Optimizing Intermodal Trip Planning Decisions in ...

K.G. Zografos, and M.A. Madas

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OPTIMIZING INTERMODAL TRIP PLANNING DECISIONS IN INTERURBAN NETWORKS

Konstantinos G. Zografos Professor (Corresponding Author)

and

Michael A. Madas Research Associate

Athens University of Economics and Business Department of Management Science and Technology TRANsportation Systems and LOGistics Laboratory 47 Evelpidon Str., 113 62, Athens, Greece tel: +3010 82 03 673 , fax.: +3010 82 03 684 e-mail: [email protected]

SUBMISSION DATE: WORD COUNT:

TRB 2003 Annual Meeting CD-ROM

08/01/02 7,534

Original paper submittal – not revised by author.


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OPTIMIZING INTERMODAL TRIP PLANNING DECISIONS IN INTERURBAN NETWORKS Konstantinos G. Zografos Professor and Michael A. Madas Research Associate Athens University of Economics & Business Department of Management Science & Technology

TRANsportation Systems and LOGistics Laboratory 47A Evelpidon, 113 62, Athens, Greece Tel.+3010-82.03.673-5, Fax +3010-82.03.684, email: [email protected]

ABSTRACT Travel and tourism activities and trip planning decisions involving the interoperability complexities and interdependencies introduced by intermodal / interurban transportation networks constitute an ample opportunity area for deploying the state-of-the-art mobile Internet technologies. As a matter of fact, it is becoming increasingly needed to provide travelers with real time information to assist them pre-plan or re-plan their transport / travel activities or particular trip elements during their trip (while being on the move). Trip planning decisions, either before or during the trip realization, although constituting a derived demand (“pushed” by demand for tourism activities), they represent the most critical “chain” of the decision making process on the grounds that they eventually determine the feasibility and the realization of the whole travel activity. From a different perspective, terminal operators, regional authorities and other transport / tourism organizations exhibit a vast interest and actively pursue alternative ways of dealing with the requirements of the demand for travel and tourism services. In this context, an integrated system providing value added logistical services related to travel and tourism, the "World in your H@nds on the Move – WH@M" system, has been implemented to support and optimize the trip planning process. The objective of this paper is threefold: i) to discuss the way that intermodality can be supported by such a technological application, ii) to present the architecture, operations, and the solution approach governing the trip planning modules, and iii) to provide a brief demonstration of the relevant trip planning modules of the system.




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INTRODUCTION Travel and tourism activities and trip planning decisions involving the interoperability complexities and interdependencies introduced by intermodal / interurban transportation networks constitute an illustrative example and an ample opportunity area for deploying the state-of-the-art mobile Internet technologies. As a matter of fact, it is becoming increasingly needed to provide travelers with real time information to assist them pre-plan before the trip realization or re-plan their transport / travel activities or particular trip elements during their trip (while being on the move). Travelers, whether leisure -tourists- or business travelers want on top of the attractions that a given destination offers, a fast, flexible, and convenient transport mean(s) to reach it, along with insight into the feasibility, connectivity, and other information elements particularly supporting intermodal trips across urban and/or interurban networks. Trip planning decisions, either before or during the trip realization, although constituting an indirect / derived demand (most frequently “pushed” by demand for tourism activities), they represent the most critical “chain” of the decision making process on the grounds that they will eventually determine the feasibility and the realization of the whole travel activity. Besides, additionally to the trip decision assistance, travelers will be certainly interested in getting information on accommodation options and availability, recreational and cultural activities, local weather conditions, traffic conditions and other value added travel and touristic information services. Travelers need only a limited amount of information at each stage of their journey, but these multiple "info bits" should be self-consistent throughout the different stages of this journey. They currently obtain such information services by alternative ways in mostly a bulky, static -no real time- and generic -non customized- manner. However, information is becoming the essential component of the travel service, and therefore it is necessary to be provided at the right time, place and format. Moreover, real time information gains extremely valuable importance due to the stochastic, dynamic changes of the travel schedules of the various transportation modes. It is more than obvious that the transportation system is subject to several operational constraints of capacity, and mainly it is quite vulnerable to the dynamic changes stem from stochastic events introduced into the network(s). This is even more evident in the case of intermodal transportation, which is, by default, subject to the constraints posed by the effective coordination and the connection alternatives of the various participating modes. In that respect, the provision of real time, dynamic information constitutes a value added service (VAS) for the traveler that could more effectively capture and cope with the stochastic elements of the intermodal system. From a different perspective, terminal operators, regional authorities and other public and private transport / tourism organizations (e.g., public transport authorities, traffic management authorities, associations of tourism enterprises, individual tourism actors) exhibit a vast interest and actively pursue alternative ways of dealing with the requirements of the demand for travel and tourism services. In particular cases (e.g., Olympic Games), the massive influx of incoming (and outgoing accordingly) tourism, renders inevitable the adoption and implementation of innovative technological applications that are capable of accommodating the demand for information services and providing decision assistance in a bulky manner due to the spatial and temporal concentration of the demand. This is particularly applicable to the Greek context, in the light of the organization of the 2004 Olympic Games in Athens that will attract a substantial number of tourists that are willing to “combine” the participation into this large-scale event with a trip in major Greek island destinations, thus creating intermodal transportation requirements in the urban and/or interurban context and transportation networks. Under such a viewpoint, these organizations seek to ensure an “acceptable minimum” level of service (i.e., transport / tourism services, mobility and accessibility of events / destinations including terminals, intermodality), while simultaneously achieving better demand management and a more efficient / rational utilization of their proprietary resources (e.g., infrastructure, equipment, human resources). In other words, what service providers would desire to (be capable of) provide and travelers expect to receive are information services and decision support that: i) are available to travelers in a timely and accurate manner, either referring to demand responsive or "pushed" information services, ii) are available to them while being on the move, and iii) are customized to their individual needs and




