Implementing City Logistics Policies in Rome: Methodology and Results
A Nuzzolo, U Crisalli, A Comi, L Rosati, Tor Vergata University of Rome, IT
The paper presents the methodology applied in the last ten years for the choice of city logistics measures implemented in the inner zone of Rome, aiming at reducing the negative impacts of the urban freight distribution.
The urban goods movements are the result of a set of choices made by customers, retailers, wholesalers, carriers and local authorities. City administrators try to rule the overall process, aiming at minimizing the global cost of the system, made of distribution inner costs, inhabitant transportation costs for shopping, congestion costs and external ones (pollution and road accidents).
The analysis and choice of possible city logistics policies/measures have to consider such actors, whose interests are often opposite, and have to explore an optimal compromise to choose the most efficient ones. This is the critical factor of possible success or failure of any city logistics policies, for which an adequate ex-post and ex-ante assessment through quantitative methods is suitable to be used. For this reason, an important role is played by the methodology used to support the decision, implementation and monitoring process of city logistics policies.
This paper presents a general methodology made of the following phases: analysis of the current situation through specific surveys, identification of the critical issues, specification and calibration of freight demand models, definition of possible city logistics policies to apply, ex-ante assessment, implementation, monitoring and ex-post assessment of new scenarios.
The proposed methodology has been applied in the last ten years for the choice of city logistics measures implemented in the inner zone of Rome, aiming at reducing the negative impacts of the urban freight distribution. It is based on two main demand surveys carried out in 1999 and 2008 (including traffic counts, interviews to retailers and truck-drivers), which allowed to identify the critical issues, to specify and calibrate the demand models, as well as to verify the results of the implemented measures and to support the definition of new city logistics scenarios.
In recent years, different city logistics measures have been implemented or planned, through which we can mention: weight and dimension constraints, time windows, emission constraints, area pricing, electronic access control, transit points, urban distribution centres.
In particular, the area pricing and the electronic access control resulted very effective in order to increase the use of environmental- friendly vehicles and third-party transport, even if other critical aspects still exist. Among these, we can refer to the temporal distributions of freight loading and unloading operations, which are still concentrated in the morning hours, and, according to the operators? stated opinions, the insufficient parking spaces dedicated to freight vehicles, even if in recent times the use of dedicated parking spaces has been increasing. Furthermore, the survey has pointed out the increase in the absolute number of freight vehicles accessing the inner area and the increase of frequency of restocking with a higher number of retailers receiving goods one or more times a day. For this reason, the study of new measures, such as nearby delivery areas and banned access to sub-zone of the inner area of the city are under experimentation.
A key role in the quantitative assessment of city logistics strategies is played by freight demand models. Therefore, the proposed methodology uses an advanced freight demand modelling system made of three model sub-systems aiming at estimating the average quantity O-D matrices characterized for transport service types (e.g. retailer in own account or wholesaler in own account or by carrier), the average delivery O-D matrices characterized for transport service types and time slice and the average vehicle O-D matrices also characterized for departure time and vehicle type.
This model system allows us to take into account the influence of: the socio-economic characteristics of a traffic zone on attracted freight traffic, the localization of freight centers (e.g. distribution centers, warehouses) on generated freight traffic for each zone, the characteristics of shops with related depots and shipment size on the choice of service type (retailer in own account, wholesaler in own account, carrier) and vehicle type. This system of models also considers the pattern of delivery tours according to freight type, origin and destination zone accessibility, vehicle type, shipment size and capacity of attraction zone.
Finally, the capability of the demand models to reproduce the structure of freight distribution and current freight traffic on the road network is also reported and analyzed.
Association for European Transport