For the week of April 23 - 29, 2003

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 transportation planner

---

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 vehicles.

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 in Ketchum.

The new highway is being designed to handle traffic volume until 2025, expected to increase by 70 percent by that time.

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 alternative.

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 direction.

"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 hour.

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 Baseline Road.

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 period.

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.

 

The Idaho Mountain Express is distributed free to residents and guests throughout the Sun Valley, Idaho resort area community. Subscribers to the Idaho Mountain Express will read these stories and others in this week's issue.