Keywords

1 Introduction

Whenever we use public transport, we are supposed to reach a target place, leaving some origin and arriving at some destination. We have a purpose and possibly walking is too much, a bicycle not available (or the hill is too steep) and the car may be difficult to park. So, we use public transport. This could be subway, bus, many others. And we have a given system that provides us what we want. Does it? Very often it works, but there is also hesitation in many places around the world. For instance, in the United States we often hear that public transport is for poor people, those who cannot afford a big car. This is prejudice, though, but unfortunately not always untrue.

Whenever we want to use public transport, we need information; for instance, which means of transportation is available at what time, how much do we need to pay and how to access transport? We expect that clever people have done some proper investigation and that everything works. This would be an ideal world. Then, however, we meet disturbances, problems and alike (for a recent survey see [14]). This could be a small delay and it could be a major pandemic like Covid19 with a lockdown. It could be a high-probability low-impact event or a very low-probability very high-impact event. No matter, the question remains on how could we make the public transport system better (or, better, those who are responsible for running the system)?

An interesting observation is that many people including the general public are discussing about the quality of public transport, even if it might only be handwaving. But then nothing changes. May be the users should pay attention. May be the users could even provide some input on how to improve the public transport system. May be, we are not properly trained in marketing but that might even be an advantage. We are not bound to use predefined, sometimes useless (sorry), knowledge from academia. May be, we just need to be careful in observing. In that sense we could all be so-called mystery shoppers in public transport.

Extending earlier work [17, 18], this research focuses on modeling and analyzing bus stations within public transit. As an example, consider a Bus Rapid Transit (BRT) station. BRT refers to a “bus-based rapid transit system that can achieve high capacity, speed, and service quality at relatively low cost by combining segregated bus lanes that are typically median aligned with off-board fare collection, level boarding, bus priority at intersections, and other quality-of-service elements (such as information technology and strong branding)” [22]. The components of BRT include: vehicles, stops, stations, terminals, and corridors. A wide variety of rights-of-way, pre-board fare collection, use of modern information and communication technologies (ICT), all-day service, and brand identity can be aligned with a BRT system. To be specific, consider the TransMilenio system, as it is found in Bogota, Colombia (see Fig. 1).

Fig. 1.
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from [37]

Typical layout of a TransMilenio station,

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Classical concepts like BPMN for modeling or also living labs [33] may help to advance the knowledge about bus stations as major access points for public transport. Nevertheless, when it comes to improving the mobility needs of todays’ populations in metropolises and mega-cities, new avenues of research need to be undertaken. That is, beyond classical modeling approaches, one may use a virtual reality environment as well as the concept of mystery shopping to gain new insights into the design of bus stations. Virtual reality (VR) deals with the computer-generated emulation of real-world environments or the creation of fictional environments [34]. Users can immerse themselves in three-dimensional digital environments and simulations through the use of devices such as head-mounted displays. Augmented reality (AR) is concerned with enhancing the perception of a real-world environment with virtual effects or additional information as opposed to the entirely virtual environment created by VR [5]. That is, a user’s perception of the surroundings is extended through information that would not be visible in reality by use of digital devices such as digitally-enabled glasses or displays.

Mystery shopping (MS) is a concept mostly used in marketing when it comes to measure quality of service (QoS), or compliance with regulation, or to gather specific information about products and services [41]. With the combined use of these technologies, i.e. VR and MS, new insights may be gained at the interface of people using public transport systems and the system itself, especially allowing the consideration of different user groups that may want to use public transport, as there are, among others, elderly, handicapped, young children or pregnant women. A major takeaway from our research is that classical questionnaire-based research as it is commonly found in recent literature (see, e.g., some contributions on https://link.springer.com/journal/volumesAndIssues/12469) is too short-sighted when it comes to advancing and influencing the managerial insights of policy makers within public transport. AR, VR and MS in combination are able to change this.

The exposition of the subsequent sections first elaborates on various aspects regarding bus station design and provides a related survey. Then, Sect. 3 is devoted to MS and its use in public transport. This is moderately interleaved with our intention to combine this topic with modern ICT. Section 4 concludes and summarizes some future research needs.

