Page 18 - AnnualReport16-17

vehicles and loads,” Meier said. “But larger
Verboort Road at OR-47 roundabout
(under construction)
Continued from page 14
Roundabouts are also more efficient, Knoebel said.
Unlike signalized intersections, roundabouts have
no stop signs, allowing them to handle more traffic
in the same amount of time and minimizing wait
times for drivers.
Still, there are challenges. Over-dimension
trucks jump curbs in roundabouts that are too
small. Matt Meier, ECS Project Manager for the
Hwy 47 roundabouts, worked with ODOT and
trucking companies and used a drone to capture
oversized vehicles driving a simulation of the
proposed roundabout design at Portland
Meadows racetrack in 2015.
“We wanted to to confirm the roundabout was
properly sized to accommodate common oversized
15 | Building Community LUT Annual Report FY 2016–17
oversized vehicles and those with over-
dimensional loads may still be too large
for roundabouts.”
To solve that problem, both OR-47 roundabouts
include bypass lanes to accommodate larger
oversized vehicles and over-dimension loads.
“The bypass lanes are gated and locked,” Meier
said. “Drivers have to obtain a permit through the
ODOT Motor Carrier Transportation Division to
gain access.”
Roundabouts are generally more expensive
than signalized intersections, Knoebel admits.
For one thing, roundabouts require more land.
“That’s why many roundabouts are built in rural
areas,” Knoebel said. “There’s generally more
available undeveloped land in the rural areas
than there is in the urban areas.”
In addition, new roundabouts in Washington
County are concrete rather than asphalt.
“Asphalt needs to be thoroughly compacted,
and that’s not easy in roundabouts,” Knoebel
said. “Asphalt compactors are really heavy
steel machines that aren’t designed to travel
in circles. Concrete holds up better, but it’s
also more expensive.”
Knoebel said any additional expense is worth it.
“Roundabouts reduce injury crashes and may save
lives of drivers, pedestrians and bicyclists,” he said.
“How do you put a price tag on that?”
Jackson School Road roundabout
(under construction)