Restidsvariation för busstrafik - Analys av restidsvariationens omfattning

Sammanfattning

Travel time variability in bus traffic creates uncertainty for both passengers and operators. For passengers, unpredictable travel times complicate trip planning and transfers, while operators face reduced timetable reliability and increased costs from larger schedule buffers. Previous research shows that passengers value reductions in travel time variation more highly than reductions in average travel time, yet the causes of this variation remain poorly understood. This thesis examines travel time variation across different traffic environments and identifies key contributing factors. GPS data from 147 line segments (sections between regulated stops) were analysed using Flowmapper to calculate Reliability Buffer Time (RBT), which measures the relative difference between the 95th percentile and median travel time. Contextual variables describing infrastructure and traffic conditions were collected from Google Maps and the National Road Database (NVDB). Results show that significant travel time variation occurs across all contexts, from rural to metropolitan environments, with average RBT values of 20-25 %. For a segment with 8 minutes median travel time, this means 5 % of trips exceed 10 minutes. A significant variation on an average line segment. While variation levels are similar across environments the underlying causes differ substantially. Simple contextual variables show limited correlation for variation levels. Detailed analysis of segments with high variation reveals that stops contribute to almost 40 % of the total variation, primarily through uncertainty in whether stops occur rather than stop duration. The comparative method developed, analysing the fastest and the slowest trips enables targeted identification of improvement opportunities.