Optimum Illumination for Nighttime Flagger Operations
Highway maintenance and construction undertaken by the Oregon Department of Transportation (ODOT) can involve the use of flaggers to control the work zone. When the work is undertaken at night, illumination of flaggers is needed to ensure the safety of the motorists, flaggers, and workers. A number of recent developments have taken place that improve the ability for motorists to see flaggers. These include highly reflective apparel and illuminated “STOP/SLOW” paddles. In addition to using such personal protective and directional equipment, consideration should be given to other factors associated with lighting of the flagger station:
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• What amount of light should be used, where should the light source be located, and how should the light be directed, to effectively and efficiently illuminate the flagger? • What light level and quality are necessary and economically practical, which avoid creating blinding glare for the motorists approaching a flagger station? • How mobile is the lighting equipment and can it be moved without creating additional risk exposure to the flagger? This study developed guidelines for the optimal illumination of flaggers during nighttime maintenance and construction operations on highway projects. The guidelines address minimum and optimum lighting levels, optimal methods of delivering the light, and maneuverability of the lighting equipment.
Washing Bridges to Reduce Chloride
Chloride ions are known to promote the corrosion of steel in reinforced concrete. This project was undertaken to investigate the efficacy of washing, to reduce existing chloride content and chloride ion uptake. The project consisted of a laboratory component over four years and a field component over two years.
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In the field component test sections of a coastal bridge were pressure washed on a once per year and twice per year schedule. The laboratory effort consisted of washing trials conducted on concrete blocks exposed to salt water to determine whether chloride ions can be removed from the concrete and whether the ingress of chloride ions can be reduced. Field testing was discontinued after two years because the laboratory results indicated that the washing frequencies used on the bridge were much too low to produce any change in chloride levels. After four years, the laboratory trials showed that daily washing with fresh water can appreciably reduce the ingress of chloride ions, but occasional washing is ineffective. Washing does not appear to significantly reduce existing chloride concentrations in the bulk concrete.
Pedestrian Safety Impacts of Curb Extensions: A Case Study
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This report documents a case study evaluating motorist yielding behavior at a crosswalk in Albany, Oregon. In 2003 the City of Albany installed curb extensions, continental markings and advance stop bars at several uncontrolled intersections along the U.S. Highway 20 one-way couplet. The City of Albany requested that an evaluation be conducted to determine if the pedestrian safety improvements functioned as intended. Since the installation in 2003, there had been no data collection effort on the operation of these features.
The focus of this study was the intersection of 4th Avenue and Lyon Street because the nearside crosswalk had a curb extension on only one side of the street, thus allowing for an analysis of motorist behavior toward pedestrians crossing from either the side with the curb extension or the side without. Specifically, this study examined the average number of vehicles that passed between the time a pedestrian arrived at the crosswalk to the time they were able to cross, the percent of vehicles that yielded at the advance stop bar, and the percent of pedestrian crossings in which a vehicle yielded.
Evaluation of Wearing Surface Materials for FRP Bridge Decks
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The wearing surface on many fiber reinforced polymer (FRP) composite bridge decks have cracked or delaminated after only a short time in service. Consequently, a set of tests were conducted on four wearing surface products in order to select the material with the best performance with respect to service conditions on an FRP deck. The products were evaluated for tensile strength, failure strain, bond strength, and abrasion resistance. Results were summarized in a ranking matrix, which showed Urefast PF60 should provide the best performance of the products tested.
Automated Data Collection Equipment for Monitoring Highway Condition
This study was conducted to evaluate automated vehicle mounted equipment to collect data on the needs of Oregon's highway inventory. Four vendors accepted invitations to evaluate their equipment. Although ODOT had conducted a similar evaluation in 1997, vendors claimed that improved technology had solved past problems. The evaluation included an assessment of the machines' performance in a survey of pavement condition, road roughness and the ODOT video log program.
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Because the video log and the road roughness inventories had been already automated (although not combined), the main focus of the evaluation was on the pavement condition rating. Several test sections on the state highway system were selected, including both asphalt and concrete pavements in various stages of wear. A standard value for the condition of these sections was established by a conventional "walk and look" survey by experienced ODOT pavement condition. A comparison was made between the crews' ratings, those of the automated equipment, and the "ground truth" established by ODOT staff. The analysis of ratings showed that those of the rating crews were closer to the ground truth than the automated equipment ratings were.
