Traffic Engineering

What You Need To Know About

Modern Roundabouts

Each year the City of Lawrence receives numerous requests from citizens to improve the safety of the streets on which they live. In an effort to find appropriate ways to deal with these concerns and make our residential areas more livable, the City has started considering the use of roundabouts.

Modern roundabouts are relatively new to the United States, but they have been used throughout Europe, Australia and other countries to reduce crashes, injuries, traffic delays, fuel consumption, air pollution and construction costs, while increasing capacity and enhancing intersection beauty. They have also successfully been used to control traffic speeds in residential neighborhoods and are accepted as the safest type of intersection design.

A modern roundabout is a circular intersection similar to the traffic circle used previously in this country. The major differences between a traffic circle and a roundabout are:

• Yield at Entry: At roundabouts the entering traffic yields the right-of way to the circulating traffic. This yield-at-entry rule keeps traffic from locking-up and allows free flow movement.
• Deflection: The entry and center island of a roundabout deflects entering traffic to slow traffic and reinforce the yielding process.

Types of Roundabouts

There are two basic types of modern roundabouts:

Conventional roundabout

A one-way circular roadway around a curbed central island for circulating traffic, usually with flared approaches. This type is constructed at the intersection of Harvard Road & Monterey Way.

Mini-roundabout

A one-way circular roadway around a raised central island of up to 30 feet in diameter, usually without flared entries. This type is constructed at the intersection of 18th Street & Sweetwater Court.

Why Use A Roundabout?

• Safety - Modern roundabouts have been shown to reduce injury-producing crashes by 76% and fatal or incapacitating injuriesas much as 90% in the United States. The reduction in crashes is attributed to slower speeds and reduced number of conflict points.
• Low Maintenance - Eliminates maintenance costs associated with traffic signals which amount to approximately $3500 per year per intersection. In addition, electricity costs are reduced.
• Reduced Delay - By yielding at the entry rather than stopping and waiting for a green light, delay is significantly reduced.
• Capacity - Intersections with a high volume of left-turns are better handled by a roundabout than a multi-phased traffic signal.
• Aesthetics - A reduction in delay corresponds to a decrease in fuel consumption and air pollution. In addition, the central island provides an opportunity to provide landscaping.

How To Drive A Roundabout

As you approach a roundabout you will see a YIELD sign and dashed yield limit line. Slow down, watch for pedestrians and bicyclists, and be prepared to stop if necessary. When you enter, yield to circulating traffic on the left, but do not stop if it is clear.

A conventional roundabout will have splitter islands on the approach to the intersection. They help guide traffic and indicate that you must drive to the right of the center island (mini-roundabouts usually do not have splitter islands, but you must still drive to the right of the center island.)

After passing the street prior to your exit, you should turn on your right-turn signal and watch for pedestrians and bicyclists as you exit. Left-turns are completed by traveling around the center island.

Citizen Concern

The City of Lawrence takes its role in solving traffic problems very seriously, yet the ultimate burden of safety rests with you, the motorist, cyclist, or pedestrian. Due to the number of citizen requests per year, we cannot always investigate your request as quickly as we would like to. However, we will respond after carefully evaluating your request. We appreciate your patience and understanding.

IF YOU HAVE QUESTIONS, REQUESTS OR SUGGESTIONS CONCERNING TRAFFIC ENGINEERING IN LAWRENCE, PLEASE CALL THE TRAFFIC ENGINEERING DIVISION