Design of multimodal transport systems: Setting the scene: Review of literature and basic concepts

(1)

The Netherlands Research Scho~ r Transport, Infrastructure and Logistics

~RAI

,~.,

TFA

200 De ign

mul -modal

tran

rt syste

Setti ng tli scene:

Review of li rature and bas concepts

!

r /

~/

,

'"

(2)

..

(3)

Design of multimodal transport systems

Setting the scene:

Review

of

literature and basic concepts

"

•

(4)

(5)

Design of multimodal transport systems

Setting the scene:

Review of literature and basic concepts

TRAIL Research School

Author: Ir. R. van Nes Transportation Section

(6)

TRAIL Studies in Transportation Sciance Series N°. S99/3 Editors:

EditorialBoard:

Prof.dr.ir. P.H.l. Bovy Prof.dr.

I.A.

Hansen

Prof.dr.ir. R.E.C.M. van der Heijden Prof.dr. G.J. Olsder

Prof.ir. F.M. Sanders

The Netherlands TRAIL Research School Delft University of Technology'/

Erasmus University Rotterdam TRAIL-office Kluyverweg 4 P.O. Box 5017 2600 GA Delft The Netherlands Telephone Telefax E-mail Internet +31 (0) 152786046 +31 (0) 152784333 mailbox@TRAIl.tudelft.nl http://TRAIL.tudelft.nl

Sales and distribution: Delft University Press P.O. Box

2600 MG Delft

Telephone: +31 (0)152783254 Telefax: +31 (0)152781661 ISBN: 90-407-1999-3

@ Copyright by The Netherlands TRAIL Research School. No part of this book may be reproduced in any form by print, photoprint, microfilm or any other means without written permission of the publisher: The Netherlands TRAIL Research School.

TRAIL Is accredited by tIle Royal Netlle~ands Academy of Arts and Scienees and is a co-operative venture in which seven faculties of the Delft Unlverally of Technology partieipate: Civil Engineering and Geoseienees (CEG), Design, Engineering and Production (DEP). Architecture (ARC),

Information Technology & Systems (lTS), Aerospaee Engineering (AE), Technology, Policy & Management (TPM), Applied Seienees and aTB Research Institute for Housing, Urban end Mobility studies; four faculties of the Erasmus Unlverally ol Rotterdam: Economie Scienees (FES), Business Administration (FBA), Social Seiences (FSS) and Law (FL), and one faculty of the Unlverslty of Groningen: Behavioural and Social Seienees (BSS).

(7)

Preface

This publication is a result of the research program "Seamless Multimodal Mobility" carried out within The Netherlands TRAIL Research School for Transport, infrastructure and Logistics, and financed by the Delft University of Technology.

The "Seamiess Multimodal Mobility" research program will provide tools for the design and operation of attractive and efficient multimodal personal transport services. This report presents results of a study that is part of project 2 "Design theory for mixed multimodal networks". The objective ofproject 2 is to develop theories and techniques to design multimodal transport service networks and multimodal transfer points. The focus in this report is on transport network design only.

The objectives of this report are twofold. First, this report presents an overview of ideas, and concepts related to multimodal transport, transport networks and transport network design. As such, it can be seen as a reference for other projects in the Seamless Multimodal Mobility program. Second, a philosophy for multimodal transport network design has been developed. The report presents the arguments to narrow the scope for further research on the subject of multimodal transport network design. Both objectives,

pres enting an overview and narrowing the scope, can be seen as setting the scene for tbe main part of the study: the development of a design methodology for multimodal transport networks.

Finally, the author would like to thank Piet Bovy for his comments. These remarks were essential in changing a set of, sometimes miscellaneous, ideas into a coherent report.

(8)

ii TRAIL Studies in Transportation Science

(9)

---Summary

Multimodal transport is an important theme in transportation science. Multimodal transport network design is one of the topics that are studied. This report provides an overview of ideas and concepts related to multimodal transport, transport networks, and transport network design. Furthermore, the concept of hierarchical levels in transport networks is discussed. The report is based on an extensive literature survey and on additional analyses. Using this overview, the scope of the research project "Design of multimodal transport networks" is narrowed and topics for further research are defined. Multimodal transport is a subject that has been studied in the Netherlands for several years. Starting with the Second Plan on Traffic and Transportation (SVV II), ideas such as transferia, that is, multimodal transfer points, and bike&ride have been analysed. Where should tI;an feria be allocated and what would be the im~t.on.çaI.mobili~ case that existing barriers for com imng bicycles and public transport would be eliminated? Such studies showed the need to develop a general framework for the analysis of multimodal transport systems, which has been done accordingly. Typical elements of this framework are the choice of tours instead of trips as basic study subject and the difference between base-bound modes, such as bicyc1e and private car, and non-base-bound modes, for instance, car passenger and public transport. This framework has been applied in a theoretical case to assess the potentialof multimodal transport from the traveller's point of view as well as from the transport service provider's point of view. Transportation planners and politicians propose a multimodal approach to solve transportation problems. Multimodal transport is seen as an important concept to improve the accessibility of city centres: it will increase the use of public transport for trips to and from city centres. Practical examples are the concept of transferia at city borders and P&R-facilities. The Dutch govemment focuses on the development of multimodal transport services for business trave!. The main line of reasoning is that since business travelIers have a high value of time, they can afford to pay the extra costs involved with the introduction of a multimodal transport service provider. It is interesting to notice that a distinction can be made between multimodal transport as a transport system, consisting of modes, networks, and transfer facilities, and multimodal transport as a typical transport service for specific populations.

The current share of multimodal transport in actual travel behaviour is smalI. Only 2.9 % of all trips can be considered to be multimoda!. This percentage increases up to 20 % if only inter-urban trips to and from the four main cities in the Netherlands are considered.

Given the literature on multimodal transport, a multimodal transport network can be seen as a hierarchical network structure. Such a structure consists of different network levels, each of which offering transport services between the nodes of that specific level and offering transport services to and from the next higher network leve!. Transfers between transport services are at the same time changes between network levels. Typical examples are the transfer at city borders from private car (regional or national transport

(10)

IV TRAIL Studies in Transportation Science

system) t~ public transport towards the city centre (urban transport system), and the transfer from train to urbàn bus or bicyc1e.

