【正文】 public transport alternatives, can usually be provided with parking spaces by their firms, since 40 to 50% of the total parking volume in German cities is privately owned and privately used. Different parking demand during the day and different parking durations, according to user groups and trip purposes, cause characteristic occupancy time graphs showing the number of simultaneously parked cars either legally or illegally at the same time during the day. contains occupancy time graphs derived from investigations in the Frankfurt city district NordendSiid which represents a typical inner city mixeduse area of about 40 hectares with some 180 residents and 130 employees per hectare. The presence of residents39。 cars are present, while at about . about 45% are present. The occupancy by employees39。 and visitors39。 Topp Consultants 1988). This allows the transfer of parking patterns from district to district without extensive surveys within each district. The similarity of the occupancy time graphs for visitors is less distinct because of the different purposes of visits. supply: Onstreet and offstreet, public and private The total parking volume of a city district consists of different types of parking spaces concerning ownership, operation and usability. The most important distinction is public or private related to accessibility for all or for certain groups and to the degree of control by municipal parking policy. Most public are onstreet spaces with the only restrictions being preferences for residents (or handicapped). These spaces are totally controlled by the municipality and, therefore, they are usually the starting point of parking concepts. The municipal influence on parking garages even those publicly operated is limited because of legal contracts concerning, for instance, the share of permanently let spaces or parking tariffs. A municipal parking pany operating as many garages as possible as, for instance, the Parkhaus Betriebs GmbH in Frankfurt operating 12 garages with about 8,000 spaces in total provides influence and creates a chance to integrate those spaces into parking concepts. About 40% of all spaces are permanently let, even in the muncipally operated garages in Frankfurt. Private spaces cannot be controlled by municipal parking concepts. They can only be indirectly affected, for instance, by no parking provision at all for employees in the public realm, to induce firms to distribute their private spaces to employees who are carbound because of handicaps, professional use of the car, and lacking in public transport alternatives. In the long term, the amount of private spaces can be controlled by zoning ordinances. The share of private spaces in the total parking is about 40 to 50% in German cities. Table 3 shows the figures for Frankfurt am Main. Parking space which is not pletely controlled by parking management measures is an oversaturated system: that means parking demand exceeds parking supply or to put it another way additional spaces attract additional cars. That is even true with illegal parking possibilities. How parking management can avoid this is indicated by spare capacities in parking lots where streets are totally crowded by parked cars. The oftencited deficit of parking spaces is often revealed as a defic it of cheap and easily accessible spaces near to the real destinations. These are, under presentday regulations, onstreet spaces legal as well as illegal. As is shown by spare capacities in parking lots except during main shopping days an equal balance below total occupancy is to be achieved by parking prices. So accessibility is granted while search traffic is avoided. In many discussions about the reasonable supply of parking spaces in a city district, parking deficits are plained of, especially by representatives of the retail trade. Such deficits are often dissolved if the underlying parking standards are changed, . if, for instance, a longer walk between parking and final destination is assumed. So when speaking about parking deficits, we have to add standards in terms of distances and costs to define them. By the way, the same occurs in other fields of transportation: so, for instance, the capacity of a road section or a junction is connected with the level of service expressed by speed or waiting times. The amount of car traffic generated by a parking space depends on parking duration and parking turnover as well as on search traffic. So, for instance, 10% of the residents39。s or employee39。 onstreet parking and on a moderate parking supply for customers and visitors suited to the service quality of public transport in the area considered. 4. Parking control of public spaces Parking control of public spaces usually called Parkraumbewirtschaftung or parking management directly affects only about one half of the total parking volume. Apart from that, there are also indirect effects on private spaces, as mentioned in Section 3. In Germany, the instruments of parking management were pleted as late as 1980 with the legal introduction of residential parking permits. This is important, because residential parking permits are a prerequisite for extending the parking management schemes, successfully applied within the mercial city centres, into the fringe of usually dense mixed use areas neighboring the city centre. So the early eighties saw the starting point of discussions about areawide or even citywide concepts of parking management. Parking concepts pursue several objectives which are interconnected: one is to cover the parking demands of residents and mercial traffic and to provide some spaces for customers and visitors at market rates。 and last, but not least, to control urban traffic, to maintain an equilibrium between parking and circulating