity, adding the equivalent of 16 lanes of motorway traffic at peak times.
