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Public Transport Network Design and Appraisal

Public Transport Network Design and Appraisal. - a case study of Porto. Álvaro Costa, Pedro Abrantes , Oana Grozavu and Sílvia Magalhães CITTA – Centro de Investigação do Território, Transportes e Ambiente 10th EWGT Meeting, Poznan, 13-16th September 2005. Contents. Introduction

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Public Transport Network Design and Appraisal

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  1. Public Transport Network Design and Appraisal - a case study of Porto Álvaro Costa, Pedro Abrantes, Oana Grozavu and Sílvia Magalhães CITTA – Centro de Investigação do Território, Transportes e Ambiente 10th EWGT Meeting, Poznan, 13-16th September 2005

  2. Contents • Introduction • Re-designing Porto bus system • Network Appraisal Methodology • Impact of LRT Network • Impact of Strategic Bus Network • Local vs Global Accessibility • Global Efficiency Indicators • Conclusions • Further Research

  3. 1.1. Introduction • Porto Metropolitan Area pop.: 1.2 mi • New light rail system (Metro do Porto) • New integrated ticketing system (Andante) • Need to restructure bus network for greater integration and efficiency • New network design based on “professional judgement” (heuristic method?) • CITTA commissioned to: • evaluate its public acceptability and efficiency • suggest improvements where necessary

  4. 1.2. Introduction - OR analogy • Starting point: existing STCP bus network (red) + metro (blue) • 81 bus lines (to be cut down to 50) • Problem: Guaranteeing public acceptability and increased efficiency while minimizing change • I.e., heavily constrained problem, but poorly defined constraints • Solution: Iterative, piece meal, client-driven approach (“trial & error”) to ensure feasibility of solution = optimization in the real world • Strong emphasis on GIS analysis of results.

  5. Change in bus service frequency (bue = increase) 2. Re-designing Porto bus system • Design criteria: • Shorten lines • Modal integration • Homogeneous frequencies • 80  50 lines • Result: • 17% veh-km reduction • Decrease in radial services • Increase in orbital services

  6. 3.1. Network Appraisal Methology • Public Transport Assignment Model (EMME/2) • Fixed demand from 2001 household travel survey • Network Scenarios: • 10: Bus0 • 20: Bus0 + Metro • 30: Bus1 + Metro • 3x: Busx + Metro • Accessibility analysis • Efficiency analysis

  7. 3.2. Network Appraisal Methology • Accessibility indicator (GIS plots) : Average generalized travel time by destination zone • Efficiency indicators: Fleet size, Veh-kms, Total trips (operator) Pax-kms, travel time, walk time, number of interchanges (users)

  8. 4.1. Analysis of Results - Impact of the LRT Network Change in accessibility between scenarios 10 and 20 • As expected, LRT brings about significant travel time reductions (up to 12 min) • Greatest benefits along LRT • Large gains up to a significant distance from LRT, because of bus-LRT difference in speed (25km/h vs 13km/h)

  9. 4.2. Analysis of Results – Impact of the LRT Network Change in bus passenger flows between scenarios 10 and 20 • General reduction in bus pax flows • Small increases in certain suburban/orbital routes • Potential complementary role of bus in new network

  10. 5.1. Analysis of Results - Impact of the Strategic Bus Network Change in accessibility between scenarios 20 and 30 • Significant travel time increases (≤ 8 min): poorer coverage or service transfer to private sector • Significant gains in some suburban zones (≤10 min): improved LRT access, successful integration ☺ • Gains from metro outweigh losses from new bus network in nearly all zones (special zones treated later) • Policy implication  Metro + Bus1 must be introduced at same time

  11. 5.2. Analysis of Results - Impact of the Strategic Bus Network Change in bus passenger flows between scenarios 20 and 30 • Reduction in radial flows, esp. around city centre, due to reduced frequency • Significant increases in orbital flows, esp. towards main metro interfaces • Explains gains away from LRT route  bus services play an important role as feeders to LRT

  12. 5.3.Analysis of Results – Impact on the pattern of trip interchanges Change in transfer boardings between scenarios 10 and 30 (red=increase) • Concentration of intechanges around key metro stations • Bus increasingly becomes a feeder mode to LRT. Bus-bus transfers decrease significantly • Policy implications: • Improve interchange facilities to take full advantage of new mode • Minimize distance between bus and metro stops

  13. Change in accessibility scenarios 1 to 3 Change in accessibility scenarios 2 to 3 6.1. Local vs Global Accessibility • Problem: Some zones lose accessibility from sce. 10 to 30 • Further investigation showed inconsistencies in network design: • Zones furthest away from metro miss out the most with the new bus network • Those zones also happen to be important centres for surrounding n’hoods

  14. 6.2. Local vs Global Accessibility Diagrams attempt to illustrate the problem • The new bus network improves access to metro stations, which in turn greatly improve access to distant parts of the city • Yet, reduced network coverage decreases local accessibility • As we started by looking at the whole metropolitan area, this problem went nearly unnoticed • Policy outcome: strengthen local bus services

  15. 7.1. Global efficiency indicators – User perspective • 3% mean travel time decrease from sc. 10 to 20 • Constant travel time from 20 to 30 • 1.5% mean travel distance decrease from sc. 10 to 20 • 1.5% mean travel distance decrease from sc. 20 to 30 • Notice significant pax-kms transfer to metro due to new bus network (+10%)

  16. 7.1. Global efficiency indicators – User perspective • Metro does not produce an increase in av. interchanges • New bus network actually reduces interchanges • But at the cost of greater walk access time • Still, no increase in travel time

  17. 7.2. Global efficiency indicators – Operator perspective • 14% decrease in fleet size requirements • 4.2% decrease in morning peak hour veh-kms travelled • Conclusion: Significant savings achieved, while maintaining or improving accessiblity by applying simple network design rules • “Operator happy, passengers happy”

  18. 8. Conclusions • Useful methodology, popular with decision makers and public • Benefits from LRT line are significant, and spread beyond the route • Scale of benefits depends on bus service design  bus plays an important feeder role in the LRT network • It is possible to achieve significant gains in accessibility by re-designing the bus system for better integration with LRT network • Furthermore,it is possible to do this while improving efficiency (inc. fewer resources) • Nevertheless there is a trade-off between local and global accessibility in some areas, which is not visible when analysing accessibility across whole area

  19. 9. Future research • Incorporate elastic demand model • Introduce outstanding operators and differentiated fare system • Develop optimization algorithms to find the “optimum network” • Test the impact of other policy measures, eg bus priority

  20. Questions & comments Pedro Abrantes CITTA Faculdade de Engenharia da Universidade do Porto pala@fe.up.pt See presentation on www.fe.up.pt/~pala from 20th Sept

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