17 environment. Collective rentability is maximal for a toll equal to zero a situation where the highest number of users benefit from the new infrastructure. In practice the toll regulation tries to reach a toll a bit below the toll which maximize the revenue, in order to get a revenue close enough to the maximum level , in order to make the motorway just profitable for the concessionnaire, without driving too much subsidies from the government, while managing the political sensitivity of the introduction of tolls. Increasingly also France is learning from some of the conflicts it has gone through between users unwilling to pay and local governments constrained fiscally. The decisions on the tolls are now set to levels consistent with the ability to pay of the majority of the potential users.

# _5.3. Forecasting Port Trafc_ **_in Antwerp22_**

Forecasting techniques used in ports tend to fit into strategic planning programs. This is important in the context of restructuring (how many ports do you really need in your country?) but more generally for most common evaluations of port expansion projects (e.g. new terminals, dock, hinterland projects,...). Most casual observers would recognize that macroeconomic trends and reforms (trade liberalization, labor market reforms,...) and the specific characteristics of each location matter but recent progress in logistics techniques and technology are also revolutionizing the demand for port activities and this needs to be taken into account by port regulators.

Consider the port of Antwerp. Located about 70km from the North sea, it stretches for some 20km along the banks of the Scheldt river. It enjoys an international maritime traffic over 1 15 million tons/year, sees over 16,000 ships every year and is one of the five largest ports in the world. It loads (about 1.6 million TEU), unloads (about 1.6 million TEU), stores, repackages, distributes and forwards goods. It has dedicated terminals for many commodities and handles dry and liquid bulk containers. The container traffic is about 35 million metric tons, 61% to roads and 25% to waterways. General cargo represents about 60% of the traffic. The port employs almost 70,000 people. It is subject to a strong competition from various ports in the Hamburg-Le Havre, a critical fact which makes forecasting all the more important.

Antwerp has been forecasting traffic formnally since the late 60s. The Transport Economics Department of the University of Antwerp has been very active in helping the port authorities with the management of the port in general but in particular with these forecasting efforts. This is coordinated in fact by a special unit of the port, the Study centre for the Expansion of Antwerp (SEA). SEA has generally had a very clear preference to prepare a base forecast to be complemented by more detailed information and insights to be provided by experts. This approach is quite common in OECD ports and this is why it may be worth to describe it in some detail.

The whole exercise is based on a base model used to forecast for two main commodity groups, bulk traffic and general cargo. An optimistic and a pessimistic variant differentiated by the forecast of macroeconomic conditions in the OECD countries are worked on for a series of specific traffic group. Bulk traffic is divided into 10 standard categories (agriculture, food and food stuffs, solid fuels, crude oil and products, minerals and ores, metal products, raw materials, fertilizers, chemicals and machinery and vehicles not included elsewhere). Initially, for general cargo, loadings and unloadings, were pooled together and an aggregate figure was forecasted.

> 22 This section is based on , Coeck, C, A. Verbeke and W. Winkelmans (1996), " Back to the Futute: an Evaluation of Traffic Forecasting Techniques used in Antwerp and Rotterdam", pp. 3-26 and Verbeke, A, E. Declercq and D. Teurelincx (1996), "The future growth of contained traffic in the Port of Antwerp", pp 51-70, both in Winkelmans, W. and T. Notteboom (eds), The issue of prognoses in maritime transport and seaport production in Belgium and Poland: a conceptual and empirical study, Garant, Leuven, Belgium