Lisa Aultman-Hall

ANALYSIS OF BICYCLE COMMUTER ROUTES USING GEOGRAPHIC INFORMATION SYSTEMS: IMPLICATIONS FOR BICYCLE PLANNING

A geographic information system (GIS) network data base is used to determine the characteristics of 397 routes used by commuter cyclists in Guelph, Ontario, Canada, and to compare them with the shortest-path routes between each origin and destination. The analysis of route data provides useful insight for understanding factors affecting travel behavior and in this case provides quantitative support for many existing assumptions regarding commuter cyclist behavior. Most commuters divert very little from their minimum path (0.4 km on average) and are found to use major road routes. The cyclists tend to avoid grades, grade-separated railway crossings, and high-activity areas, but not road (as opposed to pedestrian) bridges. Cyclists use traffic signals especially for crossing major roadways and turning. The high-quality direct off-road paths are used only infrequently by the commuter cyclists and the lower quality ones even less. The results of this analysis suggest that efforts to accommodate current commuter cyclists should be focused on improving cycling conditions on the road network, such as providing wider curb lanes, or actuated traffic signal detectors that recognize the presence of bicycles. If potential new commuters are similar to the minority of current commuter cyclists in this study who use mainly local roads, paths or trails, then projects that make the network of local roads and pathways more connective and direct may encourage a higher level of commuter cycling.

Toronto bicycle commuter safety rates

This analysis uses data from a survey of Toronto commuter cyclists that collected information regarding accident history as well as regular commute route to work or school. By relating the route information of the 1196 respondents to facility attributes in a Geographic Information System (GIS), defensible estimates of travel exposure on roads, off-road paths and sidewalks were developed. The rate of collision on off-road paths and sidewalks was lower than for roads. The relative rates for falls and injuries suggest these events are least common on-road followed by off-road paths, and finally most common on sidewalks. The rate of major injuries, an injury that required medical attention, was greatest on sidewalks and the difference between paths and sidewalks was negligible. These rates suggest a need for detailed analysis of sidewalk and off-road path bicycle safety. The absolute event rates per bicycle kilometer were found to be between 26 and 68 times higher than similar rates for automobile travel, re-confirming the urgent bicycle safety crisis. Examination of rates for sub-groups of cyclists suggest that experience is an important factor in bicycle safety. The same survey conducted in Ottawa, Canada found event rates much lower than Toronto. This result may confirm urban form, traffic levels and attitude do affect bicycle safety. The analysis also demonstrates a successful method to quantify bicycle travel exposure information and should be considered for further use as complement to other existing techniques.

Assessing Impact of Weather and Season on Pedestrian Traffic Volumes

Twelve months of automated hourly pedestrian counts in downtown Montpelier, Vermont (population 8,035), were analyzed along with weather data (temperature, relative humidity, precipitation, and wind) to determine the factors affecting count variability. This study is unique in that a large amount of data in a single location was collected in a locale with an extreme range of weather conditions. Results indicate consistent patterns in relative volumes by hour of the day and month of the year that show that good adjustment factors can be developed to use with time-limited counts to estimate usage and pedestrian exposure to accidents. Predictive relationships were found between weather variables, season, and pedestrian volumes (30% of the variation is accounted for). Consistent hourly patterns within a day and the consistency of day type (weekday or Saturday versus holiday or Sunday) suggest that correction factors and forecasting methods are feasible for pedestrian traffic volumes. The results indicate that weather such as cold temperatures or precipitation consistently reduces aggregate levels of walking by only a moderate amount (less than 20%). Precipitation and season are found to affect pedestrian levels even when time of day and day of week are controlled, but other, larger, unmeasured factors are at play.

Ottawa-Carleton commuter cyclist on- and off-road incident rates.

This analysis overcomes the known limitations of police and emergency room bicycle accident databases through use of a survey that asked cyclists to indicate their accident history as well as their regular commute route to work or school. By relating the route information of the 1604 respondents (52.5% of the distributed questionnaires) to facility attributes in a Geographic Information System, defensible estimates of travel exposure on roads, off-road paths and sidewalks were developed. The relative rates of collisions on the three different facility types were not statistically different from 1.0. The relative rates for falls and injuries suggest it is safest to cycle on-road followed by off-road paths and trails, and finally least safe on sidewalks. While there were no major injuries reported on sidewalks, the relative rate for these events on paths was greater than the rate for roads. The absolute event rates per bicycle kilometre were found to be between 10 and 41 times higher than similar rates for automobile travel. Results suggest a need to discourage sidewalk cycling, and to further investigate the safety of off-road paths/trails. The analysis also demonstrates the need for bicycle travel exposure information and the use of more than just collision databases for bicycle safety analysis.

Impact of passengers on young driver safety

An analysis of young driver accidents uses the quasi-induced exposure technique to disaggregate accidents by different characteristics or circumstances while making estimates of the relative travel exposure for those different circumstances. Relationships are developed to investigate the effect of passengers on young driver (age 16 to 20) accident propensity. Three passenger groupings are used: solo (no passengers), peer, and adult or child. The database contains 77,312 accidents involving young drivers in Kentucky in 1994, 1995, and 1996. The passenger-group variable was found to have a significant effect on young driver accident propensities. Young drivers have the lowest propensity to cause single- or two-vehicle accidents when traveling with either adults and/or children. They have an increased propensity for causing single-vehicle accidents when traveling with peers. The relative accident involvement ratios for both single- and two-vehicle accidents for young drivers traveling alone were close to 1.0, suggesting that they were at fault approximately the same percentage of the time that they were not at fault. Seven variables were considered for possible interaction with passenger group: driver gender, total occupant gender, time of week, time of day, highway type, vehicle age, and safety-restraint usage.