Translzort nètWorks can be described as consisting of nodes, links and lines, and as network structureSilaving characteristics such as access density, network density, and so on. The concept using nodes 'and links'is well lmown .The latter concept has been studied more extensively using literature on arialytical network optimisation modeis. Such models describe how to determine optimal values for key network design variables. They offer, therefore, insight into what the key design variables are, what the characteristics of these design variables are, and how these design variables influence network performance characteristics. It is interesting to notice that most studies focus on single level networks. 'The morphological network structures prove to be an essential feature with regard to the network performance characteristics. Furthermore, the following network design variables have been defined:

• Access density: number of.entry and exit points per unit area; • Network density: length of the network per unit area; .

• Network speed: average speed for a trip between an entry and exit point; • Frequency: nurilber of moments per unit of time that the network can be used

for travelling.

Transport netWork design is a subject that has extensively been studied. Three approaches can be identified:

• Design methodologies. This approach focuses on the use of· planning knowledge and experience. Basically there are two methods: methods starting with the geographical structure and methods starting with specific network structures. Most design methodologies deal with inter-urban transport networks and distinguish a hierarchical network structure.

• Optimisàtion modeis. In this ' approach the network. design problem is formulated mathematically. A common formulation is, which links or lines have to be inc1uded in the network in order te;> achieve a formulated objective? Although the formulation seems simpie, the solution of this mathematical problem is difficult. It has been shown that no algorithms exist that can guarantee to find an optimal solution within areasonabie computation-time. As aresuit thère is strong focus on all kind of search techniques to find near optimal solutions. These techniques range from simple heuristics to complex mathematical procedures. Many types of transport networks have been studied. Studies on multimodal transport networks are most1yconc~med with freight traffî.c. The transfer between modes

IS

then modelled using transfer links between the different networks. The resulting problem formulation shows, therefore, a strong similarity

witl:t

the unimodal road network design probierrt. Finally, it is intetesting to notice that nearly all optimisation modeis ' deal with single level networks. The concept of a hierarchical network structure is only used to split a large network design problem into a set of smaller ones, which are easier to solve.

(11)

Summary v

• Decision support modeis. This approach can be considered as a combination of the other two. Knowledge and experience of public transport planners is collected into knowledge databases. Starting with an existing transport network or a first design, mathematical models are used to determine thy quality of a specified network. The knowledge database and mathematica! techniques are used to fmd out whether the network design can be improved. The transport planner, however, decides which improvements are accepted. A graphical user interface is an important characteristic of decision support modeis.

The studies on optimisation models indicate that, although no optimal solution can be guarariteed, the multimodal transport network design problem is solvable. The main problem is to develop a model that gives an adequate description of the way travelIers will use a multimodal network. A typica! problem, for instance, is the sequence of modes that are used within a tour. Given such a simultaneous moda! split and assignment model, numerous mathematical techniques are available to determine a near optimal solution. An interesting difference between design methodologies and optimisation models is that design methodologies are primarily used to develop a complete network structure, more or less independent of the existing infrastructure, and that a limited amount of data is used. Optimisation modeis, on the other hand, usually start with aspecific geographical network structure and design a transport network given aspecific travel demand pattem. The initial network used in the design process implicitly determines network characteristics such as access density and network density. Furthermore, the use of this demand pattem in optimisation mode Is, either fixed or variable, might lead to suboptimal solutions if substantial changes in the demand pattem occur. Design methodologies seem to be more robust, and seem more promising for determining the key elements of a multimodal transport network.

The subject of levels in transport networks is divided into three parts. The analysis of

spatial structures shows that different levels can be distinguished, but that there is not one single mechanism that determines these levels. It is concluded that given the focus ofthe study, that is, the design of multimodal transport networks, the variety in spatial structures can be dealt with using a scale-factor 3 for distance related characteristics. Analysis of hierarchy in road networks results in a scale-factor 3 too. A simple mechanism has been found, that might make the concept of such a scale-factor quite robust. For public transport networks no scale factor was found. Because of the transfers due to changing to and from the higher level network, the analogy to road networks is not applicable. The assumption that a hierarchical public transport network is completely self-supporting, that is each network level serves as an access mode for the next higher network level, is shown to lead to very large scale-factors. It is coricluded that public transport networks are strongly dependent on spatial structures änd especially on the allocation of major urban centres, at least for inter-urban transport. As aresuit the scale-factor 3 found for settlement structures can also be applied to inter-urban public transport networks.

(12)

vi TRAIL Studies in Transportation Science

Given the overview of literature and the additional analyses, it is conc/uded that multimodal transport has astrong potential for trips to and from cities having a trip di$tance betwe.en 7.5 and 75 to 100 i<:ilometres.

In transport network design there is already a significant amount of techniques available to determine a near optimal transport network, being a road network or a public transport network. What is lacking, however, is sufficient knowledge ofwhat the constraints are in terms of the key network design variables, such as access density, network density, design speed, and time accessibility.

Overall it is concluded that, with regard to inter-urban transport, spatial structures and transport network structures are robust over time. Multimodal transport will not influence the mechanisms that have resulted in these structures, and still govem these structures. The main design problem for inter-urban multimodal networks is then reduced to allocating transfer nodes only. There are; however, only a limited number oflocations for

multimodal transfer points: .

• Existing railway stations in city centres: transfer between urban transport systems and regional and national publictransport networks;

• City borders: transfer from the regiönal and national motorway network to the high quality urban ?ublic transport network;

• Betweèn cities in non-urban areas: transfer between the local transport system ·and the national public transport network. However, it should be guaranteed that the travel times at the nationallevel will be short enough andlor that the . demand generated at such a transfer point is significant compared with the

demand of the existing stops of the national transport system.

The conclusions with regard to the inter-urban transport networks may be verified further using empirical data. For urban agglomerations the concept of hierarchical transport systems is not clear yet. Further research will fuerefore focus on the characteristics of the key network design variables with special attention for large urban agglomerations.

(13)

1 INTRODUCTION ...

.

...

.

... 1

2 MULTIMODAL TRANSPORT SYSTEMS ...

.

