Source code: github.com/npct/pct/ 2018-04-19

Contents

  • Context
  • The impacts of transport infrastructure
  • Methods
  • Results and discussion

Introduction

whoami?

The problem I

  • Bad news: it's ****ing HUGE

The problem II

  • Good news: can be broken down into chunks
  • E.g.: How to transition to active cities? From this…
Source: [Brent Toderian](https://twitter.com/BrentToderian)

Source: Brent Toderian

The Problem III

  • Needs to be framed by academics as potential solutions
  • E.g.: How do we get to cities like this?
Source: [Brent Toderian](https://twitter.com/BrentToderian)

Source: Brent Toderian

Evidence-based policy (vs policy-based evidence!)

  • Presenting the 'PCT' work to Secretary of State for Transport

Research context (source: Lovelace et al. 2017)

Tool Scale Coverage Public access Format of output Levels of analysis Software licence
Propensity to Cycle Tool National England Yes Online map A, OD, R, RN Open source
Prioritization Index City Montreal No GIS-based P, A, R Proprietary
PAT Local Parts of Dublin No GIS-based A, OD, R Proprietary
Usage intensity index City Belo Horizonte No GIS-based A, OD, R, I Proprietary
Bicycle share model National England, Wales No Static A, R Unknown
Cycling Potential Tool City London No Static A, I Unknown
Santa Monica model City Santa Monica No Static P, OD, A Unknown

The PCT team

"If you want to go far, go as a team"

Robin Lovelace (Lead Developer, University of Leeds)

  • James Woodcock (Principal Investigator, Cambridge University)
  • Anna Goodman (Lead Data Analyst, LSHTM)
  • Rachel Aldred (Lead Policy and Practice, Westminster University)
  • Ali Abbas (User Interface, University of Cambridge)
  • Alvaro Ullrich (Data Management, University of Cambridge)
  • Nikolai Berkoff (System Architecture, Independent Developer)
  • Malcolm Morgan (GIS and infrastructure expert, UoL)

Policy feedback

"The PCT is a brilliant example of using Big Data to better plan infrastructure investment. It will allow us to have more confidence that new schemes are built in places and along travel corridors where there is high latent demand."

  • Shane Snow: Head of Seamless Travel Team, Sustainable and Acessible Travel Division

"The PCT shows the country’s great potential to get on their bikes, highlights the areas of highest possible growth and will be a useful innovation for local authorities to get the greatest bang for their buck from cycling investments  and realise cycling potential."

  • Andrew Jones, Parliamentary Under Secretary of State for Transport

A live demo for Leicester

"Actions speak louder than words"

A comment on geo-tribes

  • Geography vs GIS vs Geocomputation vs GDS
  • Why geocomputation?
  • involves writing code + development (in stplanr R package)
  • The importance of reproducibility (Lovelace, Nowosad, and Muenchow 2018):
  • A process is reproducible only if the same results can be generated by others using publicly accessible code.

Definitions of geocomputation

  • GeoComputation is about using the various different types of geodata and about developing relevant geo-tools within the overall context of a 'scientific' approach (Openshaw and Abrahart 2000).
  • What distinguishes geocomputation from the older quantitative geography, is its emphasis on "creative and experimental" GIS applications (Longley 1999).
  • Source: Geocomputation with R a free, open source book (Lovelace, Nowosad, and Muenchow 2018)

GDS vs Geocomputation (and mini code example)

d = frame_data(
  ~Attribute, ~GIS, ~GDS,
  "Home disciplines", "Geography", "Geography, Computing, Statistics",
  "Software focus", "Graphic User Interface", "Code",
  "Reproduciblility", "Minimal", "Maximal"
)
Attribute GIS GDS
Home disciplines Geography Geography, Computing, Statistics
Software focus Graphic User Interface Code
Reproduciblility Minimal Maximal

Breaking the problem down

  • The impacts of transport infrastructure

The impacts of transport infrastructre

Credit: flickr user thestuff, Creative Commons Licence

Research into impacts of roads

The extension of the M74 motorway = 'natural experiment':

  • People who live near motorways seem to be less physically active ( ???)
  • And more car dependent (Prins et al. 2017)
    • Although no evidence of impacts on active travel

Active travel impacts: a typology

A typology of active travel options.

A typology of active travel options.

Methods

The study area

Parallels (Credit: Philip McErlean, CC )

Cycling potential parallel to the route

3 stage methodology to identify parallel lines:

  • Subset desire lines whose cetrepoints are far from the proposed route
  • Segment the proposed route
  • Calculate the angle of each route

Then keep only lines parallel to proposed route segments

Subsetting desire lines by centre point proximity

Finding desire lines that are (roughly) parallel

This involved the development of a new R function:

The angle_diff function

From the R package stplanr

stplanr:::angle_diff.Spatial
## function(l, angle, bidirectional = FALSE, absolute = TRUE){
##   if(is(object = l, "Spatial")){
##     line_angles = line_bearing(l)
##   } else {
##     line_angles = l
##   }
##   angle_diff = angle - line_angles
##   angle_diff[angle_diff <= -180] = angle_diff[angle_diff <= -180] + 180
##   angle_diff[angle_diff >= 180] = angle_diff[angle_diff >= 180] - 180
##   if(bidirectional){
##     angle_diff[angle_diff <= -90] = 180 + angle_diff[angle_diff <= -90]
##     angle_diff[angle_diff >= 90] = 180 - angle_diff[angle_diff >= 90]
##   }
##   if(absolute)
##     angle_diff = abs(angle_diff)
##   angle_diff
## }
## <bytecode: 0x1297fc98>
## <environment: namespace:stplanr>

What about perpendicular lines (severance)?

The same method!

3: Access to stations (Credit: M. Morgan)

  • Divide each route into 3

How to deal with long, windy routes?

  • Break the train line into segments
Method of splitting the route into discrete segments using the line segment function from the stplanr R package (a) and cycling potential severed (b).

Method of splitting the route into discrete segments using the line segment function from the stplanr R package (a) and cycling potential severed (b).

All methods together

Centre point-buffer (a), parallel (b), perpendicular (c) and station access (d) methods.

Centre point-buffer (a), parallel (b), perpendicular (c) and station access (d) methods.

Results and discussion

Cycling opportunities and threats

Scenario N. commuters N. cycling % cycling Distance (km, Euclidean)
Baseline
Touching buffer 53665 1537 2.9 11.9
Parallel selection 2583 28 1.1 13
Perpendicular selection 1678 21 1.3 18.5
Cycling to stations 574 3 0.5 17.9
Scenario

Final question

  • How to integrate this work in existing tools?
  • How to ensure maximum policy impact?
  • How reproducibility can help?

Thanks + References

  • Thanks for listening - get in touch via r.lovelace@leeds.ac.uk or @robinlovelace

Longley, Paul. 1999. Geographical Information Systems: Principles and Technical Issues. John Wiley & Sons, Inc. http://books.google.com/books?ei=yVBBT5GPHMXd8AP7sPmnDw&id=wUruAAAAMAAJ&pgis=1.

Lovelace, Robin, Jakub Nowosad, and Jannes Muenchow. 2018. Geocomputation with R.

Openshaw, Stan, and Robert J Abrahart. 2000. Geocomputation. London: Taylor & Francis.

Prins, R. G., L. Foley, N. Mutrie, D. B. Ogilvie, and M74 study team. 2017. “Effects of Urban Motorways on Physical Activity and Sedentary Behaviour in Local Residents: A Natural Experimental Study.” The International Journal of Behavioral Nutrition and Physical Activity 14 (1): 102. doi:10.1186/s12966-017-0557-0.