The major goal of this report is to discuss some of the bicycle infrastructure design issues related to safety. Because this was a seed project with limited funding, the review could not be comprehensive. The intent was to create a framework within which the major shortcomings in the approach to the system-level design of bicycle-related infrastructure could be identified and discussed. The author hopes that the identified problems will be further researched and considered in future designs. This is a critical review of existing practice. However, to improve transportation safety for all travelers, the shortcomings of existing practice must be identified before optimal improvements can be made. It should be noted that the review went beyond bicycle infrastructure. The connection to and interaction with the other modes of transportation were also considered. In addition, the role that bicycle transportation plays in the functioning of the transportation system was also considered. The latter issue is important because increased bicycling could not only increase the frequency of bicycle accidents/crashes but also possibly lead to an overall increase in transportation injuries and death. It should be noted that the review is principally conducted from the start of a transportation system plan through the implementation and operational stages. These latter stages are characterized by the fact that a change is finally implemented, whether it is constructed or the operation is changed and the debate about the implementation is finally over. The discussion also includes the importance of evaluating any changes in terms of the function (or central service delivery) of the transportation system and its components. In the case of the transportation system, the basic function is to transport people or goods from point A to point B. In the author’s opinion, one of the problematic issues related to the benefits of implementing bicycle-related infrastructure is that part of the bicycle community wishes to define the functionality of the transportation system at least partly in terms of the trip being an end in itself, such as exercise, and not moving from point A to point B. Scarce road space could then be taken away from other modes or uses directed at getting from point A to point B. This leads to a lot of debate that is, in the author’s opinion, focused or biased in favor of bicycling without a clear assessment of the performance of bicycling as a mode of transportation. The author hopes that this critical review will shed some light upon the implications of this very important issue. The focus of the discussion in this report is on the design of infrastructure for bicycling. Cycling is not restricted to bicycling; it can include tricycles and other configurations of pedalcycles. But most of the discussion in this report pertains to bicycling and the infrastructure comprising the way (bike paths, etc.) and traffic intersections. The infrastructure is discussed in terms of individual elements and also from a system perspective. These elements do not exist in a vacuum, but they are a part of the overall transportation system, land use, and other environmental components. In contrast, based on the author’s observation, a large portion of the existing literature related to bicycling focuses on bicycling alone without putting it in the context of the overall transportation system and the principal function of the system–i.e., moving from point A to point B. Comment is also made on the promotion of bicycling and the accompanying provision of infrastructure, which often occurs without giving adequate consideration or notice of the risk of injury and death when bicycling. Much has been written about the design of individual components of bicycling infrastructure, but the focus in this report is on the larger issues that affect design. The wide range of bicyclists’ physical characteristics (such as size, power, skill, response to road and traffic conditions, etc.) makes it challenging for the designer to design bicycle facilities with the same sophistication and safety as facilities for motor vehicles. While there are some design features that can be incorporated that will increase safety for bicyclists, there are also behaviors and factors inherent in bicycling that are impossible to design for. Having bicyclists and motor vehicles on the same street would mean that the different human and vehicular characteristics related to bicycles and motor vehicles respectively would be close to impossible to accomplish. An attempt should at least be made to integrate the design standards for motor vehicles and bicycles into common design manuals. Incompatibility of the standards may make it clear when separate facilities for bicyclists should be considered and when bicyclists should not be allowed on a road. Differences in speeds lead to an exponential increase in the frequency of crashes. Bicyclists commonly travel at speeds that are generally lower than motor vehicle speeds, which can then lead to an increase in crashes between motor vehicles and bicyclists. The solution would be to separate the motor vehicles and bicyclists, which has been common practice. However, this solution is costly, and there is a lack of space in which to accomplish it. A similar effect may be had by not allowing bicyclists on roads and streets with higher average speeds and by designating alternative routes through neighborhood streets. Unfortunately, of late, providing more bike lanes and bike paths has been motivated in part by statements that bicycling leads to an increase in health benefits and a decrease in the carbon footprint from travel. These kinds of statements are sometimes misleading and are not always accompanied by the facts. When more people bicycle, more people are exposed to higher risk than they would have been had they used a personal vehicle or public transportation to travel. A study3 showed that on a per