Weather factor impacts on commuting to work by bicycle

OBJECTIVE Quantify the impact of weather conditions on individual decisions to commute to work by bicycle among a diverse panel of adults who commute ≥2 miles each way. METHOD Working adults (n=163) in a northern U.S. state reported transportation mode for four seven-day periods in 2009-2010 that maximized seasonal weather variations. Personal characteristics, trip to work distances, and commuting mode data were linked to location- and time-specific weather data and daylight hours. Analyses focused on effect of weather conditions on reports of commuting by bicycle. RESULTS Participants were diverse in age, gender and bicycle use, but were relatively well-educated; they traveled to work by bicycle on 34.5% of the logged commuting days. Modeling indicated that the likelihood of bicycle commuting increased in the absence of rain (odds ratio=1.91; 95% confidence interval 1.42, 2.57) and with higher temperatures (1.03; 1.02, 1.04), and decreased with snow (0.90; 0.84, 0.98) and wind (0.95; 0.92, 0.97). Independent effects also were found for bicycle commuting distance, gender, and age, but not for daylight hours. CONCLUSION Precipitation, temperature, wind and snow conditions had significant and substantial independent effects on the odds of travel to work by bicycle among a diverse panel of adult bicycle commuters.

SIDEWALK BICYCLING SAFETY ISSUES

Bicycle route and safety data sets for 2,963 commuter cyclists in Ottawa and Toronto, Canada, containing cyclist characteristics, collision and fall history, and regular commute route, are used for this analysis. Previous analyses found sidewalk collisions and fall and injury rates significantly higher on sidewalks than on roads or paths. Of the 52 events reported on sidewalks, none were reported to police and would, therefore, not be found in a police accident database. These events did result in injuries, and in two cases major injuries. This analysis has found that commuter cyclists in Ottawa use sidewalks primarily on major roads (not necessarily high-speed roads) and often to cross bridges or to take shortcuts where no road exists. Toronto commuter cyclists use sidewalks primarily on high-volume multilane roads. Some Toronto cyclists still use sidewalks when bicycle lanes are provided. A slightly higher proportion of women are sidewalk cyclists in Ottawa; however, no age relationship was found. Sidewalk cyclists reported proportionally more near misses with bicycles in the previous month. A relatively large number of sidewalk collisions are with other bicycles. The most significant result of the analysis is that sidewalk cyclists have higher event rates on roads than nonsidewalk cyclists.

Causal Factors for Accidents on Southeastern Low-Volume Rural Roads

Low-volume roads comprise a significant portion of the rural roadway network. Because of documented higher crash frequencies and more severe injuries on such roads, it is necessary to further examine causal factors of these crashes and to determine if crash characteristics follow the patterns of other highways. The quasi-induced exposure technique is used to analyze the relationship of driver, roadway, and environmental factors involved in crashes on low-volume roads. Crashes from Kentucky and North Carolina for 1993–1995 are used. The results show that (a) low-volume roads present similar crash trends as those observed on other roads; (b) drivers under the age of 25 and drivers over the age of 65 have higher crash propensities than middle-aged drivers; (c) female drivers are safer on average than male drivers; (d) young drivers (under the age of 25) experience more single-vehicle crashes and drivers over 65 are more likely to be involved in two-vehicle crashes; (e) drivers of older vehicles have higher two-vehicle crash propensities on low-volume roads than drivers of newer vehicles; (f) in single-vehicle crashes, drivers of older vehicles are more likely to have a serious injury than drivers of newer vehicles; and (g) large trucks have the highest two-vehicle crash propensity on low-volume roads, followed by sedans, pick-up trucks, vans, and station wagons.

Modeling Stated and Revealed Route Choice: Consideration of Consistency, Diversion, and Attitudinal Variables

Data from Global Positioning System (GPS) route data collection and a survey conducted after data collection obtain both stated and revealed route choice preferences from respondents in Lexington, Kentucky. A subset of the GPS data was analyzed to reveal how much their chosen routes differ from minimum-time routes. The post-GPS data collection survey includes attitudinal data, travel habits, route descriptors, and demographic data as stated by respondents, who identified preferred and nonpreferred peak and off-peak routes between the University of Kentucky and Kentucky International Airport. Summaries are given of travel habit and work- and shopping-related attitudinal variables. The three most commonly identified routes described by participants were analyzed. Binary models are presented for diverters and people who chose the same route during peak and off-peak conditions. One-third of the respondents are diverters and revealed that they deviate more than 10% from minimum travel time routes. Approximately 60% of the sample stated that they would use the same route during peak and off-peak conditions. Attitudinal data, travel habits, route descriptors, and demographic variables were significant in the models and help explain the behavior. The revealed data and the attitudinal data both help explain consistency in route choice.

A Review of Current Practice in Network Disruption Analysis and an Assessment of the Ability to Account for Isolating Links in Transportation Networks

Abstract This paper presents a comprehensive review of the scholarly literature related to the field of network-disruption analysis. Research related to network disruption has progressed immensely since the late 1990s and now includes a wide variety of themes and approaches used to assess the impacts associated with a variety of disruptive events. Of particular relevance are those approaches which use repetitive link and/or node-removal methodologies to develop measures of network robustness or vulnerability (complementary concepts). More recently, various methods have begun to focus on the sequential application of equilibrium-based traffic assignments to measure the cost of a disruption to the network. It is crucial for these types of methods to handle the complexities of real-world transportation networks — one of which is the presence of isolating links in a network, which provide a single link to a particular region or subnetwork. A number of methods have attempted to deal with the problem of isolating links in different ways, but none has been ubiquitously successful. To develop a comprehensive and useful measure of transportation network robustness it is important to successfully address the issue of isolating network links.