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Improvement concepts

A set of four mid-term improvement concepts were identified to move forward to a two-phased screening process. Each concept discussed below includes an illustration or example of the concept and is not a depiction of what will be located on SR 516.

Improvement Concept #1: Five Roundabouts

  • A roundabout at each intersection: Covington Way Southeast, 164th Avenue Southeast, the SR 18 westbound & eastbound interchange ramps, and 168th Place Southeast. The illustration below details a multi-lane roundabout to convey the concept, and it is not specific to SR 516.
Illustration of a multi-lane roundabout (Source: Federal Highway Administration)
Figure 12: Illustration of a multi-lane roundabout (Source: Federal Highway Administration)

Improvement Concept #2: Three Roundabouts and One Peanut Roundabout

  • Roundabouts at Covington Way Southeast, 168th Place Southeast, and SR 518 eastbound ramps.
  • Single Peanut Roundabout at 164th Avenue Southeast intersection and SR 18 westbound ramps. The example below, in the City of Bellingham, shows a peanut roundabout design that includes two intersections.
Map showing Meridian Street Roundabouts Feasibility Study (Source: City of Bellingham, WA)
Figure 13: Meridian Street Roundabouts Feasibility Study (Source: City of Bellingham, WA)

Improvement Concept #3: Two Roundabouts and Diverging Diamonds

  • Roundabouts at Covington Way Southeast and 168th Place Southeast
  • Diverging Diamond traffic signal at SR 18 eastbound ramps
  • Diverging Diamond roundabout at 164th Avenue SE and SR 18 westbound ramps.
  • The example below, of US Route 50 and State Route 291 in Lee Summit, MO, details a diverging diamond traffic signal and a diverging diamond roundabout.
Aerial photo showing US Route 50 and State Route 291, Lee Summit, MO (Source: Missouri Department of Transportation)
Figure 14: US Route 50 and State Route 291, Lee Summit, MO (Source: Missouri Department of Transportation)

Improvement Concept #4: Roundabouts and Single-point urban interchange (SPUI)

  • Roundabouts at Covington Way Southeast, 164th Avenue Southeast, and 168th Place Southeast
  • Single-point urban interchange (SPUI) at the SR 18 westbound and eastbound ramps. The example below, at US-95 and Idaho Highway 53, details a SPUI interchange.
Aerial photo showing US-95 and Idaho Highway 53 (Source: Idaho Transportation Department)
Figure 15: US-95 and Idaho Highway 53 (Source: Idaho Transportation Department)