Proof of Concept for a Grounded Theory Approach to Understanding Interactions Occurring on Bicycle Facilities

Protected bicycle lanes are held up as the end-all of bicycle infrastructure, with unprotected bicycle lanes being widely considered unsafe and inferior. This perspective is supported by existing research showing people’s preference for protected versus unprotected bicycle lanes. Scant research, however, has explored this topic area using an observational research method. If an observational method is used, the research is typically count-based and focused on a predetermined sets of variables identified before the observation period and this hinders the research from advancing findings beyond frequencies and the already known variables. Without a clearer understanding of how people are using and interacting on streets with either type of bicycle lane, it is difficult, if not impossible, to adequately assess whether, and which, facility type best accommodates safe bicycle mobility. This paper introduces a new qualitative-quantitative method for conducting observational research which takes a grounded theory approach to gain new insights into how people behave and interact while using street segments, intersections, and other public places. This method follows a four-step process which involves qualitatively identifying interactions recorded on video, using deductive and inductive logic to document independent variables associated with interactions, and concludes in a quantitative analysis of the qualitatively produced data. As a display of the applications of this method, a case study is presented here which uses the new method to investigate the interactions of bicyclists with other road users on a street segment with an unprotected bicycle lane in Munich, Germany. In Munich, Germany, all bicycle lanes built on the vehicular roadway are delineated with solid or striped white painted lines, the width of which is sometimes painted red. These facilities are located between, and are physically unprotected from, the vehicular travel lane and parking lanes, if a parking lane is present. Without any barrier, the design of these bicycle lanes inherently allows encroachments into and out of the dedicated bicycle lane. Pedestrians can easily walk across the bicycle lane when crossing the street, drivers must cross the bicycle lane to access or egress from the parking lane, and bicyclists can flexibly move into and out of their dedicated travel lane to get around obstructions or access adjacent bicycle parking facilities. Owing to the permeable design of these facilities and this allowance for encroachment, it is likely that bicyclists experience interactions in the bicycle lane, not only with one another, but also with mode users crossing or traveling adjacent to the bicycle lane. The most prominent bicycle advocacy organization in Germany, the Allgemeiner Deutscher Fahrrad Club e.V. (ADFC), is currently pushing for cities to build protected bicycle lanes to increase the safety and mobility of bicyclists (1). This policy position stems from the idea that protected bicycle lanes are held up as the pinnacle of good infrastructure design for urban streets and is supported by survey research findings that people feel safer and more comfortable bicycling in protected bicycle lanes (2–4). Unprotected bicycle lanes, on the other hand, are criticized for providing no physical protection and putting bicyclists in the “door zone”, yet such facilities have also been celebrated from the perspective that it is better to have some bicycle infrastructure on the ground than none (5, 6). Existing research, unfortunately, provides only limited information on well unprotected versus protected bicycle lanes function to meet the needs of all people using the street, which hampers the ability to make informed decisions about the best type of design of bicycle facilities to build on urban streets. To date, methods used to examine travel behavior have followed traditional engineering approaches that are count-based and deductively focus on traffic volumes, user gender, and expected behavioral variables, such as speed, lateral positioning, and passing distances. There is a call to move beyond quantitative logic and advance mixed-method approaches to enlighten our understanding of how infrastructure and public space design influences travel behavior (7). Furthermore, Clifton and Handy urge for the employment of qualitative methods, used in conjunction with quantitative methods, to more thoroughly “unravel the complexities of travel behavior to better assess the sources of the problems and predict the impact of future trends” (8). Responding to these calls, this paper presents a new qualitative-quantitative observational method designed to examine people’s street use. Drawing heavily on grounded theory, this method aims to contribute new insights into people’s behavior on transportation facilities by providing a framework for identifying typologies of interactions taking place between people while using given types of transportation facilities. Based on a quantitative analysis of the nature of the types of interactions observed, the performance of the transportation facility can be evaluated and mitigation measures for facility design or traffic regulations can be developed to avoid undesirable interactions. This method was designed for investigation of the types of interactions experienced by bicyclists traveling on street segments with unprotected bicycle lanes in the City of Munich, given the infrastructure’s inherent allowance for encroachment. In the context of this research, an interaction event is broadly defined as a negotiation of movement involving a bicyclist and another person using any mode of transportation or a stationary object. This negotiation involves at least one person or object engaged in a legal, allowed, or illegal use of the roadway and at least one person reacting to the action or inaction of the person or object stimulating the interaction. Although existing research results provide hints of the types of interactions occurring on bicycle facilities—see Aldred’s research on typologies of near-miss events experienced by bicyclists or Bernardi and Rupi’s study of bicyclists’ interactions with pedestrians on at-grade facilities—our understanding of the interactions people experience is limited by methods relying on people’s reported behavior and deductive assumptions about which variables influence the occurrence of interactions (9–11). In contrast, the method presented in this paper applies a grounded theory approach using induction to identify interaction typologies and code observed variables associated with those interactions. By using this qualitative approach to coding, the data collection process is unrestrained by assumptions and flexibly allows any type of interaction or behavior to be documented, expected or unexpected. Following a discussion of the relevant existing research and background on the study of unprotected bicycle lanes below, the Methods section describes each step in a four-step coding procedure designed to qualitatively identify interactions and produce a quantitative dataset describing the behavioral, spatial, and circumstantial characteristics of identified interaction typologies. A proof of concept application of this method is then exhibited in the Case Study section, with results from a study of one street segment with unprotected bicycle lanes in Munich. This paper concludes in the Discussion section with an overview the method’s strengths and limitations, and a discussion of the potential future applications of the method in transportation research and policy evaluation