Cities are locations having a high

Cities are locations having a high level of accumulation and concentration of economic activities and are complex spatial structures that are supported by transport systems. The most important transport problems are often related to urban areas and take place when transport systems, for a variety of reasons, cannot satisfy the numerous requirements of urban mobility. Urban productivity is highly dependent on the efficiency of its transport system to move labor, consumers and freight between multiple origins and destinations. Some problems are ancient, like congestion (which plagued cities such as Rome), and others are new like urban freight distribution or environmental impacts, notably CO2(или3) emissions linked with the diffusion of the internal combustion engine. Among the most notable urban transport problems are:
• Traffic congestion and parking difficulties. Congestion is one of the most prevalent transport problems in large urban agglomerations. It is particularly linked with the diffusion of the automobile, which increases the demand for transport infrastructures that has often not been able to keep up with the growth of mobility.
• Public transport inadequacy. Many public transit systems, or parts of them, are either over or under used. During peak hours, crowdedness creates discomfort for users, while low ridership makes many services financially unsustainable, particularly in suburban areas.
• Difficulties for pedestrians. These difficulties are either the outcome of intense traffic, where the mobility of pedestrians and vehicles are impaired, but also because of a blatant lack of consideration for pedestrians in the physical design of facilities.
• Loss of public space. The majority of roads are publicly owned and free of access. Increased traffic has adverse impacts on public activities which once crowded the streets such as markets, agoras, parades and processions, games, and community interactions. These have gradually disappeared to be replaced by automobiles. In many cases, these activities have shifted to shopping malls while in other cases, they have been abandoned altogether. Traffic flows influence the life and interactions of residents and their usage of street space. More traffic impedes social interactions and street activities. People tend to walk and cycle less when traffic is high.
• Environmental impacts and energy consumption. Pollution, including noise, generated by circulation has become a serious impediment to the quality of life and even the health of urban populations. Further, energy consumption by urban transportation has dramatically increased and so the dependency on petroleum.
• Accidents and safety. Growing traffic in urban areas is linked with a growing number of accidents and fatalities, especially in developing countries. As traffic increases, people feel less safe to use the streets.
• Land consumption. Between 30 and 60% of a metropolitan area may be devoted to transportation, an outcome of the over-reliance on some forms of urban transportation.
• Freight distribution. The materialization of the economy has produced growing quantities of freight moving within metropolitan areas. As freight traffic commonly shares infrastructures with the passengers’ circulation, the mobility of freight in urban areas has become increasingly problematic. City logistics strategies can be established to mitigate this problem.