Roundabout a Safety Component of
PennDOT’s Millfair Road Project
Looking for a conversation starter? Try just saying the word
“roundabout.”
Comments and opinions are almost sure to flow.
And if you work for PennDOT, expect questions – lots of them.
Why build them? How do you drive through them? How do
trucks and buses get through? Aren’t they dangerous? Why not
just put in a traffic signal? Why are you building one here? How
much do they cost?
All those questions reflect valid concerns and we, at PennDOT,
welcome an opportunity to talk about roundabouts.
The roundabout that has been getting the most questions and
comments lately is the one being built at Millfair Road and Route 5
in Millcreek and Fairview townships.
That single-lane roundabout is part of a much larger project –
the $12.5 million Millfair Road Improvement Project.
In PennDOT’s view, the most vital element of the Millfair Road
project by far are the two 116-foot-long bridges that are to be
built over the CSX and Norfolk Southern railroad tracks between
Route 20 and Route 5.
Those bridges will separate vehicles and pedestrians from
trains at the rail crossings and make Millfair Road a safer and more
efficient travel corridor. The bridges will significantly improve
north-south access for motorists, emergency services, and
commerce delivery. This is expected to make Millfair a busier road.
However, despite the importance of the bridges, the part of
the project that has generated the most public interest is the
roundabout – hands down, no doubt.
Why are we building roundabouts such as this one? In a word,
Safety.
Roundabouts are just another type of intersection, but their
safety record is so strong that the Federal Highway Administration
advised state DOTs to at least consider a roundabout anytime
they build or reconstruct an intersection. PennDOT agreed, and
adopted that guidance as policy.
Roundabouts are not a good fit for every intersection.
Sometimes engineering, topography, cost, or development
issues make a traditional intersection a better choice. But
where a roundabout is judged to be a good fit, we and other
transportation agencies are opting for the enhanced safety of a
roundabout.
Safety statistics overwhelmingly support why so many
roundabouts are being built across the state and around the
country.
Federal statistics show roundabouts have 90 percent fewer
fatal crashes and 75 percent fewer serious injury crashes than a
comparable signalized intersection.
And crash data from the first roundabout that PennDOT built in
northwestern Pennsylvania bears out those statistics.
That first roundabout in the northwest region is located at the
southern intersection of Route 19 and Route 97 in Waterford.
The crash history of that intersection shows that an average of
five people a year were injured in crashes in each of the five years
18 Millcreek
before the roundabout was built. That’s 25 people injured in five
years.
No one has been injured at that Waterford intersection since the
roundabout was opened to traffic in August 2014.
At roundabouts, traffic moves more slowly and in the same
direction (always counterclockwise). Essentially, crashes at
roundabouts are fewer and are almost always “fender benders,”
due to the slow speeds and the flared entry. There is rarely, if ever,
the more violent T-bone or head-on crashes that can occur at more
traditional intersections.
A T-shaped intersection, such as at Millfair and Route 5,
has nine conflict points – places where vehicles can collide as
motorists either turn right, turn left or drive straight through the
intersection. A T-shaped, three-leg roundabout would have just six
conflict points.
That is because in a roundabout, every vehicle makes a right
turn to enter and exit the circle. Vehicles are all moving in the same
direction and at lower speeds.