for daily mobility. Traditional discrete choice models are mainly based on variables such as time and cost. These variables do not sufficiently explain the choice of the bicycle as a mode of transportation. Some researchers have noted a significant influence of psychological factors-such as attitudes, social norms, perceived behavioral control and habits-in the decision to commute by bicycle. Bicycle commuters show more positive attitudes toward bicycle use (2-5), more perceived social norms or psychological support for using the bicycle (2,3,6), more positive perceived behavioral control toward bicycle use (2), and less perception of barriers (4, 6). However, habits reduce the influence of these constructs in the decision to use the bicycle (7). Habits of using other modes have a negative impact on bicycle use (8), while the habit of using the bicycle for noncommuting mobility increases the frequency of bicycle use for commuting trips (7,9). In view of the limited research on the relationship between attitudes, other psychological constructs, and cycling (10), this research project aims to continue analyzing the relationship between psychological factors and bicycle commuting by following the research work of Heinen et al. (5).The paper is organized as follows. The theoretical framework is presented in the next section. That is followed by descriptions of the case study, data collection, and variables. Next come the results, which determine the differences between various types of users in their perceptions of cycling factors. On the basis of those factors, the main structures underlying attitudinal and other psychological variables are identified and defined. The analysis continues with an examination of the psychological factors influencing bicycle commuting through a binary logit model. The final section contains some policy recommendations and conclusions.
FRAMEWORKThe framework of this paper is the theory of planned behavior (TPB) (11), which is the best-known and most widely supported attitudinal psychological theory in most studies relating to behavioral decisions. This theory has been used in various studies on cycling (2,5,12) and in the field of active travel behavior (7,13). TPB states that attitudes toward a behavior, subjective norms, and perceived behavioral control combine to shape an individual's behavioral intention and final behavior, which in the case of the current research is commuting by bicycle. These components are described by Ajzen as follows: the attitude toward a behavior is "the degree to which performance of the behavior is positively or negatively valued"; the subjective norm is "the perceived social pressure to engage or not to engage in a behavior"; and the perceived behavioral control (PBC) refers to "people's people's decision to cycle to work-place of study is tested by using a logit model. In the case study of Madrid, Spain, the decision to cycle to workplace of study is heavily influenced by cycling habits (for noncommuting trips). Because bicycle commuting is not common, a...