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preferences. Advanced information and communication technologies, and in particular, mobile Internet technologies provide ample opportunities for offering the much needed real time information while being on the move for the seamless integration of intermodal passenger trips. In this context, an integrated system providing value added logistical services related to travel and tourism, the "World in your H@nds on the Move – WH@M" system, has been implemented to support the trip planning and optimize the decision making process pertaining to intermodal trips across interurban networks. Based on the above stated capabilities, the system provides the following Value Added Services (VAS): i) Pre-trip and On Trip Re-planning, ii) Transportation Mode Choice, iii) Transport Availability, iv) Destination Choice, and v) Accommodation Choice. The contextual value of this high level system description and capabilities are operationally achieved by means of a system prototype addressing an intercity / regional intermodal tourist / traveler information service in Athens/Greece. This service prototype integrates real time travel information from different sources, that is, an airport authority provides flight schedule information, while a major international port provides information on short sea shipping schedules, and a hotel association provides information regarding destination options and accommodation choices (1). The objective of this paper is threefold: i) to discuss the way that intermodality can be supported and the trip planning decision making process pertaining to intermodal trips across interurban networks can be optimized through such a technological application, ii) to present the architecture, operations, and the algorithmic part / calculations governing the system functionalities corresponding to the trip planning modules aiming to provide results on the feasibility of a given intermodal connection between the mainland and the islands of Greece, and iii) to provide a brief demonstration of the relevant trip planning modules and interfaces of the system under consideration. The remainder of this paper is structured into five major thematic sections: i) the description of the application along with the formalization of the user requirements corresponding to the WH@M demonstrator in Greece, ii) the development of the functional specifications and the system architectural design along with the associated infostructure requirements, iii) the description and documentation of the intermodal trip planning problem, algorithm and solution approach, iv) a brief demonstration of the trip planning modules’ functionality, and v) some overall concluding remarks.

USER REQUIREMENTS This section presents the user requirements elicited by both intermediate (i.e., content providers) and end users of the application (2,3). The supply side of the user requirements summarizes the perspective, preferences and the stated requirements derived by the intermediate users of the system along with a macroscopic review of the potential barriers or technical, implementation considerations. On the other hand, the demand side results address the requirements elicited by the end users, and conveys their preferences and perspective to be considered for the “real” system development. The target groups of the particular demonstrator are structured into two major types of stakeholders: End Users: The target group of WH@M end users are mainly international travelers - tourists and less business travelers - as well as national travelers making urban and interurban trips by using more than one different transport modes (e.g., air / maritime transportation, bus, metro, urban rail). Intermediate Users: the intermediate users active in the Athens site are represented by three clusters of actors, that is, the Piraeus Port Authority (PPA) in cooperation with the Ministry of Mercantile Marine (MMM), the Hellenic Civil Aviation Authority (HCAA) in cooperation with the Athens International Airport, and a tourism association (i.e., SETE). Each of these three actor groups constitute the content providers for the application through catering the system with travel information regarding the short sea shipping and flight schedules, as well as tourism information addressing accommodation activities, cultural events, destinations and local attractions. With respect to the intermediate users' part of analysis, their major business objectives, as well as the means (processes, sub-processes, functions) of accomplishing these objectives were identified per user. The importance and satisfaction derived by the above described means, and the contribution of the




