You might say the intersection has gone from a grade of F to an A.

Coming up on six months of operation, the once-criticized roundabout at High School Road and Madison Avenue is exceeding expectations – of the engineers who designed it, and its nearest neighbors.

“The improvement in traffic circulation and operation has been tremendous,” said Lorenz Eber, the city program engineer who managed the project. “It handles traffic extremely well – at least as well as designed.”

The intersection was the island’s busiest, other than those on the highway. Evening commuter traffic from the ferries frequently backed up on Madison for blocks, sometimes almost to Wyatt Way.

Despite public opposition, the city council sided with engineers and approved construction of the roundabout instead of a traffic signal.

The goal was to improve the level of service, or LOS, at the intersection from an “F” – meaning long backups and peak-hour delays of well over a minute – to a “C,” meaning a condition where any motorist’s movement is influenced by other traffic, but delays are minimal.

“We’ve achieved at least a C,” said Eber, “and I suspect that most of the time we’re at an A or a B,” in which traffic moves through delays of 10 seconds or less.

Engineers will take a traffic count in the next few weeks to confirm the roundabout’s operational ability.

Meanwhile, though, the roundabout has had a dramatic impact on traffic through the Frontier Bank parking lot, the informal but much-travelled connection between Ericksen Avenue and Hildebrand Lane.

In March 2001, when High School and Madison was a four-way stop, engineers counted an average of 2,900 cars per day on what the sign at the bank parking lot labels “Not A Through Street.”

Last September, when roundabout construction was in process and the intersection was closed, the parking-lot count jumped to 3,300 cars per day.

But a week after the roundabout opened, the change was dramatic. Parking-lot travel plummeted by almost half, to 1,720 cars per day. By last month, the number had inched back to 1,875.

“I think the novelty of the roundabout wore off,” Eber said, and that drivers were no longer going out of their way to use it.

So far, so safe

So far, safety concerns have not materialized. Bainbridge Police have logged only one traffic incident, a “sign-bender.”

In February, a trucker cut the corner too closely and whacked a signpost. And that was reportedly a case of driver error.

“The driver saw the nice paving of the apron on the outside of the circle, and wanted to avoid it,” Eber said. “He didn’t understand that we paved that area specifically so larger trucks could drive on it.”

When the intersection was a four-way stop, there had been an average of four accidents a year, Eber said.

Saint Cecilia church administrator Jim Decker said this week that he thinks the roundabout is working well, and that the concerns of some churchgoers for pedestrian safety had not materialized.

“Nothing has come to my attention, and what I assume when I don’t hear any comment is that there are no problems,” Decker said. “It has worked better than I anticipated.”

Sallie Maron said Christian Science Church members are equally sanguine.

“There haven’t been any problems with noise or anything else,” she said.

School superintendent Steve Rowley agreed.

“It has exceeded our expectations,” he said. “The traffic flow is much better, and we haven’t had any issues with pedestrian safety.”

Rowley said the district will continue to maintain a crossing guard during the morning, as the district had done when the intersection was a four-way stop. And he said the roundabout may actually make life easier for the crossing guards.

“We had lost guards because of driver behavior at four-way stops,” he said, “but we have not had any serious complaints at the roundabout.”

In fact, Eber said the city has received numerous suggestions for additional roundabouts on the island – with the most popular candidates being Sportsman Club at High School and New Brooklyn; the Island Center intersection of Miller Road; New Brooklyn and Fletcher Bay; and the intersections of Madison with Wyatt Way and Winslow Way.

No plans are in the works, though, and Eber said that at least from an LOS perspective, those intersections already function well.

But one possibility he finds personally intriguing is the ferry-terminal exit at the corner of Winslow Way and Ferncliff.

“That does get backed up pretty badly,” Eber said. “A roundabout there might be a good idea.”

* * * * *

Work on the $2.2 million High School Road project is shifting west of Grow Avenue, public works officials said this week.

With the reappearance, however fleeting, of good weather, Ace Paving crews have completed the sidewalks linking the school campus to the Madison Avenue intersection.

Now sidewalks of varying widths – seven feet wide from Grow to Weaver Road, narrowing to five feet from there to Sportsman Club – will be extended west, as will bike lanes on each side. Roadside ditches will be replaced with culverts.

The roadway will generally be restricted to one lane of travel, engineer Lorenz Eber said, but one significant closure is planned.

Sometime in May, High School Road will be closed from Weaver to Sportsman Club for two weeks. During that period, crews will dig a sizeable hole – 100 feet by 40 feet, and 15 deep – for installation of a stormwater detention system. The pipes will collect High School Road runoff during heavy rains, for gradual release into a nearby swale.

Also, probably at the end of the project, the High School/Sportsman Club intersection will be changed to a four-way stop.

Eber said questions about the project and closures should be directed to his office, 842-2016.

“I’d like to make it as transparent as possible,” Eber said. “That’s not totally possible, but we do our best not to screw up people’s schedules.”