Public Works

Roundabouts 

Resources on Roundabouts


Johnson Avenue NW Roundabouts
The project on Johnson Avenue NW stretches from 1st Avenue SW to Midway Drive NW.

Improvements:

  • Pavement reconstruction
  • Transition from 4 lanes to three lanes: one lane in each direction and a center turn lane
  • Water main replacement
  • Sanitary and storm sewer upgrades
  • Sidewalks / curb ramps

Two single-lane roundabouts are included on the project: 

  • Johnson and Wiley
  • Johnson and Jacolyn Drive
Schedule:

  • 2018: From Autumn Woods Drive to Wesley Drive
  • 2019: 1st Avenue SW to Autumn Woods Drive NW
  • *Schedule has been coordinated with the Cedar Rapids Community School District; major intersection work takes place when school is out for the summer

School Safety
The roundabout planned at Johnson and Wiley in front of Hoover Elementary is a mini roundabout, and has been designed specifically with the school in mind:

  • Pedestrian friendly, pushbutton system flashes when pedestrians are crossing
  • Crossing guards remain 
  • Pedestrians cross shorter distances
  • Pedestrians will only have to focus on one direction at a time
  • Refuge "island" for pedestrians to stand
  • Vehicles will be traveling at slower speeds than a traditional intersection
Roundabout crosswalk rendering










Rendering above depicts typical single-lane roundabout with crosswalk.

Video Simulation
The simulation video below shows actual traffic volumes on Johnson Avenue NW and how the roundabouts will operate. 


 


What is a Roundabout?

A modern roundabout is an unsignalized, circular intersection engineered to maximize safety and minimize traffic delay. Fundamental characteristics of all roundabouts include:

  • Counterclockwise Flow. Traffic travels counterclockwise around a center island
  • Entry Yield Control. Vehicles entering the roundabout yield to traffic already circulating.
  • Low Speed. Curvature that results in lower vehicle speeds, generally 15-25 MPH, throughout the roundabout

(video courtesy of Insurance Institute for Highway Safety)

Benefits of Roundabouts

SAFETY

  • Eliminates head-on crashes and right-angle crashes
  • Decreases severity of crashes
  • Reduces speeds 

TRAFFIC FLOW

  • Can move more traffic during peak hours
  • Reduces stops
  • Reduces delays
  • Reduces congestion 

ENVIRONMENT & COMMUNITY LIVABILITY

  • Reduced emissions
  • Reduced fuel waste
  • Fewer hard stops
  • Landscaping and beautification / neighborhood aesthetics 

ECONOMICAL

  • Longer service life
  • No signal maintenance 
  • Better long-term economic value

Sources: Iowa Department of Transportation, Federal Highway Administration, Center for Transportation Research and Education

© 2018  Cedar Rapids, Iowa, 101 First Street SE

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