It's not technology that will determine the shape of land transport so much as political,

economic and environmental considerations. We can build stronger, quieter roads with better skid resistance now, but we don't because of the cost.

The environmental lobby has had a huge impact on car manufacturers and emission control has improved a lot. But there's still some way to go on the air pollution front, particularly for lorries which run on diesel fuel, which is bad because of its particulate emission when it is burnt.

Cars and lorries could be driven by electric motors if fuel-cells, which convert fuel into electricity without burning it, can be made more efficient. However, they've been advertised for a generation and have never really met expectations. American domination of the automotive industry makes rapid progress unlikely. Because the cost of gasoline is so low in the States, there's not much incentive to develop fuel cells and electric vehicles for widespread use.

When it comes to communication, we already have Trafficmaster, which operates from transducers on motorway bridges to gauge the speed of the traffic and warn of blockages ahead. We also have global navigation satellites that can pinpoint your position. The challenge is to provide a full driver guidance system that can tell you the best direction to go in a way you can absorb at the wheel.

The next big step in transport technology will be automated roads: regulating vehicles in convoys on motorways so that they're safer and can be packed closer together. Sensors would establish what is around each vehicle and electronic control systems would keep them moving in the right direction, at the right safe speed, with maximum comfort and economy. The technology is massively expensive now, but eventually it will become a reality. You would just pay a toll, couple your car into an electronic convoy and sit back to enjoy the journey.

Motorways will gradually become more like railways, with freight vehicles electronically coupled in trains running at relatively high speeds. At suitable intervals, they would uncouple to travel the remainder of the journey with their own driver. That's almost certainly going to happen. In Adelaide there are already buses that run on an automated route for part of their journey.

That sort of combination if personal and centralized control is the direction we're going in road transport, probably first of all for freight. Any rail system has in the end to be inflexible, it doesn't go where you want, especially in rural communities, where the nearest station can be 30 miles away. We're wedded to private cars, because of their flexibility and the pride people take in ownership -- not to mention the huge sums we've spent on the road network.

So cars aren't going to go away. But under electronic control 'they will become greener and safer. In 50 years driving your own car on a fast motorway, mixed up with lorries, and passing at a closing speed of 150 mph within a few metres of people driving other vehicles in the opposite direction will seem. completely insanity.

The word "absorb" in Paragraph 4 means ______.

A．drive

B．suck in

C．acquire

D．run