Road congestion: the stark reality

Few would disagree that roads in Australian major urban areas are becoming increasingly congested, especially in peak periods. The peaks are also getting longer, so that it is becoming less easy to avoid the peaks by leaving earlier or later.

Looking around the world, we can see that congestion is likely to continue to worsen, and that what we consider to be serious congestion is still much less than is experienced in many other major cities. With population growth and increasing expectations of mobility, congestion will increase. Building roads and public transport systems has not kept pace with growth for many years, and is unlikely to in the future.

UK and US studies indicate that about one third of congestion is due to accidents, road works, and other temporary situations. The remainder is “recurring” congestion and occurs because there is not enough road capacity to accommodate demand.

So, what do we do about it?

Obviously, one possibility is to do nothing. However, this will result in an increasing waste of resources and time as congestion gets progressively worse and cars and trucks spend larger amounts of time in stop and go traffic. Most politicians favour improving public transport as the solution. Unquestionably, improving public transport is a necessary step in combating congestion. Even though public transport carries a minority of travellers, it is important to maintain or increase public transport’s market share as much as possible.

At the same time, we must be realistic about what public transport can do. In Sydney, public transport carries about 10 per cent of all daily travel, and about 20 per cent of commuting travel. The public transport system currently has little spare capacity.

The Sydney region is growing by around 1 per cent a year. With total public transport ridership being about 1.65 million trips a day, this means that, to keep pace with growth, public transport must accommodate 16,500 more rides each year. Roughly half of Sydney public transport users ride buses, and half ride trains.

On average, a bus in the peak period carries 36 passengers, and a train carries 850 passengers. If we split the increase equally between bus and train, then each year, we must add at least 230 new bus trips and around ten more train trips throughout each day, assuming these peak loadings. Most of these have to be added in the peak periods, where we already have congestion on both the road and rail system.

In the morning peak, Sydney public transport carries about half a million riders, so that one third of this increase has to be accommodated in the morning peak - about 80 new bus trips a year and 3 more train trips each year. In the meantime, car traffic has also grown by 1 per cent each year, so that road congestion continues to worsen.

In the morning peak period about 1.75 million cars are used and this is increasing by 17,500 each year from population growth. Using current figures, these extra cars carry about 24,600 people.

If we accommodated these on public transport, so that the number of cars stayed the same as today, then public transport ridership must grow by 1 per cent each year to accommodate growth, plus at least another 24,600 riders each year on top of that in the morning peak alone. This increase is three times as big as the natural growth increase that public transport needs to carry.

Second, using the same assumptions as before, this means another 342 bus trips and 15 train trips are needed in the morning peak, assuming that each bus and train carries this peak load. This means that 422 bus trips and 25 train trips are being added in the morning peak each day, just to accommodate growth and keep congestion from getting any worse. Actually, road congestion will get marginally worse, because extra bus trips are added to an already congested road system, and each bus causes about the same congestion as 2.5 cars, so it will be similar to adding 1,000 cars.