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proposed WH@M functionalities to the improvement / enhancement of their internal operations efficiency is described in a second level of analysis. On the other hand, end users constitute the final consumers and recipients of the system's value added services (VAS), and they are supported in their travel and tourism related decisions and activities (e.g., hotel accommodation, transport mode, on trip replanning) through the capabilities and functionalities exhibited by the proposed system. Therefore, an exploration of the importance of these services and the satisfaction derived by the current ways of obtaining them, in conjunction with the importance / contribution of WH@M functionalities to the provision of value added services was the outcome of this part of analysis (2,3). Within the context of the intermediate users' requirements analysis, the Goal Function Modeling (GFM) was used (4), while thereafter being integrated with the Quality Function Deployment (QFD) methodology (5,6,7,8). GFM can be basically defined as a means-end design method based upon the concepts of goal, function and module (4). The idea behind the use of GFM was to identify in a systematic and consistent way the various processes, functions, sub functions, as well as the associated flow of information of the actors / intermediate stakeholders involved in order to achieve their system's goals. As far as the analysis of the end user survey responses are concerned, the House of Quality Analysis (5,6,7,8) and descriptive statistics were used in order to elicit the system functionalities and value added services preferred by the end user (i.e., “What’s”), while simultaneously “translating” through the corresponding QFD matrices’ calculations - these services / functionalities into technical features and specifications of the proposed system (“How’s”) (2). This section provides an integrated analysis and a synthesis of the user requirements elicited by both types of stakeholders. In particular, by synthesizing the separate results of the intermediate and the end users' surveys, the following conclusions were drawn: The WH@M application, i) SHOULD provide real time information, ii) SHOULD provide information on the move, iii) SHOULD provide information from multiple sources, i) SHOLD support on trip re-planning decisions, ii) SHOULD provide transport availability information services, iii) SHOULD provide accommodation availability information services, iv) SHOULD support accommodation choice decisions. In addition, WH@M: v) SHALL support pre trip planning decisions, iv) SHALL exhibit capabilities of processing and dispatching the collected information, and Finally, WH@M: v) MAY use intelligent promotional / marketing techniques, vi) MAY support destination choice decisions vi) MAY exhibit capabilities of customizing the collected information and providing personalized suggestions to the users, while vii) It is not required to support interaction amongst different stakeholders, and viii) It is not required to support interoperability with other sites and tourism actors, and vii) It is not required to support mode choice decisions. Based on the results of the user requirement analysis and the synthesis of the stated preferences of the particular WH@M user groups, the system prototype was designed to be capable of collecting, integrating, processing, and disseminating well-structured travel and tourism related information with the purpose of supporting activities of the end users concerning the pre-trip planning as well as their on trip re-planning activities. The content of information stored and delivered by the system is collected from multiple sources of the public (e.g., public authorities, terminal operators) and the private sector (e.g., tourism associations, companies) and it addresses the following areas (1,3): ➲ Actual, as opposed to published, schedules of different modes of transportation, and especially those focusing on intermodal trips connecting the mainland with the Greek islands (e.g., air and maritime transport modes),




