University of AmsterdamFaculty of Sciences

Group Assignment 3

T-TrackGPS tracking of public transportation

Innovation and Information

Master of Information StudiesBusiness Information Systems

Group 11Kevin ChengRick van Erk

Gert-Jan HazelegerThomas Reuwer

Elina Sviklina

Amsterdam 2011

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Table of Contents

Introduction.............................................................................................................................................2

Literature Review.....................................................................................................................................3

Public transport for public use.............................................................................................................4

Innovation and technology..................................................................................................................5

Developing the prototype........................................................................................................................5

Functionalities.....................................................................................................................................5

Process.................................................................................................................................................6

Screens and Explanation......................................................................................................................7

Analysis and Business Case....................................................................................................................12

Conclusions and Follow-up....................................................................................................................14

Bibliography...........................................................................................................................................15

Annex I: Business case for “T-Track”.....................................................................................................16

Introduction

Since 2008, for the first time in history, the world population is evenly split between urban and rural areas and it is expected that by 2025 70% of the world population will be urban. Growing concentration of people requires increasingly efficient infrastructure solutions and high quality services.1

In 2007, the use of public transportation saved 646 million hours of travel delay and 398 million gallons of fuel in the U.S., resulting in a savings of $13.7 billion in congestion costs2. Use of public transportation reduced U.S. CO2 emissions by 6.9 million metric tons in 20053.

Public transportation has proved to be among the most significant services in urban environment and optimization of its services has become not only more important, but also more complicated. New ways and technologies are constantly developed in order to improve the service quality. For example, Smartphone applications have increasingly been used over the last few years. Research shows that at the end of 2010 over 30% of Americans who owned mobile phones had a Smartphone and this proportion is expected to exceed 50% by the end of 20144.

1 http://www.prb.org/Educators/TeachersGuides/HumanPopulation/Urbanization.aspx )

2 Davis and Hale. Public transportations contribution to US greenhouse gas reduction. Technicalreport, Science Applicationlications International Corporation, 2007.3 Schrank and Lomax. 2009 urban mobility report. Technical report, Texas Transportation Institute, 2009.4 (http://www.email-marketing-reports.com/wireless-mobile/smartphone-statistics.htm).

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The use of Smartphones to improve the urban public transport is becoming an obvious trend. Therefore Group 11 has developed an innovative application – “T-track” – an application for GPS tracking of public transportation. It already exists on a smaller scale in some cities, but it has never been used as a mainstream solution that is available to everyone.

Authors of this paper are designing an innovation project that will enable realistic estimations of the waiting time for public transport, and help choose the best use of public transportation to get from point A to B. In order to do so, some of the existing cases of similar applications and literature will be studied and reviewed in the following sections.

Then, the empirical part of this paper will illustrate the process of building a prototype, which includes a discussion of ideas, selecting and developing the chosen case, and building the prototype.

Finally, this paper will also include brief analyses of the business case for the developed product - how it will be promoted and sustained (including a SWOT analysis for the product).

As mentioned earlier, in various cases similar applications were built. All in all there has been a lot of work done for improving the information regarding the public transport and also the personal mobile devices. A transport tracking application will fill the gap of available solutions because:

1. It is unlikely that real-time transit information will be available in a public display at every stop

2. Personal mobile devices can also support additional personalized functionalities, such as customized alerts

Literature Review

GPS tracking of public transportation involves several aspects that are discussed in the existing literature. To start with the experience of an already existing similar project will be discussed and then some key terms will be pointed out, as they will be used for the SWOT analysis in the following chapters of this paper.

Users of public transport are likely to choose this application because it helps planning the waiting time for the transport. According to Dziekan & Kottenhoff (2007) these types of applications estimate the perception of waiting time in line with the true time spent waiting, thus making the overall planning more realistic.

