Crossing islandsâ€”also known as center islands, refuge islands, pedestrian islands, or median slow pointsâ€”are raised islands placed in the center of the street at intersections or midblock crossings to help protect crossing pedestrians from motor vehicles. Center crossing islands allow pedestrians to deal with only one direction of traffic at a time, and they enable pedestrians to stop partway across the street and wait for an adequate gap in traffic before crossing the second half of the street. Crossing islands can be constructed so that crossing pedestrians are forced to the right to view oncoming traffic as they are halfway through the crossing.
Where midblock or intersection crosswalks are installed at uncontrolled locations (i.e., where no traffic signals or stop signs exist), crossing islands should be considered as a supplement to the crosswalk. They are also appropriate at signalized crossings. If there is enough width, center crossing islands and curb extensions can be used together to create a highly improved pedestrian crossing. Detectable warnings are needed at cut-throughs to identify the pedestrian refuge area.
Crossing islands have been demonstrated to decrease pedestrian-vehicle incidents by 46 percent at marked crossings, and by 39 percent at unmarked crossings. The factors contributing to pedestrian safety include reduced conflicts, reduced vehicle speeds approaching the island (the approach can be designed to influence vehicle speed reduction, depending on how dramatic the curvature is), greater attention called to the existence of a pedestrian crossing, opportunities for additional signs in the middle of the road, and reduced exposure time for pedestrians.
More information on median islands is available at: http://safety.fhwa.dot.gov/provencountermeasures/.
Depending on the length of the pedestrian signal, some slower-paced pedestrians might get caught in the middle of the roadway if the traffic signal changes before they have finished crossing the roadway. At midblock crossings, it can be difficult for pedestrians to cross high-volume roadways if there is not a safe stopping place in the middle of the roadway. Crossing islands enhance the safety of pedestrian crossings and reduce vehicle speeds approaching pedestrian crossings.
- Pay due attention to impacts on bicycle facility design.
- Illuminate or highlight islands with street lights, signs, or reflectors to ensure that motorists see them.
- Design islands to accommodate pedestrians in wheelchairs. A cut-through design must include detectable warnings.
- Crossing islands at intersections or near driveways may affect left-turn access.
- The FHWA recommends particular consideration in areas with mixtures of significant pedestrian and vehicle traffic (more than 12,000 Average Daily Traffic) and intermediate or high travel speeds. They also recommend the islands be at least four feet wide (preferably eight feet to accommodate pedestrian comfort and safety) and of adequate length to allow the anticipated number of pedestrians to stand and wait for gaps in traffic before crossing.
Approximate costs range from $535 to $1,065 per foot. Typical total construction costs range from $3,500 to $40,000, depending on the design, site conditions, and whether the median can be added as part of a utility improvement or other street construction project. The cost for an asphalt island or one without landscaping is less than the cost of installing a raised concrete pedestrian island with landscaping. The service life is 20 years for asphalt, and 40 years for concrete.