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➲ Information on the expected travel time and the optimal itinerary to access the terminal supporting the desired intermodal connection (e.g., from airport to the port and vice versa) by public transport, ➲ Destination choices and tourist resorts all over Greece, ➲ Accommodation options per destination, hotel designation (e.g., luxury hotels, apartments, rooms to rent), and facilities / services provided, ➲ Car rentals, yachting companies and other supporting tourist services. The WH@M information center can be accessed through either mobile assistants (i.e., handheld devices) or PC - laptop or desktop - clients. The PC client version consists of a web site, providing the above described informational content, and is accessible through the WWW with a browser. However, the major strength of the system is reflected on its capability of supporting mobility and on the move decisions through the mobile assistants. The Mobile Assistant version exhibits operational capabilities in a simplified pattern respecting the display and performance (e.g., speed, memory) limitations of the mobile device. The WH@M wap version serves the following operational functionalities (9): ☛ User registration into the system: log in and log out ☛ Profile creation and storage: creates the personal profile into the WH@M data base that can be accessed on the move through the mobile assistant ☛ Provision of information on actual travel schedules and timetables for supporting intermodal trips ☛ Provision of information on accommodation choices and other touristic information The Value Added Services (VAS) that are provided to the end user (i.e., tourist, traveler) are the following: Pre-trip planning: the system provides the traveler with the opportunity of creating intermodal trips to connect the mainland with the Greek islands, while also recommending alternative destinations and major tourist attractions. On-trip planning: the system provides the user with the necessary travel and tourism information to replan some parts or the whole of the trip elements, due to unexpected changes and the stochastic nature of the transportation system. Customized information: the system is able to issue customized recommendations and information on tourist activities within Greece, such as alternative destinations, accommodation, restaurants, local attractions, and services / facilities based on the individual’s preferences (i.e., user profiling).

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WH@M SYSTEM DESIGN The objective of this section is to illustrate the functionalities of the WH@M system that directly correspond and accurately reflect the elicited user requirements and stated preferences. Table 1 summarizes the functionalities designed for the WH@M application in Greece (9). Architectural Design The overall hardware architecture is presented in Figure 1, where the deployment diagram illustrates the system configuration in terms of the various servers, hardware requirements, and communication mechanisms in order to deliver the requested information service to travelers. More specifically, the end user / traveler can access the system through the WAP interface (i.e., WAP enabled mobile clients), as well as through mobile web interfaces (e.g., handheld devices) capable of displaying graphical web interfaces. The Value Added Services pertaining to the pre trip and on trip re-planning modules, as well as the specific tourism information services are accommodated over external connections to the system with servers capable of delivering the specific data requirements. As a matter of fact, a combination of two separate servers is used to capture the transport related data cluster, where the shipping schedule server handles information requests addressing the maritime schedules, while the flight schedule server




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accommodates requests pertaining to the air transport schedules, accordingly. Finally, the tourism server aggregates information related to tourism (e.g., accommodation, travel agents, car rentals), and delivers it upon request. This particular infostructure is built upon various data sources and contains information classified under the following data clusters (10,11): ➲ Travel related information addressing flight and shipping schedules (i.e., published / actual). This information is collected from the respective content providers of the travel industry. In particular, shipping schedule information is communicated by the Ministry of Mercantile Marine to the WH@M database and the Pre Trip and On Trip Re-planning Modules through the HTTP application interface. As long as changes in the shipping schedules occur and are published by the Ministry of Mercantile Marine, they are updated / communicated to the system. As far as the flight schedule information is concerned, it is directly communicated by the Athens International Airport to the WH@M database. The daily, realtime flight schedule is constantly updated by the Airport and periodically forwarded to the WH@M database (i.e., approximately every 5 minutes) in order to update the On Trip Replanning Module accordingly. ➲ Leisure data addressing information requirements in terms of accommodation, car rentals, yachting/cruise companies, and travel agencies. This information is periodically communicated by the Greek Tourism Association (i.e., SETE) directly to the Tourism Module. ➲ Information related to the algorithm's data requirements and the public transport information in order to estimate the feasibility of a given intermodal connection. The former addresses the information requirements in order for the algorithm to run and provide answers on the basis of the feasibility of a given intermodal connection (Airport to Port and vice versa). In general, this cluster of information contains data representing the network configuration along with the various transport mode elements (i.e., modes, nodes, routings) statically stored in the WH@M database. The latter signifies the corresponding public transport information, that is, the time required to travel or transfer between transport modes, as well as the timetables for the various transport modes and travel directions. These data requirements have been collected from the public transport organization (i.e., OASA) and have been stored for further processing (Public Transport Module) in the WH@M database. The overall hardware architecture, communication protocols / data exchange mechanisms, and data formats of the system infostructure are presented in Figure 1. Intermodal Trip Planning Problem & Solution Approach The transportation system and its comprising elements (i.e., urban / interurban networks, operating transportation modes) are often subject to several operational constraints of capacity, while simultaneously being quite vulnerable to the dynamic changes stem from stochastic events introduced into specific elements of the network(s). This is even more evident in the case of intermodal transportation, which is, by default, subject to the constraints posed by the effective coordination and the connection alternatives of the various participating transportation modes with particular order of magnitude placed upon the interface points between urban and interurban networks. In addition to the dynamic (i.e., time-dependent) components and the stochasticity involved in the travel times per se along a particular route via a specific transportation mode, there is an inherent penalty / cost (i.e., transfer time) triggered by mode / line transfers that might be incurred (where applicable) in one or more nodes (e.g., stations, terminals) of the transportation network. This penalty might be further inflated as a result of possible waiting times (i.e., delays) that essentially convey the “holding” time - if any - for the traveler in order to catch the soonest time slot for a particular mode operating along a specific route (i.e., a pair of two adjacent nodes). Substantial problem formulation difficulties and solving complexities, however, emerge due to the fact that such a transfer delay / “penalty” actually constitutes a time-dependent, mode pairing-dependent, and node-dependent variable. These individual time elements (i.e., travel time, transfer time, delay / connection time) are accumulated and sequentially propagated from the origin to the destination node / terminal, thus essentially determining the feasibility of a given intermodal connection (terminal – urban “trip” – terminal). However, the feasibility of an intermodal connection signifies only one - perhaps the most




