Acceptance Procedures for Dense-Graded Mixes
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Recent literature related to acceptance procedures for dense-graded mixtures is summarized. Current state of practice and development of acceptance procedures are reviewed. Many agencies are reducing the number of process control-related parameters included in their specification (e.g., gradation), moving toward an end-result specification. End-result specifications are suited to Oregon’s needs at present; however, performance-related specifications currently do not appear to be suited to Oregon needs. Many agencies are increasing the use of mix volumetrics in specifications, in part because the use of Superpave mixes is increasing and these mixes are designed using mix volumetrics. Recommended specifications for Superpave and stone-matrix asphalt mixes are available and have been implemented by some states. Pay factor equations have been formulated that allow separation of the parameter mean and standard deviation, thus encouraging the contractor to hit the job mix formula target and minimize the process variability.
Implementation of any specification requires the development and analysis of operational characteristic curves, and these curves can only be developed if acceptable and rejectable quality levels and owner and contractor risks can be defined. Computer programs are available that allow the rapid development of these curves. Simulation of the performance of specifications, as well as analysis of contractor and owner risks, are also possible through the use of simulation software such as ILLISIM.
Herbicide Use in the Management of Roadside Vegetation, Western Oregon, 1999-2000: Effects on Water
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Many different herbicides have been found in small Willamette Valley streams. The purpose of this study was to assess whether the use of herbicides in roadside vegetation control programs could be a significant contributor of herbicides carried by streams in Oregon.
The field work was designed in two phases to examine the transport of herbicides from the road shoulders under both controlled and natural rainfall conditions.
Results of the study indicated that vegetation control operations could, conceivably, account for concentrations of herbicides. There appeared to be a long-term residual of certain compounds for many months after their application to the road shoulder. Because the total area that was treated for vegetation control was a small fraction of any given drainage basin, concentration in all but the most undiluted roadside drainage ditches was unmeasurable using the available method for reporting limits.
Lane Transit District "Curb Your Car" Project
Lane Transit District has been active in utilizing transportation demand management techniques to encourage use of alternatives to the single occupant vehicle. In 1993, a "Curb Your Car" project indicated that participating employees’ use of alternative modes was increased using a program of education and incentives. However, the full impacts were difficult to measure due to low response to follow-up surveys.
This project was initiated to provide additional data for analysis of the impacts that education and incentives have on mode choice. Twenty-six Oregon state government offices in the Eugene-Springfield area offered the program to their employees. The program offered free bus passes and rewards for use of alternative modes. Baseline and follow-up surveys provide information on the immediate and longer term impacts of this type of education/incentive program.
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Roadwaste Management: Field Trials
The Oregon Department of Transportation is concluding a study on roadwaste management. The first phase of the study provided a thorough regulatory analysis and synthesis of known fact compiled in Roadwaste: Issues and Options. The main emphasis of the second phase was hands-on study of the most efficient and environmentally sound management options for street sweepings and stormwater system residuals. This report documents the second phase investigations, which include field trials conducted by ODOT crews and those conducted in cooperation with the City of Portland. Dewatering, treatment methods (from composting to thermal treatment), and reuse were investigated. Field observations from crews, operators, managers, and the ODOT Principal Investigator provide an on-site account showing why some options worked and under what circumstances some methods performed poorly.
Laboratory analysis was used to further characterize roadwaste materials. The data was also used to analyze the effectiveness of selected management options. Some options for trials were not followed-up, and some were pursued only on the bench scale. These preliminary findings and discussion of other promising technologies are also presented. Central to efficient management is the question of shared facilities, which is discussed in its own chapter.
The findings of the second phase of the roadwaste management study were used to support the recommendations for a set of effective management options presented in the Phase 3 report, Roadwaste Management: A Tool for Developing District Plans. Phase 4 is planned to assist ODOT Maintenance Districts and local jurisdictions with planning and implementation. ODOT expects the documented observations to help maintenance personnel select workable methods to best address roadwaste management issues in their Districts, and to help field crews more efficiently implement the field methods, understanding that not all situations encountered in the field can be anticipated in a study.
