PhD defense and TRAIL seminar

Congratulations Dr. Nadjla Ghaemi for successfully defending your PhD dissertation on “Short-turning Trains during Full Blockage in Railway Disruption Management” today!

Nadjla’s PhD work has been published in the following journal publications:

Ghaemi N., Cats O. and Goverde R.M.P. (2018). Macroscopic multiple-station short-turning model in case of complete railway blockagesTransportation Research Part C, 89, 113-132.

Ghaemi N., Cats O. and Goverde R.M.P. (2017). A Microscopic Model for Optimal Train Short-Turnings during Complete BlockagesTransportation Research Part B, 105, 423-437.

Ghaemi N., Zilko A., Yan F., Cats O., Kurowicka D. and Goverde R.M.P. (2018). Impact of Railway Disruption Predictions and Rescheduling on Passenger Delays. Journal of Rail Transport Planning & Management. Accepted.

Ghaemi N., Cats O. and Goverde R.M.P. (2017). Railway Disruption Management Challenges and Possible Solution DirectionsPublic Transport, 9 (1-2), 343-364.

The defense was followed by a TRAIL seminar where I gave a talk on “Robust passenger transport systems: Network, operations and user adaptations”

Recovery time and propagation effects of passenger transport disruptions

How do disruptions propagate in public transport networks? for how long and how far away from the source are passengers affected?

In a new paper on Physica A: Statistical Mechanics and its Applications, we propose a method for quantifying the extent to which the network exhibits spillover effect.

Model results are evaluated for the Stockholm network using a dynamic non-equilibrium assignment model.

[News headline: Bomb threat against train travel; Travel chaos following two false bomb alarms; photo from Stockholm Central station]

TRB 2018

Looking forward to meeting many colleagues and friends at the Transportation Research Board (TRB) 97th Annual Meeting in Washington DC next week (January 7-11)!

The following studies which I have been involved in together with students and colleagues will be presented at TRB this year:

  1. The Potential of Demand Responsive Transport as a Complement to Public Transport: An Assessment Framework and an Empirical Evaluation. (Session 293, Monday 10:15 AM- 12:00 PM Convention Center, 147A) Alonso-Gonzalez M., Liu T., Cats O., van Oort N. and Hoogendoorn S.
  2. Individual, Travel and Bus Stop Characteristics Influencing Traverlers’ Safety Perceptions. (Session 556, Tuesday 10:15 AM- 12:00 PM Convention Center, 143B) Abenoza R.F., Ceccato V., Susilo Y. and Cats O.
  3. Constructing Spatiotemporal Load Profiles of Transit Vehicles with Multiple Data Sources. (Session 649, Tuesday 1:30 PM- 3:15 PM Convention Center, Hall E) Lou D., Bonnetain L., Cats O. and van Lint H.
  4. Strategic Planning and Prospects of Rail-bound Demand Responsive Transit. (Session 660, Tuesday 1:30 PM- 3:15 PM Convention Center, Hall E) Cats O. and Haverkamp J.
  5. Demand-anticipatory Flexible Public Transport Service. (Session 784, Tuesday 8:00 AM- 9:45 PM Convention Center, Hall E) van Engelen M., Cats O., Post H. and Aardal K.

In addition, will be presiding:

  • Poster session 650 on Transit Service Disruptions: Impacts and Mitigation Measures (Tuesday 1:30 PM- 3:15 PM, Convention Center, Hall E)
  • Poster session 651 on Economic and Optimization Models for Integrated Service Planning (Tuesday 1:30 PM- 3:15 PM, Convention Center, Hall E)

In conjunction with the TRB conference, Jaime Soza Parra and I meet with Washington Metropolitan Area Transit Authority on Jan 11 to present and discuss the preliminary results of our evaluation of their headway-control experiment.

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!

Added on 16-8-2017: links to all conference papers are available on the Publications page.

Exposing the role of exposure in public transport risk analysis

In the last several years, I have investigated the impact of service disruptions in public transport networks. In a series of network topology and dynamic transit assignment studies, I have looked into indicators of link criticality, measures of impacts on system performance, mitigation value of real-time information provision, identifying strategic links for increased capacity and the robustness value of new links and extension plans.

One common limitation to all of these studies was the lack of information on the probabilities associated with disruptions. This prevented a complete risk analysis and assessing the (e.g. annual) costs and benefits associated with disruptions and mitigation measures.

Together with Menno Yap and Niels van Oort, the frequency and duration of various disruption types on each public transport mode (train, metro, tram and bus) were estimated based on a unique dataset. We also identify which is the primary predictor of each variable to allow researchers and professionals in other contexts to estimate disruption probabilities in the lack of local data.


We propose a method for embedding link exposure into the identification and evaluation of critical links and perform a risk analysis for the multi-modal public transport network of the Rotterdam The Hague Metropolitan Area. By comparing the results with the conventional measures, we demonstrate that disregarding exposure risks prioritizing heavily utilized links instead of those which are actually the weakest.

Click here for the link to the full paper.