Transport innovations can result in negative side-effects. Traffic jams, oil dependency, global warming, traffic safety and noise nuisance are all examples of externalities, which are results of transport activities [7] . However, they are also directly the effect of historical innovations in transport, given the fact that all current technologies are the result of innovations in the past [8] . It is generally said that heading off a problem before it happens is a more proactive practice rather than to solve it after all is burned out [9] . Hence, innovations that are assessed on their impacts and implications in advance are more likely to manage and mitigate all future risks in the market.

The studies to date about transport innovations have thus mostly focused on the policy-making matters, designing, visioning, and solving existing problems rather than on the impacts of the transport innovation itself [10] . Though anthropologists often relegate technological innovations to very minor roles as stimuli toward social evolution and power inequities, archaeological analyses of long-term cultural change cannot afford to ignore the many social, symbolic, and practical implications of major innovations in transportation [11] . This current literature gap should be pointed out to prevent new innovations from becoming new sources of problems and to access the fail and success factors of the innovations. It is thus of vital importance to get a good understanding of the impacts it will have. Furthermore, different actors might experience different impacts. Impacts assessments often focus on a narrow set of impacts on a particular group of people and hence significant impacts may be overlooked or undervalued [12] . It is thus important to distinguish between all relevant actors that are impacted by the innovation. With the fact that no one has done similar research previously, we need to identify more impacts structured with a causal-relations impacts diagram, that will be fully described later based on literature review.

Sustainable transport is challenging to achieve [13] . The success or failure of innovations depend on a number of factors such as the willingness of people to use them, changes in regulations and investments that need to be made [14] . It is thus a complex process that, if to be analyzed, has to be at the societal level, taking all relevant aspects into account. The implementation of a transport policy can be analyzed by the use of frameworks, as they can “alert policy makers to the variables that can be manipulated to improve the delivery of public services” [15] . In this chapter, a conceptual framework will be presented based on existing theory concerning the societal success and failure factors, which will function as a basis to do the SFF analysis.

Since we are looking at innovations in the area of sustainable transport, that is, innovations that reduce in one way or another the environmental impact of transport activities (in this case: less car use as a result of better public transport), we will be looking at existing frameworks of success and failure factors that were introduced in literature in the context of transport policy.

The basis of the conceptual framework developed is the framework of Feitelson and Salomon [14] on the adoption of transport innovations. The paper identifies feasibility as the key concept for implementation of policies. It distinguishes three different types of feasibility: technical feasibility, political feasibility and social feasibility. Respectively these categories of feasibility exemplify; if it can work technically, if it is supported by a wide coalition of specific interests, and if the majority of voters are likely to support it.

The concept of feasibility used by Salomon & Feitelson [14] is however too narrow to capture the complexity of the concept of policy implementation, and is therefore extended. The starting point for the extension is based on the article of Van den Bergh [16] . The paper distinguishes 5 categories of factors that impact the implementation of innovation namely:

・ Technological factors: (e.g., availability and complexity of the required knowledge and expertise, availability of complementary technologies, compliance with technical standards).

・ Administrative and legal factors: (e.g., compatibility with current regulation, fitting in with existing procedures, consistency with legislation, and (lack of) clarity about division of responsibilities and competencies).

・ Political and process related factors: (e.g., existence/lack of necessary institutions to implement the innovation effectively or efficiently, the role of interest groups, the distribution of political power, and the time horizon (short- versus long-term) of politicians).

・ Socio-cultural and psychological factors: (e.g., involvement in and affinity with the project on the part of the stakeholders, perceived risks and interests of firms, consumers and civil servants, and degree to which drivers and passengers are asked to change their behavior).

・ Economic factors: (e.g., net benefits for market agents, availability of funding and subsidies, possible lock-in due to increasing returns to scale, expected influence on (international) competitive position, possibility of “free rider” behavior, and expected influence of the project on the regional and local economy (jobs)).

Every category can thus contain both success and/or failure factors. In the proposed conceptual model these will thus form the basis to determine feasibility, resulting in five different types of feasibility.

Vonk Noordegraaf [6] also extended the framework of Salomon & Feitelson [14] , because it states that “the framework does not give insight in how actors appraise these feasibility aspects and how this appraisal can change over time” [6] . The paper adds the theoretical concepts of policy opportunity, and political decisiveness to the framework, because the original framework only considers feasibility, which it views as not sufficient enough to ensure successful policy implementation.

The outcome is thus a framework consisting of three elements: policy actors’ appraisal of the feasibility, the opportunity to put a policy on the policy agenda, and the political decisiveness needed for the adoption of a policy instrument.