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Adiem II End Terminal for Concrete Barrier
On September 9, 1997, an ADIEM II (Advanced Dynamic Impact Extension Module) was installed on Interstate 5 near Salem, Oregon. The ADIEM II offered a redirecting, energy-absorbing crash cushion and end treatment for portable and permanent protection of concrete barriers. A three-person crew completed installation of the sloping concrete base and lightweight crushable concrete modules in about two hours.
This device was selected for use as an end treatment because of space limitations imposed by steep fill at the site. The Oregon Department of Transportation Research Group monitored the performance of the system for three years, particularly the weather resistance of the crushable concrete modules.
The modules developed soft spots after two years. An attempt was made to repair and re-coat the blocks. The new coating did not prevent soft spots. A corrugated plastic covering was also installed, and seemed to remain intact, though no analysis of the concrete inside the cover was performed. The lightweight concrete modules were replaced in October of 1999. The new modules were coated with a different type of water proofing material (Garna-Thane). By the spring of the following year a tear in the coating was found. In October 2000, one ADIEM installation was damaged by vehicular impact, but seemed to work as designed in absorbing the force. The blocks were difficult to remove and replace, due to debris in the track in the sloping base, and to the twisting of the wire reinforcing.
ODOT has removed the ADIEM from the approved product list for temporary applications. It is not approved by ODOT for use on permanent installations.
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Evaluation of Modified Work Zone Traffic Control Devices at Business Accesses
Modified work zone traffic control devices at business accesses were evaluated on two Oregon Department of Transportation (ODOT) projects in 1999 and 2000. In Sweet Home, Oregon, on the Sweet-Home WCL - Foster Dam Rd. Section project, blue "Temporary Business Access" signs were used at business accesses during driveway, curb, gutter and sidewalk construction. In Pleasant Hill, Oregon, on the Goshen - Pheasant Lane Section project, blue Temporary Business Access signs and blue tubular markers were used to delineate accesses to business during construction.
The analysis of traffic count data taken at business accesses in Sweet Home before and during construction yielded inconclusive results. The effectiveness of the Temporary Business Access signs could not be determined from the results of the traffic count data. However, results of telephone surveys of motorists and businesses in Sweet Home demonstrated the usefulness of the Temporary Business Access signs. Twelve of 14 businesses said the presence of the Temporary Business Access signs helped customers locate their driveways. Additionally, 242 of 371 motorists surveyed noticed the signs, and 83% (171) indicated the signs helped them locate the business access.
The traffic count data for four business sites in Pleasant Hill provided some evidence that businesses were not significantly impacted when blue tubular markers and Temporary Business Access signs were used during periods of construction activities at their accesses. The seven-day counts that were recorded between April 1999 and October 2000 demonstrated little difference between regular traffic volumes and construction traffic volumes with blue makers and signs. In the survey of 12 businesses in Pleasant Hill that had blue tubular markers and signs placed at their accesses, 6 of them said the markers and signs helped customers locate the driveways. 381 motorists who live along the OR Route 58 corridor were surveyed; 62% (237) of them had noticed the blue tubular markers and signs. Of the 62% who noticed the blue tubular markers and signs, 78% (185) felt these devices helped them locate the driveways to the businesses.
Based on the results of the research, the continued use of blue tubular markers and business access signs is recommended.
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Factors Affecting Sign Retroreflectivity
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This study was undertaken to better understand the factors that may affect road sign retroreflectivity, specifically age and physical orientation. A better understanding of these factors could provide guidance to ODOT in managing its inventory of road signs. The findings showed that over a twelve-year age span, most sign retroreflectivity readings were above the minimum ODOT standard. Retroreflectivity did not vary predictably with age. There was some evidence that retroreflectivity may be affected by sign orientation (direction facing), due to the weathering effects of windblown dust and precipitation. Additional data collection in more severe climates of Oregon might provide more evidence to support this finding. The report includes recommendations for further study and for record keeping in the ODOT sign maintenance program to provide a larger body of data.