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important though - problem aspect pertaining to the trip planning decision making requirements. The solution in the intermodal trip planning optimization problem might address multiple optimization criteria beyond shortest path / connection feasibility that are often involve the minimization of mode transfers, as well as particular mode (e.g., bus, urban rail, metro railway) or route / link preferences (e.g., travel through the city center). In the context of the particular application under discussion, its major purpose is to provide decision support assistance to travelers and tourists in planning or rescheduling their traveling activities in urban / interurban networks. These results will reflect the connection feasibility (along with other relevant optimization criteria) of a given intermodal trip obtained by running an algorithm that captures the particular problem characteristics and modeling aspects presented above. A large number of alternative approaches capable of generating efficient solutions have been proposed in the literature for dealing with this multi-objective transportation problem (12,13). These methodological approaches exhibit different modeling perspectives and advantages / disadvantages under different problem characteristics. On the top of these differences, there is a major decision making characteristic that classifies these methodological approaches into preemptive and nonpreemptive techniques (14). The former signifies methods (e.g., lexicographic ordering or method of sequential optimization, ε-constraint method, weighting method, distance-based methods) that the various objective functions / optimization criteria are assigned a subjective priority by the decision maker (e.g., traveler) in the form of a preemptive ordering of the objectives (e.g., shortest time, minimum number of mode transfer, mode preference, route preference). The latter essentially includes methods (e.g., interactive methods, utility function method) aiming to maximize the utility function over a feasible region of solutions. In the particular context (intermodal trip planning, and especially while being on the move), preemptive solutions seem to more accurately reflect the practical problem characteristics and directly target the real value-added service of the application (e.g., on trip re-planning). As a matter of fact, a traveler, at first, needs decision support to the intermodal connection problem, while being secondarily interested in accomplishing particular objectives such as the minimization of mode transfers, mode and route preferences. In that respect, it can be considered quite efficient and sufficient to approach this problem by optimizing the intermodal connection problem (shortest “path” / time), while thereafter optimizing the problems / objective functions that have been assigned a lower priority ranking for optimization by sequentially “bounding” the optimization process within the feasible region obtained by the solution of the previous (higher priority ranking for optimization) objective function. Based on this consideration, the lexicographic ordering method (15) is believed to address, in the most representative manner, the practical meaning and rationale of the given real-world problem. In what follows, the general lexicographic procedure as a means of dealing with the multi-objective transportation problem is briefly presented and mathematically formulated. Let P an optimization problem defined by an ordered set (assignment of subjective priority) of objective functions F ={f1,…, fF} with feasible space S. The problem is to optimize P with respect to fr ∈ F, given the feasible space Sr-1, where Sr-1 conveys the set of optimal solutions obtained by optimizing P with respect to fr-1 ∈ F (16). In particular, the lexicographic ordering procedure can be mathematically formulated as follows: S0 = S; for each fi ∈ F do determine Si; if  Si = 1 then stop; end where the statement “determine Si” denotes finding the set of optimal solutions by using the objective function fi and feasible space Si-1. An instantiation of the above described problem is reflected on the functionality and operational characteristics of the WH@M application (i.e., trip planning modules) in Greece. Within the framework of the Greek WH@M Demonstrator, a simplification of the proposed optimization technique and algorithmic solution approach was adopted. This approach was designed to cope with the optimization of




