Median Island
ELM-MDI-45 Median Island
Working assessment: this pattern's status reflects a preliminary Commonway System judgment call, pending final review.
#Why this pattern exists
Narrowing a roadway's visual and physical width slows traffic and reduces opposing-direction conflicts, independent of whether the median also serves a crossing purpose. Pedestrian Safety Island / Refuge documents the crossing-assistance case; this pattern documents the calming and access-management case, where a median exists to manage the corridor itself rather than to assist a specific crossing movement.
#Key considerations
- Access management benefits scale with how consistently the median precludes unsafe mid-block left turns and crossing movements along the corridor, not just at one isolated point
- Landscaping and drainage design should account for maintenance access and sightlines, since a raised median interrupts both the roadway's drainage path and driver sightlines around it
- Width should be sufficient to read visually as a real barrier rather than a painted gesture, while remaining consistent with the corridor's overall cross-section
- Where a crossing is also needed nearby, coordinate with Pedestrian Safety Island / Refuge rather than assuming this pattern alone provides safe pedestrian passage
#Related patterns
Pedestrian Safety Island / Refuge (ELM-PSI-09) (a related but distinct treatment built specifically for two-stage pedestrian crossing), Curb Extension (ELM-CBE-02) (a lateral narrowing approach rather than a center-of-roadway one), Boulevard (ART-BLV-02) (the Arterial-scale corridor pattern this most often appears within)
#References
- Legal / regulatory Federal Highway Administration, "Proven Safety Countermeasures: Corridor Access Management." Raised medians that preclude across-roadway movements as an access-management treatment.
- Evidence-based Gluck, J., Levinson, H.S., and Stover, V., Impacts of Access Management Techniques, NCHRP Report 420, Transportation Research Board, 1999.