2 Bus Station Design

Bus stations are access points to public transport systems (and, as the name says, especially bus systems). They can be just simple sign posts for a single stop of a single line and they can be versatile transfer centers where many bus lines or even different means of transport meet and allow for transfer. Various aspects need to be considered when designing a bus station as there are, foremost, functionality requirements and safety. Moreover, it may need to be subjectively pleasing, fulfill information management requirements as well as other types of aspects.Footnote 1

2.1 Functionality

The initial functionality requirement refers to a station being an access point to public transportation. Whatever one sees gives a first indication. And certainly the (mystery shopping) views in Fig. 2 are not necessarily typical ones.

Various measures are related to the functionality of bus stations including size, location, capacity, time of use and alike. Moreover, beyond functionality various other factors may be considered. As we started with a BRT system in the previous section, let us focus on BRT. The BRT Standard is an evaluation tool for world-class bus BRT based on international best practices. It is also meant to be a tool to exemplify a unified view on BRT systems. The somewhat initial 2014 Standard reinforces the basic BRT elements and provides some modifications to earlier drafts. The latest version dates back to 2016 [22].

Fig. 2.
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Sign posts; traveling through the world as a public transport mystery shopper (Source: own figures; Lisbon, Portugal, on the left, Brisbane, Australia, on the right and Melbourne, Australia, as the inset)

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For the case of Stockholm (Sweden), [2] undertake a study regarding the capacity of bus terminals. While the study does not clarify to full extent why a specific Swedish way is needed (as claimed), the study is interesting in its own right, taking into account various indicators to provide insights into the capacity of those terminals. In the same spirit, but more comprehensively, [39] also consider capacities. A microscopic simulation study is performed to analyze capacity. In the first of two stages, a mathematical model is presented for bus-side capacity with bus to bus interference and in the second, a model is used to estimate the relationship between average queue and degree of saturation. Results are conducted for various dwell times. A comparison between different BRT systems is provided in [19].

Especially for larger stations the question arises whether traffic flows resulting from transfer needs have to be directed in an appropriate way to avoid clashing or colliding of different flows with implied delays; see, e.g., related thinking based on [18] and Fig. 1. The functionality and design are also considerably affected by the size and location of a station. A location may be (to some extent) small, positioned at the curbside (with its relative location towards, say, the beginning, middle or end of a street segment). Beyond this, type, position and size may also be influenced by the street-side circumstances like the types of traffic flow considered in the streets where a station is built. An example of a related model based on ideas from cellular automata is given in [8]; other references include [16].

A survey has been conducted by [13]. The authors used existing transit agency manuals to gain state-of-the-practice information on bus stations. Moreover, transit agencies have been investigated and questioned. The results of [12] can be used to aid in the selection of a preferred bus stop design for a given location and traffic volume. Their analysis is divided into two separate studies: curbside versus bus bay/open bus bay, and queue jumper versus no queue jumper.

While being a silent observer, not to say a MS, we may see or encounter deficiencies [17]. If everything follows some predefined rules, everything would be nice. But this seems not the case. According to various authors including [38] one can distinguish different time periods associated with a bus stop. Assuming the perspective of a bus and also assuming a single berth, these periods can be specified as follows: Queuing time is the time spent by a bus in a queue prior to entering the bus stop, if at all (see also Fig. 7 below). Clearance time is the minimum [theoretical] time between the departure of one bus and the arrival of a subsequent bus in the bus berth. Dead time is the time that elapses in opening and closing of doors plus the time associated with extending ramps/lifts/other equipment to facilitate alighting and boarding of disabled persons, if any. Passenger service time is the time elapsed while passenger exchange takes place. Internal delay is the time spent by a bus waiting to leave the bus berth after it is ready to leave, but cannot actually leave as it is obstructed by other bus(es) in the bus stop area. External delay is the time spent by a bus waiting to leave the bus berth after it is ready to leave, but cannot actually leave as it is obstructed by other traffic outside the bus stop area. Having stated this, a case study in a British context can be found in [1].