... 3

2.1 Some terminology ... 4

2.2 Theoretical possibilities for multimodal transport ... 6

2.2.1 Typical multimodal concepts ... 6

2.2.2 Framework for multimodal transport systems ... 9

2.2.3 Application ofthe framework ... 12

2.3 Practical possibilities for multimodal transport ... ,. 13

2.4 Analysis ofthe Dutch National Travel Survey ... 16

2.4.1 Multimodal trips ... 16

2.4.2 Trip chains ... 19

2.5 Discussion and conclusions ... 20

2.6 References ... 21

3 TRANSPORT NETWORK DEFINITIONS AND

CHARACTERISTICS ... 25

3.1 Definitions ... 25

3.1.1 Transport networks ... 25

3.1.2 Transport network representation ... 27

3.2 Transport network characteristics ... 28

3.2.1 Descriptive characteristics ... 28

3.2.2 Output characteristics ... 30

33 Analytical modeIs ... 32

3.3.1 Road networks ... 32

3.3.2 Public transport networks ... 37

3.4 Discussion and conclusions ... 40

4 TRANSPORT NETWORK DESIGN ... .45

4.l Basic characteristics of the network design problem ... 45

4.2 Design methodologies ... 47

, 4.2.1 Area oriented approaches ... 47

4.2.2 Network oriented approaches ... 54

4.2.3 Conc1usions ... 55

(14)

viii TRAIL Studies in Transportation Science

4.3 Optimisation models ... 56

4.3.1 Basic characteristics ... 56

4.3.2 Road networks ... 57

4.3.3 Public transport networks .~ ... , ... 62

4.3.4 Multimodal networks ... 67

4.3.5 Airline networks ... 68

4.3.6 Demand responsive transport systems ... 70

4.3.7 Conclusions ... 71

4.4 Decision support systems ... 71

4,5 Discussion and conclusions ... : ... 73

5 LEVELS IN TRANSPORT NETWORKS ... 79

5.1 Levels in spatial structures ... 79

5.1.1 Central place theory ofChristaller ... 80

5.1.2 Economic perspective ... 82

5.1.3 Role oftransportation ... 83

5.1.4 Location of agglomerations ... 83

5.1.5 Self-organising structures ... 84

5.1.6 Morphological approach ... 84

5.2 Levels in road networks ... : ... 85

5.2.1 Some basic mechanisms ... 86

5.2.2 Reducing travel time for grid networks ... 86

5.2.3 Reducing travel time for triangular networks ... 89

5.2.4 Literature review on road network levels ... 89

5.3 Levels in public transport networks ... 91

5.3.1 Analogy to road networks ... 91

5.3.2 Literature review on public transport network levels ... 92

5.3.3 Strict hierarchy in public transport networks ... 94

5.4 Levels defined using trip distributions ... 95

5.5 Discussion and conclusions ... , ... 99

6 DISCUS SION

AND CONCLUSIONS ... 105

6.1 Characteristics of the study area ... 105

6.2 Transport network design strategies ... 107

6.2.1 Design methodologies ... 1 07 6.2.2 Optimisation modeis ... 112

(15)

Contents ix

6.3 Subjects for further analysis ... 114

6.3.1 Empirical analysis.' ... 114

6.3.2 More detailed study ofinter-urban networks ... 114

6.3.3 Multimodal networks in urban agglomerations ... 115

Appendix A: Analyses of the Dutch National Travel Survey

Appendix B: Mathematical formulation of the public transport network

design problem Glossary

(16)

(17)

Chapter 1 INTRODUCTION

A promising soIution to solve accessibility and mobility problems is that of combining private and public transport to form multimodal transport systems. In combining these modes new possibilities might emerge because the strengths of the various systems will be pooled while their weaknesses are minimised. This could in turn become a good alternative to the existing situation of competition between private car and public transport. Although multimodal transport already exists, for instance in the form of systems such as Park & Ride, the Traintaxi and the Odyssey-card, the share in the transport market is still very limited. It is expected that in the near future fundamental changes will come ab out. Using telematics it will be possible to offer travelIers all kinds of information before and during a trip. In that way the traveIler will be able to select the best combination of modes for reaching his destination. New strategies in scheduling and in traftic management will enable transport companies to guarantee seamless transfers. The increasing amount of attention being paid to marketing in transportation leads to transport companies focusing on specific groups of travelIers. Multimodal transport will be one oftheir specialities.

The networks of the different modes will be critical regarding the development of multimodal transport. They will determine the transportation options. All the existing transport networks have developed individually and are, to a large degree, historically determined. Combining modes and networks was never an issue in transport network design. Simply connecting the networks at locations where networks meet, such as at existing railway stations, will not be sufficient when it comes to the matter of creating a

truly multimodal network. .

The aim of our research is to determine what a real multimodal network should look like. The first step in the study is setting the scene: what are the characteristics of multimodal transport, what are the characteristics of transport networks, and how can transport networks be designed. This step consists of an extensive literature study on multimodal transport and on network design, as weil as of an exploration of possible lines of research.

(18)

2 TRAIL Studies in Transportation Science

It is the purpose of this report to present the results of the analyses done so far. The results are divided into 6 chapters. The first chapter (Chapter 2) is on multimodal transport and discusses three different points of view: the state of the art in transportation science, the ideas in planning practice, and the present role of multimodal transport in actual travel behaviour. Chapter 3 is concemed with transport networks: what are their characteristics and how are transport networks analysed. The analysis inc1udes infrastructure networks for private modes such as car and bicycle as well as service networks for public transport. The subject of the design of transport networks is described in Chapter 4. Different design techniques such as design methodologies,

optimisation models and decision support systems, are discussed, and a distinction is made between networks for individual transport, for public transport and for multimodal transport. Since most studies on transport network design focus on single level networks,

the issue of levels in spatial structures and in networks is discussed separately in Chapter 5. Finally, in Chapter 6, the main conc1usions from the previous chapters are discussed and possibilities for further research are presented.

(19)

Chapter 2 MULTIMODAL TRANSPORT SYSTEMS

Usually, traveIlers may choose between different modes for a specific trip, for instance, either private car or public transport. In a multimodal· transport system, however, traveIlers can also choose for a combination of travel modes. This concept is not as new as might be thought. Theoretically, all trips by public transport can be defined as multimodal trips. This is especially true for trips made by train. The trip to and from the railway station can be made by different modes, such as bicycle, private car, taxi, bus, tram and metro. Special services have been developed to accommodate these modes at railway stations. Examples of such services are bicyc1e parking lots, Park & Ride-facilities, and the introduction of the Traintaxi, i.e. a share-a-ride concept for trips to and from railway stations. The allocation of stops for bus, tram and metro has, of course, always been an important issue in the design of railway stations.

