Resources on Roundabouts
- Download a navigation guide from the Center for Transportation, Research, and Education
- Download: Iowa's Drivers Manual on Roundabouts
- Download: Federal Highway Administration "Roundabouts: A Safer Choice"
- General Information: Iowa Department of Transportation
Johnson Avenue NW Roundabouts
The project on Johnson Avenue NW stretches from 1st Avenue SW to Midway Drive NW.
- 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
- 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
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
Rendering above depicts typical single-lane roundabout with crosswalk.
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
Benefits of Roundabouts
- Eliminates head-on crashes and right-angle crashes
- Decreases severity of crashes
- Reduces speeds
- 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
- 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