Taniguchi et al. (1999)  defined city logistics as 'the process for totally optimizing the logistics and transport activities by private companies in urban areas while considering the traffic environment, the traffic congestion and energy consumption within the framework of a market economy'. The aim of city logistics is to globally optimize logistics systems within an urban area by considering the costs and benefits of schemes to the public as well as the private sector. Private shippers and freight carriers aim to reduce their freight costs while the public sector tries to alleviate traffic congestion and environmental problems. 
Importance of city logistics
The OECD (Organization for Economic Co-operation and Development) Working Group on Urban Freight Logistics  defines urban goods transport as the delivery of goods in urban areas, including the backflow of waste. Freight transportation of goods (both forward flows and reverse flows) is therefore a key activity within urban areas. Many large cities face significant challenges related to the congestion and pollution generated by the number of vehicles which need to travel within urban areas. These vehicles are one of the main causes of undesired environmental side-effects but their role is fundamental to the efficient functioning of Europe as they satisfy many of the transportation needs that occur on a day-to-day basis. Urban transportation includes not only the transportation of goods, but a significant proportion is attributed to the transportation of people. Within the OECD countries, in 1950, 50% of the population lived in cities, 77% in 2000 and it is expected that by 2020, this will rise to 85%. Currently, 80% of the European population lives in urban areas, while about 85% of the EU's GDP is generated in cities. The demand for urban freight transport is clearly growing, and will continue to do so. In Europe, "transport is the most problematic emitting sector, with upward emission trends". Between 1990 and 2007, CO2 emissions from transport rose by 29% in Europe. Road transport accounts for a sizable portion of CO2 transport related emissions, nearly 73% in 2000. Within road transport related CO2 emissions, urban traffic accounts for 40% of CO2 emissions, and 70% of emissions of other air pollutants. In terms of traffic congestion, in Europe, every year nearly 100 billion Euros, or 1% of the EU's GDP, are lost to the European economy as a result of this phenomenon.
In city logistics many stakeholders are involved. The four key stakeholders are:
- Shippers (manufacturers, wholesalers, retailers)
- Residents (consumers)
- Freight carriers (transporters, warehouse companies)
- Administrators (national, state, and city level)
Models are needed to quantify the consequences of city logistics initiatives.
Urban movement is a very complex system with many stakeholders, so it is difficult to quantify all the impacts of city logistics. In general three types models are necessary to predict the effects of city logistics initiatives, namely supply models, demand models, and impact models. These models interact and form an integrated modelling framework. In the following figure the model is shown.
- Urban freight transportation
- Urban passenger transportation
- Last mile
- Urban area
- Green logistics
- Urban mobility
- Two-tier city logistics system
- Single-tier city logistics system
- ↑ Taniguchi, E., Thompson R.G., and Yamada, T. (1999). Modelling city logistics. In: City Logistics I (E. Taniguchi and R.G. Thompson, eds.), Institute of Systems Science Research, Kyoto, pp. 3-37
- ↑ 2.0 2.1 2.2 Taniguchi, E., Thompson R.G., Yamada, T., and Duin, R. van (2001). City Logistics: network modelling and intelligent transport systems. Elsevier Science, Oxford
- ↑ 3.0 3.1 OECD, 2003. Delivering the goods - 21st century challenges to urban goods transport. Paris : OECD working group on urban freight logistics.
- ↑ 4.0 4.1 EUROPA Commission takes action to make urban travel greener, better organised and more user-friendly . [Online] http://europa.eu/rapid/pressReleasesAction.do?reference=IP/09/1379.
- ↑ URBACT. Expertising Governance for Transfrontier Conurbations. [Online] http://urbact.eu/en/projects/metropolitan-governance/egtc/our-project/.
- ↑ European Environment Agency,2009. Greenhouse gas emission trends and projections in Europe. Nr. 9/2009.
- ↑ Fuglestvedt, J., Berntsen, T., Myhre, G., Rypdal, K., and Skeie, R.B., 2008. Climate forcing from the transport sectors. Proceedings of the National Academy of Sciences of the United States of America.
- ↑ Demir, E., Bektas, T. and Laporte, G., 2011. A comparative analysis of several vehicle emission models for freight transportation. Transportation Research Part D: Transport and environment, Vol. 6., pp. 347-357.
- ↑ GREEN PAPER, 2007. Towards a new culture for urban mobility. s.l. : Commission of the European Communities.
- ↑ CONCOORD project proposal