In [23] we see the description of a model that includes not only a set of elements to determine the safety level of a public transport company but also a set of indicators and criteria to evaluate these elements by a team of auditors Regarding safety we also see the development of low-floor vehicles and related bus stations for improving the accessibility of urban buses to mobility-restricted people. In [10] we see some research and development project for the public transit system in Grenoble (France) that attempts to reduce the gaps at bus stations. Investigations regarding operating conditions of accessibility equipment on the buses (kneeling, access ramp) as well as driver capability to dock at the bus station are described with the result of an improved bus station design.

Bus stations are also social areas. An interesting study may be to observe passengers while using a bus station. This relates to accessing, deboarding and eggressing as well as waiting. Depending on various design criteria of a station this may be varying considerably. Different postures of waiting passengers can be observed such as sitting or upright standing and leaning against a wall, depending on different bus station designs. Culture may require queuing or people are just walking around. In [42] the authors investigate different standing postures providing an ergonomic perspective towards bus station design. While the implications from this study are still limited, they open up an area that deserves consideration regarding the comfort of passengers in different ways. As a next step one needs to differentiate passengers due to their specific needs, e.g., when mobility-restricted people are concerned. For instance, in [44] indicators are described measuring to some extent the quality of a station in this respect (considering aspects such as being barrier-free, incorporating height differences and alike).

Different user groups may require different design aspects based on their specific needs. These groups can be related to elderly, handicapped, small children, pregnant women etc. Specific examples considering related requirements include, e.g., [27], who provide a first investigation of the case of a kindergarten-based safety requirement.

Functionality requirements also include safety. Then the question arises, whether unexpected disturbances are included, too; see, e.g., Sect. 2.4 to think about corona-based design. Finally, we mention the issue of service systems being required to be subjectively pleasing (and eventually causing happiness [11]).

2.2 The Arts Component

Bus stations may reflect cultural aspects of a city and can be used not only regarding their functionality but reflect also other measures that might reflect more arts-based functionality or touristic aspects, but this may need further investigation. In [26] the idea of building a harmonic bus station in light of the surroundings and the culture of the place to be reflected is considered.

Researchers from the Offenbach University of Design (Germany) are concerned with the question of the role of design in promoting multimodal mobility behavior. Mobility design, focusing not necessarily on vehicles but on the design of infrastructure like bus stations and processes like accessing a station, have been an integral part of studies and research. Examples of some projects that they are developing use new visualization methods such as AR and VR. Examples include the service points of German railways as well as a related bus station design operationalized in South Korea [20]. The possible design of a mobility hub as a new extended project is shown in Fig. 3.

Fig. 3.
figure 3

from [20]

Mobility hub

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2.3 Information and Communication Technology

Over time passenger information and modern ICT of the related times had been incorporated into the interplay of customers with the public transport system and especially with their access to the system; older ideas and systems as envisaged years ago [9] have now been incorporated into station design as a natural endeavour [28].

The use of various techniques can be simulated in various ways. Living labs, as an example, can be seen as a real simulation environment that can be enhanced by various other technologies; see, e.g., Fig. 4, [33]. Extending this towards new designs is realized on a continuous basis; see, e.g., the examples in Fig. 8 below. Marrying this with AR allows for extended visualization and information provision; see, e.g., Fig. 5.

Fig. 4.
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from [33]

Living lab bus station

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2.4 Miscellaneous

Beyond the issues raised above, several additional aspects may be considered. This may be, e.g., the question of how to get energy to and at the bus station if needed (see an example for a case study in [3]) or the recent case of modified thinking related to social distancing as indicated below.

The recent pandemic has influenced all areas of life. For instance, in times of a lockdown the operations of public transport (including bus, rail, ferry and taxi) have been suspended or at least been reduced considerably in many places; cf. Fig. 6. Stations were temporarily closed or not served. For instance, in Wuhan as a starting point of the Covid19 pandemic, the municipal government expropriated, among others, bus stations to build shelter hospitals rather than using them for public transport purposes [45]. Obviously, following the requirements of a pandemia like in the case of Covid19 requires quite a few drastic changes in public transport. For instance, if social distancing is followed in an appropriate way, then systems that are already beyond their limits might need even more capacity and infrastructure. Handwaving says that not only countries like India require a multitude of buses to allow commuters to effectively perform social distancing.Footnote 2 Bus stations require different forms of queuing. Complying with social distancing already applies during access implying rethinking of station design. Similarly, bus station maintenance requires different and more intensive thinking in the same spirit.Footnote 3 The question of social distancing may also ask whether this can be enforced by the station design. Regarding the above-mentioned concerns of enabling efficient transfer becomes even more important if social distancing can be enforced through a clever assignment of buses to berths allowing for appropriate (separated or non-overlapping) transfer paths.

