Highway modeling question HOV lanes
Roundabout proposed at Elkhorn Road
"It could be telling us that you make
congestion worse with HOV than without it"
— Chuck Green, PB Associate
By GREG MOORE
Express Staff Writer
According to preliminary computer
modeling, the designation of high-occupancy-vehicle lanes on a new, four-lane
Highway 75 would increase driving time between Hailey and Ketchum for all
That conclusion was part of a presentation
on HOV lanes made by highway project consulting firm Parsons Brinckerhoff to the
Wood River Transportation Committee on Thursday. However, PB Associate Diana
Atkins cautioned that the firm is only beginning to analyze impacts of the
various project alternatives, and the HOV computer model has not been "finely
tuned." Neither did it take into account the possible imposition of paid parking
The new highway is being designed to
handle traffic volume until 2025, expected to increase by 70 percent by that
Project plans for 27 miles of highway call
for a two-lane road with some passing lanes between Timmerman Junction and
Hailey, and a four-lane road with center turn lane from Hailey to Ketchum. Other
than the "no-build" option, the plan for that section includes two
alternatives—one with designated HOV lanes during peak commuter times and the
other without such lanes. The width of the road would be the same for either
Used by cars containing two or more people
and by buses, the HOV lanes would be the right-hand lanes of both the northbound
and southbound portions of the highway. Vehicles traveling in an HOV lane could
move into the general-purpose lane to pass, but vehicles in the general-purpose
lane could not use the HOV lane to pass.
PB Associate Transportation Planner Chuck
Green said at Thursday’s meeting that there has been little experience with HOV
lanes on four-lane, arterial roads—that is, those with stoplights and frequent
access points. Most designated HOV lanes are on freeways with six or more total
lanes, allowing all vehicles a passing lane. Green said HOV lanes are less
advantageous when stoplights are involved.
PB’s computer model predicts a travel time
of 45 minutes between Timmerman Junction, at the intersection of U.S. 20, and
Ketchum on a four-lane road without designated HOV lanes. With HOV lanes from
Hailey north, it predicts a travel time of 46 minutes for vehicles using the HOV
lanes and 51 minutes for those in the general-purpose lanes.
"It could be telling us that you make
congestion worse with HOV than without it," Green said.
Given only a five-minute difference in
travel time and the current free parking in Ketchum, PB’s model predicts that
designation of HOV lanes will produce only a 1 percent increase in
carpooling—from 28 percent of drivers to 29 percent. Green said past experience
has shown that commuters tend to start carpooling when they see it will save
them about one minute per mile. Under PB’s computer model, the designation of
HOV lanes will save less than half that.
Moreover, he said, paid parking is the
biggest motivator of increased carpooling.
Ketchum appears to be moving in that
"I think we have to do it," Mayor Ed Simon
said in an interview.
Simon said paid parking in the city’s
downtown area would both encourage carpooling and reserve spaces for the
customers of downtown businesses. The city has hired a Portland-based consultant
and formed an advisory committee of about a dozen people, including city
officials, business owners and residents. Its first meeting is scheduled for
Friday, May 2, and recommendations from consultant Kittleson and Associates are
expected to be ready by late summer.
In an interview, Wood River Rideshare
Executive Director Beth Callister said the success of HOV lanes also depends on
employer incentives and a good bus system. PB’s computer model assumes that
buses will run at three an hour during peak times instead of the current one per
However, Callister questioned the computer
model’s accuracy in predicting only a 1 percent increase in carpooling with
designated HOV lanes. She also pointed out that carpooling produces less air
pollution and uses less fuel.
"The idea still needs to be talked about
by our community," she said. "The fear is that (PB’s) analysis isn’t going to be
as thorough as it needs to be."
PB Associate Atkins told Wood River
Transportation committee members Thursday that the firm will develop a second
model to predict the success of HOV lanes under the assumption that Ketchum does
impose paid parking.
Perhaps the situation most similar to the
Wood River Valley’s in which HOV lanes have been designated is on part of
Highway 82 entering Aspen, Colo. In an interview, Aspen Transportation
Coordinator Lynn Bader said that through the imposition of paid parking,
creation of a bus system and designation of HOV lanes, the amount of traffic
entering Aspen has been maintained at 1993 levels.
During an "open house" at the Wood River
Inn in Hailey on Wednesday, PB unveiled new ideas for Highway 75 south of
Bellevue and for the Elkhorn Road intersection.
Until recently, plans for the road between
Timmerman Junction and Bellevue called for a two-lane highway with a center turn
lane. The new plan replaces the turn lane with northbound and southbound passing
lanes. Each passing lane would be two miles long, with the northbound lane
extending from just north of the junction to just south of Baseline Road. The
southbound lane would extend from just south of Walker Road to just north of
At Elkhorn Road, the new plan calls for a
two-lane roundabout to replace the stoplight.
"If everyone learns to operate in a
roundabout, it moves traffic through smoothly," Green said in an interview.
However, he acknowledged that roundabouts
are less friendly to pedestrians than are stoplights. A pedestrian underpass
already exists at he southern end of the intersection, but provisions would have
to be made for pedestrian crossing at the other three sides.
Enhanced pedestrian crossings were the
subject of another presentation PB representatives made Wednesday night before
the Hailey City Council.
Due to the availability of federal money,
Atkins told council members, now is the time to put in any enhancements to Main
Street. Council members agreed they would like to see turn signals on
stoplights, better striping of crosswalks, perhaps roadway markings warning
drivers of upcoming crosswalks and flags for pedestrians who are crossing.
Atkins said her firm will begin to analyze
the impacts of project alternatives in early May, and have a first draft of an
Environmental Impact Statement done by Thanksgiving. A completed draft EIS is
expected to be ready by March 2004, to be followed by a 60-day public comment
The Federal Highway Administration is
expected to issue a final decision by late 2004. Construction is expected to
cost between $40 million to $44 million, and right-of-way acquisition at least
$20 million. Up to 80 percent of the cost will be borne by the federal
government and the rest by the state of Idaho.
The next "open house" presentation is
planned for June 17 at the Wood River Inn in Hailey.