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Publication Anchorage of Carbon Fiber Reinforced Polymers to Reinforced Concrete in Shear Applications(2008) Niemitz, Carl WWithin the past few decades a new technology has emerged using Fiber Reinforced Polymers (FRP) to rehabilitate and retrofit reinforced concrete (RC) structures. In FRP shear strengthening applications it is largely recognized that debonding is the prevailing failure mode. FRP debonding typically occurs prematurely as a brittle failure mode that limits the efficiency of the strengthening technique. No systematic tests have been conducted to investigate the capacity gained by anchoring FRP laminates to RC elements in shear applications. The objective of this research program was to study the effects of anchoring FRP laminates to RC members with FRP anchors thereby delaying or potentially eliminating debonding of FRP sheets from the concrete surface. FRP anchors used in this research were made from fibers used as part of FRP sheets that get bundled into a roll with a fanned upper end of the anchor allowing the fibers to be splayed over the FRP sheet. A single shear pull test experiment was developed to study the effects of anchoring FRP laminates using FRP anchors with varying anchor diameters, lengths, and patterning. The results of the experimental portion of this research project were used in combination with finite element analyses to develop models for anchored FRP sheets that can be used in design of shear strengthening applications.Publication Evaluating At-Grade Rail Crossing Safety along the Knowledge Corridor in Massachusetts(2013) Horan, Timothy PHighway-rail grade crossings are safer than ever, but collisions between motor vehicles and trains persist. Some collisions could be prevented by actively maintaining such grade crossings, yet many at-grade rail crossings are only evaluated following collisions. Those crossings that experience no collisions may go decades without being inspected. In recent years, the Congress has allocated funds for a national High-Speed Intercity Passenger Rail program, and it is in the public’s interest for state road/highway agencies to inspect all highway-rail crossings in high-speed rail corridors to ensure that the warning systems in place are commensurate with the crossings’ needs. The objectives of this research are to a) determine the adequacy of traffic control devices at highway-rail grade crossings along the restored Vermonter tracks in Massachusetts; and b) to recommend crossings for closure and/or grade separation if it is determined that the traffic control devices are inadequate at an intersection. The major findings of this paper are that a majority of the at-grade rail crossings need some improvements to be in compliance with MUTCD standards. Additionally, four at-grade crossings are identified for closure, grade-separation, and/or additional traffic control devices beyond MUTCD standards.Publication Spatial and Temporal Correlations of Freeway Link Speeds: An Empirical Study(2012-09) Rachtan, Piotr JCongestion on roadways and high level of uncertainty of traffic conditions are major considerations for trip planning. The purpose of this research is to investigate the characteristics and patterns of spatial and temporal correlations and also to detect other variables that affect correlation in a freeway setting. 5-minute speed aggregates from the Performance Measurement System (PeMS) database are obtained for two directions of an urban freeway – I-10 between Santa Monica and Los Angeles, California. Observations are for all non-holiday weekdays between January 1st and June 30th, 2010. Other variables include traffic flow, ramp locations, number of lanes and the level of congestion at each detector station. A weighted least squares multilinear regression model is fitted to the data; the dependent variable is Fisher Z transform of correlation coefficient. Estimated coefficients of the general regression model indicate that increasing spatial and temporal distances reduces correlations. The positive parameters of spatial and temporal distance interaction term show that the reduction rate diminishes with spatial or temporal distance. Higher congestion tends to retain higher expected value of correlation; corrections to the model due to variations in road geometry tend to be minor. The general model provides a framework for building a family of more responsive and better-fitting models for a 6.5 mile segment of the freeway during three times of day: morning, midday, and afternoon. Each model is cross-validated on two locations: the opposite direction of the freeway, and a different location on the direction used for estimation. Cross-validation results show that models are able to retain 75% or more of their original predictive capability on independent samples. Incorporation of predictor variables that describe road geometry and traffic conditions into the model works beneficially in capturing a significant portion of variance of the response. The developed regression models are thus transferrable and are apt to predict correlation on other freeway locations.Publication Publication Evaluating and Modeling Traveler Response to Real-Time Information in the Pioneer Valley(2012-05) De Ruiter, TylerThis study used focus groups and surveys to provide a comprehensive evaluation of the Regional Traveler Information Center (RTIC) at UMass Amherst. The evaluation was completed by obtaining the awareness, usage, and perceived effectiveness of RTIC’s information by residents in the Pioneer Valley. It was found that awareness of RTIC is limited due to its lack of advertisement. Usage is focused primarily on its webcams and advisory information. Surveys showed that participants perceive RTIC to be useful, even though they may never have seen the information before (the survey provided a chance for them to become familiar with the service). Revealed preference data were collected regarding the travelers' most memorable instances where real-time traffic information was provided. A binary logit model of a traveler's switch decision (route, departure time, mode, destination, trip cancellation, or combinations of them) with real-time traffic information was specified and estimated. It was found that travelers have an increasing tendency to switch away from the original option when the resulting delay caused by congestion increases. Receiving