There already are similar projects. For example: the OneBusAway research project at the University of Washington supports a variety of research on improving the usability of public transportation. Their work is all open-source so that we can reuse and build upon their efforts. Their application is used for the Seattle-area bus riders, and also provides a transit tool focused on providing real-time arrival information for busses. Displays that provide real-time arrival information for buses, subways, light rail,

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and other transit vehicles are now available in a large number of cities worldwide, at places such as rail stations, transit centers, and major bus stops. However, it is likely prohibitively expensive to provide and maintain such displays at every bus stop in a region (Ferris, Watkins and Borning, 2010). Goals of the OneBusAway project are very similar to the project described in this paper:

1. To increase satisfaction among current riders2. To increase ridership, especially among new or infrequent transit users and for nonpeak hour trips

After the research regarding the customer satisfaction conducted by the University of Washington, it turned out that 92% of the respondents were either somewhat more satisfied or much more satisfied with public transit as a result of using OneBusAway.5

Key terms that are relevant for this project are (1) public transport as a public good, (2) innovation and technology as an improvement of the service. In this case authors look at the improvement of services that aim at time saving due to accurate data, therefore making the service more appealing to people and increasing the use of it.

Public transport for public useSince the development of cities public transport has become a very important service used by people. It has started to develop centuries ago and one of the first records of it is mentioned in Paris, France, in 16626 . Since then it has developed enormously and the number of people using it has multiplied many times. Typically, public transport is accessible to everyone and it is organized by the local municipality in cooperation with private sector or - in other cases – by public authorities alone. It is funded by the income from fares that transport users pay, and it can be combined or entirely subsidized by public finance from taxes7. Services linked to the public transportation fall into the same category of services.

Public transportation services are frequently improved to meet the technology and social developments, as well as to adjust to the growing urban population. However, it is also becoming more complicated – there are more travelers that not only wish to arrive at their final destination in as little time as possible, but also want to plan their time as efficient as possible. Rietveld et al (1999) discuss one of the obvious trade-offs that one must deal with when taking into account the public transportation as it exists today. Faster transport or shorter transfer (waiting) times will make the trip faster, but will have the opposite effect on the possibility to plan and combine the services (Powell and Sheffi, 1983, Hall, 1985, Bookbinder and Ahlin, 1990, Carey, 1994).

5 OneBusAway

6 http://www.herodote.net/histoire/evenement.php?jour=18260810

7 http://en.wikipedia.org/wiki/Public_transport#cite_note-3

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A problem discussed by Carey (1998) is that public transport providers allow extra waiting time to make the trips and transfers more easy to plan. This means that the trips often take longer. Therefore, the actual gain in reliability may result in a longer time spent travelling.

This trade-off is also a central problem in this project and the application aims to minimize this challenge.

Innovation and technology

According to the research published by TelecomPaper on 28 March 20118, about one third (34%) of Dutch consumers was using a Smartphone in the fourth quarter of 2010, a considerable increase since the beginning of 2010, when just under a quarter was using Smartphones (22%). In less than six months approximately 10% of people living in The Netherlands had started to use a Smartphone. It is likely that this number will grow in the future and that almost everyone will have a Smartphone within the next few years. This technology enables people to use different applications and have new or innovative ways of doing things or obtaining new practices.

Literature discusses the differences between an invention and an innovation. They may overlap, but to innovate requires other skills than to invent something. The word practice is important for innovation, it refers to habits and daily routines taken with conscience. Innovators are there to change the practice, by offering and supporting the end-users with tools and processes that are perceived as high value. Inventors on the other hand are different, the inventions they make do not need to be accepted or adopted. It is like the first personal computer that was built by Kildall in the 70’s and later innovated by Bill Gates with DOS and brought to the masses (Denning & Dunham, 2006).

There are many different applications and services that can be delivered using a Smartphone. Considering that in some years time everyone will have a device of their own, the technical implications will be the main challenges, rather than the accessibility. Yet, the first challenge in this case is access to the real-time streaming of data, otherwise the application is useless. In an area with a weak telephone connection, it is possible that no real-time data will be available. During rush hour on a train station, where many Smartphones are connecting to a hotspot or telephone tower, data congestion can occur. However, protocols (Mach, 2009) and algorithms (Larzon, 2000) can tackle this problem. It is not clear whether this solution is already implemented in the existing telephone towers in The Netherlands and is therefore a subject to further exploration.

Developing the prototype

FunctionalitiesThe application requires the real time locations of public transportation means, and are provided by the GPS system9 of the public transportation companies. This data is downloaded onto the phone through its

8 http://www.telecompaper.com/pressrelease/34-of-dutch-consumers-use-a-smartphone

9 Global Positioning System, http://en.wikipedia.org/wiki/Global_Positioning_System

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Internet connection, which can either be 3G/4G10 or WIFI11. The user’s location can be determined through GPS, the phone’s wireless connection, or it can be specified by the user himself. The preferred option is the use of GPS, because it is the most precise method.