Combining these insights leads to the following conceptual framework for determining implementation as shown in Figure 1. Base on the feasibility analysis on adoption of transport innovations by Feitelson and Salomon [14] , we develop three layers to access the timetable-less traveling policy, which is constituted by

three question: “Do the policy actors view the policy as feasible?”, “Is there a policy opportunity?”, “Does the policy require political decisiveness?”.

As can be seen in Figure 2, the policy of timetable-less travel has several consequences. One of those consequences is an increase in the number of passenger trains running, since the frequency is upped. This increase will lead to more passenger trips made by train. This increase has several causes. Firstly, due to the higher frequency of the trains, the average waiting times (and transfer times) will decrease, which will enhance the number of passenger trips made by train. Secondly, the chance of having a seat in the train increases (due to the increased capacity), which might lead to more people opting for the train as well. However, as a consequence of more passengers using the train, the chance of an available seat decreases after a while. This interdependency is shows by introducing a

feedback loop in Figure 2. And lastly, supply attracts demand, but it is questionable to what degree this still applies in this case, since underlying factors have been distinguished that might explain this phenomenon.

This increase in number of passenger trips performed by train results in a change in the modal shift and, assuming people will not travel more, it also leads to a decrease in the number of trips made by car. This decrease in car trips will lead to less car emissions, like NOx in the air.

The increase in the number of trips made by train also increases the need for access and egress trips. This increase in access and egress trips leads to an increase in the number of trips made by regional public transport and to an increase in the number of trips made by bike/foot (and possibly short car trips). The increase in trips performed by bike leads to an increase in demand for the number of bike parking spaces needed (and the possible increases in short car trips lead to an increase in the demand for car parking spots).

Furthermore, the increase in the number of operating passenger trains leads to more noise pollution and to less availability of the infrastructure for container trains to a longer occupation time (per unit of time) of the crossings with other modalities [17] . This increase in occupation time might lead to less safety due to for instance impatient other modality users who will take more risks to cross the crossing while the signals already indicate that a train is approaching [18] . Additionally, the increased occupation of the crossings will lead to larger travel times by car, because they will, on average, have to wait longer before they can cross the railway. This increase in car travel time might lead to a modal shift.

Secondly, the implementation of SpoorboekloosReizen will lead to more infrastructure to accommodate the increased frequency [19] . The extra infrastructure will take up some landscape.

Lastly, the policy is also aimed at changing the behavior of the travelers in such a way that they will act more like metro (or subway) users. This change in behavior will lead to less preparation time before a trip, since travelers know that they will not have to wait more than ten minutes (just like the metro system). However, the decrease in preparation time will also lead to less awareness of altered train schedules due to for example planned infrastructure management or accidents resulting in an alteration of the schedule. This in turn ensures that more passengers will be delayed or even stranded.

All these relations are represented in Figure 2. A positive relation means that when one factor increases, the other increases as well (or they both decrease). A negative relation indicates an inverse relation, meaning that one increases when the other decreases and vice versa.

SpoorboekloosReizen, as a public transport project, involves multiple stakeholders, including the Dutch government, enterprises and the public. Examples thereof are for instance the Ministry of I & W, railway related companies like the NS and ProRail, other public transport providers (tram/bus) like the RET, citizens living nearby rails, train commuters and car commuters. In Appendix A, a stakeholder analysis can be found which explains their interests and all potential impacts per actor category.

Using the stakeholder analysis framework (see Figure 3) to classify stakeholders based on their power and influence and interest-related level, we identified four key players who are both high in interest and power lever and have significant influence on the implementation of timetable-less travelling. They are Ministry of I & W, NS, Suppliers (materials & ICT) and Train commuters.

Any social change initiative or any policy project needs for strategic and tactical reasons to get an inventory of institutions involved, identify the key players, assess potential support or opposition among them [20] . For example, NS, the passenger railway operator, is responsible for providing the transport on a commercial basis. The NS needs to update their software and hardware facilities, like staff arrangement or scheduling ICT facilities to meet the need of timetable-less travelling for the sake of safety and operation. This means that the project needs to reach a certain occupancy rate to meet the financial targets of NS, or more government subsidies is needed from Ministry of I & W. Ministry of I & W, the governmental agency for improving mobility in the Netherlands, is the policy decision maker and founder of timetable-less travelling. They need to gain the public support for the policy and raise money for the expense of railway company. To gain the support of the public, train commuters should benefit from the project and get a safer, cost-saving, more reliable, sustainable train service. In a word, the implementation of timetable-less travelling requires a close cooperation of key players. We should focus on the key players group, engage and consult with regularly.

As shown in paragraph 2.3 (Conceptual Framework), certain criteria have to be

met in order for the policy to be implemented. The first criterion that has to be met is the feasibility component of the policy. In total five feasibilities will be examined.