Fig. 5.
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Augmented reality adoption in bus usage

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Fig. 6.
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Decline of bus patronage worldwide; https://moovitapp.com/insights/en/Moovit_Insights_Public_Transit_Index-countries, last access June 19, 2020.

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3 Mystery Shopping

As indicated above, mystery shopping is a marketing research-based method intended to measure QoS, gather specific information about a market, competitors, or even economies. Mystery shoppers are intended to mirror common consumer behavior and to investigate the habits of customers, sellers and service providers. It is also a tool allowing to measure compliance with regulations etc. General considerations include [29, 41].

The history of MS goes way back into the 1940s. The focus was on manufacturing and retail with the financial sector coming next. Specific observers or people were trained to act as normal customers realizing or simulating real sales and customer situations.

MS as a tool in the service industries has been explored especially in [41]. Other sources include [24]. While known and applied in practice, MS in public transport has not yet been fully explored in academic literature and only few papers are available including [7, 15, 35, 40]. Those are building the base of our elaboration below. Finally, with mystery shopping in mind we return towards bus station design.

Another option to undertake mystery shopping is to some extent known under the name of field studies.

3.1 Questionnaire-Based Studies in Public Transport

Customer satisfaction surveys are part of important research. For instance, once performing customer surveys, public transport companies or authorities gain insights into the areas where possible improvements are needed. Our criticism, though, is that recently quite a few of these studies have been published or submitted for publication without bringing any additional value. That is, while this methodology is important for public transport companies and regulating bodies, their one-dimensional application in academia is often lacking good reasoning. Older questionnaire-based papers with that type of reasoning for existence include [13, 21, 31].

What we should gain are factors influencing QoS and also hints on how to use scarce financial resources. While it seems interesting to see whether, just to name a few examples, station cleanliness and on-time arrival of buses are important in one place or another based on some, say, 384 interviewees being users of a public transport system, the resulting numbers might not really tell us on how to use scarce financial resources to improve the system and they also lack to explain anything about non-users of the system if they are not considered. In that sense we claim that other types of methodology should be appended (as indicated below) while public transport companies still undertake these studies. They should also be published, but rather as company-oriented quality reports than academic papers.

Again, a major concern relates to those who are involved into customer satisfaction surveys, i.e., is it just customers or also non-customers (those who might be interested or even need to be motivated to switch to public transport). Moreover, detailed information regarding access points and places where questionnaires were handed out are often missing (like enhancements by additional information about the station design etc. considering using a single signpost versus major transfer stations).

3.2 Examples for Mystery Shopping Applications in Public Transport

To exemplify, we refer to four cases as they are London (UK) [40], Thessaloniki (Greece) [15], Moscow (Russia) [35] and Hamburg (Germany)Footnote 4.

Copying from [29], one may ask upfront about how to set up a MS application. Among several steps one should start with the scope of the MS assessment (e.g., which attributes are to be tested). Next, the way on how to conduct the study should be defined. This may include benchmarking, a way to find out about the strengths and weaknesses of something or an ongoing effort to continuously measure and improve an offered service. Then comes the simulation of an actual customer experience. Beyond that, quite a few additional mostly self-explanatory aspects need to be considered touching base regarding the way MS results are reported, how employees are informed about the implementation of MS etc.

