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Operational Guidance for Bicycle-Specific Traffic Signals

Operational Guidance for Bicycle-Specific Traffic Signals in the United States

The research consisted of two phases: 1) a synthesis of practice and 2) and analysis of cyclist performance characteristics. The synthesis of current practice reviewed the literature, current engineering design and operational guidance documents, and surveyed the jurisdictions about their current deployments of bicycle-specific signals. This report summarizes research of cyclist behavior at signalized intersections in Portland, Eugene, Corvallis, Beaverton and Clackamas County, OR. These signals had both bicycle-specific indications and vehicle-only signals. A total of 4,673 cyclists were observed. For each cyclist observed arriving on red, a set of descriptive variables were collected (e.g., age, sex, helmet use, presence of cargo, arrival in group). Time-based event data were collected to establish reaction times, crossing times, waiting time, gap acceptance, and saturation flow rates. Compliance behavior was also established for these cyclists.

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Advanced Traffic Signal Systems

Criteria for the Selection and Application of Advanced Traffic Signal Systems
 
The Oregon Department of Transportation (ODOT) has recently begun changing their standard traffic signal control systems from the 170 controller running the Wapiti W4IKS firmware to 2070 controllers operating the Northwest Signal Supply Corporation’s Voyage software. Concurrent with this change in standard signal control systems, ODOT has taken the opportunity to install test sites with adaptive signal control systems and evaluate advanced features in the Voyage software.
 
The evaluation of advanced features and adaptive signal control systems has led to a series of questions about how to measure performance, when to apply a given feature, and when should one system be preferred over another. To answer these questions a survey of literature and practicing professionals was conducted to determine the current state of the practice regarding conventional and adaptive signal control systems. The survey of practitioners indicated that practitioners in general were seeking answers regarding when and how to implement adaptive systems. To assist ODOT’s engineers in selecting when and which systems to evaluate more closely, a methodology frame work has been developed and implemented in a Microsoft Excel based evaluation tool. This framework uses queuing models and simplified control logic to estimate corridor performance. Selected additional features have also been enabled to allow engineers to evaluate the performance benefits that may be realized through enabling them with the existing systems.
 
Finally, to compare performance across different systems and different measures of effectiveness, the research team implemented a cost to benefit ratio calculation. This calculation encompasses performance measures produced by the evaluation model as well as external data regarding existing equipment, required upgrades, and additional costs such as those associated with retiming operations. By including as many cost factors as practical, the methodological framework and its Excel-based implementation may offer a means to make the selection of systems to evaluate as simple and straightforward as possible.
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Analysis and Design of Pipe Ramming Installations

Analysis and Design of Pipe Ramming Installations
 
The trenchless technology known as pipe ramming for construction of culverts and buried pipes under roadways or other infrastructure has gained significant popularity due to its cost-effectiveness and ability to alleviate surface disruptions associated with open-cut trenching. Although the experience with pipe ramming is increasing, there has been remarkably little technical guidance available for engineers to appropriately specify aspects of a pipeline or culvert installation, including the planning of feasible layouts, rates of penetration, pipe diameters, and hammers. This research provides a comprehensive engineering framework for evaluation of culvert installations at the planning phase to address the gaps in knowledge associated with pipe ramming.
 
Presently there are no existing and proven techniques for prediction of settlement, vibration, driving stresses, soil resistance to ramming, and drivability for pipe ramming installations. This study has adopted existing drivability, soil resistance, settlement, and vibration prediction models from pipe jacking, microtunneling, and pile driving models and examined their applicability in pipe ramming installations, resulting in new and technology-specific design guidance. The development of this comprehensive engineering guidance is based on engineering calculations empirically tuned using a database of actual performance measurements. Field observations of five productions installations and a full-scale experiment were conducted to form the performance database employed to understand the mechanics associated with pipe ramming installations, ranging from vertical ground movements, ground vibrations, and installation performance.
 
Settlement prediction was evaluated using the inverted normal probability distribution based models, and these methods overestimated the observed settlements close to the center of the pipes and under-estimated settlements at radial distances away from the pipe. A pipe-ramming-specific hyperbolic model was developed for better prediction of the vertical settlement induced by pipe ramming in granular soils. Attenuation of observed pipe ramming-induced vibrations was modeled using a simple semi-empirical approach, and the calibrated model resulted in reasonable predictions of the ground vibrations for granular soils. The static soil resistance to ramming was evaluated using the traditional quasi-static pipe jacking models and the models resulted in inaccurate predictions for instrumented pipe ramming installations. Therefore pipe ramming-specific static soil resistance models were developed for both the face and casing resistance in granular soils. Principles of stress wave theory routinely applied in the drivability analyses for pipe foundations were adopted for the evaluation of the dynamic response of pipes during ramming. Reliable estimates of the static soil resistance and dynamic soil parameters were obtained through signal matching processes. Date-informed drivability analysis were performed to simulate the magnitude of driving stresses and develop drivability curves which relate the penetration resistance of a given pipe and hammer to the range of static soil resistances. The study culminates in the first comprehensive framework and recommendations for the installation of pipes by ramming, and should help owners, consultants, and contractors to appropriately plan pipe ramming installations.
 
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Development of Shrinkage Limits and Testing Protocols

Development of Shrinkage Limits and Testing Protocols for ODOT High Performance Concrete
 
ODOT has observed varying degrees of cracking in their concrete structures. Cracking of high performance reinforced concrete structures, in particular bridge decks, is of paramount concern to ODOT. Cracking at early ages (especially within the first year after placement) results in additional costs and a significant maintenance burden to ODOT. The causes behind cracking in high performance concrete are well known and documented in the existing literature. However, appropriate shrinkage limits and standard laboratory/field tests that allow proper criteria to ensure crack-free or highly cracking-resistant high performance concrete are not clearly established either in the technical literature or in specifications. The purpose of this research was to provide shrinkage threshold limits for specifications and to provide a robust test procedure that allows easy determination of compliance with specified threshold limits. It has been shown that the “restrained ring” tests are the most comprehensive accelerated laboratory tests to accurately identify cracking potential. In addition, acceptable correlation between the ring test and the field test has been observed and documented. However, a simplified yet robust test procedure is in demand from materials suppliers and Departments of Transportation. Analysis of data obtained from this research project showed that the ratio of free shrinkage to shrinkage capacity (theoretical strain related to tensile strength and modulus of elasticity), referred to as a cracking potential indicator (CPI), was a promising assessment of cracking resistant performance. In this way, only the free shrinkage test (ASTM C157) and basic mechanical properties (ASTM C39, C469 and C496) are required to assess cracking risk of candidate high performance concrete mixture designs. This research investigation showed that a CPI less than 3.0 indicated low cracking risk when correlated to standard restrained ring tests. For ODOT HPC concrete bridge deck mixtures, a limit of 450 microstrain for free shrinkage at 28 day from initiation of drying is recommended to achieve satisfactory cracking resistance. Correlation to field experience is also recommended if these recommended thresholds/limits are adopted by ODOT.
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