Automated transport systems/Light, shared urban vehicles
Imagine a city with clean air free of the noise of engines, where you can get from anywhere to anywhere at 50mph (80km/h) or more, without any danger of death, where the problems of traffic and parking are fully solved. This is entirely feasible with technology that has been around for many years; all we must do is eliminate the gross inefficiencies inherent in using private cars for urban commutes.
Small, light, vehicles
If you look at the cars choking up city streets at rush hour, you will notice that over 75% of them are carrying only one passenger. Yet that one passenger is using a vehicle over 3m long and 1.5m wide and weighing over 1000kg. To travel, you really only need something the size and weight of a bicycle; to travel in luxury you need something about the size of an armchair. If we reduce the amount of road-space these people take up from a car-footprint to an armchair-footprint, we increase the capacity of the roads four or five times. This in itself would almost entirely eliminate traffic congestion. If these small vehicles are driven by sophisticated AI capable of driving close together at speed, safely weaving in and out of other moving vehicles, then congestion will certainly be a thing of the past. This would allow vehicles to move around cities at, say, 50mph (80km/h). By comparison, the average speed around London is just 12mph (19km/h) 
Cars are designed to be able to travel hundreds of miles carrying five people and a full boot. However, they are used for such road trips only rarely; the majority of trips they make are short commutes. For example, 77% of Americans drive cars to work with no passengers . This represents a huge waste of energy and space and causes the aggravation of parking and traffic - which are a huge waste of time. We can reclaim this if we make these short urban commutes in vehicles like:
- 3D printing could greatly reduce that. . Velomobiles are recumbent bicycles enclosed in an aerodynamic shell. They are more comfortable than bicycles, require less effort, and keep rain off the passenger - solving all the main drawbacks of cycling. The main obstacle to adopting velomobiles thus far has been the expense of crafting the shell. However,
- - bicycles assisted by electric motors.
- Electric scooters like RoboScooter
- Tiny electric cars or enclosed electric motorcycles built for one or two passengers, such as the Audi Snook or the MIT City Car.
Vehicle sharing schemes
Cars spend 96% of their time parked. That is to say, they spend 96% of their time wasting space. We can decrease this amount of time to perhaps 50% if we share vehicles so that when one person parks a vehicle, another person can come along and use it. This can be done either by leaving the vehicle at a shared dock, or, if this is not convenient, having a wireless transmitter that allows people to pinpoint the nearest vehicle to them using a smartphone. (And these are small vehicles; parking needs can be reduced from the footprint of a car 96% of the time, to the footprint of a bike 50% of the time).
Many cities already have winner of the 2009 Buckminster Fuller challenge was a proposal for a fleet of shared small electric cars and electric scooters which would be docked at points around a city (where their batteries charge). There are plans to bring this in for several cities and commercialization is planned for late 2012 .and there is no reason the same model cannot be extended to other light, urban vehicles. The
The bicycle sharing scheme in Lyon achieves 10-15 uses per bicycle per day, while in Paris the bikes are taken out 8-10 times per day. Compared to privately-owned cars, which are used perhaps 3 times a day, this is much less wasteful of space and of vehicles themselves.
(A rather more futuristic extension of this idea is also possible — rather than going to pick up a parked vehicle, what if you use your phone to get it to come to you? This would be possible with current autonomous vehicle technology.)