Temporal sampling and service frequency harmonics in transit accessibility evaluation
Andrew Owen
Accessibility Observatory University of Minnesota Center for Transportation Studies
Brendan Murphy
Accessibility Observatory University of Minnesota Center for Transportation Studies
Keywords: transit accessibility, temporal sampling, spatial analytics,
Abstract
In the context of public transit networks, repeated calculation of accessibility at multiple departure times provides a more robust representation of local accessibility. However, these calculations can require significant amounts of time and/or computing power. One way to reduce these requirements is to calculate accessibility only for a sample of time points over a time window of interest, rather than every one. To date, many accessibility evaluation projects have employed temporal sampling strategies, but the effects of different strategies have not been investigated and their performance has not been compared. Using detailed block-level accessibility calculated at 1-minute intervals as a reference dataset, four different temporal sampling strategies are evaluated using aggregate sample error metrics as well as indicators of spatially clustered error. Systematic sampling at a regular interval performs well on average but is susceptible to spatially-clustered harmonic error effects which may bias aggregate accessibility results. A constrained random walk sampling strategy provides slightly worse average sample error, but eliminates the risk of harmonic error effects.References
Hansen, W. G., How accessibility shapes land use. Journal of the American Institute of Planners, Vol. 25, No. 2, 1959, pp. 73–76.
Ingram, D. R., The concept of accessibility: A search for an operational form. Regional Studies, Vol. 5, No. 2, 1971, pp. 101–107.
McFadden, D., M. Johnson, and F. Reid, Travel Demand Forecasting Study. Institute of Urban and Regional Development, University of California, 1973.
Geurs, K. T. and B. van Wee, Accessibility evaluation of land-use and transport strategies: review and research directions. Journal of Transport geography, Vol. 12, No. 2, 2004, pp. 127–140.
Owen, A. and D. M. Levinson, Modeling the commute mode share of transit using continuous accessibility to jobs. Transportation Research Part A: Policy and Practice, Vol. 74, 2015, pp. 110–122.
Geurs, K., A. Montis, and A. Reggiani, Recent advances and applications in accessibility modelling. Computers, environment and urban systems, Vol. 49, 2015, pp. 82–85.
Legrain, A., R. Buliung, and A. M. El-Geneidy, Who, what, when, and where: Revisiting the influences of transit mode share. Transportation Research Record: Journal of the Transportation Research Board, 2015.
Farber, S., M. Z. Morang, and M. J. Widener, Temporal variability in transit-based accessibility to supermarkets. Applied Geography, Vol. 53, 2014, pp. 149–159.
Widener, M. J. and J. Shannon, When are food deserts? Integrating time into research on food accessibility. Health & place, Vol. 30, 2014, pp. 1–3.
Karner, A., Development of highly resolved spatial and temporal metrics of public transit accessibility 1 and their application to service equity analysis 2. In Transportation Research Board 94th Annual Meeting, 2015, 15-5677.
Tasic, I., X. Zhou, and M. Zlatkovic, Use of Spatiotemporal Constraints to Quantify Transit Accessibility: Case Study of Potential Transit-Oriented Development in West Valley City, Utah. Transportation Research Record: Journal of the Transportation Research Board, , No. 2417, 2014, pp. 130–138.
Lei, T., Y. Chen, and K. Goulias, Opportunity-Based Dynamic Transit Accessibility in Southern California: Measurement, Findings, and Comparison with Automobile Accessibility. Transportation Research Record: Journal of the Transportation Research Board, , No. 2276, 2012, pp. 26–37.
Ding, Y., J. Zhou, Y. Li, et al., Transit accessibility measures incorporating the temporal dimension. Cities, Vol. 46, 2015, pp. 55–66.
Cryer, J. D. and N. Kellet, Time series analysis, Vol. 101. Springer, 1986.
Owen, A., B. Murphy, and D. Levinson, Access across America: Transit 2015 methodology. University of Minnesota Center for Transportation Studies, http://access.umn.edu/ research/america/transit/2015, 2016.
Delling, D., T. Pajor, and R. F. Werneck, Round-based public transit routing. Transportation Science, 2014.
American Association of State Highway and Transportation Officials, Commuting in America 2013. American Association of State Highway and Transportation Officials, http:// traveltrends.transportation.org, 2015.
