Along with the growth of cities and towns around the world, our focus on enviromental problems increases, and so do the demands on a functional distribution system for all kinds of goods. One way of meeting these demands is to coordinate the distribution of goods, a method that has been tested and evaluated in different national as well as international projects. In the national project SAMLIC (coordinated distribution of goods in Linköping City), similar aspects have been discussed, but with the focus being on creating an economically and logistically efficient distribution system for all parts involved. The effects of such a focus are particulary positive since improved enviroment as well as improved service are acheived.
One important aspect of the SAMLIC-project, is that the initative was taken by the industry in the year 2000. It was motivated by the realization that the great amount of transport in and out of the centre of Linköping resulted in crowding, which proved very costly. The reason for crowding was that the numbers of loading zones were too few in relation to the number of distributors and companies in the City. These problems increased as the City expanded and it was inevitable that something had to be done in order to improve the situation.
Participants of the SAMLIC-project are the network for conveyors within Linköping City, “Svensk Biogas”, the working-team Inner City Transports, The Group for City-Cooperation, the University of Linköping and the Swedish National Road and Transport Research Institute (VTI), which since spring 2003 is pursuing the project. A PILOT-project was undertaken during spring 2004 within the framework of the SAMLIC-project. The purpose of the PILOTproject was to gather data forming a foundation for the design of an economically and logistically efficent system of distribution. The purpose of the present study was to establish what effects different changes of the present distribution system would give rise to on transport and traffic. Thus, the effects of codistribution on transport were studied by means of statistical modelling, while the traffic simulation program CONTRAM was used to investigate the effects of codistribution on traffic, a program not yet used in this context, to our knowledge.
The results of the statistical modelling showed that codistribution may reduce the total driving-time by 14 % in average. The statistics also indicated that the average weekly time reduction may be approximately 26 %. The results further reveal that codistribution would reduce the number of stops, which would result in an increased number of custumors per stop.
The average reduction of the number of stops per week was estimated to approximatly 30 %. The results of the traffic simulations were analyzed by comparing ordinary distribution procedures with distribution according to PILOT- or SAMLIC- distribution and revealed that codistribution as compared to ordinary distribution resulted in positive as well as negative changes of traffic flow. In some parts of the road the flow increased while in other places it decreased. The important point, however, is that the reduction of truck-flow occurred primarily in the most central parts of the City, whichled to a reduction of exhaustemissions.
This study suggests that different effects on traffic may be induced by codistribution and reveals in which areas these effects would be likely to occur. In terms of the effect of codistribution on queueing, speed differences and time consumption, this study failed to establish any difference between the two distribution procedures compared. This may be due to a lack of a sufficiently sofisticated analyzing technique. It may, however, be possible to produce a more detailed analysis of possible differences between the distribution procedures by using a micro-simulaion tool. Still, the results of the present study suggest that codistribution would improve the present transport situation in several ways.
The SAMLIC-project is an ongoing project which at present is at a stage when decisions are to be made about matters such as responsibility assignment, criteria of specification, insurance matters and the allocation of different benefits. Not until these and similar further problems are solved will it be possible to initiate a long term system of codistribution.