Selecting Improvements for Bicyclists
Addressing bicycle safety is a process that may include:
- Identifying factors affecting bicycle safety
- Analyzing crash data
- Analyzing roadway design and operation characteristics that affect bicycle safety
- Establishing crash-related and/or performance-based goals
- Selecting and implementing countermeasures that address bicycle safety
Typically, this process starts with bringing the right agencies or individuals and resources together. Transportation and land use planners, engineers, law enforcement officers, emergency and health services, and community leaders need to work collectively to address bicycle safety. Engaging stakeholders from these different disciplines can help to both identify the problems and facilitate the sharing of ideas to reach consensus for implementing a set of treatments that will provide the greatest safety and mobility benefits.
Bringing together the appropriate resources is also critical when getting started. Practitioners may consult their State’s Strategic Highway Safety Plan (SHSP) to look for opportunities to address bicycle safety. An SHSP is a data-driven, comprehensive, coordinated safety plan that provides a framework for reducing fatalities and serious injuries on all public roads within a State. Local agencies may consult the State’s SHSP to determine whether there are emphasis areas, data, or other programs that provide opportunities to coordination to address bicycle safety.
Practitioners can also use data to identify safety problems. One method is to review historical crash data to identify high-crash locations and examine pre-crash maneuvers that lead to bicycle-motor vehicle collisions. A second, or complementary method, involves identifying hazardous locations through the use of tools like audits and checklists.
Since many of the problems faced by bicyclists either do not result in crashes or the crashes are not reported, practitioners may need to use a more broad-based and focuses on performance objectives that will lead to changes in behavior that, in turn, will result in a safer and more accessible environment for bicyclists. The countermeasures discussed in BIKESAFE can be used to address specific crash types or to meet performance objectives, such as maintaining quality surfaces for bicyclists. In addition to crashes between bicycles and motor vehicles, the countermeasures address other crash problems, such as bicycle-bicycle crashes or bicycle-pedestrian crashes.
One of the steps in the problem-solving process of improving bicycle safety and mobility is to identify locations or areas where bicycle crash or other safety issues exist and where engineering, education, and enforcement measures will be most beneficial. As noted above, this is typically accomplished by evaluating bicycle conditions in multiple ways.
Analysis of crash databases can provide information on where bicycle crashes occur (city, street, intersection, two-lane road, etc.), when they occur (time of day, day of week, etc.), and characteristics of the victims involved (age, gender, injury severity, etc.). However, the use of crash databases for developing effective strategies to accommodate bicyclists and prevent crashes can be hindered by insufficient detail in state and local crash files. Agencies may want to supplement crash file databases with other data, such as hospital injury information.
In the 1970s, methods for typing pedestrian and bicycle crashes with motor vehicles were developed by the National Highway Traffic Safety Administration (NHTSA) to better define the sequence of events and precipitating actions leading to pedestrian- and bicycle-motor vehicle crashes.1,2,3 These methodologies were applied by Hunter et al. in a 1996 study to more than 8,000 pedestrian and bicycle crashes from six states.4 The results provided a representative summary of the distribution of crash types experienced by pedestrians and bicyclists. Some of the most frequently occurring bicycle crash types include:
- A motorist failing to yield to a bicyclist (21.7 percent of crashes)
- A bicyclist failing to yield at an intersection (16.8 percent of crashes)
- A motorist turning or merging into the path of the bicyclist (12.1 percent of crashes)
- A bicyclist failing to yield at a midblock location (11.7 percent of crashes)
- A motorist overtaking a bicyclist (8.6 percent of crashes)
- A bicyclist turning or merging into the path of the motorist (7.3 percent of crashes)
The crash-typing methodology has evolved over time and has been refined as part of a software package known as the Pedestrian and Bicycle Crash Analysis Tool (PBCAT).5 The development of PBCAT was sponsored by FHWA and NHTSA through the University of North Carolina Highway Safety Research Center.
PBCAT is a software product intended to assist state and local pedestrian and bicycle coordinators, planners, and engineers with the problem of lack of data regarding the sequence of events leading to a crash. PBCAT can assist with evaluating crash data through the development and analysis of a database containing details associated with crashes between motor vehicles and pedestrians or bicyclists. One of these details is the crash type, which describes the pre-crash actions of the parties involved. The more than 70 specific bicyclist crash types used in PBCAT may be categorized into 20 crash-typing groups. Several of these groups (including rarer or unusual crash types) have been further combined into 14 BIKESAFE groups for purposes of selecting treatments. A few PBCAT types that include rarer or difficult to remedy crashes that cannot be very specifically defined are not treated in the Crash Matrix. Examining the closely-related crash groups for countermeasures could be helpful, as well as using the Performance Objectives Matrix to identify appropriate countermeasures.