The main goal of the attention paid to the accessibility of railway stations is to increase railway patronage. The Dutch Railway Company (NS) played, obviously, an important role in the design of railway stations and in the development of special services for taxi and private modes such as bicyc1e and private car. Other objectives such as accessibility of city centres and environmental purposes were not systematically taken into account, and the existing railway facilities were dominant in the allocation of specific services.

It is expected, however, that multimodal transport could be more than just connecting other transport systems to the existing railway network. Many studies exist that analyse the possibilities and the limitations of multimodal transport in a broad view. Section 2.2 gives a state of the art of studies in the field of transportation science. At the same time, transportation planners and authorities, both on the local and on the national level, have presented their ideas for multimodal transport. These concepts are discussed in Section 2.3. Section 2.4 shows the actual role of multimodal transport in travel behaviour. Finally, the conc1usions that can be drawn given these three viewpoints are presented in Section 2.5. But first,attention is paid to some of the terminology that is used in this report.

(20)

...

4 TRAIL Studies in Transpûrtatiûn Science

.

2.1 Some terminology

All impûrtant instrument fûr the analysis .of the transpûrtatiûn system is the layer mûdel. Figure 2-1 gives a representatiûn .of the layer mûdel based .on the ideas .of Schûemaker et al. (1999). The tûp layer represents the activities emplûyed by peûple. Fûr many activities, it is necessary tû make a trip in .order tû reach the lûcatiûn where the activity can be emplûyed, resulting in a trip. pattem. The secûnd layer cûntains the transpû-rt services that make it pûssible tû travel. A typical example .of a transpûrt service is public transpûrt. These transpûrt services result in a trip pattem .of vehicles. The bûttûm layer represents the traftic services, that is, the services necessary tû make an actual trip. Netwûrks are essential p~s .of bûth transpûrt services and traffic services. A public transpûrt netwûrk is a typical example .of a transpûrt service netwûrk and a rûad network i:; clearly a part ûfthe layer 'traffic services'.

Figure 2-1: Layer model ofthe transportation system

Between these three layers there are twû markets: the transpûrt market between the activities and the transpûrt services, and the traJfic market between the transpûrt services and the traffic services. The transpûrtatiûn market describes the interactiûn between the demand fûr and the supply .of transpûrt services. In transpûrtatiûn mûdelling this market is usually· defined as transpûrt demand mûdelling (distributiûn and mûdal split mûdelling). Similarly, the traffic market describes the interactiûn between the demand fûr traffic services and th~ s~pply .of traffic services. Using, again, the analûgy with transpûrtatiûn mûdelling, the traffic market cûrrespûnds tû the traffic assignment. It is interesting tû nûtice that using the same analûgy.the public transpûrt assignment is a part ûftranspûrt services layer and is nût a descriptiûn ûfthe traffic market.

(21)

Chapter 2 Multimodal transport systems 5

Multimodal transport is essentially a transport service. Therefore, the concept of transport services deserves more specific attention.(! transport service offers transportation from one location to another. The characteristics of the actual service that is offered may vary

from just putting a vehic1e at the traveller's disposal (e.g. rent-a-car service)to

performing the complete trip (f~r example, a taxi service). The main goal, as far as the

traveIler is concemed, is to travel from his origin to his destinatio]JIf we look at a

transport service from the traveller's point of view, we can assume that the traveIler will

judge a transport service by all trip attributes and not just by those arranged by the transport service provider. Therefore, transport services are not only limited to public transport companies. The use of arental car and the use of a private car are transport services too. The difference between these types of transport services is that a public transport company determines the main characteristics of a trip, while, for instance, a rent-a-car company influences only the characteristics of the vehic1e and its availability. In the case of a private car, the driver provides his own transport service. The remaining trip attributes are dictated by the characteristics of the available physical infrastructure for that specitic type of service.

A transport service is therefore characterised by three components:

1. Conveying vehic1e, determining maximum speed (partially), comfort and

costs;

2. Network, that is the service network andlor the physical network, describing

the available transport service facilities in space and in time;

3. Service attributes, for instance features such as the availability of travel

information, the quality of the services offered, and the travel costs; determine the service components of a transport service.

The network description inc1udes aspects such as:

• Space accessibility: where can a user enter. and leave the transport service;

• Time accessibility: when can a user actually use the transport service;

• Travel speed or travel time: how long does it take to travel from an entry

point to an exit point.

An overview of transport services is presented in Table 2-1. It c1early shows the shifting

influence of traveIler, transport service provider, and infrastructure, when it comes to determining the characteristics ofthe transport service as a whoie.

A multimodal network is essentially a transport service network. The transport services are complementary to each other. However, due to the shifting relationship between the service network and the physical network, the traftic network primarily determines the characteristics of specific modes. In general, when dealing with public transport networks, the focus is on service networks, whereas when modes such as private car or bicyc1e are concemed, traftic networks will be the main object of study. Therefore, this report will consider both network types: transport service networks and traffic networks.

(22)

6 TRAIL Studies in Transportaticin Science

Finally, becaiJse. of the readability the tenn mode in this chapter is more or less equivalent to the tenn -transport service, or put in another way, transport services are primarily d~finedby the vehicle type that is used.

Table 2-1: Characteristics of different transport services

Transport service Service Network Vehicle

Provider

Walk trip TraveIler Authorities: Footpaths Not relevant Bicycle trip TravelIer Authorities: Cycle paths TravelIer: Bicycle Private car, driver TraveIler Authorities: Road network TraveIler: Car Private car, Driver Authorities: Road network Driver's car passenger

Rent-a-car Rental Rental company: rental Company's car

company locations

Driver Authorities: road network

Taxi Taxi-company Authorities: Road network Taxi-company

Bus Public transport Authorities: road network Public transport company Public transport company: company: e.g.

Bus network Bus

Metro Public transport Authorities: rail network Public transport company Public transport company: company: e.g.

Metro network Metro

Regional bus Public transport Authorities: road network Public transport company· Public transport company: company: e.g.

Bus network Bus

National railways Public transport Authorities: rail network Public transport company Public transport company: company: e.g.