The Effect of Crack Motion During Epoxy Crack Injection and Curing
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One strategy to regain structural integrity of cracked reinforced concrete bridge deck girders is to inject the cracks with epoxy. Many bridge owners allow all traffic to use the bridge during injection and curing, while other bridge owners restrict traffic to produce a hold time in which cracks do not open and close. This research study used a laboratory set up to determine the effect of temperature and hold time on epoxy undergoing curing. The comparative measure was the tensile strength of the epoxy after curing. The results showed that traffic should be restricted to stop the crack motion during injection and until the epoxy sets. After the epoxy has set, crack motion while the epoxy undergoes full cure degrades the tensile strength of the epoxy, but not to levels that would affect the structural integrity of the beam.
Intermittent Application of Cathodic Protection - Interim Report
Oregon’s coastal highway includes over 120 bridges, most of which are reinforced concrete (RC) bridges. Over 40,000 m2 (430,566 ft2) of bridge surface has been repaired and protected from further corrosion damage using thermal-sprayed (TS) zinc anodes in impressed current and sacrificial cathodic protection (CP) systems. In addition, thermal-sprayed titanium, conductive carbon paint, and zinc-hydrogel anodes are being evaluated in demonstration projects on coastal RC bridges.
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Field and laboratory studies were conducted to evaluate commercial corrosion rate monitoring devices (CRMDs) suitable for use in intermittent CP (ICP) field operation on Oregon's coastal RC bridges. These studies showed that there was good agreement between mass loss and linear polarization resistance (LPR) measurement of rebar corrosion rates when the Stearn-Geary constant B was estimated using harmonic distortion analysis (HDA). There was good agreement between laboratory LPR corrosion rate measurements for rebar in concrete and measurements made using three commercial CRMDs (Gamry RPX1 LPR, SmartCET LPR, and SmartCET HDA). Since ICP operation uses depolarization and protection current measurements to monitor the CP system performance, it is necessary to install the CP system with conductive coating anodes isolated from the rebar. The studies showed TS zinc anode CP systems on RC bridges exhibit long-term increases in CP system circuit resistance and decreases in anode bond strength that would benefit from the application of ICP. However, there was no evidence that TS titanium and carbon paint ICCP anodes or zinc hydrogel SACP anodes would benefit from the application of ICP.
A two year field study is recommended for an Oregon coastal RC bridge with multiple TS zinc anode CP zones to assess the effectiveness of ICP compared to present Oregon DOT CP practices for protecting coastal bridges from corrosion damage. Four ICP test zones are proposed along with two impressed current CP (ICCP) control zones. The four zones include: (1) current-interrupt ICCP, (2) corrosion-rate controlled ICCP, (3) constant-voltage CP, and (4) sacrificial CP.
Methods for Detecting Defects in Composite Rehabilitated Concrete Structures
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Fiber reinforced polymer (FRP) composites are increasingly being used to rehabilitate understrength or deteriorating concrete structural elements and to prolong useful service-life of bridge structures. The rehabilitation is conducted through the external bonding of FRP strips onto the concrete substrate using either the wet layup process or the adhesive bonding of prefabricated strips. While the method has been shown to be extremely effective, there is a need for the development of expertise relating to identification of defects during inspection. This report addresses four specific aspects of defect identification: (1) identification of the types of defects in composite strengthened concrete structural elements; (2) determination of the potential effect of selected defects on the performance and integrity of the structural system; (3) identification of state-of-the-art quality assurance and non-destructive evaluation (NDE) technologies that can be used for detecting defects; and (4) preliminary investigation of selected technologies that have a high likelihood of being successfully used for purposes of quality assurance. Potential defects are identified, classified by type and stage at which they could occur, and their effects are listed. Criticality of selected defect types is assessed using an experimental fracture mechanics based approach. The range of NDE techniques identified is assessed based on pertinent characteristics required for inspection in the field, and the techniques are classified based on applicability. Two techniques – thermography (representative of a non-contact local technique) and vibration based modal analysis coupled with a damage detection approach (representative of a global technique) – are explained in more depth with examples of use.
Evaluation of Latex Polymers to Resist Stripping in Asphalt Pavements in Oregon
This study assessed the effectiveness of latex polymer anti-stripping treatment by inspecting and evaluation the condition of pavements constructed in Oregon from 1997-2001. Ten hot mix asphalt concrete paving projects were identified throughout the state. Five of the projects used hydrated lime as an anti-stripping additive, and five used latex polymer (UP-5000) as an anti-stripping additive. Each paving project that used UP-5000 as an anti-stripping additive was compared to a paving project that used hydrated lime as an additive. Both sites being compared shared similar aggregate sources.
