Oregonian covers the Terwilliger Curves on I-5
Malarky
Sunday, February 20, 2005
LISA GRACE LEDNICER
On a chilly morning last December, 17 minutes before the start of rush
hour, the murmur of a crisis flashed across Ron Kroop's pager.
The district manager for the Oregon Department of Transportation hopped
into his truck and threaded past a conga line of cars before stopping
in the Terwilliger Curves, one of the region's most accident-prone
stretches of highway. In front of him on Interstate 5 lay a jackknifed
tractor-trailer, splayed across two lanes of traffic.
The truck driver -- traveling about 65 mph, according to an
investigator -- unwittingly had demonstrated that normal freeway speed
is too fast for this curvy stretch of I-5, which now carries five times
the traffic as when it opened in 1961.
Even though highway workers did what they could to divert drivers, the
relatively minor accident locked up the region's freeways for 31/2
hours and caused delays up to 20 miles away.
It's a scenario likely to play out again and again as commuters
stubbornly ignore the 50 mph speed limit and traffic continues to mount
between Portland and some of its rapidly growing suburbs.
While Washington has the Beltway and New York has the Long Island
Expressway, in Portland it's hard to beat the Terwilliger Curves for
sheer rush-hour vexation. Squeezed between bluffs and a river, the
highway twists and turns through an area with few alternative routes,
making it a flash point for crashes, congestion and commuter
frustration.
Transportation officials say there is a way to significantly reduce the
number of accidents on the curves: strictly enforce the 50 mph speed
limit as cars negotiate their way through the 7-degree bends. But that
would further snarl the daily commute for the 129,400 drivers funneling
through each day.
Officials note that while the accident rate is above the state average,
few people die on the curves. The number of accidents is declining
because of safety improvements that include repaving and upgrading the
median between north and southbound lanes.
No one is pushing for a change in the speed limit, even though the
impact of a big accident on the daily commute grows more severe each
year. Officials say the occasional three-hour backup is a reasonable
price to pay to keep the cars flowing most mornings.
"We're always going to have crashes," says KC Humphrey, transportation
safety advocate for ODOT's Region 1 division in Portland. "At some
point we say, 'What can we live with?' "
Demonstration of physics
For those who drive the 1.7-mile stretch of I-5 between Spring Garden
and Iowa streets, the Terwilliger Curves pose challenges unique to
freeways in the state.
Five times in just over a mile, the curves change from gentle to sharp.
The result for a driver comes down to a physics lesson: It's harder to
keep a vehicle in one lane when going around a curve than when
traveling a straight stretch of road. The tighter the curve and the
higher the speed, the harder it is to keep the car in the same path.
Driving even 5 mph over the speed limit increases the difficulty of
going around a curve by about 20 percent. The boatlike cars popular
when the road was built had an easier time negotiating the road;
today's SUVs and tractor-trailer rigs, already prone to tipping with
their higher centers of gravity, are especially vulnerable as they
speed around curves.
Additionally, the sharpness, or radius, changes near entrances and
exits to the freeway. Drivers get pulled to the right and left as they
attempt to dodge merging cars. Navigating all that gets especially
dicey for distracted commuters punching numbers into a cell phone,
thumbing their BlackBerrys and sipping coffee.
Transportation workers have posted caution signs as well as 50 mph
speed limit signs along the curves. But commuters, accustomed to
gliding to work along the straight stretches of I-5 to the north and
south at 60 mph, tend to ignore them. As the number of cars per lane
has increased, the number of rear-enders has gone up, too, as compacts
jostle with tractor-trailers for space.
"Nobody could have imagined in 1960 that the curves would carry the
traffic volumes of today," said Brian Ray, an engineer with Kittelson &
Associates, a local transportation consulting firm. "The volumes
uncovered a multitude of sins."
Competition and pressure
The road that would become a source of frustration for today's
commuters was met with little discussion or controversy when it was
proposed as the final segment of I-5 in the early 1950s, a time when
states competed with each other to see who could finish their
interstates first.
Influential state Highway Engineer R.H. "Sam" Baldock, who led the
construction of the interstate system in Oregon, urged a state panel in
1952 to approve the twisty course, even though it ran counter to the
federal ideal of a straight road. Pressure to relieve overcrowding on
nearby Southwest Barbur Boulevard was intense, and Baldock told panel
members that if they didn't act quickly, developers would snap up
chunks of the planned route for pricey houses. Besides, he added, there
simply wasn't a better option.