Rail network Train

2.2 Theoretical possibilities for multimodal transport

2.2.1 Typical multimodal concepts

2.2.1.1 Transferia

In the Second Plan on Traffic and Transportation (SVV 11) of the Ministry of Transport, Public Works, and Watennanagement, the concept of Transferia was introduced. The objective of transferia is to reduce car mobility and therefore to improve the

(23)

environmental quality, and at the same time to reduce congestion on the main routes to the economically important centres. Transferia can be defined as facilities dedicated to the transfer from private car to public transport. In this definition public t~anspor:t includes all modes available for public transport and not only railways. . The transfer between private car and public transport should be as pleasant as possible. Transferia, therefore, not only consist from necessary elements such as parking facilities and railway, bus, tram or metro stops, but also include special services in order to make the use of transferia more attractive. Examples of such services are information centres, small shops and fast-food facilities.

Egeter et al. (1990) developed the concept of Transferia further. They distinguished four different types of transferia (see Figure 2-2):

1. Located on the main routes to the major cities;

2. Located in predominantly rural areas and offering public transport facilities to important cities in the Randstad (field transferia);

3. Located close to urban concentrations (mainly existing P&R facilities); 4. Located in rural areas outside the Randstad.

Type 1

Type 3

o

Type 4

(24)

The order of these four types is' strongly related to their expected potential. Transferia close to the major cities are likely to be used often and can result in a reduction of the congestion on the main' routes to these cities if these transferia are located before the route" segments where" congestion might occur. The effect on the total amount of car kilometres, however, may be limited due to the fact that the main part of the trip will still

'be made by private car. Public transport wil! be used as an egress mode for the motorway system. Field transferia may have the advantage that private car will only be used as an access mode to the public transport system, which will then be used for the main part of the trip. Since field transferia are mainly located in more rural areas, the amount of trips, however, may be limited. The potentialof the other two categöries may be limited too, because of the fact that the number of trips, for which they can be used, wil! probably be small.

Van Binsbergen et al. (1992) developed a methodology to allocate transferia, which consists of fow' steps:

1. Selectión of suitable destinations: good access by public transport and sufficient transport demand;

2. For every possible destination: Selection of relevant origins in such a way tha! a limited number of corridors will result.

3. For every corridor: Selection of optimal location within the corridor and ca1culation ofthe expected number oftravellers for each altemative;

" 4. For every locatiop: Determination of the effects on accessibility and the

" environment.

The methodology was applied to the Netherlands (steps 1,2 and 3 (partially» and to the corridor Rotterdam - Noord-Brabant West (steps 1 up to step 4). These analyses showed that a systematic approach would lead to a consistent system of transferia, without interference between indivi<Jual transferia. Furthermore, it was found that in addition to the existing railway system Jast bus lines were necessary and that several existing P&R-locations were not suitable as transferia. Finally, they conc1uded that transferia near the main routes to the major eities might easily be realised, as theymight lead to better use of existing local public transport systems. The realisation of field transferia, on the other hand, could be more problematic, since field transferiawould often lead to extra stops on regional or national public transport lines, and hence to 10nger travel times for passengers who are already travelling on these lines.

2.2.L2 Public tran5port and bicycle

Another multimodal approach initiated in the SVV 11 is the combination of public transport for the main part of the trip and bicycle as access or egress mode. Nägele et al. (1992) studied the motivation of car users for not using the combination of public transport and bicyc1e. They gave special attention to the use of the bicycle as an egress mode. They found that the combination of both modes was promising. In order to make people switch from private car to public transport and bicycle, it would be necessary to provide good facilities such as an integrated fare-system and fixed parking 10ts.

(25)

Furthermore, the public transport system itself should be improved in terms of travel speed, frequency and reliability.

Van Goeverden & Egeter (1993) found that the combination of public transport and bicycle would lead to a reduction of car mobility of approximately 1.2 %. The effect of bicycle as an egress mode near the destination was nearly twice as important as the effect of bicyc1e as an access mode. Furthermore, the combination proved to be successful for trips ranging from 10 to 40 kilometres.

2.2.2 Framework for multimodal transport systems

Transferia and the combination of public transport and bicyc1e can be considered as typical examples ofmultimodal transport. They give, however, a fragmented view on the possibilities and limitations of multimodal transport and they do not give a complete view on the possibilities of the concept as a who Ie. These possibilities were studied by Egeter et al. (1994).

Egeter et al. (1994) developed a theoretical framework for the analysis of multimodal transport systems. Using this framework they selected a number ofpotentially interesting combinations of travel modes. In the framework a distinction was made to the characteristics of demand for and supply of transport.

In the analysis ofthe demandfor transport, Egeter et al. used tours rather than trips as the travel unit. This point of view is based on the fact that the mode choice when leaving home will determine the mode choice for the rest of the tour as well. Furthermore, the characteristics of a part of a tour may determine the mode choice for the whole of the tour and vice versa. F or example, when the first trip of a tour is made by public transport, transport means such as private car or bicyc1e are no longer available for the remainder of the trips of the tour. The second situation occurs when, for instance, the second trip can only be made by private car. In that case it is likely that private car will be the best alternative for the whole of the tour.

The impact of the availability of vehicles led to the concept of base-bound modes. These are transport modes that can only be used given aspecific location, mostly the home address, and should return at that location at the end of the tour. Examples of base-bound modes are private car and bicyc1e, but also rent-a-car of rent-a-bike. Typical non-base-bound modes are public transport and taxi.

Furthermore, Egeter et al. used the concept of lifestyles as a characteristic of a traveIler or of a tour. The lifestyle would determine the importance of each of the main attributes of a tour: travel time and reliability, comfort and costs. Other characteristics of the demand for transport inc1uded in the analysis were socio-geographic characteristics combined with accessibility to railway stations, trip lengths and time schedules for the activities within the tour.

(26)

In the description of the supply of tro:nsport Egeter et al. make a distinction between functional ançl technical characteristics (see Table 2-2).

TaPle 2-2: Functional and technical characteristics distinguished by Egeter et al (1994)

:

.

Transfers;

•

Comfort;

•

Costs;

(27)

A multimodal combination was considered to be interesting if the combination proved to be more attractive than unimodal transport. The analysis showed that, when only simple tours were taken into account, eight combinations had significant potential (see Table 2-3). For three combinations it is necessary that a bicycle is available at the transfer point close to the destination and there are three combinations for which it is required that a car is parked at a transfer point close to the origin or home address.