An interesting question relates to who is going to set up the mystery shoppers. For instance, in case of several transit companies working together in a transport association (say the Hamburger Verkehrsverbund (HVV) in case of Hamburg, Germany), should it be the single bus company or the association. In case of Hamburg, the above mentioned reports are provided by the association and the MS program is set up to allow for year-round check-ups. The different modes of transportation within the HVV have different sets of quotas. That is, all buses and half of all bus stops are visited at least once a year. There are three groups of indicators for buses and ferries and their corresponding attributes:

  • Stop sign/mast: stop-symbol, name line, tariff line, route line, color of mast

  • Passenger information (related to the bus station): schedules, tariff information, possibly network plan

  • The stations themselves are also monitored, but the responsibility for them lies often not with the HVV member, but other parties, which poses another issue.

For London the well-documented study of [40] focuses more on London Underground rather than the bus system, but they provide useful reasoning why MS should be superimposed on customer satisfaction results. Especially the allocation of funds regarding different attributes requires detailed business cases defining the scope of the study. MS teams of two were deployed four times a year on strictly specified routes. On their journey they collected measurements of 26 train-specific and 116 station-specific attributes using a paper questionnaire.

Also the Moscow study of [35] focused more on metro than other means of transportation, though, testing a comprehensive number of vehicles overall. Different from Hamburg and London this was a one-shot endeavour in summer 2014. Moreover, the extent of the study was to some extent focused (cleanliness, wifi quality etc.). The Thessaloniki case [15] is interesting in its own right as the related authority had no prior experience on MS so that a pilot study is reported providing insights on how to set up such an endeavour.

3.3 Mystery Shopping and Bus Station Design

While the previous sections revealed the possible use of MS in public transport it has not really been used in literature for bus station design. Modeling attempts like the one in [18] may be extended but have not used the concept of MS. Narrative papers could also be seen as educated MS attempts on how to design bus stations, like in [25, 46], but the real attempt is still missing.

As a first attempt, we utilize the visualization tools of some simulation to design an ideal bus station; see, e.g., Fig. 7 for a first step in that direction. This may overcome some of the deficiencies encountered in various places in the world as very briefly sketched in [17]. That is, if a way can be found to let bus drivers behave appropriately and train them in a sustainable way, that might help a lot. Moreover, issues as those related to ICT adoption in bus station design as indicated in Fig. 8 may be encountered, too, especially if they can be married with those attempts performed related to the living lab concept of [33]. VR would allow to let MS with different background to not only use the system but also to envisage possible design changes in a simulated environment. While this does not compensate for the real experience, it still allows for upfront measures to incorporate meaning and comprehension of mobility restricted people, minors or pregnant women, just to mention some groups of interest. For the hybridization of BPMN and VR, tools are available; see, e.g., [32]. That is, regarding bus station design MS may provide a lot of food for thought.

Fig. 7.
figure 7

Simulation of a bus station

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Fig. 8.
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ICT adoption in bus station design

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4 Conclusions

In this paper we have looked at bus station design based on selected literatures. Implicitly an information management approach and incorporating a marketing-based mystery shopping idea as well as modern ICT (including augmented reality and virtual reality) gave us a slightly different edge over existing references. In passing, we have seen quite a few issues that are worth being explored further. In that sense we can see the value of this paper as one providing food for thought and initializing further research. Let us distinguish between some food for thought and some explicit future research directions.

The upcoming idea of autonomous vehicles allows to conceptualize quite a few ideas of innovative public transport systems, including private rapid transit (PRT) and mobility-as-a-service (MaaS) [43]. During the 1990s, PRT was mainly envisaged for automated people movers in airports, but more recently, individualized solutions seem to become more and more possible. While these systems are built and/or simulated, their possible station design needs to be considered, too. The interesting issues relate to differently-sized vehicles that need to be accommodated in an appropriate way, like car-sized electric vehicles running on a separated (say, underground road) network; see, e.g., [30, 36]. In [4, 6] the authors suggest layouts and operations strategies for transfer stations between PRT and heavy rail.

Moreover, we claim that public transport companies need more research on mystery shopping married with augmented and virtual reality-based simulation rather than academic questionnaire-based studies. This methodology should be applied inhouse by public transport companies, though. While this methodology seems well understood, especially if they consider the sharing of scarce resources (which many of them do not do), ideas on mystery shopping still seems to be underrepresented and need more evidence.