Photo: Brandonrush, CC BY-SA 3.0, via Wikimedia Commons
Wisconsin’s Motorists’ Handbook gives roundabouts, metered freeway ramps and diverging diamond interchanges (DDIs) their own section, and all three can come up on the knowledge test. This explainer covers how to drive each one, the rules you can be ticketed for, and where Wisconsin’s DDIs are.
Roundabouts in Wisconsin
Traffic moves counterclockwise. Read the overhead and roadside signs on the approach to pick your lane.
Step by step
- Slow down.
- Yield to pedestrians and bicycles.
- Yield to traffic on your left already in the roundabout, and to semitrucks.
- Enter when there is a safe gap. If the roundabout is empty, you don’t need to wait.
- Keep your speed low and stay in your lane. Don’t change lanes inside.
- Signal right as you reach your exit, then exit.
Lane choice on two-lane roundabouts
| Where you’re going | Lane |
|---|---|
| Left turn or U-turn | Left lane |
| Right turn | Right lane |
| Straight | Follow the pavement markings, arrows or signs |
Emergency vehicles
If you haven’t entered yet, pull over and let the vehicle pass. If you’re already in, exit at the next right, then pull over. Avoid stopping inside the roundabout.
Bicyclists may ride through in the travel lane or leave the road and use the crosswalk. National guide: how to drive a roundabout in the US.
How metered ramps work in Wisconsin
Some freeway entrance ramps have traffic signals that space out merging cars. This cuts congestion on the freeway and the ramp.
- The meter is on when the “Ramp Metered When Flashing” sign is flashing.
- Pull all the way up to the white stop line so your tires trigger the pavement sensors. If you stop short, the signal may not detect you.
- Each lane has its own signal. Go when yours turns green, then merge.
- Disobeying a ramp signal can get you a ticket.
Merging after the meter
Use the acceleration lane to match the speed of freeway traffic, and find a safe gap. It’s your responsibility to merge legally. See freeway driving for new drivers.
What is a diverging diamond interchange?
A DDI (sometimes called a double crossover diamond) briefly moves traffic to the left side of the road between two signals at a freeway interchange. Left turns onto the freeway then don’t have to cross oncoming traffic. WisDOT uses them where there are heavy left-turn volumes to and from a freeway.
How to drive through a DDI
- Follow the signs, signals and pavement markings through the first set of traffic lights. You cross to the left side, and traffic looks like a one-way street.
- To turn left onto the freeway, take the ramp. Left turns onto the freeway are free flow, so you don’t stop.
- To go straight, continue through the second set of lights, which crosses you back to the right side.
Pedestrians use designated walkways and cross only at crosswalks. Bicyclists may use the bike lane or the pedestrian walkways.
Why WisDOT builds them
WisDOT says DDIs remove the left turn across oncoming through traffic, a movement that often causes severe injury crashes. It reports that Wisconsin DDIs have seen reductions of over 50% in total crashes and 65% in fatal and injury crashes.
Where are the diverging diamond interchanges in Wisconsin?
The 2026 handbook lists:
- I-39/90 and WIS 11/Avalon Road, south of Janesville
- WIS 441 and Oneida Street, Appleton
- I-39/90 and WIS 26/Milton Avenue, Janesville
- I-39/90 and WIS 81, Beloit
WisDOT’s DDI page also has project videos for I-41 and WIS 15/County OO (Appleton) and I-43 and WIS 100/Brown Deer Road (Milwaukee), and a map of existing and proposed DDIs. Check the map for the current list.
Flex lanes and reversible lanes
These are two other Wisconsin lane controls on the test:
- Flex lane: on some highways the paved shoulder opens as a travel lane. Green arrow means open. Yellow X means merge out. Red X means closed. No large trucks may use it.
- Reversible lane: marked by double dashed yellow lines, with lane lights. Green arrow means open. Yellow X means the lane is changing, so move to a green arrow lane. Red X means closed.
Common questions
What happens if I run a ramp meter in Wisconsin?
The handbook says you can be ticketed for disobeying a ramp signal.
Why didn’t the ramp light change for me?
You may have stopped short. Pull right up to the white stop line so the pavement sensors detect your car.
Do I yield to trucks in a roundabout?
Yes. The handbook lists yielding to semitrucks among the steps for entering a roundabout.
Is driving on the left in a DDI legal?
Yes. The signs, signals and markings guide you to the left side and back on purpose.
Do I stop to turn left onto the freeway at a DDI?
No. WisDOT says left turns onto the freeway are free flow.
Related: Learning to drive in Wisconsin, Wisconsin knowledge and signs tests, Wisconsin 50 hour driving log.
Sources
- Wisconsin Department of Transportation, “Wisconsin Motorists’ Handbook 2026 (BDS126)” (wisconsindot.gov)
- Wisconsin Department of Transportation, “Diverging Diamond Interchanges” (wisconsindot.gov)