Network evolution

Network indicators are widely used for characterizing  transport network topology and its performance as well as provide insights on possible developments. Public transport networks change dramatically over time and are have a significant impact on urban and regional development. The structure of transport networks is the outcome of a large number of infrastructure investment decisions taken over a long time span. Little is known however on how rail bound public transport networks and their network indicators have evolved into their current form as it is surprisingly difficult to obtain data on historical network states.

This study reports a longitudinal analysis of the topological evolution of a multimodal rail network by investigating the dynamics of its topology for the case of Stockholm in 1950-2025. The starting year marks the opening of the metro system while the end year is set to mark the completion of the current development plan.

In the link below you can get an impression of the network evolution with 5 years intervals. Note the changes in coverage (scale) and density.

https://www.dropbox.com/s/iklil4shu2wgd6b/Evolution.wmv?dl=0

Based on a compilation of network topology and service properties, a year-on-year analysis of changes in global network efficiency and directness as well as local nodal centrality were conducted.

Changes in network topology exhibit smooth long-term technological and spatial trends as well as the signature of top-down planning interventions. Stockholm rail network evolution is characterized by contraction and stagnation periods followed by network extensions and is currently undergoing a considerable densification, marking a shift from peripheral attachment to preferential attachment. It is remarkable that in 2025 the Stockholm network will offer the same level of directness, connectivity and accessibility that were offered in 1950 for a much smaller area. This is driven by the dramatic shift in the modal composition of Stockholm rail-bound network during the analysis period.

Read the full paper following this link.

MT-ITS 2017

Will be attending MT-ITS 2017, the 5th IEEE International Conference on Models and Technologies for Intelligent Transportation Systems, together with colleagues with whom I collaborated on public transport -related studies.

I am involved in the following contributions that will be presented in the upcoming conference:

  • Analysis of Network-wide Transit Passenger Flows based on Principal Component Analysis. (Presenter: Ding Luo)
  • Simulating the Effects of Real-time Crowding Information in Public Transport Networks (Presenter: Arek Drabicki)
  • Impact of Relocation Strategies for a Fleet of Shared Automated Vehicles on Service Efficiency, Effectiveness and Externalities (Presenter: Konstanze Winter)
  • Real-time Short-turning in High Frequency Bus Services based on Passenger Cost (Presenter: David Leffler)
  • Measuring Spill-over Effects of Disruptions in Public Transport Networks (I will present work performed with Sanmay Shelat)

Looking forward to my first MT-ITS experience!

How much are you willing to pay for flight safety?

Following the tragic events of MH17 plane crash where 298 passengers and crew members were killed in July 2014 (for details see this article on the BBC), flight safety and security was high on the public agenda in the Netherlands.

This made me wonder:

(1) how important is safety in our choice of flight?

(2) what are the factors that determine how safe do we perceive a flight alternative to be?

Joey Blange decided to take this challenge for his master thesis work, and together with Eric Molin and Caspar Chorus, we designed two stated preference experiments: in a first experiment, combinations of airline and route attributes are evaluated in terms of safety that is captured on a rating scale; in a second experiment, safety perception is treated as an attribute and traded-off against other flight attributes to arrive at a flight choice

The results of both models are then combined to calculate the willingness to pay values for improvements made to a range of airline and route attributes, taking into account socio-demographic variables and psychological traits. The median willingness to pay value to improve safety perception with 1 point on a 1-7 scale varies between 75 and 448 euro, depending greatly on the initial value.

For the full details of the study including the results, see our publication on the Journal of Air Transport Management. 

TRB2017 and related events

Will be attending the Transportation Research Board (TRB) 96th Annual Meeting in Washington DC next week and will also take part in several events that organized in conjunction with TRB.

The following studies which I have been involved in will be presented on TRB this year:

  • Stated-Choice Experiment on Mode Choice in the Era of Free-Floating Carsharing and Shared Autonomous Vehicles (Session 336, Monday 10:15 AM- 12:00 PM Convention Center, 144B)
  • Exact Optimization of Bus Frequency Settings Considering Demand and Trip Time Variations (Session 463, Monday 3:45 PM- 5:30 PM , Convention Center, Hall E)
  • Real-Time Transfer Synchronization of Public Transport Services Using Passenger Data  (Session 463, Monday 3:45 PM- 5:30 PM , Convention Center, Hall E)
  • Constructing Transit Origin-Destination Matrices Using Spatial Clustering (Session 491, Monday 6:00 PM- 7:30 PM, Convention Center, 147A)
  • Investigating Potential Transit Ridership by Fusing Smartcard and Global System for Mobile Communications Data (Session 491, Monday 6:00 PM- 7:30 PM, Convention Center, 147A)
  • Willingness to Pay for Safety Improvements in Passenger Air Travel (Session 678, Tuesday 1:30 PM- 3:15 PM , Convention Center, Hall E)
  • How Do People Cycle in Amsterdam? Estimating Cyclists’ Route Choice determinants Using GPS Data from an Urban Area (Session 878, Wednesday 2:30 PM- 4:00 PM , Convention Center, 102B)

In addition, will take part in:

  • Poster session 250 on New Tools to Inform Transit Management and Decisions (Monday 8:00 AM- 9:45 AM, Convention Center, Hall E) which I will be presiding
  • Lecture session 748 on Ensuring Public Transport Networks are Connected: For Everyone, at All Times (Tuesday 3:45 PM- 5:30 PM, Convention Center, 144A) on which I will be the discussant

In conjunction with the TRB conference I will also participate and present in the following events:

  • Winter General Meeting of the PTV Scientific Advisory Board on which I will present past and on-going research on transit assignment models, Jan 10
  • Shared Mobility from a Public Transport Perspective at the workshop on Shared Mobility at the Netherlands Embassy in Washington, Jan 12
  • Towards Passenger Experience of Service Reliability: Field Implementation and Smartcard Analysis, invited talk at Washington Metropolitan Area Transit Authority, Jan 13

Looking forward to meeting many colleagues on one of these events or elsewhere in what will surely be an intriguing week!

The Tallinn experiment: what happens when a city makes public transport fare-free?

Was interviewed by the Guardian for a piece on the Tallinn experience with free-fare public transport: “According to Cats, free public transport is not the no-brainer everyone might initially think it to be.”  Hope that I was able to provide evidence and nuances into a debate which is often dominated by political views.

Read the full article on the Guardian here.

You can find here the scientific paper which reviews other experiments, reports the evaluation conducted in Tallinn and the key findings.

Tallinn