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the transportation problem pertaining to the urban transportation network in Athens via public transport means supporting the intermodal connection between the two network extremes / major terminal nodes (i.e., Athens International Airport, Port of Piraeus) accommodating outgoing and incoming tourism from/in the inland and mainland of Greece. An abstraction of the transportation network (major nodal points and transportation links) was initially used to test the operational functionality of the given algorithm under the particular network / problem complexity. Based on this network, a complete enumeration approach was implemented in order to list all possible results, while thereafter checking and ranking the resulting solutions / “paths” according to the user-specified optimization criterion. The proper functionality and reliability of the algorithm has been already documented (implementation results will be demonstrated in the following section), while the development of an algorithm (with the use of the lexicographic ordering solution procedure) capable of dealing with the full-scale transportation problem beyond the scope of this application is currently under development. A brief conceptual description of the implemented algorithm based on the WH@M application requirements and complexity is provided in the following paragraphs. The “trip planning” algorithm uses a dynamic routing table to determine the desired route or routes, and all relevant details, such as trip duration, mode or modes of transport, etc. The table constructs all the possible routes from the Port of Piraeus to the Athens International Airport and vice versa, by chaining or linking together all possible combinations of bus and rail (i.e., metro railway, urban train) stops. While many nodes can exist, only the Port of Piraeus and the Athens International Airport nodes can act as origin or destination nodes, these being the start and end points of the route traversal. A complete route therefore, begins from either one of these two nodes and is called the origin node, progressing sequentially along successive nodes until reaching the end or destination node. Hence, no other node can come before the origin node in the chain, and no other node can succeed the destination node, so that all nodes exist between the origin and destination. The routing table consists of a series of entries or links in an open-ended chain, each of which points to a next link. A link therefore represents one distinct node along with one distinct mode of transport. Since a node can offer more than one mode of transport, a separate entry is constructed for each node and mode combination, and it is only then that it constitutes a link in the routing table. Furthermore, the order of nodes is predetermined. Another very important characteristic of the algorithm, is that no adjacent node can be bypassed or skipped. Each node on this route follows a distinct and predetermined order as mentioned previously and has an adjacent node before and after it. Hence, by traversing the routing table, starting from one of two origin nodes and following successive adjacent links, a complete route can be established. The fact that a node can offer more than one mode of transport, indicates that a node can branch forward to more than one link in the routing sequence, thus offering several options of routes, all of which can pass through the same nodes but continue on using different modes of transport. Other factors that determine the final route or routes constructed are the user-defined transportation preferences, such as “Pass through center” / “Use minimum transport modes”, and preferred transportation means. In order to determine if a route meets this criterion, the entire route is constructed and upon reaching the destination node, if neither Omonia nor Syntagma (i.e., city center) is included in any of the links, the route is rejected, and continues to the next route traversal. Similarly, when “use minimum transport modes” is indicated, this influences the construction of the route, when each node is examined for the selection of the next mode to be used (when a node supports more than one transport modes. Hence, during route traversal, determination and construction, the process stores the following relevant information: i) node-to-node duration times, ii) transportation mode, iii) transit times when transferring from one mode to another. A timetable can then be constructed which determines each successive node along a route, starting from the origin node and ending at the destination node. It further indicates the travel times between successive nodes, the mode of transport from node to node, and the transit time if there is a change of mode at any particular link along the route. Collectively, these three pieces of information, (node-to-node travel time, transport mode and transfer time), are used to calculate the arrival and departure times at each successive node in the routing table. Finally, other factors that




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must also be taken into consideration are the time of day, which can adversely affect the travel time from node to node (e.g., during early morning and late evening hours, the frequency of service is diminished as opposed to peak hour services, and in the case of the Athens Urban Bus service, the trip duration is also shorter during these times due to lighter traffic conditions, when compared to normal daytime hours).

