4/16/2009 4:52:00 PM Michigan road design may solve 260 dispute
Parkway concept offers best of three worlds
By Steve Ayers
Staff Reporter
The Michigan Left Turn is not a new idea to people living in the upper Midwest. They have been negotiating the u-turn, right turn concept of moving traffic for more than 40 years.
But it may be coming to an intersection near you.
The Michigan left turn is just one aspect of the "Arizona Parkway" design concept currently being explored by the Arizona Department of Transportation as a solution to road design of State Route 260 between Interstate 17 and Cottonwood.
For years communities at the upper end have clamored for mobility, wanting to travel between I-17 and the upper end as unimpeded as possible. Camp Verde, on the other hand, has wanted as much access to the roadway as possible to help develop its commercial corridor.
The Arizona Parkway design offers both, plus an element of safety not offered by traditional designs.
"We like the idea because it moves a lot of traffic and is in some instances less expensive than a traditional highway," ADOT spokesman Bill Williams said. "And it allows for almost unlimited access. It's a great tool to have in the tool box."
To keep traffic moving, traditional left turns are eliminated. Instead drivers must make a two-step maneuver that involves a right turn and a U-turn. It is called an "indirect left turn."
U-turns are made at "crossovers," placed immediately after lighted intersection and at regular spaced intervals between intersections.
Because no left turns are permitted at lighted intersection, traffic lights can be timed to allow vehicles moving at or near the speed limit to travel non-stop. That aspect satisfies the mobility demands of the upper valley.
"The time allotted to left-turn movements greatly reduces the capacity of the intersection to move traffic," said Jim Witowski, a former Michigan resident and consultant for ADOT.
In addition, by providing regularly spaced crossovers, drivers can access private property on the opposite side of the roadway at convenient intervals.
"There is also less pressure or emphasis to consolidate access to commercial property or other developments at signalized intersections. It eliminates the need for lighted intersections opposite large box store properties," Witowski said.
There is also the element of safety. By eliminating left turns at intersections, the number of what designers call "conflict points" is cut in half.
"You will see a dramatic reduction is crashes,' said Bob Hazlett, senior engineer with the Maricopa Association of Governments. "In Oakland County, MIch., their crash rate is 0.5 crashes per million miles of travel. Here in Maricopa County it is 2.5 crashes per million miles of travel."
The only drawback is the need for additional right-of-way space. Traditional four-lane roadways require about 130 feet of right of way.
The parkway design, because of its need for 50-foot-wide medians and turn-out areas at crossovers, large enough to accommodate tractor-trailer commercial trucks, need 200 feet rights of way.
"There are other elements that can be included that allow the movement of over 100,000 vehicles a day, safely and efficiently," Witowski said. "It makes traffic operations smoother and keeps traffic lights to a minimum."
A public presentation of the concept is planned for the Verde Valley.
CAMP VERDE - Could there be a possible solution to the long-running dispute over State Route 260?
That looks to be the feeling among valley mayors following an initial introduction to the Arizona Parkway model.
The communities at the upper end of the valley fought a battle with Camp Verde three years ago over how to design a roadway linking the two ends of SR260.
An opportunity to build a four-lane road was squandered when the two sides failed to reach an agreement on the number of access points between Western Drive and Interstate 17.
It has remained a stalemate ever since.
In late March, the Verde Valley mayors and town managers attended a special presentation provide by the Arizona Department of Transportation in Prescott, unveiling the road design concept known as the Parkway (see related article).
Originating in Michigan 40 years ago, it has the ability to satisfy the upper valley's need for unimpeded access to and from Interstate 17 and Camp Verde's need for unlimited commercial access to the busy corridor.
"At first glance it looks to be something that could work on 260, because it provides that mythical mix between mobility, having a lot of traffic going down that highway quickly, and access," Clarkdale Mayor Doug Von Gausig said.
Cottonwood Mayor Diane Joens said she has received glowing recommendations from her staff.
"Conceptually it appears it will work," Joens said. "Our staff, who is the expert, really likes the idea. But it will have to go before the council. It's up to them to decide if it is our best option."
Camp Verde Mayor Tony Gioia, who has often found himself the odd man out in discussions on SR260, said he is also optimistic.
"I would love to see our differences settled so we can move on. If we can all come to an agreement we overcome the first hurdle. Then as a group we can throw are political weight and united effort behind getting money to build it," Gioia said.
Efforts are currently under way to have the idea presented to the various town councils as well as having a public presentation. No dates have been set.
Posted: Tuesday, April 21, 2009
Article comment by:
Walt mcIntosh
As long as Camp Verde has any say in the improvements to Hwy. 260 they will never happen. Remember this is still the same town that wrote a letter to ADOT requesting that the improvements to 89A be canceled as not required after it was 75% complete and all contracts let. Camp Verde has to be taken out of the picture for any improvements to take place.