Maps that are used in the application are acquired through the integration of Google Maps, so permission by Google is required for the functionality of the application.

For the navigation functionality, the application keeps track of all the transportation vehicles that can be used by the user to get to his destination. When a vehicle is no longer a suitable option for the user to take due to a lack of time, the application calculates a different route for the user.

For the implementation of the application authors had to choose between the operating systems (OS) Android from Google and iOS from Apple. An OS for a Smartphone was needed and these two are currently mainly used. Android is chosen in this project, because it is the easiest platform to introduce new applications on. Apple has a very strict selection process for applications to be distributed through their market. Nevertheless, the final application can be implemented on both OS.

In the actual application there will be the ability to change the view of the map and change the user specific settings of the application itself by means of the 'View' and 'Settings' buttons shown on the bottom of the screens in the prototype. For the prototype, these are considered secondary functionalities and were not selected to be implemented in this preview of the app.

Process

During the second FabLab12 session of the course the team made a paper prototype of the application. This provided a preliminary idea of the look and feel of the application with regard to layout and button selection.

In order to build the prototype the team first looked at two different versions of software development kits (SDK) for the Android platform. Unfortunately the available expertise of the programming language

10 http://www.practicalecommerce.com/articles/2377-Mobile-Bandwidth-An-Expert-Explains-3G-4G-WiFi

11 http://www.practicalecommerce.com/articles/2377-Mobile-Bandwidth-An-Expert-Explains-3G-4G-WiFi

12 Fablab: http://fablab.waag.org/

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Java wasn't sufficient enough to use any of the SDK. Therefore authors decided to use Adobe Flash and Adobe Fireworks to create a basic working prototype.

To reduce the amount of time needed to create a working prototype most images were taken from the internet and slightly adjusted for the project needs.

Screens and Explanation

Note that the application is still a prototype and not the final product. The design focuses on the functionalities of the application and not on visual esthetics.

This is the standard home screen of an Android Mobile phone. It is used for the prototype to

illustrate how the application would look and work on a phone.

This is the standard Android application drawer where all the available applications on the phone are shown. In the lower left corner the T-Track application icon is visible. When one clicks on the icon the application will start.

The icon consists of two images. One is a tram, which represents the public transport used in the application. The second image is a satellite, since GPS is used to track the locations of public transportation means.

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This introduction screen automatically appears at the start of the application to let the user know that the application is working, while necessary files are being loaded. Here, an image of a public transport vehicle and an antenna are used to illustrate the key elements behind the functionalities of the application. In the final product, other or more detailed images can be used.

GPS is the preferred communication device for operating the application, as it is the most precise method for determining the user's and vehicle’s location. Therefore, through the message box shown on the screen, the user is asked permission to activate GPS communication on the phone. The message box actually comes from Apple’s iOS and is used because it explicitly shows that GPS has to be activated and is used by the application.

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This is the actual home screen of the application. When one presses the home button in the lower left corner, the app will returns to this screen.

The map shows the user’s current location in the form of a blue filled circle surrounded by another circle. The map also shows, in real life, all current public transportation vehicles in the user's vicinity.

The five icons with complementary text that are placed at the bottom of all screens are used as shortcuts to the functions of the application. Commonly used images that are easy to associate with the underlying functions of the buttons are applied in the creation process of the icons.

After one presses the Transport icon at the bottom of the screen, the transport page appears. Then, the user will be able to select which transportation vehicles he/she wants to include in the query.

Each transportation type is represented by a red button with the image of the transportation mean itself. The buttons are simple checkboxes for easy use and understanding. When a checkbox is pressed a black cross will appear on the icon. When pressed again, the cross will disappear.

When the button 'Go' is pressed the user will be taken to the next screen of the Transport function where more details are asked with regard to the transportation means.

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In this screen the user can select through the use of checkboxes which specific numbers of the transportation means that were selected in the previous screen he/she wants to include in the query.

The button 'Go' takes user to the result of the query.

This screen shows the result of the previous Transport screens combined. The trams have numbers above the tram icons to show which tram it is.

Each stop of a transportation mean shows a timer which tells the user how long it will take for the vehicle to arrive at the stop.

Note: this screen doesn't show a navigation path for the user.

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This is the Search screen which will appear after the Search button on the bottom screen is pressed. If the user has given permission to the application to use GPS at its startup, the current location of the user is used. In the destination field the user can enter the place where he wants to go. When a user enters the destination in the destination field, suggestions in relation the destination are made and shown by the application in a dropbox below the field.

