U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
In the European countries visited, the general philosophy for roadway design and project development is to develop a transportation program and system that enhances community values and integrates roadways into communities and the environment. This philosophy permeates their project development process, safety improvements, roadway design concepts, geometric design guidelines, public involvement, and environmental commitments. This same philosophy is the essence of the recent push to promote the CSD approach in the United States, a shift that is supported by FHWA and many State DOTs. The design philosophy of the Europeans is to develop a roadway that is designed for a specific purpose, implements an aesthetic approach to visually explain this concept, and addresses safety in a way that considers all users. Finally, all countries have very high safety goals (ranging from zero fatalities to reductions of more than 40 percent in all crashes), which guide their design approach and philosophy. To achieve these goals the Europeans are willing to provide roadways that self-enforce speed limits, potentially increase levels of congestion, and promote alternative modes of transportation. This approach contrasts with the U.S. design philosophy, in which wider roads are deemed safer, there is a heavier reliance on signs to communicate the intended message, and there is a lower tolerance of congestion and speed reduction.
The visits to these five countries exposed the panel to a variety of practices and programs that may be transferable to specific locations and situations in the United States. A wide variety of practices was found among the agencies of these countries that stem from differences such as size, population, safety goals, and general design philosophy. Although all practices are not entirely new to all States in the United States, we may be able to learn from their form and the extent of their application in Europe. Therefore, each U.S. agency should evaluate the application and use of the ideas presented in both the previous and this section. To this end, the U.S. scan team has developed the following list of implementation strategies for enhancing existing project development and roadway geometric design practices in the United States.
A practice common in all five countries visited was the longer period of time devoted to the planning process and the consideration of longer sections, typically entire corridors. This is an approach some agencies may want to consider, since it provides the opportunity for long-range planning by allowing for a more systematic overview and for defining needs and deficiencies over the entire system. The greater emphasis in urban areas on integrating projects in communities by addressing the public's concerns for speed management and aesthetics is an additional area that State and local agencies may consider while developing projects.
All five countries involve the public in most projects and involve a variety of other stakeholders depending on the project type and stage. Early public involvement is considered a significant means for decreasing project times and resolving potential conflicts in early stages of the project. The participation of local agencies in this process and their ability to control decisions in certain projects is an aspect that merits further consideration. Such local agencies may be capable of addressing specific needs and local concerns more appropriately than State agencies and, thus, their participation is often beneficial in developing a project that is responsive to local needs. Involvement of the public and appropriate stakeholders at the earliest possible stage of the project enables a successful project that addresses their concerns. This concept could be applied in the United States not only to reduce the project times by minimizing conflicts but also to improve relationships between State agencies and the public by developing a constructive dialogue.
The Dutch are using a process of design workshops in which all project alternatives are developed with public involvement. This process seems to alleviate conflicts between highway agencies and the public and reduces project planning time by resolving issues in the early stages of the project. This system merits additional examination and could be transferable to the United States.
The concept of 2+1 roads has been shown to simultaneously address safety and capacity issues on two-lane roadways. This design is more economical than conversion to four-lane roadways and, thus, is considered an applicable concept. This design is similar to the U.S. practice of providing passing lanes on two-lane roads. However, specific design elements for successful implementation need to be specified and design guidelines for their implementation need to be developed. Morever, some safety concerns still exist among the Europeans, and these issues need to be examined prior to adopting this design.
Another concept that could benefit the United States is the concept of self-explaining, self-enforcing roads. Such roads are designed for a specific purpose or function and they address safety in an efficient way for all users by implementing an aesthetic approach to explain the road function and enforce speeds. This is the ultimate goal of a roadway design, since roadways designed this way meet drivers' expectations rather than surprise them. Reliance on the roadway design to transmit its operating speed is integral to this concept and conflicting messages should be avoided. The higher reliance in the United States on traffic signs to convey the desired operating speeds may create additional problems, since often there are conflicting messages between the traffic signs and the roadway image. It is reasonable to examine these possible conflicts and evaluate whether the wider roadway widths that have been utilized in the United States are more conducive to crashes by encouraging the driver to drive at inappropriate speeds.
