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What are the costs and benefits of new road transport technology?
Technology is transforming every sector of society – and road transport is no exception.
It seems that every day we hear new, breathless predictions about how driverless vehicles are going to disrupt the conventional motor vehicle and dramatically reshape the way we move around on our roads.
It is not hard to believe that in fifty years – perhaps even in twenty years – the vehicles we use will be very different.
A much harder question – for both governments and the private sector – is what we do in the next year, two years or ten years.
For example, some predict that the arrival of driverless vehicles will free up large amounts of road capacity, as vehicles no longer need to be left parked by the sides of roads and hence curbside lanes will become available for through traffic. Others predict that driverless vehicles will be used much more intensively than today’s vehicles, meaning we will need more road capacity.
How should governments make decisions today about investing in additional road capacity, in view of this uncertainty?
The Australian Government in 2017-18 plans to spend over $8 billion on transport infrastructure around the country, much of that being investment in new or upgraded roads. State governments spend many billions more.
A key tool used by governments at all levels in making such spending decisions is the ‘benefit cost ratio.’ This is the ratio of the total benefits from investing in a new road – such as reduced travel times and reduced accidents – to the total cost of the project.
Recently the Australian Government’s Bureau of Infrastructure, Transport and Regional Economics (BITRE) issued an important research report which looked at the benefit cost ratios of the various new technologies affecting motor vehicles and road transport which are either available today, or which are expected to be available in coming years.
BITRE looked at three classes of technology. The first was intelligent transport systems. Increasingly used on Australian motorways, these are systems which use information technology to help control the flow of traffic, for example by putting traffic signals on motorway on-ramps. By timing the entry of vehicles to fit into gaps in the traffic, these systems can improve traffic flow along the motorway.
The second was the use of wireless communications between vehicles and either other vehicles (V2V) or a central control point for the road network (V2I), to support various applications which improve safety and network operation. For example, a vehicle which senses a collision can send a warning to the vehicles travelling behind it; a vehicle turning across traffic (making a right hand turn) can send a signal to vehicles travelling towards it.
The third class of technology BITRE looked at was the introduction of automated vehicles, at various levels. (The Society of Automotive Engineers defines 5 levels, from driver assistance at level 1 to full automation at level 5.)
BITRE found that benefit cost ratios for some kinds of intelligent transport systems – such as ramp metering – can be above 10. This is an extremely high number for a transport investment, and means that for every dollar invested in a ramp metering system, the benefit exceeds $10. That makes it a pretty good use of taxpayers’ money!
Applications using V2V or V2I communications also appear to offer high BCRs, at least in densely populated urban areas, with one European study of ‘co-operative intelligent transport systems’ finding a BCR of 2.9 on urban roads.
As for automated vehicle technology, again the BCR of particular applications seems to be high: for autonomous emergency braking systems, up to 4.1 and for and lane departure warning systems, up to 3.3.
Estimating the impact of our entire transport system switching over to fully automated vehicles is much more challenging, but again early estimates suggest potentially very significant benefits. These however are sensitive to key assumptions – such as whether a world of automated vehicles will see less road usage or more road usage.
There are lots of predictions about the future of motor vehicles and road transport. But it can be hard to get a clear understanding of what these changes will cost – and what benefits we will get. The BITRE paper does a good job of explaining the issues – and providing credible estimates of what the numbers are. If you want more detail, you can find the paper here.