For years, electric cars have been struggling to build momentum in large cities.

Except in Oslo, where 5,000 electric vehicles can be seen cruising around the Norwegian capital - an impressive number given that the city's metropolitan area has just 1.2 million people.

This achievement, however, is not a result only of an increased ecological awareness of the local population. It also took an efficient set of incentives, from tax and road-toll exemptions and free parking, to free access to bus lanes. Some 400 free recharging stations were also deployed for car owners.

The city's administration is also aiming to convert most of its municipal fleet of 1,000 vehicles to electricity by 2015.

Oslo's green-transport efforts have made Norway the leading European market for electric vehicles, which now account for 5 per cent of the country's vehicle registrations. It shows that it will take a combined effort by individuals, corporations and governments, if the world is to clean up its transport systems.

This is important because making transportation systems sustainable and reducing their impact on the environment is a critical part of reducing the world's greenhouse gas emissions, which are widely blamed for climate change and global warming.

"Any serious attempt to deal with climate change must involve transport," notes a 2008 report by the Organisation for Economic Cooperation and Development. "A look at CO2 emissions - from only fuel combustion - shows the transport sector accounts for about 23 per cent worldwide."

Without a serious mitigation effort, the organisation warns, transport-related CO2 emissions will increase another 58 per cent by 2030.

Better technology should improve the efficiency of vehicles and see the emergence of more low-emission vehicles, propelled by electricity, hydrogen and biofuels.

But a concerted effort is needed by national governments, city administrations and planners to improve sustainable mobility, especially in urban settings.

This could mean the development of better public transportation and innovative sharing systems that are better adapted to the population's needs.

Trams, for instance, are returning to the streets of many large cities, along with bike sharing and self-service car-sharing systems.

One example of a small revolution that is under way is the return of car-pooling, which had its heyday in Europe and America during the 1970s oil crisis.

Today, Web-based communication tools have helped make car-pooling popular again.

Online services could also help turn drivers to public transport: Motorists can get messages on their smartphones about available parking at the nearest train station, as well as the departure times of the next trains - encouraging them to avoid entering already-congested urban centres.

And finally, some cities are going back to basics - walking and cycling.

These are promoted through low-tech mobility policies, such as the development of bike lanes, wider sidewalks and pedestrian zones. To encourage walking, some cities have even installed street signs with time and distance by foot to various destinations.