Public Transport Network Design and Appraisal

- a case study of Porto

Álvaro Costa, Pedro Abrantes and Oana Grozavu SantosFaculty of Engineering, University of Porto

19th Annual International EMME/2 Users’ ConferenceSeattle, 19-21 of September, 2005

Contents

1. Introduction2. Re-designing bus network3. Network Appraisal Methodology4. Impact of LRT Network5. Impact of Strategic Bus Network6. Local vs. Global Accessibility7. Global Efficiency Indicators8. Complementarities between EMME/2,Enif and

ArcView9. Conclusions10. Further Research

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

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.

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

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

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

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

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)

iiD

iiDiD

DT

TGTTGTT

)(

ijijijijij InVehTTransferTWaitTWalkTGTT

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)

dTT20-10-30 - -16-16 - -8-8 - -4-4 - -2-2 - -1-1 - -0.5-0.5 - 0.5-0.5 - 11 - 22 - 44 - 88 - 1616 - 30

Linhas metro_a.shpAmp_conc.shp

dTT média global - cenário 20 vs cenário 10

Mapa nº 3

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

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

dTT média global - cenário 30 vs cenário 20

dTT30-20-30 - -16-16 - -8-8 - -4-4 - -2-2 - -1-1 - -0.5-0.5 - 0.5-0.5 - 11 - 22 - 44 - 88 - 1616 - 30

Linhas metro_a.shpAmp_conc.shp

Mapa nº 4

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

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

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

Subseccoes ine.shp

z190_53.shp-24 - -12-12 - -6-6 - -3-3 - -1-1 - 11 - 33 - 66 - 1212 - 24

Linhas metro.shp

#Y#

190

Análise da Acessibilidade a Partir da Zona 190 (5-3)

Análise da Acessibilidade a Partir da Zona 190 (7-3)

Subseccoes ine.shp

z189_73.shp-24 - -12-12 - -6-6 - -3-3 - -1-1 - 11 - 33 - 66 - 1212 - 24

Linha_39d_i.shpLinha_39d_v.shpLinhas metro.shp

#

190

#Y

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

Local vs. Global Accessibility

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%)

36.16

34.98

34.95

34 34.5 35 35.5 36 36.5

10

20

30

Sce

nar

io

Average generalized travel time (min)

198,951

162,949

154,650

33,347

36,352

0 50,000 100,000 150,000 200,000 250,000

10

20

30Sce

nar

ios

Pax-kms

bus

metro

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

1.45

1.44

1.41

1.39 1.4 1.41 1.42 1.43 1.44 1.45 1.46

10

20

30

Sce

nar

io

Average number of boardings per trip

7.45

7.17

7.91

6.60 6.80 7.00 7.20 7.40 7.60 7.80 8.00

10

20

30Sce

nar

io

walk time (min)

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”

 

Fleet size Veh-kms

    (AM peak hr)

Bus_0 517 7676

Bus_1 485 7350

delta -6.0% -4.2%

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

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

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

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