The 'Show' button shows the map with the chosen destination.

After the user has entered a place where he/she wants to arrive. The 'Navigate' button has to be pressed to show the route on a map.

In the first screen the first possible route from a user’s location towards the destination is shown. The red line indicates the route of the user towards the destination. The black dotted line shows the route of the suggested transportation vehicle. When a different route becomes a quicker option the application will suggest a new route as shown in the second screen. A finish flag tells the user where his destination is located on the map.

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Analysis and Business Case

Implementing this innovation project can have social implications along with the technological development. Therefore it is important to understand the rich picture of all the involved elements. Authors use the CATWOE (Checkland, 2000; Checkland & Poulter, 2006) analysis to illustrate the real world situation, full of events, actions and movements into an image of a structured and conveniently arranged conceptual world.

In this situation people using public transportation or possibly using it in the future are seen as clients. So indirectly it is the urban society as a whole that eventually benefits form an efficient public transportation service. For the application to be created and used several involved actors are necessary. Vehicles of public transportation will be in the center of the picture. They are the objects that are being followed. They have a GPS signal that is following them everywhere and sending information through web access and several channels to the smart phone. Distance to the nearest tram stop, tram stop itself, GPS signal, estimated time and Smartphone are other necessary elements that play important role in this picture.This innovation will really be the transformation of the usual service that is already provided. Transport companies and public authorities have typically been working together to provide not only the service itself, but also information about the service. Now, instead of setting up physical posts, screens and announcements aimed at reaching masses of people an application will be launched that will eventually turn the process of informing in personalized and equally accessible feature. It will require minimal human involvement and will be precise and situation specific. Application will have access to the GPS signal and be able to reflect it in the map provided by applications. It will be up to the judgment of each individual traveler to choose the desired destination, type of transport, waiting time, etc. Transformation will be related to the change from the focus on masses to individual, customized information.In the new reality the worldview of service providing will shift. Instead of providing the information service to the people, this innovation will provide an opportunity to individual people to access meaningful and customized information themselves. It is public transport companies in cooperation with public authorities that authors would categorize as owners. Without the access to the GPS systems built in public transport this innovation would not be possible. Besides, by increasing the number of clients the position of public transport providers would be strengthened. Public authority is identified as an important shareholder due to their duty to organize and facilitate the service of public transportation. They are in the position to support and organize the implementation the “T-Track” application. In case of Amsterdam, provider of the public transport and public authority already is one entity – GVB (GemeenteVervoerbedrijf Amsterdam)13. The rapidly growing cities form the environment that demands for efficient services to assure the mobility of countless people or clients. Owners of this service: public authorities and transport companies need to transform their usual ways of providing the service and start looking at it different.

13 http://www.gvb.nl/Pages/default.aspx

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Technologies and devices that have been developed lately can act as important object in the scene of providing public transportation related services.

The project group has tried to approach the potential owners of the innovation: Conexxion and GVB – companies providing public transport services in The Netherlands. Unfortunately given the time constraints it was not possible to further explore the feasibility and implications of using the built-in GPS systems.

The worldview of user of the public transport is illustrated in the picture below. It shows how it all starts with a person (local or tourist) wanting to get to the Rembrandtplein in Amsterdam, and wondering how to get there. Normally he/she would read the map, follow the signs on the streets or look for transport displays and information stands. Now he/she opens the application on the Smartphone. The app is linked to the satellite and can combine the information from a map of Amsterdam with the current location of public transport, as well as with the current location of the person. This saves time, and assures that the person will arrive in the desired destination on time and safely.

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To present the feasibility of the project, authors have come up with a brief business case of the project, including a SWOT analysis.

Strengths Weaknesses

Affordable, apps are cheap Unique in the market Implementable in an existing phone market Can plan your trip more accurately, you can actually see when the bus arrives at the bus station

Possibility of ‘going too far’ with expanding the application Unforeseen bugs that occur during updates of a Phone OS Needs to support a lot of Phone OS to reach a wider audience Hic-ups in the data-transfer, extra load on telephone towers Is real-time streaming infrastructure ready for this?

