How to Drive Indiana Roundabouts, and Where Drivers Actually Crash

Indiana has more than 400 roundabouts, and roughly a quarter of them are in one city. Carmel has built more than 150, more than any other city in the United States, and Hamilton County as a whole has over 200.

If you drive in central Indiana, you are navigating them constantly. And the research on where drivers actually crash in them produces a genuinely counterintuitive answer: it depends heavily on how many lanes the roundabout has.

The Five Rules

Every roundabout runs on the same basic rules, and one of them matters more than the rest.

• Yield on entry. Vehicles already circulating have the right of way. This is the single most important rule, and failing it causes most entry crashes.

• Choose your lane before you enter. In a multi-lane roundabout, pick the correct lane on approach and stay in it while circulating. Changing lanes inside a roundabout is where multi-lane crashes come from.

• Signal when you exit. Many Indiana drivers skip this, and it contributes directly to entry-path crashes because waiting drivers cannot read your intent.

• Keep your following distance. At the yield line and inside the circle.

• Yield to pedestrians in marked crosswalks at both entry and exit points.

Not All Roundabouts Are Equally Safe

The Insurance Institute for Highway Safety studied 64 Carmel roundabouts, comparing crashes for two years before and after each conversion. Injury crashes came in 47 percent lower than expected overall.

But the results split sharply by design.

Roundabout type	What the study found
Double-teardrop	Injury crashes down 84%, total crashes down 63%
Single-lane	Total crashes down 51%, property-damage crashes down 50%
Multi-lane	No comparable benefit; total and property-damage crashes rose

Multi-lane roundabouts did show a 15 percent decrease in injury crashes, though the study noted those multi-lane results were not statistically significant. The clear takeaway is that single-lane and double-teardrop designs deliver the safety gains, while multi-lane roundabouts are where drivers still get into trouble.

Where the Crash Happens Depends on the Design

This is the practical detail worth carrying with you.

At single-lane roundabouts, crashes cluster at the entry. Drivers misjudge the gap or fail to yield to circulating traffic.

At multi-lane roundabouts, crashes cluster at the exit. Drivers end up in the wrong lane and cut across someone to reach their exit, or two vehicles try to occupy the same exit lane.

So the attention shifts depending on what you are approaching. At a single-lane roundabout, the work is done before you enter. At a multi-lane roundabout, the work is done before you enter and the whole way around, because your lane choice at the approach determines whether you can exit safely.

Read the overhead lane signs on the approach. In a typical two-lane roundabout the left lane serves left turns and straight-through movements, and the right lane serves right turns and straight-through. If you find yourself in the wrong lane inside the circle, go around again rather than cutting across.

Why They Work at All

The physics explains the numbers. The Federal Highway Administration notes that a modern roundabout's curvature forces drivers down to 15 to 25 mph.

Roundabouts also eliminate the crash types that hurt people most. There are no left turns across oncoming traffic, which removes head-on and right-angle collisions. And with no signal, nobody accelerates to beat a yellow light.

Lower speeds and fewer conflict points mean that when crashes do happen, they tend to be property damage rather than injury. That is the entire safety case, and the Carmel data supports it.

Frequently Asked Questions

Who has the right of way in an Indiana roundabout?

Vehicles already circulating inside the roundabout. Drivers entering must yield at the yield line and wait for a safe gap.

Do I have to signal in a roundabout?

You should signal a right turn as you exit. Many drivers skip this, and it makes it harder for waiting drivers to judge whether it is safe to enter.

Which lane do I use in a multi-lane roundabout?

Choose on approach using the overhead lane signs, and stay in that lane the whole way around. Generally the left lane serves left turns and straight ahead, and the right lane serves right turns and straight ahead.

What if I miss my exit?

Go around again. Cutting across a lane to reach your exit is the most common cause of crashes at multi-lane roundabouts.

Are roundabouts actually safer than traffic lights?

The IIHS study of Carmel found injury crashes 47 percent lower than expected after conversion, with the strongest results at double-teardrop and single-lane designs. Multi-lane roundabouts showed less clear benefit.

The Bottom Line

Yield on entry, choose your lane before you enter, signal on the way out, and if you miss your exit, take another lap. Single-lane roundabouts demand attention at the entry, multi-lane roundabouts demand it all the way through.

Roundabout navigation is exactly the kind of habit defensive driving is built on: reading the road early and reducing your own conflict points. ABetterDriver offers the Indiana Bureau of Motor Vehicles approved Driver Safety Program fully online for $28.95, self-paced, with completion reported directly to the BMV.