Public transport accessibility measure based on weighted door to door travel time

Providing accessibility by public transportation is one of the main concerns in sustainable transportation development. An appropriate accessibility index should not only take transportation and land use into account but also the people who want to attend activities via the transport system. Travel time as the most common variable is used to indicate the role of transportation. A trip with public transport includes different parts: walking from the origin point to the bus stop or from the bus stop to the destination point, waiting for the bus to arrive, and in-vehicle time. These different parts have different weight values for passengers which affect their tendency towards traveling by public transportation. In this paper, a GIS-based multimodal gravity model is developed based on the weighted door to door travel time to compute accessibility by public transportation. Five main distinct urban activities including employment, education, healthcare, shop, recreation opportunities, and services are considered and the accessibility of the target population at the census block level to these destinations through public transportation is computed. In the next step, in order to consider all activities together and report a single unique index, the five computed accessibility indices are integrated into a composite index using a principal component analysis (PCA). The integrated accessibility measure helps to get an insight into the relative distribution of the benefits of public transportation and its interaction with the land use. The proposed method is applied to the City of Isfahan in Iran. The results indicate where places, for each activity and in overall, would benefit from the better land use and public transportation interaction and where regions would suffer from low accessibility level. This work provides a methodological framework as a tool for measuring the performance of public transportation and its interaction with the land use pattern.