Roundabouts

Roundabouts

The City of Sterling is planning a roundabout at the intersection of Lynn Blvd and W. Lefevre.  Design engineering work is ongoing with anticipated construction in 2019.  Work is expected to take around 5 months if the intersection is left partially open to traffic during construction (3 months if completely shut down).

Lynn/Lefevre Proposed Roundabout


FAQs

Why is the City considering work at the intersection of Lynn and Lefevre? 
The City was approached in 2016 and 2017 by several people and organizations about the number of near-misses and accidents at Lynn and W. Lefevre.  It was also noted that grain trucks were having difficulty getting across at certain times of the year.  Further, the City knew the traffic was going to get worse with the move and expansion of HALO.  In response, the City asked its planning firm to conduct a traffic impact analysis to determine the best solution to the traffic issue then and for the future. The City did not seek to install traffic signals nor a roundabout when it commissioned the study from a professional traffic engineer. The City's goal was to find the best solution to the known complaints and forthcoming traffic growth based on a professional, data driven assessment by traffic engineers.

Why not just add stop signs?
A 4-way stop allows for the least traffic to flow through per hour and additional stop signs do not significantly reduce the potential for injury accidents (which tend to be caused by angle crashes (t-bones) when one driver fails to stop for a stop sign.  The Traffic Intersection Analysis the City had commissioned projects a "level of service" of “F” (on a scale from A-F) for a 4-way stop due to the lengthy backups and wait times a 4-way stop would create at peak hours. 

During off-peak hours, vehicles could safely pass through a roundabout without stopping instead of being forced to stop when there is no traffic present, thus saving time, aggravation and money (by reducing gas and wear and tear on brakes and vehicles from needless stopping).  The reduced stop and go also provides a bit of an environmental benefit to the roundabout.


AARP Conflict Points Diagram
AARP Conflict Points Diagram
Why not just add traffic lights?
1) A signalized intersection is not always cheaper due to equipment, ongoing maintenance and the need for turn lanes. Long-term, there is no cost savings.

2) A roundabout can handle more cars per hour than either a traffic signal or all-way stop, meaning more cars per hour and lower wait times than either.   

3) While traffic lights may reduce accidents from the current rate, roundabouts, particularly single-lane ones like the one being designed, are statistically far safer, especially for severe injury and fatal accidents

4) During off-peak hours, vehicles could safely pass without stopping instead of stopping when there is no traffic, saving time and money (by reducing gas and wear and tear on brakes and vehicles from needless stopping).  This also provides a bit of an environmental benefit to the roundabout.

5) Traffic lights don’t stop accidents.  Sterling’s most accident-prone intersection is 1st Avenue and 3rd Street, which has a traffic light. 

Wouldn’t traffic lights be cheaper?
Modern roundabouts are usually less expensive than signalized intersections:

1) Traffic signal equipment is a six-figure expense upfront and requires ongoing maintenance of that equipment by specialized vendors.

2) Roundabouts usually do not require separate left- and right-turn lanes, which helps lower costs of intersection approaches.

3) Property acquisition for the larger footprint of a roundabout makes some roundabouts cost more.  The only property needed at this site is City and Park District property

Can semi-trucks, busses, farm equipment or even oversized vehicles negotiate a roundabout? 
Roundabouts have design features specifically intended to accommodate trucks, buses, tractors, and larger vehicles. The main characteristic is a truck apron, a slightly raised area around the inside of the roundabout. It is typically 3 to 4 inches higher than the paved roadway and is purposely designed for semi-trucks, farm equipment, busses, etc. to use to help make the turns.  With a properly designed truck apron, a roundabout is able to accommodate all types of larger vehicles.  The engineer planning the Lynn/Lefevre roundabout has been in communication with Astec to make sure even their largest oversized loads can make the corner.

How can pedestrians use a roundabout? Is a roundabout more dangerous?
Roundabouts are pedestrian friendly. They provide fewer conflict points (places where traffic intersects with pedestrians). The splitter islands between approaching lanes provide a space for pedestrians in the middle of each crossing. Therefore, pedestrians only need to cross one direction of traffic at a time. The pedestrian crosswalks are set at least one full car length back from the yield line. That way, pedestrians do not have to cross in front of drivers that are looking for their gap in traffic.

Crosswalks at traditional intersections can provide a false sense of security.   They still require drivers, particularly making turning movements, to be paying attention and yield appropriately.  Pedestrians also have larger lengths to travel across lanes at one time.  Roundabouts also ensure traffic is moving slower through the intersection, which also reduces fatality rates.

Do Roundabouts Save Lives?
Intersections are among the most dangerous and complex traffic features that drivers encounter.  According to National Highway Traffic Safety Administration data, 21 percent of all traffic fatalities and roughly 50 percent of serious traffic injuries can be attributed to intersections. Roundabouts almost completely eliminate fatalities and significantly reduce injury crashes.

A 2015 safety study produced by the University of Wisconsin Traffic Operations and Safety (TOPS) Lab showed that fatal and severe injury crashes decreased by 40 percent at Wisconsin roundabouts.

