What is the robustness value of public transport development plans?

Investments in transport are increasingly motivated by the need to improve its robustness — the capacity to absorb disturbances with a minimal impact on system performance. Nonetheless, there is lack of knowledge on how to assess and quantify the robustness value of new investments as part of strategic planning. This study investigates the robustness of alternative public transport networks by assessing the consequences of link failures on network performance. A full-scan disruption impact analysis is performed and its implications on passenger’s group composition and travel time losses are analysed for a public transport development plan in Stockholm, Sweden. A decision to extend this system substantially with 23 new stations and 35 km of new tracks by 2025 was recently undertaken.

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The results suggest that as a result of the development plan, the robustness of the case study network will improve in terms of average performance deterioration as well as worst case scenario for all performance indicators. Neglecting abnormal operations in project appraisal can potentially lead to the underestimation of its benefits. Moreover, the critical links in each network are identified and impact disparity is investigated. The analysis method presented in this study can support the consideration of development plan impacts on network robustness in the strategic planning process.

See here the full paper

 

 

 

Two public transport proposals granted

Two public transport projects will be soon launched in the Department of Transport and Planning at TU Delft:

(1) SCRIPTS – on flexible demand-anticipatory services. Granted in the Smart Urban Regions in the Future (SURF) program by NWO [2016-2018; total of 1,800,000€, of which 500,000€ in TU Delft]. ‘Smart Cities’ Responsive Intelligent Public Transport Systems’ will develop advanced models for the optimal design of hybrid public transport systems, involving demand responsive transport services that are flexible in route and schedule and (self-)organized through ICT platforms, and the simulation of their performance, including a series of pilots and showcases.

(2) TRANS-FORM – on real-time transfer and congestion management. Granted in the Co-fund Smart Cities and Communities (ENSCC) call [2016-2018; total of 1,800,000€, of which 315,000€ in TU Delft]. A consortium of universities, industrial partners, public authorities and private operators from Switzerland, Sweden, Spain and the Netherlands, led by TU Delft. ‘Smart Transfers through Unravelling Urban Form and Travel Flow Dynamics’ will develop a multi-level approach for monitoring, mapping, analyzing and managing urban dynamics in relation to interchanging travel flows. Analysis of pedestrian and traveler flows at the hub, urban and regional networks.

Three new PhD positions in the area of public transport modelling will be soon available to work in these projects. Relevant background and skills include simulation modelling, network analysis and optimization.

UPDATE (28-01-2016):

Interested? See the job ad here. Applications are due by February 10.

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The more links the better network robustness is?

Investments in public transport projects are increasingly motivated not merely based on travel time savings but also in relation to improvements in service reliability, comfort and robustness. However, there are no standard practices for incorporating the impacts of alternative investments on network robustness.

Together with Erik Jenelius from KTH,  a methodology for assessing the value of new links for public transport network robustness, considering disruptions of other lines and links as well as the new links themselves, was developed. We applied this methodology to a light rail line in Stockholm.

A distinction is made between the value of robustness, defined as the change in welfare during disruption compared to the baseline network, and the value of redundancy, defined as the change in welfare losses due to disruption. Topological studies concluded that redundancy is an important feature for network robustness. Interestingly, we found that In some cases, the new line results with seemingly paradoxical effects as it leads to greater disruption costs.

Check the full paper here

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Planning for the unplanned – where shall we allocate reserve capacity?

In the field of network vulnerability and resilience, there is growing evident that network redundancy is a key determinant of network capability to withstand shocks. However, introducing redundancy to rapid public transport networks is very expensive and it is thus important to identify the network elements that will benefit most network performance in case of disruption.

It is crucial to invest in network redundancy without making redundant investments!

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Together with my colleague from KTH, Erik Jenelius, we propose and demonstrate in a new paper a methodology for evaluating the effectiveness of a strategic increase in capacity on alternative public transport network links to mitigate the impact of unexpected network disruptions. For a given disruption scenario, a set of links is first identified as candidates for capacity enhancement based on (i) their initial saturation levels in terms of volume to capacity ratios, and (ii) the overloading in terms of increased saturation that occurs due to the disruption. Second, the effect of capacity increase is evaluated for each candidate link by comparing the disruption impacts with and without increased capacity. Based on the evaluation the most effective of the mitigation actions can be identified.

We applied the methodology to  a case study of the high frequency public transport network of Stockholm. To evaluate the public transport system performance under varying conditions, BusMezzo, a dynamic public transport operations and assignment model was used.

The method presented in this paper could support policy makers and operators in prioritizing measures to increase network robustness by improving system capacity to absorb unplanned disruptions.

 

Click here for the full paper.

 

MIT transit group seminar

On Thursday, November 20, I had the privilage to present highlights from my research to MIT transit group led by Prof. Nigel Wilson and thereafter had the opportunity to disucss ongoing research activities with group members.

The seminar was entitled: “Unraveling and modeling the dynamics of public transport systems: Theory and applications”, where I briefly presented the transit operations and assignment model, BusMezzo, and its applications to service reliability and control, congestion and evaluation of increased capacity as well as service disruptions and the value of real-time information provision.

For a reduced version of the presentation, click here: MIT seminar 20112014 v1

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