trip basis, a bicyclist is 2.3 times more likely to be killed than a person using a personal motor vehicle. Another study showed that funds are more efficiently spent on improving traffic flow and public transportation to decrease pollution than on spending it to create a bike path, for example.4 More than 50% of bicycling is for exercise and recreation, which do not substitute for a motor vehicle trip and therefore do not decrease pollution. A study5 of the risk of injuries in sports showed that bicycling has a higher injury rate per 100,000 people than, for example, basketball or soccer. Planning and designing infrastructure for bicycling, such as bike paths, could lead to the increased safety for existing bicyclists. But creating more and better bicycle infrastructure could possibly attract people to bicycling and lead to an increase in overall risk of injury and death. Moreover, the dilemma is that there may never be adequate funds to create enough facilities to separate bicyclists from motor vehicles in the U.S. Additionally, bicyclists would still have to navigate the streets, without separation of bicycles from motor vehicles, to reach the bike paths. Bike paths may not aid in low-volume conditions at night, when lack of visibility creates relatively unsafe conditions. “Safety in numbers” is a commonly held belief. It essentially comes down to the possibility that the presence of more bicyclists will make motorists more aware of bicyclists, but it also exposes more bicyclists to risk when they are in areas where large numbers of bicyclists are not present. Additionally, having more bicyclists increases the likelihood of crashing in the absence of motor vehicles. A study in Orlando, Fla. showed that 64% of bicycle-vehicle crashes involved an unsafe choice by bicyclists.6 These collisions cannot be eliminated by design. Additionally, the bicyclist’s choice not to wear a helmet and consequently being exposed to more serious injury in a crash cannot be solved by designing better facilities. The aging of the population in the US is an important factor in design of roads and traffic control systems. This factor has led to changes in design and control standards used in design of roads and streets for motor vehicles and pedestrians. This factor will impact the overall risk of bicycling. Older people have comparatively lower balancing skills, and riding a bicycle may lead to an increase in falls. Better road and traffic control will probably have a negligible effect on reducing such falls. The false belief that bicycling is always healthful and decreases environmental impact could lead to an overinvestment in bicycling infrastructure while not placing enough emphasis on enforcement to affect bicyclists’ and drivers’ dangerous behavior and on laws that would require bicyclists of all ages to wear helmets. Much has been accomplished in the last few years to establish and improve standards for the design of individual bicycle facilities. However, because separate bike paths and even sufficient space for bicycle lanes were not incorporated into the design of arterial streets in typical major U.S. cities and metropolitan areas, it is very difficult to establish separate lanes and separate paths for bicycles. Because of urban sprawl, the average commute distances could preclude commuting by bicycle for many people. Implementation of “complete streets,” in which emphasis is given to all modes, may lead to a breakdown in the functioning of the hierarchical structure of the street system, wherein arterial streets are intended to fulfill the function of mobility. If lanes were taken away from general use and designated for the exclusive use of bicyclists, motor vehicles may deviate to streets that are not suited to accommodating large volumes of motor vehicle traffic, and those streets may experience less safe conditions. Conditions on the “complete streets” may also become less safe for all users. In some cities in Europe, it is difficult to use a personal motor vehicle because of inadequate road space. These cities, such as the center of Barcelona, generally have a very high population density and relatively good public transportation systems. It is not convenient to use personal motor vehicles under these circumstances. Separate bike lanes are provided on sidewalks, and bicycles are also extensively used in areas where motor vehicles are not allowed. Most U.S. cities do not have such a high population density, and people working in the central business districts of U.S. cities must rely on personal motor vehicle transportation to access workplaces, at least in the absence of good public transportation. When scarce road space is allocated for exclusive use of bicycles, then poor mobility and poor travel safety may result. More research into and development of standards are necessary. Designing better individual facilities probably cannot, by itself, significantly improve the safety of bicycling. More research is necessary, especially regarding the impact of re-allocating traffic lanes and road space on arterials for the exclusive use of bicyclists. Additional research is also needed for dealing with bicyclists when they are concentrated in intersections by having bike lanes entering those intersections. Increased enforcement and regulation, as well as education on the risks of bicycling, could make significant contributions to improving bicycling safety. The design of individual streets, lanes, and other transportation system components is dictated primarily during the planning stage. Moreover, the allocation of road space and resources is made during the planning stage. To make the allocation of resources effective and efficient, benefit-cost analysis should be utilized as much as possible. It is already extensively used in allocating funds for road safety improvements. The selection of possible projects for implementation is based on the reduction of crashes (benefits) and the cost