An Insurance Institute for Highway Safety (IIHS) study found roundabouts reduced injury crashes by 75 percent at intersections where stop signs or signals were previously used for traffic control. Studies by the IIHS and Federal Highway Administration have shown that roundabouts typically achieve:

  • A 37 percent reduction in overall collisions
  • A 75 percent reduction in injury collisions
  • A 90 percent reduction in fatality collisions
  • A 40 percent reduction in pedestrian collisions

The reasons roundabouts reduce fatal and severe injury collisions are:

  • Low travel speeds – Drivers must slow down and yield to traffic before entering a roundabout. Speeds in the roundabout are typically between 15 and 20 miles per hour. The few collisions that occur in roundabouts are typically minor and cause few injuries since they occur at such low speeds.
  • No light to beat – Roundabouts are designed to promote a continuous, circular flow of traffic. Drivers need only yield to traffic before entering a roundabout; if there is no traffic in the roundabout, drivers are not required to stop. Because traffic is constantly flowing through the intersection, drivers don't have the incentive to speed up to try and "beat the light," like they might at a traditional intersection.
  • One-way travel – Roads entering a roundabout are gently curved to direct drivers into the intersection and help them travel counterclockwise around the roundabout. The curved roads and one-way travel around the roundabout eliminate the possibility for T-bone and head-on collisions.

People don’t know how to use them, so why would we use them?
Since roundabouts are currently rare around the United States, all types of drivers may experience initial confusion upon their first encounter. However, as roundabouts become more common and motorists become more familiar with their operation, the initial confusion will be significantly reduced. Most people quickly learn their operation. Plus, because of the low speeds, there is generally much less risk of a crash or injury compared to a traditional intersection.

Thousands of roundabouts have been constructed across the United States in the last decade.  As more places experience success, they continue to be built.  Illinois as an area has been a very slow adopter nationwide.  Illinois has the fewest reported roundabouts per capita in the country.  Our less populous neighbors have many more than Illinois.  Iowa has twice as many.  Missouri has 4 times as many.  Indiana has almost 7 times as many.  Wisconsin has more than 11 times as many. 

What are public perceptions/Why are they opposed?

Drivers may be skeptical of or even opposed to roundabouts when they are proposed. However, several Insurance Institute for Highway Safety studies show that opinions quickly change when drivers become familiar with them. A 2002 Institute study in three communities where single-lane roundabouts replaced stop sign-controlled intersections found:

  • 31 percent of drivers supported the roundabouts before construction, compared with 63 percent shortly after.
  • Another study surveyed drivers in three additional communities where a one- or two-lane roundabout replaced stop signs or traffic signals.
  • Overall, 36 percent of drivers supported the roundabouts before construction compared with 50 percent shortly after. Follow-up surveys conducted in these six communities after roundabouts had been in place for more than one year found the level of public support increased to about 70 percent on average!

 Source: https://www.iihs.org/iihs/topics/t/roundabouts/qanda

What’s been the experience in other cities?

People have cited the Rockford roundabout at Auburn and Main as a reason not to construct a roundabout in Sterling.  The Auburn/Main roundabout in Rockford is a more complex multilane roundabout.  The Lynn/Lefevre roundabout is a simple one-lane roundabout.  Rockford has actually had good success at their single lane roundabouts (such as Auburn and Meridian). 

The Peoria area has 5 and plans to do more based on their successes: Officials Say Roundabouts Are Working. Prepare For More (Peoria Journal Star)

Carmel, Indiana has 100 roundabouts in their city. Camel, IN Loves Roundabouts, Here's Why (Indianapolis Star)

Why not spend the money on other bad roads?
The City was receiving complaints about safety issues at the intersection prior to HALO's move and expansion.  Traffic patterns have changed over the last 20 years as the concentration of industrial jobs has gone from the riverfront area to the west side business parks (hundreds more jobs are now located on the west side) and the Lynn Boulevard extension connected the far east side of the community to the far west at this intersection.  Add in people travelling down Lefevre/Lynn for Westwood and even the WalMart Distribution Center and the need is evident.  The professional traffic analysis study determined adding stop signs would not solve the peak time traffic issues. A signal or a roundabout was required and the costs were similar.  Having adequate infrastructure is one of the most important things a City can do to attract or retain jobs.  Having an intersection that flows is very important, particularly for a City not directly on an interstate highway.

How do I drive through a roundabout?
It’s very simple! 

  • Slow down as you approach the roundabout, and look for pedestrians in the crosswalk (yield to pedestrians!).
  • Continue toward the roundabout and look to your left as you near the yield sign and dashed yield line at the entrance to the roundabout.
  •  If there is no traffic in the roundabout, you may enter without yielding. If there is traffic in the roundabout, yield to the traffic in the roundabout and enter the circle when there is a safe gap in traffic and proceed to your exit.
  • Look for pedestrians and use your turn signal before you exit.

Video: IIHS How Roundabouts Work (YouTube link)
FAQ: How to Drive in a Roundabout (IowaDOT)




Resources/Sources:

AARP Modern Roundabouts: A Livability Fact Sheet

Insurance Institute for Highway Safety: Roundabouts Q&A

Insurance Institute for Highway Safety: When roadway design options are wide open, why not build a roundabout?

Federal Highway Administration  Intersection Safety

Washington State DOT: Roundabouts

Wisconsin DOT: Roundabouts

IDOT (Iowa) Dispelling the common myths about roundabouts

City of Carmel, IN Roundabouts

As Americans Figure Out the Roundabout, It Spreads Across the U.S.(New York Times)

Americans don’t like roundabouts, but they should (Washington Post)

Europe’s Beloved Roundabout Finally Invades America: Traffic circles have been spreading quickly if unevenly on this side of the Atlantic. It’s about time. (Bloomberg)

Sterling, Illinois Traffic Intersection Analysis by Mead & Hunt

December 18, 2017 Presentation to Sterling City Council

January 7, 2019 City of Sterling Open House PowerPoint (pdf form)

FHWA Case Study https://safety.fhwa.dot.gov/intersection/innovative/roundabouts/case_studies/fhwasa09013/

FHWA Case Study https://safety.fhwa.dot.gov/intersection/innovative/roundabouts/case_studies/fhwasa09018/