None of the committee members objected. Portland city commissioners,
given the chance to hold public hearings on the proposal, declined. At
the ribbon-cutting in December 1961, elected officials bragged that
Oregon now had the longest stretch of freeway in the country.
But the curves have bedeviled engineers and commuters since the first
decade of their opening. By 1970, highway engineers were reporting that
the accident rate near Terwilliger Boulevard was more than 50 percent
higher than the statewide average, making it one of the five worst
sections in Oregon for freeway accidents.
In response, engineers installed concrete dividers and lengthened the
entrance ramps. Later they built guardrails, reinforced barriers and
installed rumble strips to jolt drivers awake. In 1992, they re-built
the Terwilliger Boulevard interchange to ease traffic flow problems.
Three years later, officials lowered the speed limit from 55 mph to 50
mph. Police intensified patrols and wrote more than 1,000 tickets in
just two months.
The effect was dramatic: In the month before the change, police
received 45 calls for accident assistance. In the first full month
afterward, the number fell to 12. The trend continued for six months,
but when police backed off the patrols, the calls for accident
assistance crept back up.
Portland Police Officer Tom Larson, nicknamed "Terwilliger Tom" because
he regularly patrols the area, said increased ticketing would shrink
the number of crashes but it's not a perfect solution.
"No matter how hard you enforce the limit," he said, "there's always
gonna be a numbskull coming by and screwing it up."
Persistently high crash rate
The fixes have helped somewhat. ODOT statistics over the past decade
show the number of accidents has decreased, as has the crash rate -- a
measurement of the number of crashes per million miles traveled.
Yet the problems persist. For 15 of the past 19 years, statistics show,
the curves' crash rate has remained higher than the statewide average.
And although the crash rate on the curves has been falling, it has been
falling more slowly than the statewide rate.
With an average of 100 crashes per year in the curves over the past
decade, the stretch is one of the most frequent accident locations on
I-5 in Oregon, according to federal officials. One senior federal
official said Oregon should study whether the road needs redesigning.
"I don't think they're looking at the cumulative effects of safety and
congestion," said David Cox, division administrator for the Oregon
office of the Federal Highway Administration.
The cost of an accident goes beyond injuries and crumpled fenders, Cox
said. With alternative routes either overcrowded or hard to reach,
ambulance drivers, delivery people and commuters all lose valuable time
when trapped in an accident-induced jam.
"If an accident happens," Cox said, "there's not a lot of opportunities
to back out and go a different way."
Realignment would be disruptive
If state highway engineers were building the road today, they said,
they'd straighten the curves to allow commuters to drive through the
section at the normal freeway speed of 60 mph.
A blueprint sketched by an ODOT engineer 16 years ago shows gentler
curves near the Terwilliger Boulevard and Brier Place interchanges,
where most of the accidents over the past five years have occurred.
Engineers who re-built the Terwilliger Boulevard overpass positioned
the columns far enough from the curves to allow for an eventual
realignment.
But just because a plan is technically feasible doesn't make it
politically doable. Even a minor adjustment to the curves,
transportation officials say, would cut a swath across Southwest
Portland, chopping into Fulton Park and demolishing homes on Canby
Street. It would cost upward of $100 million -- roughly what it took to
film the movie "The Aviator."
So instead, highway officials continue to nibble around the edges. Last
year, they began a $23 million safety improvement project scheduled to
end this spring. Workers will install new flashing yellow warning
lights at the north end of the curves, repave the highway, add
reflective road striping and refurbish nine concrete slabs where police
can park their cars and aim their radar guns.
There are no plans for extensive work on the curves over the next 20
years. Officials said it's not necessary, noting that there have been
only two deaths on the road in the past 18 years. More congested roads
such as Sunset Highway deserve more money, they said.
"Compared to other highways in the state, that's not a horrific
section," said Robin McArthur, manager for planning and development for
ODOT's Portland region. "We've seen success with what we're doing on
that segment of highway, and we hope we'll see the crashes go down."
Researcher Sandy Macomber contributed to this report.
In addition to all of this, the print edition had a real nice aerial
imagery of the curves.
Christopher Steig