TRIP PLANNING MODULE DEMONSTRATION The user interface elements presented in this section address the pre-trip planning use case, that is the support provided to the traveller in order to plan his/her trip from the Athens International Airport to the Piraeus Port and then to the Greek islands (with the reverse also being true). The on-trip planning function has approximately the same interface, with the major difference being in the type of schedules considered (i.e., published for pre-trip, actual for on-trip). Through the first set of cards, the user is initially prompted to specify the arrival details (i.e., arriving at the Port of Piraeus, or at the Athens International Airport?, date and time of arrival), while the request for departure details (e.g., flight number/id, departure time) follows (Figure 2). Thereafter, the system presents the available alternative routes from the origin to the destination terminal by taking into account the stated preferences (mode / route preference) by the user / traveler, while simultaneously ranking results according to the selected / desired optimization criterion (e.g., shortest time, minimum number of mode transfers). Furthermore, in case that the user / traveler selects the shortest trip, the application will first display an automatic warning message that will notify the user to allow some extra time (i.e., “time buffer”) for the timely and proper accomplishment of the relevant terminal handling procedures (e.g., check-in, baggage screening, ticketing). Finally, the pre trip planning results are summarized (Figure 3) to allow the user / traveler drawing conclusions on the feasibility of the given intermodal connections and other additional details such as the total trip duration, and the number of mode transfers involved. Similarly, the on trip replanning functionality can be used / accessed by a remote user (while being on the move) through a mobile assistant / device in order to provide results on the feasibility of an intermodal connection based on the actual (as opposed to published) schedules of the various transportation modes involved in the particular urban / interurban trip.

CONCLUDING REMARKS Travel and tourism activities and trip planning decisions involving the interoperability complexities and interdependencies introduced by intermodal / interurban transportation networks constitute an illustrative example and an ample opportunity area for deploying the state-of-the-art mobile Internet technologies. Travelers, whether leisure -tourists- or business travelers want on top of the attractions that a given destination offers, a fast, flexible, and convenient transport mean(s) to reach it, along with insight into the feasibility, connectivity, and other information elements particularly supporting intermodal trips across urban and/or interurban networks. Trip planning decisions, either before or during the trip realization, although constituting an indirect / derived demand (most frequently “pushed” by demand for tourism activities), they represent the most critical “chain” of the decision making process on the grounds that they will eventually determine the feasibility and the realization of the whole travel activity. Moreover, real time information gains extremely valuable importance due to the stochastic, dynamic changes of the travel schedules of the various transportation modes. It is more than obvious that the transportation system is subject to several operational constraints of capacity, and mainly it is quite vulnerable to the dynamic changes stem from stochastic events introduced into the network(s). This is even more evident in the case of intermodal transportation, which is, by default, subject to the constraints posed by the effective coordination and the connection alternatives of the various participating modes. From a different perspective, terminal operators, regional authorities and other public and private transport / tourism organizations (e.g., public transport authorities, traffic management authorities, associations of tourism enterprises, individual tourism actors) exhibit a vast interest and actively pursue alternative ways of dealing with the requirements of the demand for travel and tourism services. In




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particular cases (e.g., Olympic Games), the massive influx of incoming (and outgoing accordingly) tourism, renders inevitable the adoption and implementation of innovative technological applications that are capable of accommodating the demand for information services and providing decision assistance in a bulky manner due to the spatial and temporal concentration of the demand. In other words, what service providers would desire to provide and travelers expect to receive are information services and decision support that: i) are available to travelers in a timely and accurate manner, either referring to demand responsive or "pushed" information services, ii) are available to them while being on the move, and iii) are customized to their individual needs and preferences. In this context, an integrated system providing value added logistical services related to travel and tourism, the "World in your H@nds on the Move – WH@M" system, has been implemented to support and optimize the decision making process for trip planning across interurban networks in Greece. This service prototype was designed to be capable of collecting, integrating, processing, and disseminating well-structured travel and tourism related information with the purpose of supporting activities of the end users / travelers concerning the pre-trip planning as well as their on trip re-planning activities.

ACKNOWLEDGMENTS The research work presented in this paper has been partially supported by the European Commission – Directorate General INFormation SOciety (DG INFSO) within the framework of the project titled “The World in your H@nds on the Move (WH@M)”.




