enter new era of design exceptions;
Practical Design will save time, money
projects scheduled to begin next year will do more than realign a highway
and extend the width of travel lanes. They literally will help pave
the way for a more streamlined approach to project design that bases
decisions on the context in which the projects will fit.
Design exceptions are not new; they have been used when projects deviate
from national or established department standards without compromising
quality or safety. The one-size-fits-all approach to designing highway
projects isn’t always practical or efficient.
This summer ITD Director Pam Lowe challenged districts to re-evaluate
their projects and determine whether smaller or simpler will suffice.
She encouraged districts to adopt the “Practical Design”
concept that tailors project designs to their intended use and to expedite
the process at the local level.
build a Cadillac when a Chevy will do,” a Missouri Department
of Transportation representative asked rhetorically when explaining
Practical Design at the 2007 Project Development Conference in Boise.
of the districts have been working on Practical Design plans and have
submitted proposals that, when implemented, will save Idaho taxpayers
millions of dollars, according to the director.
districts have all done an exceptional job pulling these plans together.
This effort is going to be successful because of the work that the districts
have done,” Lowe said.
of the Practical Design changes do not need a design exception. However,
for the ones that do, we have implemented a new process, where the district
approves the design exception. For projects on the National Highway
System or the interstate, the district will recommend the design exception,
and Headquarters will forward the district’s recommendation onto
District 2 was
the first to take advantage of the new philosophy when it forwarded
two projects for design exceptions under Practical Design. The first
will reconstruct and realign a one-mile segment of U.S. 95 north of
Riggins – an area vulnerable to major rock slides. The other is
a widening project planned for a 23-mile stretch of U.S. 12 east of
Planners forwarded the requests, along with detailed rational according
to Practical Design guidelines, to Roadway Design at Headquarters for
a cursory review. With minimal delay, the requests were sent to the
Federal Highway Administration for design exception approval, explains
District 2 Design Engineer Curtis Arnzen.
got some very innovative people working in the districts who
will come up with excellent
– Jim Carpenter, D-2
Because there is
little room for modifying the proposal under Practical Design, district
staffs must be even more vigilant in preparing the projects, said District
2 Engineer Jim Carpenter. “It requires a heightened awareness
– the need to be even more accurate and to make a good case,”
Carpenter is a
firm believer in the benefits of the Practical Design concept. They
Greater flexibility to tailor designs to the environment
streamlining without compromising quality of the end product
savings that result from an expedited process, and
to apply cost savings to other district projects that improve travel
makes sense to do as much of the work at the district level, Carpenter
got some very innovative people working in the districts who will come
up with excellent in-house designs.”
offers District 2’s proposals as prime examples.
From submission to approval, the process took about six weeks; normally
it occurs in a matter of months.
to Tumble Creek is a 23-mile project planned for the summer
of 2008 that considers the unique aesthetics of the U.S. 12 corridor
east of Kooskia. The route is part of the Northwest Passage National
Scenic Byway System and follows a nationally designated wild and scenic
waterway – the Clearwater River.
Owned by the U.S. Forest Service and managed by ITD under the jurisdiction
of the Federal Highway Administration, the highway is clearly visible
from a large number of river users, primarily rafters and kayakers.
Narrow and windy, the road also presents challenges for drivers and
ITD has agreed to add guardrail only when absolutely necessary for travel
safety. It also will limit cuts and fills along the route and will add
retaining structures on steep slopes, where appropriate, to contain
Because of the horizontal alignment challenges and the narrow right-of-way,
it would be extremely difficult to meet AASHTO’s standards for
curves. Practical design and the exceptions granted will enable ITD
to adjust the radius without compromising safety, Arnzen said.
The $15 million project will widen U.S. 12 from 24 to 28 feet where
possible. Construction is expected to take two seasons. Ken Helm is
the project manager while Doug Langley is the lead designer and Bud
Henson is the transportation staff engineer assigned to the project,
along with Arnzen.
The 210 Slide north of Riggins on U.S. 95 also faces
unique design challenges. At the foot of a steep slope that is prone
to rock slides, the highway will be realigned slightly to the west.
Moving the centerline normally would have required the highway to meet
current AASHTO width standards, but the adjacent Salmon River makes
it difficult to conform to those standards.
ITD asked for, and received, a design exception under Practical Design
to incorporate a five-foot shoulder, rather than the eight feet required
by AASHTO standards. The $4.5 million project should be completed late
next summer, Arnzen said. Kevin Dammon is the lead designer; Henson
and Arnzen also helped with the in-district design.
am impressed with the District 2 design exception documentation,”
Lowe said. “They are leading the way in demonstrating how quickly
and efficiently ITD can work. We have shared what District 2 did with
the other districts, and I expect we will have more in the future.”
the districts all have done a great job putting together their Practical