Traffic calming is an effective means for controlling speeds through urban areas and deserves wider implementation in the United States. A variety of components are available with different uses, applications, and effectiveness. All studies completed indicate that, indeed, these devices do reduce speeds at a variety of levels. Traffic calming is most effective if done on a neighborhood or area-wide basis and not just at spot locations. While some of the measures have been tried to a limited degree in the United States, more testing of various European traffic calming strategies is needed in U.S. cities. Reliance on speed limit and STOP signs and police enforcement does not fully achieve the desired speed reductions, since the roadways are not conveying the intended message and are not forcing the driver to slow down. Use of these designs also reduces the need for police enforcement efforts.
Roundabouts are a very safe and efficient means for intersection control. Roundabouts with a single-lane approach are used widely and successfully in Europe and they can easily accommodate peak flows of 2,500 vehicles per hour without significant delays. Roundabouts with two approach lanes are widely used in England but are being introduced more cautiously in continental Europe because of concerns about driver confusion and safety. Safety studies completed in most of these countries indicate that significant safety gains were achieved by implementing roundabouts in place of conventional intersections. (It should be noted that the studies conducted in continental Europe predominantly relate to single-lane roundabouts, not necessarily to roundabouts in general.) Although roundabouts have been introduced in a few areas in the United States, this modern tool is still underutilized. State and local agencies should consider the implementation and use of roundabouts as an alternative to conventional intersection designs as well as a means for improving traffic safety. When roundabouts are introduced for the first time in a community, they should be placed in areas where single-lane approaches would accommodate the existing traffic. This approach will ensure the successful and smooth operation of the site and, thus, promote the use of this alternative design.
All countries visited place significant emphasis on addressing the needs of pedestrians and bicyclists. Bicycle networks exist in all countries; in some they are complete and rival the vehicle networks. For some countries addressing the needs of these users is as important as improving vehicle mobility, and promoting use of bicycles as an alternative mode of transport is a strong commitment of the highway agencies. A change in philosophy is needed in the United States to focus directly on promoting use of bicycles and other transport modes in conjunction with automobile travel. Addressing mobility needs has been viewed traditionally in the United States as providing a roadway network in which drivers can move as quickly and freely as they desire. This notion needs to be altered in order to address the safety needs of vulnerable road users. State and local agencies should focus on providing bicycle and pedestrian networks, since they are essential in promoting use of these modes of transport. A lesson learned from the scan tour was that a high level of commitment is essential in promoting bicycle usage, and a systematic accommodation is required to increase use of alternative modes of transport. Completion of existing networks is also central to a successful campaign. Morever, zoning and development practices may need to be revisited to create an environment to promote biking and walking in urban centers.
All countries visited follow the practice of developing transportation projects and systems that enhance community values while integrating roadways into the environment. Several agencies employ the use of multi-disciplinary teams to develop design solutions, which allows them to approach problems from several possible angles. Such an approach considers and addresses all phases of the project when appropriate and thus reduces project time and possible costs. Moreover, consideration is given to the desires and needs of the community by inviting the appropriate stakeholders to participate in the development of the project and thus shape some of the solutions that are acceptable to the community. This approach is currently promoted by FHWA and AASHTO and it should be continued in the future until it becomes an integral part of the design process in the United States Although not unheard of in the United States, design solutions that reduce motor vehicle speeds or reduce the space available to vehicles may increase trip times and are not often viewed as appropriate. But wider, high-speed roads that address only the mobility needs of automobile users may not meet the needs of other users of the transportation system. Most often design solutions seek to reduce delays to motorists at all costs. Such road designs encourage higher travel speeds that contribute to greater severity of crashes. These are important aspects of applying the concepts of CSD, since community desires may conflict with high-speed designs.
CSD implies a flexible application of the established geometric criteria in designing roadways. The use of innovative design to address local problems and provide solutions within the context of the area is essential in applying the CSD concept. The self-enforcing, self-explaining road is an example of such innovative design, since it encourages lower operating speeds for automobiles while incorporating safety and mobility for all transport modes. To facilitate this flexibility, some countries explicitly indicate that deviations from their design manuals are accepted and provide reasons and situations in which such changes are appropriate. In addition, documentation exists that describes the appropriate supportive documents to justify these deviations. Consequently, the Europeans use design exceptions to address CSD concepts and they use aesthetics both for safety enforcement and visual appeal.
A summary of proposed activities and implementation strategies for each of the findings discussed here is presented in Table 5.
|Subject||Recommendations and implementation strategies|
|Geometric Design Philosophy||
|Context Sensitive Design||
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