Complex or multi-legged intersections are common in non-grid street networks, or where two grids at different orientations come together.
Multi-legged intersections can be reconfigured to improved access for people walking and bicycling, while capturing large amounts of surface area to gather and infiltrate runoff.
Existing Conditions
In the condition shown, two neighborhood streets come together at a larger collector street, resulting in difficult crossings for pedestrians who are forced to either detour or cross at an unmarked location.
People bicycling and driving encounter a confusing circulation pattern. Additionally, vehicles may park (legally or illegally) in the center island space, restricting sight-lines.
The footprint of the junction is a large swath of impermeable streetscape, with most runoff being directed past pedestrian crossings and increasing incidents of pooling.
Recommendations
Observe intersection movements and desire lines. Identify opportunities to capture excess impermeable space in the roadbed and organize traffic movements. Enable pedestrians and people bicycling to move along natural desire lines or intuitive paths through complex intersections.
Test traffic reconfigurations with tactical or interim treatments before making capital investments.
1Reduce the number of conflict points between motor vehicles and other users. In the illustrated example, motor vehicles are routed through turns sequentially to simplify signalization and turning movements. Pedestrians are given more space to walk, and are provided crossing treatments at expected locations.
2In the recaptured plaza space, stormwater can be directed and retained in a high-capacity graded facility, adding green space to a formerly imposing streetscape, and treating and infiltrating a large amount of water. The green infrastructure provides a large amount of edging which can incorporate seating and placemaking elements to engage users. Stationary activities can be encouraged by providing flexible, movable seating and tables in plaza area. Newly reclaimed street space can also be used to site bike share stations.
Incorporate shade trees to provide canopy and encourage people to stay and use plazas and public realm.
3Tree wells or connected tree trenches can capture and infiltrate runoff while contributing to tree canopy and increasing walking comfort. Because tree wells have a smaller footprint, they may be included more easily where sidewalk width is limited or pedestrian volumes are moderate to high. Consider using low fencing or curbs to prevent accidental incursions by pedestrians, and site clear of crossings and curb ramps.
Avoid siting drainage grates and catch basins at corner apexes or in places where pedestrians are likely to trip stepping on or off the curb.
Potential GSI Features
Plaza / Curb Extension
Planting Zone
Bikeway or Parking Lane
Kate Fillin-Yeh