Evaluation of Infrared Treatments for Managing Roadside Vegetation
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Environmental concerns have prompted many agencies to seek alternatives to herbicides in controlling vegetation on roadway shoulders. This study was implemented to evaluate the potential for infrared technology to address this need. Infrared technology users radiant energy to kill unwanted vegetation. Intense heat generated by liquid propane coagulates plant proteins and burst cell walls, killing seedling plants and destroying the tops of established vegetation. Repeated treatments at regular intervals deplete the root reserves of established plants and leads to their decline and eradication. Infrared treatments were applied at three rates (8, 6, and 4 treatments/year) along Oregon highways from November 1996 through June 1999. These treatments were compared to shoulders treated with herbicides and to shoulders where vegetation was left unmanaged (controlled sites). Results suggest that infrared technology can keep vegetation under control on roadway shoulders.
Roadwaste Management: A Tool for Developing District Plans
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The Oregon Department of Transportation (ODOT) conducted a study to examine roadwaste management options. Phase 1 consisted of a thorough review of regulations and standards, roadwaste characterization, current management practices, and new technology. Phase 2 researched promising alternatives and gathered data in field trials. This report documents the efforts of Phase 3, providing guidance to ODOT maintenance personnel on the protective and most effective management of roadwaste materials.
Roadwaste categories are identified and risk is assessed. Identifying and separating differing roadwastes allows more ready management while requiring less frequent analysis. District-level baseline waste characterizations help identify the most appropriate management methods to address actual risks. Recommended practices address testing, "hot" load separation, mainstream roadwaste, and wet waste management. Ready reuse is available for some materials. Other materials require simple treatment. More contaminated materials may require a significant investment in treatment or ongoing tracking unless a conservative management option is selected; e.g., disposal in a permitted landfill. A statewide plan cannot account for all of the varying circumstances and environmental conditions in the state; District-level plans are needed. This guide supports the development of District-level roadwaste management plans by providing and understanding of the roadwaste types and associated risks, what an overall roadwaste plan must address, and details on specific workable options. The ODOT Research Group plans to support the development of several District Roadwaste Management Plans, both by sponsoring training on the use of this guide and offering support for plans may lead to negotiations with environmental regulatory agencies leading to formal adoption of roadwaste Best Management Practices.
Ashland Reduced Transit Fare
Ashland Reduced Transit Fare Demonstration Project
This report analyzes the results of an effort to promote high transit ridership through lower fares and increased service frequency. The Rogue Valley Transportation District implemented the Reduced Fare Project in Ashland, Oregon, lowering fares by 75% to 25 cents. The project was initiated to address air quality and congestion goals for this community as they experienced rapid growth in vehicle miles of travel (VMT).
The research suffered from flawed methodology due to changes in routes concurrent with the fare reduction study period. But while accurate measures of success are not available, the ridership trends showed positive increases which were sustained after the demonstration project. A ridership survey indicated that 13% of the transit users were former drivers. The City of Ashland and the Southern Oregon University continue to financially support the transit service.
Recommendations for future research of this type are included in the report.
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Laboratory Comparison of Solvent-Loaded and Solvent-Free Emulsions
Asphalt emulsions have been widely used in highway construction and maintenance since the 1920s, initially as dust palliatives and spray applications. More recently, they have been used in more diverse paving applications such as base and surface course mixes, surface treatments and maintenance activities. The Oregon Department of Transportation (ODOT) uses nearly 450,000 Mg (500,000 t) of cold mix, i.e., emulsified asphalt concrete (EAC), for construction and maintenance at a cost of approximately $10 million per year. For safety, environmental and economic reasons, the use of emulsions is likely to increase dramatically in the next ten years. The decrease in highway funding and the public’s heightened environmental awareness demand innovative technology for roads of the 21stcentury. Recognizing the opportunities inherent in this challenge, some commercial enterprises have already developed solvent-free alternatives. Preliminary laboratory testing of solvent-free emulsions in standard dense- and open-graded EAC mixes indicated that mechanical properties are comparable to or exceed those of conventional solvent-loaded emulsions. Accordingly, the objective of this research was to quantify the difference between conventional solvent-loaded and solvent-free EAC as measured by indirect tensile strength.
