On-demand rail-bound system

On-demand public transport is expected to become an increasingly important component of public transport systems, facilitated by vehicle automation. The potential of rail-bound on-demand services has been largely overlooked. Together with Jesper Haverkmap, who did his master thesis in the Dutch Railways, we determine the capacity requirements of an envisaged automated on-demand rail-bound transit system which offers a direct non-stop service.

The full paper published on Transportation Research Part B: Methodological is available here.

How many vehicles would such a system require? What are the costs associated with such a system? What are the track and station capacity required? What level of service will it deliver? What are the network saturation patterns given that vehicles can now perform route choice and choose the shortest path to passengers’ destination? What are the consequences for equity in service provision?

An optimization model is formulated for determining the optimal track and station platform capacities for an on-demand rail transit system so that passenger, infrastructure and operational costs are minimized. The macroscopic model allows for studying the underlying relations between technological, operational and demand parameters, optimal capacity settings and the obtained cost components.A series of sensitivity analyses are performed to test the consequences of a range of network structures, technological capabilities, operational settings, cost functions and demand scenarios for future automated on-demand rail-bound systems.

The model is applied to a series of numerical experiments followed by its application to part of the Dutch railway network. The performance is benchmarked against the existing service, suggesting that in-vehicle times can be reduced by 10% in the case study network while the optimal link and station capacity allocation is comparable to those currently available in the case study network. While network geometry and demand distribution are always the underlying determinants of both service frequencies and in-vehicle times, line configuration is only a determinant in the conventional system, whereas the automated on-demand rail service better caters for the prevailing demand relations, resulting in greater variations in service provision.

Here is a clip made by the Dutch Railways (NS) on the concept of on-demand services, denominated as Swarming transport. 



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]

How does satisfaction sum up?

Is satisfaction the sum of its parts? Behavioral scientists such as Daniel Kahneman and Dan Ariely provide ample evidence that human experience is not a simple summation of its parts. Different biases such as recency and salience effects have been observed.

How is it then with travel satisfaction? Is satisfaction with the door-to-door journey simply the sum of its parts? does the last part determine the overall impression? or does the worst experience loom over anything else?

Read the results of our research – together with Roberto Abenoza and Yusak Susilo from KTH – published in Transportation here. (open access)

Method for the reliable determination of service frequencies

Service reliability is often considered only at the operational management phase, while services are assumed to be perfectly reliable at the strategic and tactical planning phases. However, service (un)reliability has consequences on the effective frequency and thus on deficiencies in capacity allocation and passenger waiting times and on-board comfort.

Determining the dispatching headways of bus services in a city network is a multi-criteria problem that typically involves balancing between passenger demand coverage and operational costs.

Together with Costas Gkiotsalitis from NEC Labratories Europe, we develop and apply a reliability-based optimization framework for setting the dispatching headways of bus lines that considers historical operational data and is aware of the passenger waiting time variability at each stop and how it is affected when changing the planned dispatching headways.

Check out the full paper published on Transportation Research Part C – Emerging Technologies following this link

We hope that this work will contribute to a new generation of tactical planning methods that account for service uncertainty.

Demand anticipatory operations

On-demand (known also as flexible or demand responsive) services rely on algorithms that determine which vehicle to assign to which passenger travel request. This becomes especially relevant as developments in vehicle automation and the shared economy call for new developments in routing flexible transport services.

Together with colleagues from Applied Mathematics and Transdev (Connexxion) in the Netherlands, we propose a new type of insertion algorithm: an online dynamic insertion algorithm with demand forecasts. Hence, this algorithm beyond responsiveness by incorporating demand anticipatory capabilities. The performance of this algorithm is tested in a simulation model for a case study network located in vicinity to Amsterdam.

See the full paper in Transportation Research Part E, by following this link.

When combining the new insertion algorithm with empty vehicle rerouting, 98% of passenger rejections are eliminated and travel and waiting times are reduced by up to 10 and 46% respectively, compared to traditional insertion algorithms. A sensitivity analysis tested performance robustness to variations in operational and demand conditions including different fleet compositions.