We’re running out of road in Sydney, so think twice about that new car

The still unfolding Rozelle spaghetti junction fiasco is the latest sign our road system is not managing to keep up with the growth in traffic. There are three main reasons for this, which motorists may ponder on as they spend increasing amounts of time in gridlock. The first is the growth in the number of motor vehicles.

There were 21. 2 million registered motor vehicles in Australia at the end of January, according to the Bureau of Infrastructure and Transport Research Economics . This number is growing by almost half a million per year.

Cars trying to get onto the Anzac Bridge during peak hour. Credit: Kate Geraghty In NSW, there are 6. 2 million motor vehicles.

Since 2001, the growth in the number of registered vehicles has been about 2. 4 per cent per annum, which is faster than the population increase. Recently, NSW has been adding more than 100,000 new vehicles every year including 1500 campervans; 7500 trucks; 500 buses; and 6000 motorcycles.

So our roads are becoming more crowded. We are also driving more. Since 1971 , we have driven over 2.

2 per cent more kilometres per year than the one before. Australia-wide this totals 240 billion kilometres a year. In NSW, we drive about 70 billion kilometres per year, more than half of that in Sydney alone.

The third reason is the real kicker. The total length of the roads we drive on is not growing at anywhere near the rate of growth in the number of vehicles or the rate of growth in the number of kilometres we drive. Between 2010 and 2018, the amount of urban highway added in NSW was less than 50 kilometres, about six kilometres a year.

The total length of all NSW urban roads increased by about 230 kilometres a year. The growth rate of road length is about a tenth of 1 per cent a year. The story is as bad if we examine the length of carriageway, a figure which allows for multi-lane roads.

A crude calculation shows that in Australia in 1982 there were 200 metres of carriageway per vehicle. This had halved to less than 100 metres by 2015. There is no reason to expect this shrinkage in road space per vehicle will have done anything but decline in the period since 2015.

In NSW, the length of lane per vehicle is less than 80 metres and just 40 metres if we only include paved roads. In 1982 there were 200 metres of carriageway per vehicle. This had halved to less than 100 metres by 2015.

A corollary to all this is the road safety issue. Authorities recommend leaving a three-second gap between vehicles. It is easy to work out that under the three-second rule, the maximum number of cars one carriageway can carry in an hour is 1200 regardless of speed.

That makes us safer but exacerbates the problem and extends the length of time drivers wait in gridlock. This all suggests we cannot keep ahead of traffic congestion by building more roads. Doing what we have been doing – throwing ever-larger amounts of money at our road system – is not an answer to our transport chaos.

Most solutions are well known and have been canvassed widely. Some, our politicians are toying with. They include improving the public transport network and reducing road travel demand by providing well-located housing.

New housing developments need to be provided with appropriate infrastructure before residents move in. At the moment, people are forced into their cars to do just about anything. Shops, jobs and schools are not close and two cars per family are often a necessity.

City congestion charges and time of day tolling work overseas, and if we have technology good enough to detect mobile phone use it cannot be hard to charge higher tolls for cars with a single occupant. At a federal level, net immigration should not get ahead of infrastructure. Successive governments, federal and state, need to share the blame for this situation.

Unfortunately, we have not been blessed with politicians who have a good grasp of the future, and laying blame does not yield a solution. Adding in hyper-partisan politics means there may be no way to form a consensus that will get us out of this traffic mess. What hasn’t been widely discussed is simply to cease funding new roads, allow the road network to congest further and at the same time invest heavily in public transport.

It is probably cheaper to make public transport free than to build new roads. Real solutions to this dilemma appear to be long term and painful. That is something for motorists to ponder as they face that merge from three lanes into one.

Greg Baker is an author, freelance writer and research specialist. Get a weekly wrap of views that will challenge, champion and inform your own. Sign up for our Opinion newsletter .

.