Two aggregates typically used in ODOT Regions 4 and 5 were combined with three asphalt emulsions: a conventional CMS-2S and two commercially produced solvent-free emulsions. The results from this laboratory study are extremely promising. Specimens made with solvent-free emulsions had consistently greater indirect tensile strengths than did those made with conventional solvent-loaded emulsions. Furthermore, specimens made with the solvent-free emulsions achieved that strength gain more rapidly. Minor problems with the solvent-free emulsion consistency, i.e., uniformity, were encountered, but are considered an artifact of the production process rather than a problem with the material. Given the obvious effects on mixing, coating, adhesion and strength properties, this product consistency problem should be addressed prior to field trials, the logical extension of this very promising laboratory study. To that end, experiment designs for additional laboratory testing and field trials have been proposed.
The results of this and subsequent research could reduce, if not entirely eliminate the use of volatile solvents in EAC, yielding both economic and environmental benefits. Elimination of volatile solvent minimizes the fire hazard enhancing worker safety during manufacture of the emulsion and construction of the pavement section. Two-fold environmental benefits are expected with the use of solvent-free emulsions: improved air quality because of the elimination of volatile fumes; and reduction in the possibility of ground water contamination.
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Injected Polyurethane Slab Jacking
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Conventional methods for raising in-place concrete slabs to align roadway sections or to counteract subsidence requires pressure-injecting grout under the slab. As other transportation organizations have had success with the URETEK Method, which utilizes injected polyurethane, Oregon DOT elected use this method to raise and stabilize a bridge end panel and adjacent concrete slab. A two-year project was initiated to monitor the stability of the injected slabs and to evaluate the material. Benchmark elevation measurements were made for comparison with future elevation data. Density and strength of the polyurethane material was documented and will be compared to similar measurements after approximately 22 months of underground exposure. The ability of the injected polyurethane to penetrate through holes was characterized. An attempt was made to measure the water permeability of the material.
Lighted Guidance Tube Evaluation
This report summarizes the evaluation of the Lighted Guidance Tube (LGT), a 3MÔ product used to delineate a temporary detour curve section on the Eddyville-Cline Hill Section construction project. The3MÔ LGT system can reduce accidents on highway curves or through construction work zones by providing motorists with continuous, positive guidance along the roadway.
The installation of the LGT proved to be more challenging then envisioned, primarily because the crew was unfamiliar with the device. The LGT was first installed in December 1999 but did not work as designed. This was because the tube portion of the LGT had been stored for two weeks outside at the job site. Dirt and water had accumulated on the interior of the tube, thus reducing its optical light transmission characteristics. When 3M was consulted, they provided additional tubing for replacement. The new tube was reinstalled in February 2000.
During its five months in service, the LGT was evaluated to observe its effect on vehicle speeds, accidents, and driver perceptions. The effect on vehicle speeds was inconclusive; no relationship between the presence of the LGT and vehicle speeds could be established. During the LGT’s time in service, no accidents occurred at the site. In a survey of local residents, 86% of the drivers surveyed said the LGT helped them travel through the curve section. The majority of comments received from the survey respondents was very positive. Generally, remarks focused on how much the LGT helped drivers see the layout of the curve.
The LGT remained in service until June 2000 when it was dismantled to accommodate the completion of the new highway alignment. The LGT is available for reuse on future Oregon Department of Transportation projects.
