## 1 Introduction
In some cities, there are existing consolidation-based systems in the city logistics system of (primarily) shopping areas, e.g., in Bristol, Padova, and Nijmegen [8], and in Budapest, there was such a system in the 1970s. The implementation of these solutions led to significant savings, and their results were used as inputs. In the research of our Research Group, several innovative, gateway-concept-based city logistics solutions were developed. We examined fuel oil-powered small trucks, green trucks, and vans, the use of urban railways and cargo boats; the suitability of the metro  
Figure 1: Groups of urban delivery locations [3]. network for freight transport was examined too, and cargo bikes had different roles in several solutions, such as deliveries, home deliveries, or deliveries between stores. In this paper, we would like to examine a concept of serving the shopping malls of Budapest using small green trucks and cargo bikes, based on the investigation of the geometrical structure of the logistics network [9]. The primary purpose of the paper is to present this new concept, which is basically a new city logistics approach, where cargo bikes are combined with electric trucks in a city logistics system of concentrated sets of delivery locations, based on the geometrical structure of the logistics network. In our paper, we show how this new approach can be examined and described. It was expected that such a solution could help to reduce emissions in the examined city logistics system and to reduce the load of the urban roads at the same time. It can be assumed, too, that such a solution can be more expensive than a simple city logistics system with direct, consolidated deliveries, but regarding this question, it is very important that in the case of any traffic issues, the cargo bikes can have better possibilities to perform the delivery tasks. To show these expected effects is an essential purpose of this paper. For this, first, we present those existing city logistics solutions and previous research projects which provided data, ideas, and experience for our work. From these, those projects were the most important where the combined use of cargo bikes and lorries were examined. Next, a complex data analysis will be presented for the concentrated sets of delivery locations of Budapest to show the usage possibilities of cargo bikes in their city logistics system. In the case of this data analysis, 327 stores from 3 shopping malls (while in the sum 32 shopping malls of the city there are 3432 stores) and 163 stores of the biggest shopping area of Budapest (where the sum number of stores at the data collection was 418) were examined, as in their case, we had available data about the cargo bike delivery-related questions. After the data analysis, we present a macroscopic simulation model to examine this new city logistics approach in the case of all 32 shopping malls of Budapest, and the results of the simulation will show the expected effects of the examined approach with cargo bikes and electric trucks. At the simulation, the most important purpose is to get data about the expected number of delivery vehicles, about the performances, and about the expected delivery costs of the examined system. Before the simulation, it was necessary to estimate the demands of the unknown shopping malls as well; for this, an ABC-analysis-based new solution was used, which will be presented in this section, too. After these, we show the relevant urban structures and the theoretical, symmetrical, and real geometrical model of the examined city logistics system, with a graph theory-based notation and its application for the simulated city logistics system from Budapest. In the last section of our paper, we write about the next steps of the research, where the possible reference structure of the geometrical model must be highlighted, and the use of a multicriterial model will be very important as well to make possible for any examined city a decision about the use of the new approach.