Vermont Agency of Transportation

Vermont, Vermont, United States

Vermont Agency of Transportation

Vermont, Vermont, United States
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Zimmerman K.A.,Applied Pavement Technology Inc. | Corley-Lay J.,Pavement Management Unit | Wlaschin J.B.,FHWA | Tetreault R.M.,Vermont Agency of Transportation
Transportation Research Record | Year: 2013

Nine pavement and asset managers from the United States participated in the International Scan on Managing Pavements and Monitoring Performance. The scan team sought input on processes for implementing sustainable performance-based programs; effective communication methods for garnering upper management and legislative support; agency cultures that support performance-based programs; and techniques, tools, analyses, and reporting that support performance-based management. The team traveled to New Zealand, Australia, Sweden, the Netherlands, and England and gathered information from 14 agencies. The agencies selected for consultation had experience with managing their pavement networks under constrained budgets. Although the initial focus of the scan was on pavement management, the team found that some of the agencies conducted pavement management within an asset management framework. The findings are thus equally applicable to assets other than pavements. The key findings are (a) agency culture supports a long-term view toward managing pavements, (b) elected officials understand their responsibilities as stewards of public funds, (c) the road network is managed as a service provided to the traveling public, (d) agency priorities are known and agency personnel are held accountable for their actions, (e) the agencies recognize the importance of building internal capacity and capabilities, and (f) efficiency and value drive program delivery approaches. The scan team selected four implementation strategies for moving scan findings into practice: communicating scan findings, developing guidelines for asset management plans and long-term financial plans, encouraging use of recurring program assessments, and developing agency capabilities in the areas of engineering, contract administration, economics, and accounting.

Hurwitz D.S.,Oregon State University | Knodler M.A.,University of Massachusetts Amherst | Nyquist B.,Vermont Agency of Transportation
Journal of Transportation Engineering | Year: 2011

Unlike traditional Type I dilemma zones, where inappropriate signal timings or detector placements restrict the ability of motorists to safely proceed through the intersection or safely stop in advance, Type II dilemma zones are attributed to driver difficulties in decision making. Type II issues become more prevalent at high-speed intersections, which have greater variability in operating speeds and greater potential for serious crashes. Although several features related to Type II dilemma zones are known, inconsistency remains in the application of the boundary definitions. This research characterizes driver behavior and comprehension related to Type II dilemma zones for the purpose of defining these boundary conditions. Empirical observations of 10 high-speed signalized intersection approaches were conducted, and the analyses of the observed driver behavior resulted in an expanded understanding of how and where drivers make their decision to stop or proceed when approaching a signal. Specifically, distributions of vehicle location and driver behavior were examined using multiple boundary definitions, and in several instances the distributions of driver behaviors varied depending on the dilemma-zone definition employed. © 2011 American Society of Civil Engineers.

Civjan S.A.,University of Massachusetts Amherst | Kalayci E.,University of Massachusetts Amherst | Kalayci E.,Thornton Tomasetti | Quinn B.H.,University of Massachusetts Amherst | And 2 more authors.
Engineering Structures | Year: 2013

Two integral abutment bridges in Vermont, USA were instrumented and monitored to report behavior under seasonal thermal load. This paper describes substructure response from 30. months of field data. The bridges are single span steel girder bridges of approximately 40. m on pile foundations. One bridge is straight while the other has a 15° skew. Variations in substructure displacements, backfill pressures and pile moments are reported under hot, cold and moderate ambient temperatures. Abutment and pile deformation plots highlight maximum displacements at the top of piles that are often only 1/3 to 1/2 of the values at the top of the abutment. Maximum pile moments correspond to concentrated curvature at the pile-abutment interface which did not correspond to peak temperatures. Substructure deformation response was predominantly elastic under bridge contraction, but highly non-linear under bridge expansion and varied from year to year. No indication of soil ratcheting was observed in the backfill materials and design for full passive pressure appears to be overly conservative for these single span structures. No indications of pile yielding were observed in the Grade 345 steel piles. Backfill pressures were consistent across the abutment in the straight bridge, but highly variable in the 15° skew bridge. © 2013 Elsevier Ltd.

Kalayci E.,University of Massachusetts Amherst | Civjan S.A.,University of Massachusetts Amherst | Brena S.F.,University of Massachusetts Amherst | Allen C.A.,Vermont Agency of Transportation
Structural Engineering International: Journal of the International Association for Bridge and Structural Engineering (IABSE) | Year: 2011

Load testing of two instrumented single-span integral abutment bridges (IABs) in Vermont, US, was conducted using loaded multiple tandem dump trucks. Data was used to validate finite element (FE) models of each structure. Field data and FE model results were compared to gain an understanding of the distribution of live load on completed integral bridges and resulting stresses and deformations in structural components. The superstructure of the two bridges consists of a concrete deck supported on steel I-girders that are cast integrally into concrete abutments at the bridge ends. Abutments are supported on H-piles oriented with their weak axis resisting deformations in the direction of bridge alignment. The spans of the two bridges are 43 and 37 m, with girders connected to the abutments perpendicularly and with a skew angle of 15°. Correlation of measured data, such as girder strains, pile strains and deflections, abutment displacements, and backfill pressures, with FE model values are presented. Important considerations in the interpretation of field data are presented, including evaluations of the degree of composite action in girders, effects of thermal fluctuations over the course of testing and challenges faced when using field data directly to compute live load distribution factors.

Gomez B.W.,University of Vermont | Gomez B.W.,URS Corporation | Dewoolkar M.M.,University of Vermont | Lens J.E.,University of Vermont | Benda C.,Vermont Agency of Transportation
Transportation Research Record | Year: 2014

For cast-in-place abutments and retaining walls, structural backfill is preferred to be free-draining, which generally implies less than 5% fines content. This fines content is expected to eliminate the need to design for hydrostatic pressures. The availability of high-quality structural backfill with naturally low fines content is declining. This situation warrants an evaluation of whether granular backfill materials with greater than 5% fines content could be successfully used in practice. Flexible wall, hydraulic conductivity tests on a granular structural backfill with 0%, 5%, 10%, 15%, 20%, and 25% nonplastic fines content were conducted at 41, 83, and 124 kPa (6, 12, and 18 psi) confining pressures followed by consolidated drained triaxial compression tests for obtaining associated drained shear strength parameters of these gradations. The 15.2-cm (6-in.) diameter specimens were prepared at optimum moisture content and 95% of maximum standard Proctor density. To enable a comparison with respect to modified Proctor maximum densities, modified Proctor tests were also performed for all base soil-fines content mixtures. The experimental results were compared with relevant studies found in the literature. This research indicates that a nonplastic fines content up to 10% may be justified in structural backfill specifications for retaining walls and abutments.

Byrne B.,Vermont Agency of Transportation | Carr M.,Vermont Agency of Transportation | Sumner J.,Vermont Agency of Transportation
ITE Journal (Institute of Transportation Engineers) | Year: 2012

The Traffic Research Unit of the Vermont Agency of Transportation conducted more than 1,000 trip generation counts at various land uses, especially retail and service locations. The counts were conducted to either verify the validity of or confirm the need for alternatives to the ITE trip generation rates used in traffic impact studies conducted throughout the state. The result of the findings of this research was published in the Vermont Trip Generation Manual. The purpose of the research was to measure trip generation for the most widely proposed types of development in Vermont and relate that to some measures of the intensity of the particular land uses. The results were published in the Vermont Trip Generation Manual to be used along with the preparation and review of traffic impact studies within the state.

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