Location Analysis Tools
Mapping the locations of reported bicycle crashes in a neighborhood, campus, or city is a simple method of identifying sites for potential bicycle safety improvements. One tool for analyzing crash locations is computerized Geographic Information Systems (GIS) software. This type of map can help transportation engineers and planners focus safety improvements on intersections, corridors, or neighborhoods where bicycle crashes have occurred. Two issues should be considered when creating GIS maps of reported crash locations. First, the volumes of bicycle and motor vehicle traffic that use each location will affect reported crash density. Second, bicycle crashes may not be reported frequently enough to establish a pattern of unsafe bicycling locations. In either case, there are specific ways to identify potential factors in crashes involving bicyclists.
Since bicycle crashes tend to be widely dispersed, mapping of crash locations may not yield a strong indication of problem locations. Therefore it is also important to consider risk factors in crashes when evaluating measures to improve safety for all road users. One way to get a general understanding of factors that affect bicyclists’ safety is to use a bikeability checklist, such as the one available through the Pedestrian and Bicycle Information Center. Conducting a Bicycle Road Safety Audit (RSA) can also be useful for identifying roadway improvements and other strategies that may improve the safety of bicyclists. A RSA is a formal safety performance evaluation of an existing or future road or intersection by an independent, multidisciplinary team. RSA programs have been established in most states and FHWA has guidelines regarding the RSA process. FHWA also provides Bicycle Road Safety Audit Guidelines and Prompt Lists.
The 2010 Highway Capacity Manual (HCM 2010) includes methodologies for calculating a bicycle level of service (LOS).6 This tool can be helpful for identifying perceived safety concerns for bicyclists and evaluating how different street designs impact different roadway users. The LOS score for bicycles is based on perceived safety and can be calculated for a variety of system elements, including signalized intersections and urban street segments. The resulting numeric score and grade of the bicycle environment is based on geometric design and other conditions, including the volume and speed of traffic in the outside travel lane, pavement condition, and heavy vehicle percentage. The HCM 2010 includes service measures for autos, pedestrians, and transit, which can be analyzed and compared simultaneously with the bicycle level of service.
Additional tools that can help to evaluate the suitability of a roadway for bicycle use include:
- Performing a conflict analysis
- Noting bicycle and driver behavior
- Examining roadway and bicycling characteristics at specific sites
- Observing and recording the number of bicycle-motor vehicle conflicts at specific sites7
- Mapping locations known to have a high potential for bicycle crashes in an area
- Conducting an intersection safety analysis to help prioritize additional evaluations
In regard to conflicts, a number of studies have been performed using bicycle-motor vehicle conflicts as a study variable in lieu of crash data.7,8 A conflict is usually defined as a sudden change in speed or direction by a bicyclist, pedestrian, or motorist to avoid the other.
Provided below are the definitions of the 14 crash groups included in the BIKESAFE application (13 are included in the interactive crash matrix). For any crash group, there are multiple problems or possible causes that may have led to the crash. The following section provides examples of a few possible causes and problems for each group and some of the countermeasures within BIKESAFE that may be applicable. Neither the list of problems and possible causes nor the suggested countermeasures are to be considered comprehensive. Practitioners will still be required to supplement the analysis and recommendations with their own investigations and knowledge of local policies and practices.
In addition to selecting countermeasures based on the crash problems or possible causes listed below, a matrix of performance objectives is also provided for practitioners to select appropriate countermeasures for consideration based on specific challenges at the study location.
A total of 46 different bicyclist countermeasures are presented in the Countermeasures section. To assist engineers and planners who may want further guidance on which measures are appropriate to address certain types of bicycle crashes, an interactive matrix of 13 bicycle crash groupings by eight categories of countermeasures is provided by clicking on the graphic to the right.
The "X" in the matrix suggests the countermeasure categories that may be primary candidates to address a given crash type, which takes into account whether the crash type occurs at an intersection or midblock location.
To illustrate how to use the table, consider the sixth crash type group in the table ("Bicyclist rode out—midblock"). This is a crash involving a bicyclist riding out into the roadway from a location in the middle of the block, such as a residential driveway. This tends to be a right-angle crash and often involves younger bicyclists.
