No abstract

A concern raised by some motorists in relation to the presence of bicycles on urban roads without bicycle lanes, discussed in part of the traffic literature, is that cyclists will slow down motorized vehicles and therefore create congestion. This research answers this question: do bicycles reduce passenger car travel speeds on urban roads without bicycle lanes? To answer this question, a detailed comparative analysis of the travel speeds of passenger car (class two vehicles) on lower volume urban roads without bicycle lanes is presented. Speed distributions, the mean, and the 50th and 85th percentile speeds for two scenarios were examined: (i) a passenger car that was preceded by a bicycle and (ii) a passenger car that was preceded by another passenger car. Peak hour traffic and 24-h traffic speeds were analyzed using t-tests and confidence intervals. Although a few statistically significant differences between scenarios (i) and (ii) were found, the actual speed differences were generally in the order of 1 mph or less. Therefore, differences in class two (motorized passenger) vehicle speeds with and without cyclists were found to be negligible from a practical perspective.

Transit goals have typically focused on commuter trips but facilitating urban last mile freight logistics is a potential strategy to increase transit ridership and mitigate the demands of parcel distribution on the transportation network. Presently, most parcel lockers operate out of private businesses, but consumer surveys have found that transit users may be interested in locker facilities at transit facilities. The implementation of an unmanned, secure, common carrier parcel locker system could have benefits for non-transit users as well. This research presents a multiple-criteria approach for analyzing the potential of public transportation facilities as hosts for a common carrier locker system. Several accessibility and equity metrics, including ridership, mode of transportation, spatial distribution, and sociodemographic profiles of coverage areas are utilized. A case study utilizing real-word data from the Portland, OR region and its transit facilities is used to illustrate accessibility and equity tradeoffs. The results demonstrate that multiple facility types have the potential to host a locker system but there are complex accessibility and equity tradeoffs to be considered by stakeholders and policy makers when prioritizing locations.

This thesis presents a compilation of papers exploring passenger car and bicycle speeds through their interactions with each other and with urban roadway factors.First, following a concern raised in part of the traffic literature that a large mode shift toward bicycling may cause travel time delays and potentially exacerbate congestion instead of alleviate it unless bicycle lanes are installed, an empirical study detailing how the presence of bicycles on urban roads without bicycle lanes may affect passenger car speeds is presented. Pneumatic tube data from six predominantly low speed, low volume roads in Portland, Oregon were utilized to identify observations of passenger cars (class two vehicles) belonging to one of two vehicle following scenarios. In scenario (i), a passenger car was directly preceded by a bicycle (class one vehicle), and in scenario (ii), a passenger car was directly preceded by another passenger car. Speed distributions were examined, and the mean, the 50th, and the 85th percentile speeds of scenario (i) and scenario (ii) vehicles for both peak-hour and 24-hour traffic were compared using t-tests and confidence intervals. A few statistically significant differences between scenario (i) and scenario (ii) were found, but the actual differences in speed were generally on the order of one mile per hour or less. Thus, from a practical perspective, the presence of bicycles on these roads without bicycle lanes was deemed to have negligible effects on passenger car speeds.Following the results of the initial study, a second study was conducted to address limitations in the initial study regarding the homogeneity of site characteristics. This second study also expanded the research to explore how oncoming (opposing direction)

Higher bicycle mode share has been suggested as part of a solution to reduce the burden of congestion in urban areas. As strategies to promote cycling are implemented, concerns have been raised by some road users and stakeholders citing simulation-based traffic studies that indicate that an increase in the bicycle mode share generates major travel time delays via reduced vehicle speeds unless bicycle lanes are provided. The current research investigates the effects bicycles may have on motorized vehicle speeds on a variety of lower speed and volume urban roads without bicycle lanes. A detailed comparative analysis of passenger car speeds was performed using two vehicle scenarios: (i) a passenger car that was preceded by a bicycle; and (ii) a passenger car that was preceded by another passenger car. The mean and 85th percentile speeds of scenarios (i) and (ii) were analyzed using t-tests. Relationships between speed and gap times with oncoming (opposite direction) traffic were also investigated. The results indicate that, at most sites (92%), bicycles do not reduce passenger car mean speeds by more than 1 mph. Speed reductions are not generally observed in local streets or facilities with adequate gaps in oncoming traffic for overtaking.