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Evaluation of Rock Point Viaduct Concrete Beam
This study was intended to determine why it was necessary to replace the Rocky Point Viaduct (1954 - 1994), on the Oregon coast south of Port Orford, after a period of service that was much shorter than that of many other reinforced concrete bridges on the Oregon coast; to identify construction practices that may have contributed to its early failure; and to identify evaluation methods that are most effective for characterizing bridge condition. A 14.3 m (47 foot) section of concrete Beam A1 and bridge deck between the north abutment and pier 1 was removed from the seaward side of the Viaduct for evaluation of: (1) concrete properties; (2) reinforcing bar (rebar) corrosion; and (3) chloride migration in the concrete.
The harsh environment at the site was an important factor in the premature failure of the Viaduct. This led to substantial salt penetration of the concrete to the depth of the shear stirrups and square rebar. The severity of chloride penetration of the concrete was such that neither the original concrete cover nor subsequent efforts to repair the structure and prevent further corrosion could mitigate its effects on rebar corrosion. Shear stirrups had inadequate concrete cover for the severity of the environment. Early corrosion damage could be predicted from chloride depth profiles, concrete cover depths, and the rebar corrosion threshold. Application of the patch concrete merely delayed, but not for long, the occurrence of highly corrosive conditions around shear stirrups and the square rebar. Other efforts at preventing further corrosion damage (corrosion resistant coatings on the rebar, coal tar and linseed oil barrier coatings) were ineffective.
Chloride profiling, using concrete powder samples taken at small depth increments, was one of the most powerful techniques Oregon DOT has for assessing the condition of bridges on the Oregon coast. The other was half-cell potential mapping. Chloride profiles, when fit by Fick’s second law of diffusion, yield an effective diffusion coefficient, D, for chloride in concrete and a surface chloride concentration, Co, characteristic of the bridge-environment combination. Sampling to a depth of 15 cm (6 inches) in 1.3 cm (0.5 inch) increments would adequately define the chloride profile for bridges on the Oregon coast. The D and Co obtained can be used to assess the severity of environmental conditions, to look back in time to understand performance problems related to corrosion damage, or to look forward in time to anticipate maintenance and repair needs. Once good values of D and Co are obtained, chloride measurement using concrete powder sampling may not be necessary, except on a long-term basis (every 10 to 15 years) to check predictions.
Impressed Current Cathodic Protection (ICCP) over a period equivalent to 15 years service at Oregon coastal bridge conditions resulted in significant extraction of Cl from around the outer rebar. Chloride migration under the influence of the potential gradient dominated migration due to the concentration gradient. ICCP shifts the rebar to a state of diminished corrosion, i.e., a protected state, gradually reduces the aggressiveness of the concrete environment surrounding the rebar by reducing chloride ion concentrations, and increases alkalinity at the rebar surface so that the rebar may eventually return to a naturally passive state.
Bridge construction practices should consider, in addition to quality concrete and adequate cover, the aggressiveness of the site environment, including meteorological conditions and washing and sheltering that affect chloride deposition. Assessment of site environmental conditions would be a useful to bridge design to assure a structure would achieve the desired service life. Such an assessment recognizes that a wide range of microclimates exist on the Oregon coast. Site environments could be characterized by one of the following: measurement of atmospheric corrosion rates for mild steel, measurement of salt deposition rates, or determination of Co from chloride profiling an existing or nearby structure. Chloride profiles for coastal bridges and a knowledge of corrosion initiation threshold chloride levels provide solid evidence supporting the selection by Oregon DOT of stainless steel rebar and microsilica (high-performance) concrete for use in new ridge construction on the Oregon coast.
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Asphalt Cement Chip Seals in Oregon
Most chip seals in Oregon have been constructed using an emulsified asphalt binder. However, chip seals using an asphalt cement (hot oil) binder have been tried in limited situations in Oregon. This report includes a literature review and summarizes the construction and short term performance of asphalt cement chip seals constructed during the summer of 1999 in Lane, Clackamas, Lincoln and Deschutes Counties. The hot oil, supplied by Wright Asphalt, was AC-15-5TR which includes 5% tire rubber and 2.5 to 3.0% SBS polymer.
