estimating distance decay for the national propensity to cycle tool
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Estimating distance decay: for the National Propensity to Cycle Tool (NPCT)
Robin Lovelace, University of Leeds. Talk at the Institute for Transport Studies (ITS)
Slides: speakerdeck.com/robinlovelace
I What is distance decay?
Discovering distance decay
Source: Lovelace (2014): my thesis
Distance of trip != distance/yr
Source: Lovelace (2014): my thesis
Distance decay in active travel
Data: derived from Iacono et el. (2010)
Distance decay: the formula
p = f(d)
Euclidean or route distance?
Source: Lovelace (2014): my thesis
Distance decay in the literature
Source: Lovelace et al., forthecoming.
Tested functional forms
Source: Martínez and Viegas (2013)
DD functional forms
Exponential vs cubic vs linear
Some real data
Source: Lovelace et al. (forthcoming)
Linear model to the data
Cubic polynomial models
Log-square-root model
II Why distance decay?
Source: NPCT modelOutput (Leeds)
Distance decay in everyday life
Source: Lovelace (2014): my thesis
Distance and energy use
Distance and mode dependence (Sheffield)
Distance and mode dependence (England)
Source: Lovelace (2014): my thesis
Energy and travel mode
Source: Lovelace (2014): my thesis
III The uses of distance decay
Uses of dd: a few ideas
● If we're to transition away from fossil fuels, we must use modes that are less energy intensive
● Distance decay for sustainable travel modes can tell us what future travel patterns must look like
● Characterising travel systems● Especially relevant for active travel● The National Propensity to Cycle Tool (NPCT)
'Spatial interaction
models'
Source: Lovelace et al. (forthecoming), Geographical Analysis
DD to characterise travel systems
Modelling travel
Source: Lovelace et al. (2014)
IV Wider context of distance decay
Resulting report: national benefits
Benefits of cycling nationwide
See https://tinyurl.com/conversation-cycling
Webtag estimates of benefit:cost
See https://tinyurl.com/conversation-cycling
https://www.gov.uk/government/publications/webtag-tag-overview
An open source policy planning tool (+ live demo!)
DD in the NPCT
Further work on distance decay
● The distance-decay of road traffic incidents?● Its use to estimate non-work travel?● Verification of dd parameters using Big Data
Key references
● Iacono, M., Krizek, K. J., & El-Geneidy, A. (2010). Measuring non-motorized accessibility: issues, alternatives, and execution. Journal of Transport Geography, 18(1), 133–140. doi:10.1016/j.jtrangeo.2009.02.002
● Lovelace, R., Clarke, M., Cross, P., & Birkin, M. (n.d.). Verification of big data for estimating retail flows: a comparison of three sources against model results. Geographical Analysis.
● Lovelace, R., Malleson, N., Harland, K., & Birkin, M. (2014). Geotagged tweets to inform a spatial interaction model: a case study of museums. Arxiv Working Paper.
● Lovelace, R. (2014). The energy costs of commuting: a spatial microsimulation approach. University of Sheffield. Retrieved from http://etheses.whiterose.ac.uk/5027/
● Martínez, L. M., & Viegas, J. M. (2013). A new approach to modelling distance-decay functions for accessibility assessment in transport studies. Journal of Transport Geography, 26, 87–96. doi:10.1016/j.jtrangeo.2012.08.018
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