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WH@M Project Consortium. Description of Work. Report submitted to the European Commission, Directorate General INFormation SOciety (DG INFSO), 2001. Zografos, K.G., and M.A. Madas. Deployment of Advanced Mobile Internet Technologies to Provide Value Added Logistical Services in the Travel and Tourism Industry. 17th International Logistics Conference, Thessaloniki, 2001. WH@M Project Consortium. User Needs and Requirements. Technical Report submitted to the European Commission, Directorate General INFormation SOciety (DG INFSO), 2001. Sorensen, U.M. Application of functional modeling in the design of industrial control systems. Reliability Engineering & System Safety, Vol.64, Issue 2, May 1999, pp 301-315. Bossert, J.L. Quality Function Deployment: A Practitioner's Approach. ASQC Quality Press, 1991. Park, T., and K.J. Kim. Determination of an optimal set of design requirements using house of quality. Journal of Operations Management, Vol.16, Issue 5, October 1998, pp. 569-581. Temponi, C., J. Yen, and W.A. Tiao. House of quality: A fussy logic-based requirements analysis. European Journal of Operational Research, Vol.117, Issue 2, September 1999, pp. 340-354. Govers, P.M. QFD: not just a tool but a way of quality management. International Journal of Production Economics, Vol. 69, Issue 2, 2001, pp. 151-159. WH@M Project Consortium. WH@M Prototype Specifications. Technical Report submitted to the European Commission, Directorate General INFormation SOciety (DG INFSO), 2001. WH@M Project Consortium. Software Modules and Service Platform Design. Technical Report submitted to the European Commission, Directorate General INFormation SOciety (DG INFSO), 2001. WH@M Project Consortium. Infostructure Requirements. Technical Report submitted to the European Commission, Directorate General INFormation SOciety (DG INFSO), 2001. Szidarovszky, F., M. Gershon, and L. Duckstein. Techniques for Multiobjective Decision Making in Systems Management. Advances in Industrial Engineering (2), Series Editor G. Salvendy, Elsevier Science Publishers B.V., 1986, 22-61. Ehrgott, M., and X. Gandibleux. An Annotated Bibliography of Multiobjective Combinatorial Optimization. Report in Wirtschaftsmathematik, Nr 62/2000, 2000, 20-31. Sherali, H., and A. Soyster. Preemptive and Nonpreemptive Multiobjective Programming: Relationships and Counter-Examples. Journal of Optimization Theory and Applications, 1985. Fishburn, P. Lexicographic Orders, Utilities, and Decision Rules: A Survey. Management Science, Vol. 20, No. 11, 1974, pp. 1442-1471. Volgenant, A. Solving some lexicographic multi-objective combinatorial problems. European Journal of Operational Research, Vol. 139, Issue 3, June 2002, pp. 578-584.




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LIST OF TABLES TABLE 1: WH@M System Functionalities

LIST OF FIGURES FIGURE 1: Deployment Diagram FIGURE 2: Arrival & Departure Details FIGURE 3: Trip Planning Results




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TABLE 1: WH@M System Functionalities FUNCTION On Trip Re-planning

PURPOSE OF THE FUNCTION To provide the end user with real time, “actual” (as opposed to published) information in order to support the desired intermodal connection and on trip re-planning decisions or the rescheduling of activities while being on the move. Pre Trip Planning To provide the end user with (published) information on public transport schedules to access the port from the airport and vice versa along with the feasibility of a given intermodal connection. Flight Schedule Information To provide the end user with information on the flight schedules (published and/or actual) from/to the Athens International Airport. Short Sea Shipping Schedule To provide the end user with information on the short sea Information shipping schedules (published and/or actual) from the Port of Piraeus to the Greek islands. Accommodation Search by Type To provide the end user with information on certain accommodation options by type, location, and facilities offered. Car Rental Services’ Information To provide the end user with information on car rental services by location. Yachting / Cruise Services’ To provide the end user with information on yachting / Information cruise services by location. Travel Agencies’ Information To provide the end user with information on travel agencies by location. Registration To register a person as a WH@M user. Direct Profiling To create an initial user’s profile through the registration process provided that the user is willing to provide the system with personal information to elaborate a specific profile for future customized recommendations. Login To log the end user and manage access into the system (= turn WH@M on). Information Update To support (where applicable) the dynamic update of information provided by the content providers (i.e., updated travel schedules and tourism information). Logout To log the end user out of the system (= turn WH@M off).




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WH@M Database

Administrator Console (Stored Procedures)

PHP Public Transport Module

Tourism Module

FTP

Flight Schedule Server

Periodic Exchange Trip Planning Module Tourism Server

Authentication & Profiling Module

WH@M Athens System

Infopackaging & Broadcasting Module (Mobile UI, web UI)

Content Aggregation Module

Shipping Schedule Server

Web Client

WAP Client

FIGURE 1: Deployment Diagram




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FIGURE 2: Arrival & Departure Details




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FIGURE 3: Trip Planning Results