The matrix shows that five out of the eight countermeasure categories contain potential countermeasures that may reduce the probability of this type of crash, depending on the site conditions. To view the specific applicable countermeasures in each category, click on the "X." A new page will appear, listing the names of the applicable countermeasures. These countermeasures include shared roadway improvements, such as removal of parking to increase sight distance; traffic calming measures such as speed humps that could slow motor vehicle speeds and decrease the braking distance; and other possible countermeasures. Click the name of a countermeasure in the gray box to view the page containing its detailed description.
The matrix is intended to give general information on candidate solutions that should be considered when trying to reduce a pattern of bicycle crashes at a specific location or roadway section.
Regardless of whether or not practitioners have access to comprehensive crash data, performance objectives are useful for addressing concerns about conditions that are hazardous for bicyclists. The following is a list of requests (objectives) that transportation professionals are likely to receive when working to provide bicycle safety and mobility:
- Provide safe on-street facilities/space for bicyclists.
- Provide off-road paths or trails for bicyclists.
- Provide and maintain quality surfaces for bicyclists.
- Provide safe intersections for bicyclists.
- Improve motorist behavior/compliance with traffic laws.
- Improve bicyclist behavior/compliance with traffic laws.
- Encourage and promote bicycling.
The interactive matrix to the right lists the eight performance objectives by eight categories of countermeasures. Each of the performance objectives can be accomplished through a variety of the 46 individual countermeasures included in BIKESAFE. Yet, most treatments will work best when used at multiple locations and in combination with other treatments. In addition, many of the countermeasures will accomplish two or more objectives. The key is to make sure that the right treatments are chosen to accomplish the desired effect.
When using the matrix, it is important to remember that it is simply a guide. In all cases, good engineering judgment should be applied when making decisions about what treatment will be best for a specific location.
Some bicycle safety problems are associated with deficient roadway designs; however, human error often contributes to these problems through a disregard or lack of understanding of laws and safe driving or riding behavior.9 Since most crashes are a result of human error, crashes will not be completely eliminated as long as bicyclists and motor vehicles share the same space. The consequences of these crashes are exacerbated by speeding, failing to yield, or failing to check both directions for traffic. While severe motor vehicle-bicycle crashes are reported by police, less serious bicyclist crashes are underreported, especially if they occur in off-road areas like sidewalks, parking lots, or paths. Thus, education, enforcement, and engineering tools are all needed to improve the safety of bicyclists. An example program of bicyclist safety improvements includes:
- Shared roadway accommodations, such as provision of roadway surface improvements or lighting where needed.
- Provision of bicycle facilities, such as bike lanes, wide curb lanes, and separate trails.
- Provision of intersection treatments, such as curb radii revisions and sight distance improvements.
- Maintenance of roadways and trails.
- Use of traffic calming treatments, such as mini-circles and speed control measures.
- Adequate signs, signals, and markings, particularly as pertains to intersections and share-the-road philosophies.
- Programs to enforce existing traffic laws and ordinances for motorists (e.g., obeying speed limits, yielding to approaching bicyclists when turning, traffic signal compliance, obeying drunk-driving laws) and bicyclists (e.g., riding in the same direction with traffic, obeying traffic signals and signs).
- Encouraging bicyclists to use reflective clothing and appropriate lighting when riding at night.
- Encouraging and educating bicyclists in proper helmet use.
- Education programs provided to motorists and bicyclists.
- Providing support facilities, such as bicycle parking and events, such as ride-to-work days or fundraisers to support bicycling.
Roadway improvements can often reduce the likelihood of a bicycle-motor vehicle crash. Physical improvements are most effective when tailored to an individual location and traffic problem. Factors to consider when choosing an improvement may include: location characteristics; bicycle and motor vehicle volume and types; motor vehicle speed; design of a given location; city laws and ordinances; and financial constraints. Many of these factors are included for consideration in the BIKESAFE Countermeasure Selection Tool.
While facilities and shared roadway accommodations for bicyclists can, in many cases, reduce the risk of collisions, crash reduction is not the only reason for providing such accommodations. Other benefits include improved access to destinations by riding, better air quality due to less dependence on driving, and improved personal health.
For a program of improvements to be successfully developed, implemented, and maintained, different disciplines across varying levels of government (e.g., local, regional, state) will need to commit to ongoing collaboration and coordination.