Measuring road space consumption by transport modes: Toward a standard spatial efficiency assessment method and an application to the development scenarios of Rajkot City, India

The space “consumed” by various urban passenger transport modes varies greatly depending on the size and the speed of vehicles. Past studies have shown that public transport (PT) and non-motorized transport (NMT) can be up to 20 times more space-efficient compared to a typical car. This optimal use of space is of relevance in an urban context where space is often a constrained resource. Yet space used by vehicles is rarely assessed in the practice of transport planning. There exists no standard method for quantifying the use of space in complex urban settings. This study proposes an approach based on the space-time concept for quantifying and comparing the dynamic (on-road) and still (parking) space used by different transport modes for a specific road network. Transport planning scenarios developed in the Low-carbon Comprehensive Mobility Plan (LCMP) prepared for the city of Rajkot are used to demonstrate the method. The indicators show that significantly less space is used by transport in a scenario that promotes higher use of PT and NMT in comparison to a business-as-usual scenario based on traffic projections for private motorized vehicles. These results provide evidence that could contribute to alleviating chronic congestion expected from car- and motorcycle-based transport development only. Overall, this research describes an assessment framework for low-carbon transport development that would include spatial efficiency concerns.