Design Recommendations 2012 Top Ten Short List Chefornak Airport Dust Palliative (TPD1302157)

ANC Taxiway E & RON 2 (51149)

When design pipe and existing pipe cross with an elevation difference of less than a foot, we should design for a structure installation. This project had an existing pipe 3 tenths below our design pipe, per plan. But actual field conditions were in conflict and the project had to pay additional costs for an expedited structure.

Chefornak Airport

Item P-167b Dust Palliative. This spec has been updated and seems very concrete .

Old spec was not clearly stated for the Designer’s intention but it was ambiguous and contradicting in many areas.

For an examplei; Section 167-3.2 Rate of Application, it reads” .. . Obtain the manufacturer’s recommended application rate based on the sample submitted. A rate of 50 square feet for gallon was used for estimating purpose. ”

This spec was leading the contractor to get a thinner rate of application because it was depended on the sample testing.

New spec is enforced and eliminate the second guessing. It reads “The minimum rate of application shall be 1 gallon per 30 square feet for products that do not contain (ex .

Durasoil) and I gallon per 40 square feet for products that do contain a binder (eg. EK- 35).”

This application rate is the Design Engineer’s original intention .

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Parks Hwy: Stanley Road Signal

Key Issue : Department Furnished Materials.

Signal poles to be furnished and available to the contractor on August 24 per the specification and date on the procurement contract. The project was bid with an interim completion date of October 31 for the traffic signal to be fully functioning. To date, the materials have not been furnished to the contractor to complete the work. The interim completion date would have been met if the materials were made available.

Seward Hwy 89 to 96.6

We had issues with longitudinal cracking in our top lift pavement. All of the longitudinal cracking occurred along the edge of the pre-level where it dropped down the ½” to the existing asphalt in the adjacent lane that was not pre-leveled. We feel the solution to this problem is to either mill the roadway surface for the entire width, or pre-level it for the entire width.

During paving operations we had an issue with the material that maintenance uses to seal the surface of the transverse cracks throughout the roadway. In the areas where top lift pavement was placed directly on top of the existing asphalt , the material used to seal the cracks would swell up under the mat, creating a bump in the mat along with a transverse crack mirroring the old one. We feel that this existing crack sealant should either be completely removed, or completely covered up by pre-level prior the top lift being placed . I spoke with Jason Lamoreaux and he said they had the same issue on the section of the Seward Highway he did with Granite.

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Cold Bay Airport:

Maintain drainage surface overflows (warp the pavement ) from the last inlet/manhole so when they freeze-up or fail water can still flow off the apron.

Bethel Airport Pavement Rehabilitation

Paving Test Sections should be completed prior to closing a runway for paving , and be located so they don’t impact aircraft ops.

Kipnuk Airport

The design called for a thin (12 inches) lift of subbase over geo grid and fabric, over mounded native soil (high water content silt)that had been sitting for roughly 8 yea rs. This proved very difficult to build to a standard due to the haul equipment having to use, concurrently, the fill for their haul route. With this heavy equipment constantly traversing the subbase and the high water content silts being sandwiched between the subbase and the underlying permafrost, the new fills were constantly “pumping “. Since the subbase has no angularity to it(i.e. ability to bridge) the fills were very tender for the duration of construction . It is recommended that crushed material be used with a specification of 0-6% on the p200’s and an upper end of 4 inch minus with 90% passing the 2 inch. When using thin fills over “soft” bases, use a material that can “bridge ” – especially when this placed material will be the haul route.

Economically, the subbase was 105/cy and the crushed was 135/cy , so the price difference was not that great.

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