Opportunities Threats

Easy and fun way for tourists to see up to date public transport information. Good for tourism promotion Might lead to replacement of other systems, because of the integration with other information systems with public transport providers: substitution Can lead to real-time narrowcasting of advertisements. A new market for advertisers

Competitors that copy the idea or integrate the idea in existing public transport application Phone OS needs a lot of updates, intensive work Depends on buyer reviews and mouth to mouth advertisement Legal issues, public transport might not share this information freely

In short, it is clear that this innovation should be introduced by its owners. The group would be honored to organize the development the application, but given the nature of the service it is aimed at it should be the responsibility of the public authorities and public transport organizations to maintain and develop it further. Therefore GVB, Municipal Transport Corporation of Amsterdam should be the owner and responsible party for this project. The business case (Annex I) indicates the main feasibility assumptions for implementing this project.

Conclusions and Follow-up

During the planning and implementation of this project it became more obvious that there is a need for an application like T-track. Without doubt the public would welcome this product.

On the other hand it would only work if all the actors involved would work together. There can be no success without reliable real-time data provided by transport companies and their GPS systems. There would be no sense having this type of application if people would not have devices to view it on – the

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owner would still end up investing substantial amounts of money in other activities for providing information.

Further work is needed to exploring the existing projects like OneBusAway, perhaps even having a pilot project on small scale to see how it goes. Further, possible technical issues (bugs, access to GPS, high density of users, etc.) need to be foreseen and relevant measures need to be implemented to prevent them.

This paper serves as the first proposal to the project owner of how to proceed. After discussions the scope needs to be set and a more concrete planning that considers needs and possibilities of various actors needs to be developed.

Bibliography

Allen, W.B., M.M. Mahmoud and D. McNeil (1985), The importance of time in transit and reliability of transit for shippers, receivers and carriers, Transportation Research B, Vol.19

Bookbinder, J.H. and F.J. Ahlin (1990), Synchronized scheduling and random delays in urbantransit, European Journal of Operations Research, Vol. 48, pp. 204-218

Carey, M. (1998), Optimizing scheduled times, allowing for behavioural response, Transportation Research B, Vol. 32, pp. 329-342.

Checkland, P. (2000) Soft systems methodology: A thirty year retrospective, Systems Research and Behavioral Science, 17 (S1), pp.11-58

Checkland, P.B. and Poulter, J. (2006) Learning for Action : a Short Definitive Account of Soft SystemsMethodology and Its Use for Practitioners, Teachers and Students.

Denning, P. J., & Dunham, R. (2006). Innovation as Language Action. Communications of the ACM, 49(5), 47-52.

Dziekan, K., Kottenhoff, K.(2007). Dynamic at-stop real-time information displays for public transport:effects on customers. Transportation Research Part A, 41(6):489–501,

Ferris, B., K. Watkins, and A. Borning (2009). OneBusAway: A transit traveller information system. International Conference on Mobile Computing, Applications and Services (MobiCase).

Ferris, B., Watkins, K., and Borning, A. (2010). OneBusAway: Results from providing real-time arrival information for public transit. Proc. CHI 2010. New York: ACM Press, 1807-1816

Larzon, L.-A.; Hannu, H.; Jonsson, L.-E.; Svanbro, K.; , "Efficient transport of voice over IP over cellular links," Global Telecommunications Conference, 2000. GLOBECOM '00. IEEE , vol.3, no., pp.1669-1676 vol.3,2000

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Mach, T.; Tafazolli, R. (2009), Mass mobility signaling congestion avoidance mechanism using randomized time distribution of cell reselections, Telecommunications, 2009. ICT '09. International, pp.238-242,

Owen, C. L. (2006) Design Thinking: Driving Innovation. BPM Strategies Magazine, September 8, 2006

Powell, W.. and Y. Sheffi (1983), A probabilistic model of bus route performance, Transportation Science, Vol. 17, pp. 376-404.

Rietveld et al. (1999) Dealing With Unreliability In Public Transport Chains, Department of Spatial Economics, Free University

Schrank and Lomax. (2009) Urban Mobility Report. Texas Transportation Institute

Annex I: Business case for “T-Track”

The industry

This application is designed for public transportation in the Netherlands, starting in Amsterdam. The public transportation business in Amsterdam holds 264 million travelers each year, which can be divided in the following: subway 295.000 travelers a day, for the tram 354.000 travelers a day and finally for the bus 168.000 travelers a day 14. We strongly believe that if we improve the communication about public transportation for the travelers, there will be much more travelers a day.