Table 2-3: Attractive multimodal combinationsjor simple Q-D-tours (Egeter et al., 1994)

Access mode Mainmode Egress mode

Bicycle Private car Public transport or

Demand responsive transport systems Bicycle Public transport or Bicycle

Demand responsive transport systems

Public transport or Private car

-Demand responsive transport systems

-

Private car Public transport or

Demand responsive transport systems

-

Private car Bicycle

Bicycle Private car

-Bicycle Public transport or

-Demand responsive transport systems

/

-

Public transport or Bicycle

Demand responsive

, transport systems

The results for complex tours were more or Ie ss identical. A single mode will be used for the main part of the tour, usually private car or public transport, in combination with another mode, mostly bicycle, public transport or demand-responsive transport systems, as an access mode or as an egress mode for aspecific destination.

A qualitative analysis by Egeter et al. of the sensitivity of these findings to the characteristics of the demand for transport, showed that multimodal transport might be especially interesting for traveIlers who have a high value of time. TraveIlers, who are sensitive to travel costs, can opt for combinations of public transport and bicycle. When only travel comfort is considered, multimodal transport can not be shown to be of any importance. Van Goeverden et al. (1998) showed that time is an importànt trip attribute for more than 80 % of all trips.

(28)

Looking at the travel distance, the analysis by Egeter et al. showed that the length of the longest .trip .af the tour should be 3 kilometres at least and favourably more than 30 kilometres. The social-geographic characteristics led to evident results, for instance, whert theaccessibility for public transport was high, public transport was included in the multimodal trip chain. The time-schedule for the activities within the tour showed no significant effect on the results.

The study of Egeter gives a systematic view on the complexity of multimodal transport systems. The study has, however, three serious restrictions:

• The different combinations have been rated on a scale consisting of three categories only: A, Band C. The actual values of, for instance, travel time or waiting time, Were not taken into account.

• The concJusion that a certain multimodal combination might be interesting was determined by the number of categories of the demand for transport for which the combination proved to be the best. The actual demand, described by the number of tours, was not considered.

~ In the selection of the basic mode types, car-passengers were excluded on the argument that the characteristics of this mode are equal to those of the basic mode private car. Multimodal combinations included car-passengers were , therefore not analysed. There is, however, a significant difference between private car and car passenger, since private car is a base bound mode and car passenger is not base bound.

2.2.3 Application of tbe framework

As a follow up to the study of Egeter et al., Mu-Consult (1996) studied the possibilities for developing a multimodal transport system using this framework. This study included four analyses: ' .

1. Reformulation of the framework developed by Egeter in order to present the concept to traveIlers and transport providers;

2. Quantification ofthe share ofmultimodal transport nowadays. 3. Assessment ofthe appraisal oftravellers by means ofa case study;

4. Assessment of the interest of transport providers to develop multimodal transport services;

While reformulating the framework developed by Egeter, Mu-Consult made several si~plifications. First, they dropped the concept of tours. It was their opinion that the concept of tours is too complicated to communicate with traveIlers and transport providers. 'Second, they eliminated the distinction between modes that are and that are not base-bound. And finally, they reduced the impact ofthe distinctions for the supplyof transport facilities and emphasised strongly that co-ordination between transport providers would be essential.

(29)

Analysis of the actual share of multimodal transport shows that its share is currently limited (see also Section 2.4). At present, most multimodal trips are made by train. The use of more uncommon combinations such as bicycle - private car proved to be minimal, that is, less than 0.1 %, or could not be found in the database of the Dutch National Travel Survey (NTS).

The case study was situated in the corridor Amersfoort - Utrecht. Two multimodal alternatives were designed, using the hub-and-spoke principle:

1. Train as the main mode between the central stations of Utrecht and Amersfoort, and public transport, bicycle, taxi and private car as access and egress modes;

2. Private car, that is carpool, or express busses as the main mode between Amersfoort and Utrecht and bicycle, taxi, public transport and private car as access and egress modes.

Analysis of these alternatives and discussion with travellers who of ten made trips between both cities showed that only familiar multimodal trip chains were considered to be interesting. It was especially the combination ofpublic transport and bicycle that proved to be attractive to travellers. It was emphasised that such a concept should be presented as a single service and not as a coincidental combination of two different modes.

Finally, interviews with transport providers showed that the possibilities for realising a multimodal transport system were limited. They recognised that multimodal transport could become an important issue, however, multimodal transport would still be a small share compared to their core business. Furthermore, the existing regulations of public transport were considered to be an important barrier when it comes to developing multimodal transport systems. Last but not least, it was expected that travellerswould be conservative in their modal choice and, therefore, the demand for multimodal transport would remain limited.

2.3 Practical possibilities for multimodal transport

Most of the studies described in Section 2.2 were initiated by the govemmental research agency Projectbureau Integrale Verkeers-en Vervoerstudies (PbIVVS). At the same time other authorities, and transport providers too, have been working on the concept of multimodal transportation from a more practical point of view.

Zonnenberg & Brohm (1995) analysed locations for multimodal transfer points near the orbital motorway of Amsterdam (AIO). Graumans (1995) presented a concept of multimodal transfer points or transferia for the city of Utrecht. These transfer points were located at three cordons around the city centre (see Figure 2-3).

(30)

1. Near the city centre: transfer facilities to bicycle, city bus and city taxi; .

2. At the edge of the city: transfer facilities to public transport (in the case of Utrecht busways), city taxi and shuttle services;

3. At the edge of the agglomeration: transfer to public transport, mainly rail transport.

À First ring • Second ring • Third ring

Figure 2-3: Mu/timO(lal transfer points for Utrecht (Graumans, 1995)

The main goal of this network of transfer points is to improve the accessibility of the city

. centre. Utrecht .started a shuttle service from the parking space near the football stadium Gàlgenwaard to the city centre on shopping evenings and on Saturdays. The shuttle service proved to be very successful. furthennore, an experiment with the city taxi was started in 1996. City taxi is a share-a-ride system to and from two stops within the city centre.

Shuttle services during shopping hours were also introduced in other cities such as Leiden, 's-Hertogenbosch and Groningen. The emphasis on the accessibility of the city centre as the' main goal for developing multimodal transport is underlined by Bovy (1997).

