We read today of a future of driverless transport with a mixture of excitement and foreboding.
Excitement, because it offers the prospect of fewer accidents, fewer injuries and fatalities, fewer cars parked on city streets, fewer cars everywhere.
For along with driverless cars we will get the ability to use them more efficiently, ordering them with a phone app rather than owning one that is parked somewhere most of the time. They will drive closer together at permitted speeds, co-ordinating their movements more safely than human drivers can manage.
But there can be foreboding, too, at the idea of travelling in a car driving and navigating itself without your help.
Aeroplanes have been doing this for decades but we still want pilots in the cockpit and they are needed.
If the change is voluntary and gradual, driverless cars will be sharing the road with cars under human control.
The Ministry of Transport is already looking at the implications of a technology that could be here in a few years and car manufacturers are trialling them now.
They may be beaten by the ICT industry. Google reckons it will have a fully autonomous car on the market by 2020.
So it is not too soon to plan for their introduction and to be careful about committing public funds for roads and public transport as we know it. Nearly $40 billion is forecast to be spent on land transport over the next 10 years.
But there will be no need for road signs and traffic lights if all cars are navigating by GPS and rooftop radar to detect other vehicles and smaller objects on the road.
There may be less demand for buses and passenger rail services if commuters can just as cheaply call up a personal car to take them door to door.
Freight transport would change, too. Remote controlled vehicles could form trains for fast, long-distance travel, peeling off for door-to-door delivery without extra handling.
The possibilities are exciting but human beings do not take to all technological innovations as readily as expected.
Many enjoy driving cars and like being in control of them. Some will be slower than others to trust the technology. It is one thing to embrace a stationary tool of communication, quite another to put your life in the hands of one that is moving.
We may always demand the ability to over-ride the automatic pilot and if so, what is the law to say about collisions?
Will the human driver always be at fault? Can machines be held responsible? Would they crash the car to avoid a child? It bears thinking about and it is not too soon to start.