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Condition surveys were conducted on all of the sites, and in-service cores were taken from each project. The cores were tested using the AASHTO T283 test method to determine the Tensile Strength Ration (TSR). The TSR and condition ratings were used to assess the effectiveness of the UP-5000 compared to hydrated lime. Based on the condition surveys, and the TSR testing, the UP-5000 was shown to be comparable to hydrated lime in preventing moisture induced distress in hot mix asphalt pavements in Oregon.
Durability of Truncate Dome Warnings on Existing Curb Ramps
In 2002 the Federal Highway Administration (FHWA) notified ODOT that the state was required to use truncated dome detectable warnings on curb ramps. Products appropriate for use on cured concrete surfaces were of particular interest to ODOT. A research project was undertaken to monitor four products that appeared to be best suited from retrofitting existing curb ramps. Over a two-year monitoring period adhesion to the concrete was good, and physical damage was not a problem. Changing color and contrast over the two-year period was an issue, however. Three out of the four products in the study exhibited noticeable color fading, and contrast with the adjacent surfaces decreased in two cases, due to the accumulation of dirt on the truncated dome products.
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Fish Passage Through Retrofitted Culverts
Long term and short term studies of fish movement were conducted at several retrofitted culverts within Oregon. This was done to assess the effectiveness of retrofitting culverts with baffles to improve fish passage. The long term results showed that the baffle equipped culverts do in fact allow fish passage, even though the fish in the study areas did not appear to move a great deal in any part of the study reaches. The short term results indicated a definite improvement in the ability of juvenile steelhead trout to move upstream after the addition of certain baffle configurations. Measurements of hydraulic conditions showed that the baffles do create areas of lower flow velocity, deepen the flow, and create resting pools. These observations indicate that fish can and do move through culverts retrofitted with baffles and that the addition of baffles can improve the ability of juvenile fish (especially steelhead trout) to move upstream through a culvert.
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Assessment Methodology for Diagonally Cracked Reinforced Concrete Deck Girders
This report details the results of a research program conducted to estimate the capacity and remaining life of 1950’s vintage conventionally reinforced concrete deck girder (RCDG) bridges with diagonal cracks. The investigation encompassed field testing, laboratory testing, and analysis to develop a reliability based assessment methodology. Background, findings, and conclusions from each of these components are provided in individual sections of this report. Current limitations are described, including the impact of skew, temperature and shrinkage effects on capacity, as well as serious stem-flange interface cracking. There are also limitations in predicting the capacity of bent caps. Finally, recommendations are made for implementing the assessment methodology.
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GIS Mapping of Environmental Justice Census Characteristics
As an entity utilizing federal funds, ODOT is responsible for successfully integrating environmental justice (EJ) into its program and planning activities. The objective of this project was to assemble a Geographic Information System (GIS) database which identifies census tracts and block groups statewide where low-income and minority populations reside. In addition to minority and poverty status, the other census characteristics that have been used by various jurisdictions to describe EJ communities include the elderly, linguistically isolated, people dependent on public transportation, and people with go-outside-the-home disabilities. Data from the 2000 Census on these characteristics were also acquired for this mapping project. The primary GIS shapefiles include census tracts and block groups with the EJ characteristic database. Sample maps are included in the report.
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Evaluation of 3M Scotchlite Linear Delineation System
Major construction projects present many hazards for drivers to negotiate. Detours, lane shifts and confusing curves present unique challenges to all drivers. At night, the difficulties in negotiating these obstacles are amplified due to reduced visibility. Over the past several years, the Oregon Department of Transportation has been particularly interested in evaluating concrete barrier marking products the improve the delineation of lane shifts, sharp turns, and detours within highway work zones. This project evaluated the installation, maintenance and effectiveness of the 3M™ Scotchlite™ Linear Delineation System (LDS) mounted on concrete barriers within three different highway work zones.
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The installation of the LDS panels proved to be more challenging then envisioned, primarily because installation is a time intensive process. Users need to be aware of the productivity rates for installation. A maintenance concern with the panels is to keep them relatively clean from dirt and road grime to maintain an optimal level of retroreflectivity.
