Public Transport Network Design and Appraisal

1. Public Transport Network Design and Appraisal - a case study of Porto Álvaro Costa, Pedro Abrantes and Oana Grozavu Santos Faculty of Engineering, University of Porto 19th Annual International EMME/2 Users’ Conference Seattle, 19-21 of September, 2005

2. Contents • Introduction • Re-designing bus network • Network Appraisal Methodology • Impact of LRT Network • Impact of Strategic Bus Network • Local vs. Global Accessibility • Global Efficiency Indicators • Complementarities between EMME/2,Enif and ArcView • Conclusions • Further Research

3. Introduction • Porto Metropolitan Area pop.: 1.2 mi • New Light Rail (Metro do Porto) • New integrated ticketing system (Andante) • Need to re-design the bus network to improve integration and efficiency • New network design based on “professional judgment” (heuristic method?) • FEUP was commissioned to: • evaluate its public acceptability and efficiency • suggest improvements

4. Introduction • Starting point: existing STCP bus network (red): 81 bus lines (to be cut down to 50) • Driving force: introduction of the new light metro network (blue) • Problem: Guaranteeing public acceptability and increase efficiency (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 (blue = increase) Re-designing bus network • Design criteria: • Short lines • Modal integration • Homogeneous frequencies (10min) • 20% veh-km reduction • Result: • Decrease in radial services • Increase in orbital services

6. PT Modeling Approach • Public Transport Assignment Model (EMME/2) • Detailed zoning system: 350 zones covering an area with aprox. 1 million inhabitants (City of Porto: 105 zones and 350 000 inhabitans) • Household travel survey from year 2000. Fixed demand • The match between the two zoning systems was done applying a gravity-type model

7. PT Modeling Approach Network Characteristics: • 350 centroids • 3266 regular nodes • 8051 links • 7 modes • 9400 transit line segments • 140 lines: 81 present bus lines, 50 future bus lines, 4 metro lines, 4 train lines, 1 elevator

8. PT Modeling Approach • Network Scenarios: • 10 (Reference case): Current STCP Network + Suburban Railways • 20: Reference Case + LRT • 30: STCP Strategic Network + Suburban Railways + LRT • 3x: Modifications of STCP Strategic Network + Suburban Railways + LRT • Accessibility analysis and efficiency analysis • Impact of LRT network (Scenario 20 vs. 10) • Impact of STCP Strategic Network (Scenario 30 vs. 20) • Impact of the new transport system (Scenario 30 vs. 10) • Impact of the modifications on the Strategic Network

9. 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)

10. 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)

11. 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

12. Impact of the Strategic Bus Network Change in accessibility between scenarios 30 and 20 • 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 + SN must be introduced at same time

13. Impact of the Strategic Bus Network Change in bus passenger flows between scenarios 30 and 20 • 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

14. Impact on the pattern of trip interchanges Change in transfer boardings between scenarios 10 and 30 (red=increase) • Concentration of interchanges 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

15. 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 centers for surrounding neighborhoods

16. 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

17. 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%)

18. 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

19. Global efficiency indicators – Operator perspective • 6% decrease in fleet size requirements • 4.2% decrease in morning peak hour veh-kms traveled • Conclusion: Significant savings achieved, while maintaining or improving accessibility by applying simple network design rules • “Operator happy, passengers happy”

20. EMME/2 - Enif - ArcView • ArcView is a great help in the construction of EMME/2 network files • ArcView is a good tool for “translating” in a friendly image the results of the assignments (especially OD pairs related data) • In both cases, Access is a priceless help • Enif is a useful tool for analyzing data regarding interfaces, boardings, alightings, flows on links

21. Conclusions • The methodology is understandable to decision makers • 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 and productivity by re-designing the bus network for better integration with LRT network • Nevertheless there is a trade-off between local and global accessibility in some areas, which is not visible when analyzing accessibility across the whole area

22. Future research • Schedule the implementation • 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, e.g. bus priority

23. Questions & comments Álvaro Costa < afcosta@fe.up.pt> Faculdade de Engenharia da Universidade do Porto Oana Grozavu Santos <oana@fe.up.pt> Faculdade de Engenharia da Universidade do Porto