congestion and crash information also provided a tendency to take an alternative travel method. It was found that males tend to switch more often than females, and young individuals switch less often.Publication Automated Enforcement Using Dedicated Short Range Communication(2012-05) Kim, GilbertThis thesis presents a set of system algorithms and a feasibility analysis of an automated enforcement system that uses dedicated short-range communication with an emphasis on seatbelt and speed enforcement. The current seatbelt and speed enforcement limitations and disadvantages can be overcome because future vehicles will be equipped with devices that can be used to communicate with other vehicles or the traffic infrastructure. One limitation of the current seatbelt enforcement system is that it relies only on human vision. Today’s automated photo speed enforcement also has the following major limitations and disadvantages: fixed position enforcement, system installation and maintenance costs, enforcement based only on spot speed, sensitivity to lighting conditions, and vulnerability to sprays and obstructions that might block the license plates. This thesis proposes an automated enforcement system that uses wireless communication (IEEE 802.11p protocol), which can resolve all of the above-mentioned problems and is also more efficient, accurate, and cost effective.Publication Driver Dynamics and the Longitudinal Control Model(2012) Leiner, Gabriel G.Driver psychology is one of the most difficult phenomena to model in the realm of traffic flow theory because mathematics often cannot capture the human factors involved with driving a car. Over the past several decades, many models have attempted to model driver aggressiveness with varied results. The recently proposed Longitudinal Control Model (LCM) makes such an attempt, and this paper offers evidence of the LCM's usefulness in modeling road dynamics by analyzing deceleration rates that are commonly associated with various levels of aggression displayed by drivers. The paper is roughly divided into three sections, one outlining the LCM's ability to quantify forces between passive and aggressive drivers on a microscopic level, one describing the LCM's ability to measure aggressiveness of platoons of drivers, and the last explaining the meaning of the model’s derivative. The paper references some attempts to capture driver aggressiveness made by classic car-following models, and endeavors to offer some new ideas in study of driver characteristics and traffic flow theory.Publication Using Micro-Simulation Modeling to Evaluate Transit Signal Priority in Small-to-Medium Sized Urban Areas; Comparative Review of Vissim and S-Paramics Burlington, Vermont Case Study(2012-02) Tyros, Joseph CWith many advances in transportation technology, micro-simulation models have proven to be a useful tool in transportation engineering alternative analyses. Micro-simulation software packages can be used to quickly and efficiently design new transportation infrastructure and strategies, while helping transportation planners and traffic engineers identify possible problems that might arise in a particular design alternative. Over the years these simulation packages have become more advanced, and their capabilities in terms of modeling complex, intricate intersections and producing useful outputs for analysis have increased. Today’s simulations can reproduce many facets of transportation design alternatives while generating outputs that help increase efficiency, reduce cost, optimize financing, and improve safety. Recently micro-simulation models have been employed in the analysis and design of alternative transit signal priority (TSP) strategies. This research reviews the similarities, differences and functional capabilities of two micro-simulation software packages: 1) VISSIM, and 2) S-Paramics. A special effort is made to discuss the usefulness of each package when used to analyze TSP alternatives for small and medium sized urban areas, where data and staff availability are typically limited. The paper includes a case study of Burlington, Vermont in which each software package is employed to evaluate several alternative TSP strategies. Each package is evaluated in terms of ease of use, usefulness of outputs, and consistency of results. The results of the evaluation are intended to guide planners and traffic engineers in small and medium urban areas in the selection of an appropriate simulation package for TSP analysis and design.Publication A Quantitative Analysis of the Impacts from Selected Climate Variables Upon Traffic Safety in Massachusetts(2012) Hecimovic, Katrina M.Current literature predicts that climate change may increase both the occurrence and severity of heavy rainfall events and winter precipitation in the Northeast United States. A potential increase in intense precipitation events related to climate change would theoretically also cause an increase in weather-related delays, increase in overall traffic disruptions, a substantive shift in travel behavior, and presumably a negative effect on safety and maintenance operations of highways. This current research study examines the existing impacts from both an operational and behavioral perspective of how weather events currently impact overall safety along routes in Massachusetts. A secondary objective of the research effort is to evaluate the extent to which this information is captured on the crash report form for subsequent use in safety analyses. Utilizing data from Massachusetts Department of Transportation, National Climatic Data Center (NCDC) and the University of Massachusetts Data Warehouse, crash statistics were examined during varied levels of weather events and compared with non-weather conditions. In addition, crash report forms were analyzed in comparison to NCDC weather data to determine the correlation between of the weather specific fields of the reports and to help determine if crashes were weather-related. The results from the investigation show how the character of precipitation events impact traffic safety including both occurrence and intensity levels and in conjunction with existing weather predictions the relationships developed in this study are useful in evaluating how changes in extreme precipitation events projected for the Northeast may impact drivers’ safety in the future.Publication Development of Anchorage System for Frp Strengthening