Medians are raised barriers in the center portion of the street or roadway that have multiple benefits for bicyclist, motorist and pedestrian safety, particularly when they replace center, two-way left-turn lanes. Two-way left-turn lanes can create problems for bicyclists and pedestrians as well as opposing left-turn vehicles and may be used as acceleration lanes by some motorists. A median (or median island) helps manage traffic, particularly left-turn movements, and reduces the number of conflict areas. Left-turn bays may be incorporated at specific locations. The restricted access to side streets may also help to reduce cut-through traffic and calm local streets. Raised medians are most useful on high-volume roads. Bicyclist (and pedestrian) access to side streets, transit stops, or shared-use paths should be maintained by providing access pockets through the median.
Another use of median islands and bicycle crossings is to provide a refuge for bicyclists crossing a busy thoroughfare at unsignalized locations where gaps in traffic in both directions are rare. The median should be at least 2 m (6.6 ft) wide to provide sufficient waiting space for bicyclists.2 If a full 2 m (6.6 ft) is not available, the bicycle storage area may be angled across the median with bicyclists directed toward oncoming traffic for crossing the second half of the roadway. Railings may be provided for bicyclists to hold so they need not put their feet down to aid in quicker start-ups.
If travel lanes are sufficiently narrowed, installation of medians may also help to slow traffic speeds. Finally, medians provide space for street trees that may improve the aesthetic environment.
- Manage motor vehicle traffic and reduce the number of conflict areas. Provide comfortable left-hand turning pockets with fewer or narrower lanes. May help to slow traffic if roadway is narrowed sufficiently.
- Assist bicyclists in crossing high-volume streets at non-signalized locations by providing a protected refuge for bicyclists crossing or making left turns.
- Provide space for street trees and other landscaping.
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- Provide bicyclist access to cross streets (or shared use paths) where a median restricts motor vehicle movements.
- Evaluate whether there is sufficient width for appropriately wide sidewalks, bike lanes, and planting strips before proceeding with median construction. Intermittent median islands may be a preferable option for some locations.
- Landscaping in medians should not obstruct visibility between bicyclists (and pedestrians) and approaching motorists.
- Pedestrian median crossings should also be provided at appropriate midblock and intersection locations and designed to provide tactile cues for pedestrians with visual impairments. Examples of good and bad designs for raised median crossings can be found in Chapter 8 of Designing Sidewalks and Trails for Access: Part II of II, Best Practices Design Guide.11
- Desired turning movements need to be carefully provided so that motorists are not forced to travel on inappropriate routes, such as residential streets, or make unsafe U-turns.
- Bicyclist median access pockets may be difficult to keep clear, depending on width.
- Continuous medians may not be the most appropriate treatment in every situation. In some cases, separating opposing traffic flow and eliminating left-turn friction might increase traffic speeds by decreasing the perceived friction of the roadway.
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From PEDSAFE: The cost for adding a raised median is approximately $15,000 to $30,000 per 30 m ($15,000 to $30,000 per 100 ft), depending on the design, site conditions, and whether the median can be added as part of a utility improvement or other street construction project.10
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