---
title: "Turbo-Roundabout"
url: "https://commonwaysystem.org/patterns/intersections/turbo-roundabout/"
id: "INT-TRB-02"
description: "A higher-capacity roundabout variant reserved for the highest-volume Arterial-to-Arterial junctions."
updated: "2026-09-26"
---

# Turbo-Roundabout

`INT-TRB-02`

Recommended Intersections & Crossings

Turbo-Roundabout

A roundabout variant using spiral lane markings and raised lane dividers to guide multi-lane traffic without the weaving conflicts a standard multi-lane roundabout allows.

## Related Media

The items below come from outside the Commonway System, external videos, podcasts, and articles related to this page's topic, not part of the guidebook itself.

Aligned

### [Are Streets Too Complicated Now?](https://www.youtube.com/watch?v=u1Xs5EA5_uU)

City Beautiful

Asks whether today's proliferation of lines, signals, and lane types on streets is overcomplication or a needed response to modern demands, a question that runs directly through CS's Element-scale catalog and the density-tiered Corridor retrofit paths this video is tagged to.

Context only

### [America Built the Wrong Roundabout (The Dutch Didn't)](https://www.youtube.com/watch?v=CKjTkXljhWc)

Safe By Design

Traces the turbo roundabout's origin and safety data, but also reports the Fietsersbond's documented cyclist/pedestrian crossing hazards at turbo roundabouts directly, worth noting since it complicates a clean "aligned" label.

Typical at: Compact Urban

Suburban and Core are edge cases. Undeveloped and Rural are unlikely pairings.

## Design notes

Reserved for higher-volume Arterial-to-Arterial junctions, where a standard roundabout's capacity is not enough but a signal is still not the preferred default. This keeps the roundabout-first philosophy intact at higher volumes rather than defaulting to a signal once traffic grows.[1]

## Related patterns

[Roundabout (Single/Multi-Lane)](https://commonwaysystem.org/patterns/intersections/roundabout.md) (INT-RAB-01) (the base pattern this scales up from), [Signal](https://commonwaysystem.org/patterns/intersections/signal.md) (INT-SIG-03) (explicitly named on this page as the alternative not preferred even at these volumes)

## Getting there: Retrofit path options

[Signal-to-roundabout conversion](https://commonwaysystem.org/retrofits/intersection/signal-to-roundabout-conversion.md) (RFT-INT-01)

## References

1.  Evidence-based [Fortuijn, L.G.H., "Turbo Roundabouts: Design Principles and Safety Performance," _Transportation Research Record_ 2096 (2009).](https://doi.org/10.3141/2096-03)