of implementation. In the event that benefit-cost analysis is used for the selection of projects for implementation –and even when it is not used for allocating funds–the same benefit and cost categories must be considered for all modes, and the function of the system or project should be clearly defined. The principal function of road space is for traveling from point A to point B and is not intended for exercise and recreation. People may use it for the latter purpose, but it is very much a secondary purpose and should not detract from the principal function. Bicycle facilities such as trails designed for exercise and recreation should be considered separately to serve these functions. One of the major problems with considering dissimilar benefits for selecting projects for implementation is that the project alternatives cannot be prioritized on the same basis. This would lead to a misallocation of resources. It would appear prudent for transportation agencies to refrain from promoting bicycling, especially in the absence of a clear assessment of the risk and the possible significant cost to society resulting from increased injury and death. These agencies certainly should not promote bicycling based on health benefits and reduced environmental impact without making the risk of injury and death clear. It is probably unlikely that the percentage of all trips undertaken by bicycling will constitute a significant percentage of trip-miles in the foreseeable future because the base from which it has to grow is so low. There is also the danger that this assumption could result in planning and increased implementation of bicycle-related facilities instead of making improvements to infrastructure for other transportation modes–which would be more efficient in fulfilling the principal function of transportation. Until a clear determination is made of the role that bicycling could reasonably play in the future transportation system, the focus should be on the safety of short-distance bicycle trips and not on bicycle networks for which the function is unclear–i.e., serving the health and recreation function versus traveling from point A to point B. Attention should be given to the needs of the captive riders, and pressure from bicycle advocacy groups should be resisted. A planning and decision-making system should be established that trades off the needs of all modes when allocating resources. This would be in contrast with a decision-making system that includes a bicycle committee, which may not be inclined to focus on the needs of all modes of transportation. The rapid aging of the population will result in different demands on the transportation system. Increased automation of motor vehicles could benefit older drivers. Bicycling will, in all probability, not benefit as much from improved technology, thereby rendering bicycling a less desirable personal mode of transportation for the elderly than motor vehicles. This factor should be considered when envisioning the future of transportation. Bike lanes are often considered along an arterial street in a neighborhood in which changes in the transportation situation are made to adjust to the development. The goal may be to make the street more “bikeable” and walkable. To achieve this end, general-use travel lanes may be reduced (“road diet”), and the street could be made more “complete” in the process. However, these types of actions should not be taken before ensuring that the motor vehicles displaced by these actions are not going to cause problems elsewhere without explicitly taking action to accommodate those displaced motor vehicles. Similarly, bike lanes and bike paths could be considered where changes to transportation systems are made in downtown areas of cities to make the downtown more livable. In this case, bypass streets to the downtown area should be established before committing to the “livable” downtown. In the absence of an effective public transportation system, such a downtown design should not be undertaken without proper provision of access and parking for motor vehicles. In the author’s opinion, the idea that a large percentage of people will commute long distances with a bicycle and forsake their personal vehicles in most U.S. cities is probably folly. Some college towns in the United States may present an opportunity in which the environment can be structured to allow extensive bicycling. This is in part due to the fact that housing and the campus can be close together and that a great number of students may not have cars. However, due diligence still must to be paid to ensure that the mixing of motor vehicles and bicycles is minimized. It is the author’s view that the way in which safety improvements for bicyclists is approached should be fundamentally changed. Decreasing fatalities and injuries should be considered for the transportation system as a whole instead of trying to decrease the fatalities and injuries to bicyclists alone by implementing countermeasures, or for that matter looking at individual statistics for other modes. Even better, assessing the overall performance of the transportation system when making improvements should be based on the decrease in the overall cost of transportation. The cost should include the infrastructure cost, travel time cost, vehicle operating cost, and accident/crash cost, taking the explicit function of the system into account. Environmental impacts should also be assessed by taking into account vehicle impacts as a whole and not assuming that improving bicycle facilities decreases environmental impacts or is emissions-neutral under all circumstances. This kind of approach will also shed light on the extent to which bicycling should be promoted or whether scarce resources for transportation should be allocated elsewhere, including transportation services for the rapidly-expanding elderly population. (Author/publisher)
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