Van Binsbergen & Bovy (1996a, 1996b) presented an overview of the use of transfer facilities in the Netherlands and abroad. Most P&R-facilities were used intensively, including the transfer points at the metro in Rotterdam. P&R facilities abroad proved to be successful too. Because most P&R railway stations are situated near the city centre, P&R facilities are also used as a cheap parking space for a visit to the city centre. The transferia projects, which were recently realised in the Netherlands, were less successful. The transferium near the city of Groningen is not located optimally, with regard to the orientation of the transport demand. The transfer between private car and metro at the

(31)

Amsterdam ArenA is rather complicated. One has to choose between walking more than

500 metres or using a shuttle bus service. .

Van Binsbergen & Bovy also discussed other aspects concemed with multimodal transport, such as comfort, information technology, policy strategies and financial aspects. They asserted that as a transfer in itself is not attractive, the transfer in a multimodal trip chain should be as comfortabie as possible. This requires that car drivers should be able to park their car quickly, for instance, by means of parking guidance systems, the distances between parking space and public transport platform should be short and should be protected against rain, and the fare for parking and public transport should be integrated. Since multimodal transport involves different authorities, it is necessary that the transport policies of these authorities should be co-ordinated, especially at a regional level. Finally, the financial structure of multimodal transport will deserve extra attention, an assessment that was also made by Hablé et al. (1997).

The Ministry of Transport, Public Works and Watermanagement initiated research focussed on the feasibility ofmultimodal transport. Bockstael et al. (1996) distinguished four strategies, each of which going a step further:

1. Development of a multimodal travel information system;

2. Introduction of trip chain managers, who advise and support traveIlers in multimodal trip making;

3. Realisation of transfer points;

4. Development of a truly multimodal transport system including information facilities, trip chain managers, physical infrastructure, multimodal organisations, operational control and integrated fare systems.

Van der Hoeven & Theunissen (1997) studied the possibilities of a fully multimodal transport service: i.e. offering tailor-made trip chains; which are especially suited to the traveller's personal preferences. They state that there is a substantial market for such a service, however, they did not incIude travel time in their analyses. Transport providers proved to hesitate in developing multimodal transport services. When asked why, three types of answers were given:

1. Multimodal transport services do already exist, especially the Odyssey Card. It will take time to find out if these initiatives re sult in more interest in multimodal transport;

2. Existing regulations do not stimulate the development of multimodal transport services;

3. Most transport service providers are hesitant to take financial risks by developing new services.

Transvision, the organisation that is responsible for the ·Traintaxi, introduced the pdessey-Card. The owner of an Odessey-Card can contact Transvision to arrange a tailor-made trip, or trip-chain ifnecessary, using the following modes: rent-a-car, with or without a chauffeur, train, taxi, and Traintaxi. Transvision makes all necessary arrangements, including paying the fares, and informs the traveIler about the scheduled

(32)

trip. All the traveIler has to do is to enjoy the trip. The use ofthe Odyssey Card, however, proves to be limited: a few hundred trips a day, resulting in 100,000 trips per year. When these numbers are compared to those for the Traintaxi, more than 4 million trips per year in 1996 (De Bruijn, 1998), it is clear that multimodal transport services are still a very small niche market.

Recently, the Ministry of Transport, Public Works, and Watermanagement presented its view with regard to trip chain mobility (Ministry of Transport, Public Works, and Watermanagement, 1998). The main points of its policy are:

1. The development of multimodal transport systems should be done by transport providers and not by regional or national authorities;

2. The focus. in the development of multimodal transport services should be on

business trips; .

3. The regulations should be changed in order to facilitate the development of multimodal transport services instead ofhampering these initiatives.

2.4 Analysis of the Dutch N ational Travel Survey

In the preceding sections, many assumptions on the demand for multimodal transport have been made. It is interesting to see what the characteristics of multimodal transport are at present. Therefore, an analysis has been made using the data of the Dutch National Travel Survey. The NTS is an annual household survey, which started in 1978. Since 1995 more than 70,000 households per year are included in the survey, which results in detailed data on more than 600,000 trips per year. The analyses presented are based on the yearS 1995 up to 1997. For the main characteristics, a comparison is made with results for the years 1985-1987. Detailed results of the analyses can be found in Appendix A.

2.4.1 Multimodal trips

A multimodal trip can be divided into different legs in each of which a single mode is used. A trip is a multimodal trip if at least two different modes are used. The main mode of a trip is defined as the mode that is used for the largest distance. In general, walking is considered to be a universal access or egress mode. Legs with the mode walkirig are therefore excluded from the analysis, unless walking is used for the longest leg. Using these definitions, the NTS shows that 2.9 % of all trips can be considered as multimodal trips. This share has increased with 0.6 % in the last 10 years. The introduction of the Students Public Transport Card (SOV) accounts for the main part ofthe growth (0.4 %). The share of multimodal trips is twice as large as that of carpooling. Recently the Ministry of Transport, Public Works, and Watermanagèment advertised that more than 750,000 people were carpooling per day. This figure results in a share for carpooling of 1.5 % of all trips.

(33)

Table 2-4 shows that train is the most frequently used main mode involved in multimodal : transport, accounting for more than 50 % of all multimodal trips. 80 % of the train trips

are multimodal. Since travelIers have more modes available for the home-based leg than

for the non-home-based leg, a distinction is made between both parts of the trip . . Frequently used modes for the home-based leg of train trips are cycling (30 %), transit

(19 %), private car (8 % (driver aild passenger». For the non-home-based leg the share of

public transport in the modal split increases to 28 %. The share of taxi is I %. Private car passenger trips can still considered to be unimodal: only I % of these trips are multimodal. Cycling and driving are common modes for the other legs of the trip.

Tram/metro has a small share (0.1 %) for the non-home-based leg. Tram/metro and bus

are complementary modes. The mode used most for both sides of a tram/metro trip is bus

(8 % and 4 %). For bus trips is cycling the most important mode for the home-based leg. In non-home-based legs tram/metro is used most. It is interesting to see that using these

definitions, the main mode walking includes multimodal trips too. Apparently, people make trips using other modes in which the longest distanee, however, is covered by walking.

