Emissions can be further cut through changes in maintenance and operating practices. Many vehicles are not adequately maintained due to high costs or to the limited local availability of spare parts. In some areas, maintenance may simply be a low priority for drivers and vehicle owners. Policies to reduce road traffic congestion can save both emissions and costs . The energy intensity of transport and the amount of congestion on the roads are strongly influenced by the average occupancy rate for passenger vehicles.
Urban planners can encourage low-emissions transport.
A vital part of encouraging this transition is providing safe and efficient public transport systems. The introduction of computerized traffic-light control systems, more informative signs, and improved network designs, especially in urban areas with a high density of vehicles during peak travel hours, can also boost efficiency. In the short term, the greatest potential that urban planning has for affecting transport is in rapidly developing cities where cars are still in limited use. Policies to reduce air traffic congestion can cut emissions while improving safety. Present flight patterns seek to reduce fuel consumption and other in-flight costs.