Geographic accessibility analysis and evaluation of potential changes to the public transportation system

Abstract: Modern public transportation systems are required to be more efficient. The efficiency and the quality of the service is based on several aspects, such as availability, frequency, travel speed, reliability and safety. Stop spacing system is a significant part of the public transport service design and it deeply affects its efficiency. In particular, the stop spacing system has consequences on the accessibility, access and egress time, travel speed, transit time and the operating costs. The purpose of this study is to propose potential changes to the surface public transportation system in the City of Milan to create a more efficient service. In particular, the study aims to analyze what happens if the stops spacing system changes, increasing the distance between the bus stops. The model developed in the thesis was created working on the distance between consecutive stops and the introduction of three new potential stop spacing systems, with a target distance between the stops set to 400, 500 and 600 meters. The model is mainly based on three different steps: (i) select the stops that could not be moved or eliminated because of the importance of their location; (ii) select the stops that could be moved or eliminated; (iii) relocate the stops considering the target distance between the stops (400, 500 and 600 meters). According to the model, eliminating some of the stops could have a positive effect on travel times and operating cost reductions. In particular, changing the stop spacing system eliminating an average of 1.7, 2.5 and 3.4 stops per route for the three model scenarios (respectively 400, 500 and 600 meters of target distance between the stops), would decrease the travel time by respectively, 3.0%, 4.4% and 5.7%. Results also indicate that in an optimal situation, with traffic light priority and public transport fast tracks for public transport vehicles, the travel time could decrease by 3.9%, 5.8% and 7.6%. The operating costs analyses indicate that the three different scenarios could reduce the annual cost per km by about 0.5%, 1% and 2%. The evaluation of the effects of the proposed potential changes to the surface public transport stop spacing system was also made analyzing the mobility demand and the accessibility. In particular, the network analyses made on the mobility demand show that the travel time averagely decreases by 1.6%, 1.9% and 2.2%, the transportation time decreases by 2.0%, 3.7% and 5.0% and the pedestrian time changes by -0.4%, +2.8% and +5.2% for the three model scenarios. In terms of minutes, the pedestrian time is balanced with a more efficient surface public transport system. The raster analyses made on the accessibility, using a model called PTAL, shows that the accessibility level didn’t change for 94.2%, 91.1%, 89.9% of the cells and that it is lowered just by 1.0%, 1.5% and 1.9% of the cells. The model developed in the study is merely theoretical and it generally gives positive and interesting results in terms of efficiency. However, to be able to understand its real efficiency it is necessary to make other studies on a closer scale.