The LDS panels provide a good alternative to traditional concrete barrier delineation methods (such as reflective barrier markers). At the end of construction, panels can be removed from the barrier and reused on future projects. The success of the panels has led ODOT to consider further implementation on future construction projects, as well as permanent installation in areas where crash histories warrant additional safety measures.
Development and Application of a Statistical Quality Assessment Method for Dense-Graded Mixes
This report describes the development of the statistical quality assessment method and the procedure for mapping the measures obtained from the quality assessment method to a composite pay factor. The application to dense-graded mixes is demonstrated with an example. This report also describes the development of a smoothness specification based on the IRI. A draft smoothness specification is also included in the appendices.
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The research team developed a methodology to measure the quality of dense-graded asphalt mixes based on a statistical function called a loss function. Various formulations of the loss function are routinely used in manufacturing to provide quality control/quality assurance measures. The methodology developed for this project provides a pay incentive to contractors that exceed quality expectations, and a penalty to those who fall short of quality expectations. The methodology encourages contractors to produce asphalt mixes that are consistent with specifications with minimum variability.
Two principal specification-related products were produced. The first product allows ODOT to statistically judge the HMA quality using the loss function. Second, data analyses showed that project smoothness, as measured by IRI, could be incorporated into an ODOT specification, but only in the form of percent improvement in ride over the existing roadway.
Using Archived Data to Measure Operational Benefits of ITS Investments, Volume 2: Region 1 Incident
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The objective of this project is to use the existing data, surveillance and communications infrastructure (to the extent possible) to develop two case study evaluations for Oregon, including an devaluation of the COMET incident management program and the Portland ramp metering system. The COMET evaluation will include a thorough literature review of other incident management program evaluations, as well as a determination of the costs and benefits of the program. Benefits will include reduction in vehicular delay, fuel consumption and emissions due to early incident response, prevention of secondary accidents as well as benefits stemming from public perceptions. To the extent possible, the existing ITS infrastructure, Oregon State Patrol computer aided dispatch database and statewide accident database will be used as data sources to minimize the amount of new data collection required. It is envisioned that one corridor will be selected for a focused analysis, using video surveillance to observe actual incident durations and COMET response times. The ramp metering system case study will select a corridor ( e.g. 1-205) where "before" and "after" data are available. The intent will be to measure savings in delay, emissions and fuel consumption and safety improvements due to the implementation of the ramp metering system. Existing data sources are the ITS infrastructure and the statewide accident database, thus no dedicated data collection program is necessary. These two case studies will set a precedent for future evaluations of ITS programs. The evaluations are immediately feasible using existing data sources.
Using Archived Data to Measure Operational Benefits of ITS Investments, Volume 1: Ramp Meters
The objective of this project is to use the existing data, surveillance and communications infrastructure (to the extent possible) to develop two case study evaluations for Oregon, including an devaluation of the COMET incident management program and the Portland ramp metering system. The COMET evaluation will include a thorough literature review of other incident management program evaluations, as well as a determination of the costs and benefits of the program. Benefits will include reduction in vehicular delay, fuel consumption and emissions due to early incident response, prevention of secondary accidents as well as benefits stemming from public perceptions. The extent possible, the existing ITS infrastructure, Oregon State Patrol computer aided dispatch database and statewide accident database will be used as data sources to minimize the amount of new data collection required. It is envisioned that one corridor will be selected for a focused analysis, using video surveillance to observe actual incident durations and COMET response times. The ramp metering system case study will select a corridor ( e.g. 1-205) where "before" and "after" data are available. The intent will be to measure savings in delay, emissions and fuel consumption and safety improvements due to the implementation of the ramp metering system. Existing data sources are the ITS infrastructure and the statewide accident database, thus no dedicated data collection program is necessary. These two case studies will set a precedent for future evaluations of ITS programs. The evaluations are immediately feasible using existing data sources.
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Remaining Life of Reinforced Concrete Beams with Diagonal-Tension Cracks
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This report concerns the initial efforts of a research study investigating the remaining capacity and life of cast-in-place reinforced concrete deck-girder (RCDG) bridges with diagonal tension cracks. A database of 442 bridges constructed from 1947 to 1962 was developed to identify salient parameters related to bridges with diagonal tension cracks in the Oregon Department of Transportation bridge inventory. The database was queried to provide summary details for individual parameters and relationships between parameters. In additional, a bridge analysis was conducted on an in-service RCDG bridge with diagonal tension cracks. A linear finite element model of the bridge provided reasonable prediction of cracking.