Previous research on asphalt cement chip seals has been done in Texas. Freeman and Rmeili studied six types of maintenance treatments, including asphalt cement chip seals, on 20 test sites. They found that all chip seal treatments including asphalt cement, reduced alligator, transverse and longitudinal cracking. Gransberg and others documented the Texas Department of Transportation chip seal construction program including asphalt cement chip seals. They noted that asphalt cement chip seals are advantageous because "the roadway can be opened for traffic early."
The Oregon Department of Transportation (ODOT) evaluated construction on asphalt cement chip seals constructed on OR Route 126, U.S. Route 101, four Clackamas County roads, and one Deschutes County road. The chip seals were applied using conventional construction techniques. Asphalt cement, pavement, air temperature and humidity measurements were recorded throughout construction operations. Samples of aggregate and asphalt cement were taken for laboratory analysis. Additionally, skid resistance testing was conducted on OR Route 126 and U.S. Route 101.
The chip seals were monitored for chip retention and condition, one month after construction. Localized chip loss was observed on OR Route 126 between MP 29.0 and MP 31.6 in April 2000. Chip loss was attributed to variability in the underlying pavement surface and the low asphalt cement shot rate used during construction. Each chip seal section will be monitored annually for two years, and a final report prepared at the end of the monitoring period.
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Testing of Full-size Reinforced Concrete Beams Strengthened with FRP Composites: Experimental Results and Design Methods Verification
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In 1997, a load rating of an historic reinforced concrete bridge in Oregon, Horsetail Creek Bridge, indicated substandard shear and moment capacities of the beams. As a result, the Bridge was strengthened with fiber reinforced polymer composites as a means of increasing load-carrying capacity while maintaining the historic appearance. Because composites were a relatively new construction material in infrastructure projects, subsequent tests were conducted to verify the design used on the Bridge. Four full-size beams were constructed to match the dimensions and strength capacity of the Bridge crossbeams as closely as possible. One of these beams was used as the control, while the other three beams were strengthened with various composite configurations including the same configuration used on the Bridge crossbeams. The beams were loaded in third point bending to determine their capacity. The beam strengthened with the same composite design used on the Bridge could not be broken with loading equipment used. Based on the maximum loads applied, the Bridge beams have at least a 50% increase in shear and a 99% increase in moment capacity over the unstrengthened condition. Design calculations show the Bridge beams now exceed the required shear and moment capacities.
Desert Varnish Evaluation Dabney State Park
In 1998, ODOT mitigated a rock fall hazard on the Historic Columbia River Highway. Loose rock was removed from the overhanging cliff while the sandstone near the base of the cliff was covered with shotcrete to prevent erosion. The shotcrete was then coated with desert varnish to hide the new looking concrete face. The desert varnish is intended to help blend the project into the surrounding environment in this area of high tourist traffic.
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The project was completed in the summer of 1999. The desert varnish was applied without any problems. It continues to darken with age so that the shotcrete blends in well with the natural cliff. This report documents the application and initial inspections of the results.
Watertight Pipe Joint Survey
Oregon Department of Transportation (ODOT) has been specifying watertight pipes for storm sewer and some culvert pipe installations. The ODOT designer is responsible for specifying the watertight requirement, but there is no currently accepted standard for where a watertight pipe should be specified. Plastic, concrete and metal pipes are being used, and there is concern that all of the pipes do not perform equally in terms of watertightness. There are specifications for watertightness for plastic and concrete pipes, but no standard for metal pipes. To determine the state of the practice, a literature search and electronic survey of state Departments of Transportation were performed.
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Based on the results, it is recommended that ODOT develop standards for where and when watertight pipes should be required, as well as laboratory testing requirements for pipe joint systems. Test methods are readily available for testing polyethylene, concrete, and polyvinylchloride joints. AASHTO test method M 198 appears to be effective for metal pipes.