Table 2-4: Share ofunimodal and multimodal trips in percenta~es (NTS, 1995-1997)

Main mode All trips Unimodal trips MuItimodal trips

(%)

Private car, driver 36.1 36.0 0.2

Private car, passenger 13.1 12.9 0.2

Train 2.1 0.4 1.7 Tram/Metro 0.9 0.7 0.2 Bus 2.0 1.6 0.4 Cycling 27.6 27.5 0.0 Walking 16.0 15.9 0.1 Other 2.1 2.1 0.0 All modes 100.0 97.1 2.9

.

_{Unimodal is defined as access and egress mode are both walking}

The share of multimodal trips increases for inter-urban trips, and for trips with destinations within one of the four major cities in the Netherlands. These relationships are illustrated in Table 2-5. Limitation to trips starting at the home address increases the percentage ofmultimodal trips with a factor 1.1 to 1.3.

Table 2-5: Share ofmultimodal trips according to trip types (NTS, 1995-1997)

Trip type Share of trip type Share of multimodal

trips per trip type

All trips 100.0 % 2.9%

(34)

TRAIL Studies in Transportation Science

Inter-urban trips 31.2 % 7.9%

Inter-urban trips to major cities 3.2% 20.5 %

The importance of trip length cau be illustrated by theaverage trip length in relation to the I).umber oflegs per trip, as shown in Figure 2-4. The share ofmultimodal trips defmed in trip kilometres is four times as large as that for trips: it increased from 9.9 % in 1985-1987 to 1·2.2 % in 1995-1997. 200 180 160 140 Ol ! 120 0; 100 E .!! 80 ~ 60 40 20 0 2 3 4

Number of leg8 per trip

.Average 10-Percentile 90-Percentile

Figure 2-4: Trip length characteristics in relation to the number oflegs per trip

(NTS, 1995-1997)

The statistics presented in Tab1e 2-5 and Figure 2-4 are in accordance with the findings by Egeter (1994), Graumans (1995) and Bovy (1997):

'

.

•

Trip lengths of multimodal trips are preferably greater than 3 kilometres and favourably more than 30 kilometres.

• Multimodal transport is especially relevant for trips to and from city centres. Multimodal trips éonsisting of more tban three modes are rare. In the case where access or egress modes

are

relevant, 98 % of the access or egress modes can be considered as unimodal. In the case that the National Travel Survey indicates four modes, walking is usually incIuded as one ofthe four modes used in the trip.

A last characteristic of multimodal trips, is the trip purpose. Multimodal trips are especially relevant for the trip purposes work and education. Tbe share of multimodal trips for these trip purposes is more tban twice as high as for all trips. Trip purposes such as shopping and recreation are less important in multimodal trips.

(35)

2.4.2 Trip chains

The influence of the home address, as the starting point of a trip, on the share ·of multimodal trips indicates that the concept of tours should not be ignored in the analysis of multimodal trips. More than eighty percent of all trips start or end at the home address and nearly eighty percent of all tours consist of one or two trips (see Figure 2-5). Tours consisting of one trip usually occur when the travel purpose is touring or recreation. Nearly 40 % of all none home-based trips are re1ated to shopping, 30 % to visiting relatives or friends, and 27 % to working.

70 UI ₆₀

...

~ 0

..

50 ca ~ ₄₀ 0 GI :: 30

..

C GI ₂₀ u

...

GI 10 a..

o

2 3 4 5 6 7 >7 Numberoftrips pertour

Figure 2-5: Distribution of tours with regard to the number of trips per tour (NTS, 1995) The share of complex tours has increased with circa 10% since 1975. This is less than

was expected by Brohm & Beck (1997). Recent research in Amsterdam showed that

people have a tendency to split complex tours into two simple tours.

The total distance travelled increases as the complexity of the tour increases. Tours consisting of one or two trips have an average di stance of 16 or 19 kilometres, and tours consisting of three or four trips have an average distance of 34 and 48 kilortletres. It is interesting to note that, for complex tours, the average trip length of the non home-based trips is about aquarter to one third of the total trip length of the tour. The mode used for the non home-based trip is strongly correlated with the modes used for the home-based part ofthe tour.

(36)

20

TRAIL Studies in Transportation Science

2.5 Discussion and conclusions

This ,chapter discussed the concept of multimodal ,transport systems as seen by researchers, authorities, and travelh~rs. The presented results give rise to the following conclusions

On

multimodal transport systems.

First, multimodal transport is espeeiall)f suited to longer distances. If we look at the number of trips, the trip di stance should be ranging between 7.5 and 75 to 100 kilomytres. The most important attribute of a multimodal trip seems to be total travel ti~e. Furthermore, multimodal transport should be presented as a consistent concept in which the barriers of transferring between modes. are minimised or eliminated. The combination of longer trip lengths and of seamless transfers is essential to make multimodal transport more attractive than unimodal transport.

Second, multimodal transport is used more often for frequent trip types, such as work and education. The transfer is, apparently, less a barrier than might be suspected. On the other hand, these trips are mostly made within the peak hours, that is, the periods in which the quality of public transport in terms of time accessibility is best. Furthermore, trip frequencies associated with these trip purposes might imply that sufficient knowledge ab out the transport system is necessary. Both aspects, good quality and good knowiedge, seem to be essential for multimodal transport systems. Additionally, it is interesting to notice that, while commuters and students use multimodal transport most, the national policy with regard to multimodal transport is focused on travellers having a high value of time, such as business travellers.

Third, multimodal trips are especially interesting in situations where the accessibility of city centres has to be maintained or to be improved. This is partly due to the good accessibility of city centres by public transport and partly because of the parking regulations within the city centres.

Fourth, the availability of vehicles is an important issue in multimodal transport. The availability is, of course, relevant forthe beginning of the multimodal trip, but also for the transfer possibilities near,the destination. The concept oftours should, therefore, not be ignored in the analysis of multimodal transport systems. This is espeèially true, as complex tours tend to hav~ significant larger trip distances. A consequence of tours, however, is that a distinction has to be made between multimodal trips, trips consisting of legs for which different modes are used, and multimodal tours, tours consisting of trips trips for which different modes are used. A multimodal tour, for instance, might consist ofunimodal trips only.

Fifth, the importance of train in multimodal trips at present and the expected performance of transferia located near the major eities, implies that multimodal trips will consist of a main mode with which the main part of the trip will be made, complemented by access and egress modes. Furthermore, a maximum of two transfers seems realistic. Transfer points should, therefore, be located close to the origin and/or close to the destination .. In these situations a maximum of modes is available for access and for egress within a multimodal trip.