There are lessons in Australia’s history we can learn from. One of them is the screw-up that is Sydney.

Sydney was well-placed to become the London of Australia. A prime location, settled first, the early seat of power. It had it all. But while London remains by far the wealthiest and biggest city in the UK, Sydney is on-track to be overtaken by Melbourne in population.

If Melbourne overtakes Sydney, it won’t be the first time. Sydney had a 40-year headstart and yet lost its lead in the 19th century. At that stage the reason was the Gold Rush. Sydney got its lead back when a financial crisis hit in the 1890s.

If Sydney is overtaken by Melbourne in population, you can’t blame the Sydney-siders. They work hard, but they’re behind the eight-ball. The problem is the harbour.

If you think of it as public space, it’s lovely to look at and nice to use. But if you think of it as distance, is it smart to put so much of it right in the middle of your city? Do you really want so much distance between inner-city suburbs? Wouldn’t it be better to have a network of streets?

I contend that the harbour creates a massive problem in the middle of Sydney. The CBD is unable to connect properly into adjacent suburbs because they are a ferry-ride away.

That explains articles like this: “Why is Sydney’s CBD growing slower than Melbourne’s?”

There is plenty of evidence to suggest that connectivity is absolutely crucial to how cities work. It is no coincidence that the areas best connected to lots of other productive areas are also the most productive and expensive real estate.

Sydney has more than one major business cluster. The city competes with North Sydney and Parramatta.

But I’d argue that’s a sign of weakness, not of strength. Of course every city has suburban centres, but powerhouses like New York and London aren’t confused about where might be the centre of power, or the best spot to locate a business. Sydney’s situation whispers: this city is too big to really be one functional city. But globally-speaking, Sydney is not even that big, population wise.

So, the harbour in the middle could be part of the problem. But the harbour became the centre of Sydney only when a bridge was built that made the north shore more accessible. You can see the population develop in this video and the north only really takes off after 1932, when the final rivet was painted.

The smart move would have been to densely fill in the area to the south, intensively, before building to the north.

We’ve all played computer games where you have to build certain things in a certain order. If you build too many of the wrong thing too early, you get out of whack, run out of gold and you can’t beat the game. I’d argue that’s what Sydney did.

The Bridge was built using £6.25 million of public money. That represented about 2 per cent of NSW’s GDP at the time. For comparison, 2 per cent of GDP now would be about $10 billion. (sources: 1, 2)

Despite using tolls to pay it off, the debt lingered until 1988.

The opportunity cost? Not just the proper development of contiguous land areas, but also what that money might have bought if spent differently. When the rest of the world was building world class public transport systems, Sydney let theirs go.

There is a common trope that argues the Sydney Harbour Bridge would not have passed any sort of cost-benefit analysis. This is generally used as part of an argument against cost-benefit analysis, with the assumption being that the Sydney Harbour Bridge is good. Of course it has a lot of value now, in tourism terms. But in 1932, when it opened, tourism was a rather minor part of the economy. (It’s worth noting that the Bridge was built against the advice of the government’s infrastructure adviser, which recommended a cheaper tunnel.)

If Sydney didn’t build the bridge, the city might have simply left the harbour as a boundary on the north. Of course some people would have chosen to live there still, but probably fewer. There’s plenty of space to the south that could have become very desirable had the economic centre of the city not been shifted north by the “coat-hanger”.

But building the bridge was not the end of Sydney’s attempts to link north and south. With booming northern suburbs and an incipient northern CBD, it threw good money after bad with years of very expensive ferries and then the construction of a tunnel opened in 1992. The Bridge may soon need to be replaced, due to rust.

But forget the money. I’m arguing that the bridge moved the harbour from the north to the middle of Sydney, and that hurt.

This whole argument rests on the idea – coming back into fashion – that infrastructure is “city-shaping.” That means you oughtn’t merely provide for existing demand, you should understand what you provide will shape future demand.

Bodies of water are city-shaping. They are often part of cities because of the history of water transport, but now hurt urban connectivity. For example, Oakland remains the very poor cousin of San Francisco.

Even rivers seem to have an impact.

London has lots of bridges but the wealth and the productivity is overwhelmingly on one side of the Thames. It required Manhattan house prices to reach many millions before Brooklyn got any buzz, and Shanghai only developed the far side of the Huangpu in the last 20 years.

By this logic, curvy rivers would be especially bad because they divide the city more. In that respect, Tokyo is better off than Brisbane, because the Sumida River flies like an arrow compared to the meandering Brisbane River. (There is evidence that a single bridge built in Brisbane recently has had a big influence on where people live.)

I’d be very interested to see a meta-analysis of whether, in the last 50 years, the value of having a river has turned from positive to negative in terms of a city’s economic growth. The impediments a big river would create to city connectivity are likely to be significant, especially where bridges are in short supply.

All this is very interesting, but we can’t go back and unbuild the Sydney Harbour Bridge. So what’s the point?

The point is we can learn a valuable lesson. Don’t spend valuable taxpayer resources providing infrastructure that will “shape” your city in the wrong way.

Infrastructure is extremely durable. Every mis-spent dollar will spend centuries choking your city. If it accidentally facilitates growth in hard-to-access places, or encourages inefficient kinds of transport use, infrastructure spending can be the enemy of a good city.