Traffic study recommends roundabout for Canongate, Amberly intersection | Community

Sam Crisler, The Waverly News

WAVERLY – On school mornings, Lindsay Erickson is on call for her three children, and each has a different destination. One attends Waverly High School, another Waverly Middle School, and the third Waverly Intermediate School.

The family drives south over the Canongate Road overpass from the north side of town to approach the intersection with Amberly Road, just outside the campuses of Waverly High School and Waverly Middle School.

But if the Ericksons don’t leave the house soon enough, they often find themselves stuck playing a waiting game.

“If we don’t get there by 8 a.m., we can easily sit for seven to 10 minutes,” Erickson said.

Erickson’s situation is not unique, as many parents have similar issues with the Canongate and Amberly intersection on school days. Drivers on Canongate Road are greeted by stop signs on both sides of Amberly Road, while eastbound and westbound traffic is a steady stream which makes crossing difficult.

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The city of Waverly heard the complaints, and in March the city council voted to hire traffic infrastructure engineering firm Iteris to initiate a study that would observe the intersection’s problems and provide possible traffic control options. the circulation.

Iteris Traffic Engineer John Albeck presented the study results Aug. 2 during an open house at the Waverly Community Foundation Building.

Albeck said the study was conducted on normal school days in May that were not affected by holidays or irregularities that could lead to changes in traffic patterns. What they found was heavy rush-hour traffic at the intersection that was at its worst between 7:30 a.m. and 8:30 a.m. Nearly 40% of that hour’s traffic occurred between 8 a.m. and 8:15 a.m.

The next worst time slot for the intersection was 3:30 to 4:30 p.m., after classes ended for the day.

In the morning, the intersection’s longest delay was just over four minutes, with southbound traffic from Canongate Road facing the worst movement. Iteris observed 200 southbound vehicles at the intersection during the morning rush hour.

Using an A to F scale rating the functionality of the intersection, the study gave the Canongate and Amberly intersection an “F” during its morning rush hour and a “C” during its peak of the afternoon. According to the study, an “F” denotes “excessive delays and congestion” and “very long” queues with “obviously irritated” drivers.

Albeck presented four possible routes the city could take to solve the intersection’s traffic problems: a four-way stop, a traffic light, a single-lane roundabout, and a single-lane roundabout with a Dedicated right-turn lane for each direction.






MODEL: Terry Spoor asks questions of Schemmer transportation engineer Matt Shimerdla (left) and Iteris traffic operations manager John Albeck (right) Aug. 2 during the Open House on the traffic study at the Waverly Community Foundation Building. (Staff photo by Sam Crisler)


Albeck explained that to justify the installation of a traffic light, an intersection must meet nine “mandates”, many of which did not apply to the Canongate and Amberly intersection. The intersection failed to meet traffic volume mandates because its greatest congestion was concentrated at short time intervals in the morning.

The intersection also failed to meet the vehicle collision mandate, as few accidents had been reported at the intersection in recent years.

Albeck noted that traffic lights are expensive to maintain and, if implemented, are 24-hour commitments for drivers – even if it’s late at night and only one car is stopped at the intersection. He said his expertise is in timing traffic lights.

“I love traffic lights,” he said. “But I’m also a fan of everything else when it’s viable. Based on the traffic that exists today, we do not warrant the installation of a traffic control signal. »

The study used existing traffic volumes to model which options would work best at the intersection, with the four-way stop performing the worst, although it was still an improvement over a grade “D” during the morning rush.

Both roundabout options received ‘A’ grades, with the single-lane roundabout model showing a nine-second delay for drivers during rush hour, and the roundabout with turning lanes right displaying a seven-second delay. The traffic light also received an “A” grade for functionality.

The study also considered future population growth and the higher traffic volumes it would create.

Assuming a 3% growth rate at Waverly over the next 15 years, the study shows that a signalized intersection would continue to work well during the morning rush, but would still not be warranted during the rest of the day. Similarly, the four-way stop was deemed unnecessary because it would “delay eastbound and westbound traffic for the rest of the day,” according to the study.

At future traffic volumes, the roundabout with right-turn lanes received a “C” grade for its future morning peak functionality. At worst, traffic would be delayed by 19 seconds. The single lane roundabout was given an ‘E’, with a 40 second delay.

Albeck said each option would still result in backups that would extend to intersections to the west and east on Amberly Road.

“Normally we like to design for nothing worse than a ‘D’,” Albeck said. “But we can’t always design for an ‘A’; it becomes almost impossible.

Comparing the options, the study explains that the roundabout with right-turn lanes has the best cost advantage, although it would have the highest construction cost due to its greater width. and barriers to right-of-way.

“There are pros and cons to all of this, there really are,” Albeck said. “But considering all the factors, (the roundabout with right turn lanes) is a very viable alternative. A roundabout is very viable and the recommended solution for something like this.

He acknowledged the concern that some citizens may have about roundabouts and the potential increase in accidents and pedestrian difficulties associated with these traffic systems.

But he said the roundabouts in question at the intersection of Canongate and Amberly would have dedicated pedestrian crossings. And he said modern roundabout designs lead to fewer accidents because drivers have to yield and reduce their speed before entering the circle.

“There is clear evidence that roundabouts have better collision mitigations than signals and other alternatives,” Albeck said.

If the City Council chooses to install the roundabout with right-turn lanes, Albeck estimated that construction would take place in the summer of 2024 and could be completed in phases to avoid the closure of Amberly Road.

The council has yet to choose a traffic option for the intersection of Canongate and Amberly roads, but city administrator Stephanie Fisher said a decision will need to be made before city budgets for his next exercise.

“The first step will be engineering,” Fisher said. “So, are we designing a traffic light? Or are we designing a roundabout? »

Albeck said Iteris and engineer Schemmer would welcome further community input and expect there to be a second open house showcasing potential design options.

“I would consider much more in-depth design discussions,” Albeck said. “There will be feedback from the public and all stakeholders throughout the process.”

For her part, Lindsay Erickson was delighted that Iteris’ recommendation was for a roundabout, and she thinks Waverly residents would see a roundabout as an improvement over the current intersection layout.

“I think a roundabout is by far the best (solution),” she said. “If you use them, they’re so easy and they’re so fast. And they’re like anything else, aren’t they? Try it, and I think you will really like it.

Read the full Iteris report here.

Sam Crisler is a reporter for The Waverly News. Contact him by email at [email protected].