Background

The company we started is a joint venture with the local public transportation company GVB (Gemeente Vervoersbedrijf Amsterdam) and a small group of students of the UvA (University of Amsterdam). Our main goal is to provide better and more information about public transportation in the Netherlands. With this goal we want to improve the quality of public transportation so that there will be more people taking the bus, tram and subway. This will eventually lead to lesser cars on the road and thus a better environment.

Description of the product or service

The app we created shows real-time data for the travelers of public transportation on almost any mobile device. The app can be installed on an android device like your mobile phone or tablet. For real-time location based information, travelers will need a live GPS feed or other internet connections. When the app is installed users can find public transportation information on their mobile device, information on which bus, tram of subway to take or information about detours.

The market

The first market we try to capture is the public transportation public of Amsterdam. We will try to do this by reaching as much students as possible, because students in general use public transportation.

14 http://www.gvb.nl/overgvb/feiten-en-cijfers/Pages/feiten-en-cijfers.aspx

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Because we are all students at the UvA we can reach many students. Another option is advertising in all the busses, trams and subways of GVB. When the application is working properly, after a period of testing under a couple of students, we can try to publish information in journals and (student) magazines.

Pricing and delivery policies

We cannot think about pricing yet because we haven’t reached the GVB yet. Delivery of the app will be through the markets of the given devices.

Operations

We will operate from home as long as this is needed and possible. When we meet, we meet at the UvA mainly for discussing our project and development. Another option is a small working space at the local office of GVB or any other public transportation company.

Assets

We need cooperation of the public transportation companies. We need a technical development member or team and an experienced graphical designer. And we need access to real-time transportation information like locations and stops of busses, trams and subways.

Management and employees required

At first we will not need any management of our T-Track application. Because our team is very small in later stages we maybe need management when our company increases in size.

Potential challenges or risks

No cooperation from any public transportation company. Possibility of going too far with expanding the app. Unforeseen bugs that occur during updates of a Phone OS. Needs to support a lot of different Phone software, in order to reach a wider audience. Hic-ups in the data-transferring, extra load on telephone poles. We don’t know of the infrastructure is ready for real-time tracking. Competitors that copy the idea or integrate the idea in existing public transport app. Phone OS needs a lot of updates, intensive work. Depends on buyer reviews and mouth to mouth advertisement

Investment

We will need money for the development of our T-Track app and money for advertising. This money can be collected through advertisement within our app, the public transportation company or by collection money by selling the app.

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One pole with information about real-time bus, tram of subway arrival approximately costs the GVB or other public transformation system 15.000 euro.15 For example the GVB has 1900 stops including subway stations in and around the city of Amsterdam.16 This means that if they want to provide real time information at every stop they need to invest approximately 28 million euros.

If they invest in an application that is ready to us for almost any platform (iOS, Android, Symbian and windows mobile) they could reduce the cost significantly. Year 1

Costs For what Revenues For what100.000 Android/ iOS specialist 1.000.000 Profit100.000 Symbian/ Windows /

Blackberry specialist500.000 Advertisement300.000 Infrastructure150.000 Support staff200.000 Management150.000 Use of GVB systems

1.500.000 Total investment a year. 1.000.000 TotalYear 2

Costs For what Revenues For what100.000 Android/iOS specialist 1.000.000 Profit100.000 Symbian/ Windows /

Blackberry specialist1.000.000 Advertisement

500.000 Advertisement50.000 Maintenance

150.000 Support staff200.000 Management150.000 Use of GVB systems

1.250.000 Total investment a year. 2.000.000 Total

In the year 2010 there were 3.3 million Smartphone users in the Netherlands, indicated by research done by GfK 17. Also March 2011 is the first year that more Smartphones are being sold than normal mobile phones.18 With this development the time seems right to make a switch to real-time arrival information on mobile devices. That can contribute to lower costs in public transportation which eventually will lead to lower ticket prices for busses, trams and the subway.

15 http://drimble.nl/bericht/1214362

16 http://www.gvb.nl/overgvb/feiten-en-cijfers/Pages/vervoer-in-cijfers.aspx

17 http://www.connexie.nl/actueel/3659/nederland-telt-3-3-miljoen-smartphonegebruikers.html

18 http://www.automatiseringgids.nl/markt-monitor/nederland/2011/14/meer-smart-phones-verkocht-dan-mobieltjes.aspx

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