Applications Using Integrated Frp Composite Anchors(2011-09) Mcguirk, Geoffrey NOver the past three decades the use of externally bonded fiber reinforced polymer (FRP) materials for structural strengthening applications has become an accepted and widely used method. A primary concern of FRP structural strengthening systems is that the FRP often debonds from the concrete well before the load capacity of the FRP material is reached. In addition, debonding failures are often brittle and occur with little warning. Past research concluded that fastening FRP sheets with FRP anchors is an effective method for delaying or preventing debonding failures. However, there is a clear lack of research pertaining to fastening FRP sheets with FRP anchors, and a corresponding lack of design guidance. The primary objective of this research program was to better understand the behavior of bonded FRP sheets that are secured with FRP anchors to aid in future development of design recommendations of this anchorage system. This thesis deals with carbon fiber unidirectional sheets applied using the wet layup system. Design parameters that were investigated include: manufacturer of the FRP materials, unanchored and anchored sheets, number of anchor rows and spacing between rows, number of sheet plies (single or double), and length of bonded sheet behind the anchors. A total of sixteen specimens were tested. Experimental results show that FRP anchorage systems are very effective in increasing load capacity by delaying debonding. Finite element models were also developed of anchored and unanchored bonded FRP sheets.Publication Safety and Operational Assessment of Gap Acceptance Through Large-Scale Field Evaluation(2011) Tupper, Steven MaxwellGiven that “driver error” is cited as a contributing factor in 93 percent of all crashes, understanding driver behavior is an essential element in mitigating the crash problem. Among the more dangerous roadway elements are unsignalized intersections where drivers’ gap acceptance behavior is strongly correlated to the operational and safety performance of the intersection. While a basic understanding of drivers’ gap acceptance behavior exists, several unanswered questions remain. Previous work has attempted to address some of these questions, however to date the research has been somewhat limited in scope and scale due to the challenges of collecting high fidelity gap acceptance data in the field. This research initiative utilized software newly developed for this project to collect gap acceptance data on 2,767 drivers at 60 sites, totaling 10,419 driver decisions and 22,639 gaps in traffic. This large-scale data collection effort allowed many of these remaining questions to be answered with an improved degree of certainty. This research initiative showed that naturalistic driver gap acceptance behavior can realistically be observed and accurately recorded in the field in real time using a newly developed software tool. This software tool and study methodology was validation using high fidelity video reduction techniques. This research compared different methods of analyzing gap acceptance data, in particular determining critical gap, seeing that the method used significantly affects the results. Conclusions were draw about the merits of each of the ten analysis methods considered. Through the analysis of the large data set collected, the research determined that there exist appreciable and identifiable differences in gap acceptance behavior across drivers under varied conditions. The greatest differences were seen in relationship to wait time and queue presence. If a driver has queued vehicles waiting behind them and/or has been waiting to turn for a long period of time, they will be more likely to accept a smaller gap in traffic. Additionally, an analysis of gap acceptance as it relates to crash experience identified critical situations where a driver's gap acceptance behavior contributes to the occurrence of a crash. Characteristics of the driver such as gender and approximate age associated with specific crashes were examined. Teen drivers were identified as exhibiting aggressive gap acceptance behavior and were found to be overrepresented in gap acceptance related crashes. Ultimately, a better understanding of the driver and environmental factors that significantly contribute to increased crash risk will help guide the way to targeted design solutions.Publication Evaluating Alternative Toll-Based Financing Approaches: A Case Study of the Boston Metropolitan Area(2011-05) Berliner, Rosaria MThe current condition of the nation’s transportation system is of great concern to State Departments of Transportation. Currently, funds in many state transportation budgets are depleting. Nowadays, State DOT officials together with researchers are exploring various transportation financing approaches and they are considering the utility, merits, challenges, and impacts of these approaches. A major financing approach being considered relies on the collection of tolls on existing toll roads and on roads on which tolls are not presently collected. Recent technology advancements in Open Road Tolling and All-Electronic Tolling have provided State DOTs with the opportunity to consider expanding the use of toll revenue to finance transportation investments. These two types of tolling technologies appeal to motorists by allowing them to maintain their current highway speed while going through a toll plaza. In addition, many State DOT officials now view toll based approaches as viable “user fee” based strategies together with other alternative approaches such as the fuel tax and sales tax. Central to this research is a case study of the Boston Metropolitan area. The case study includes the formulation and preliminary evaluation of toll based financing approaches potentially suitable for consideration in Massachusetts. The approaches include increases to existing tolls and placing tolls on selected roadways not currently tolled. The evaluation includes estimates of changes in demand and anticipated revenues associated with these toll based approaches. It is expected that the results of this research will be of interest to State DOT officials in Massachusetts and other states.Publication Analysis of Measurement Errors Influence on the Quantitative and Qualitative Results of Car-Following Model Calibration(2011-02) Maslova, Mariya AIn the past two decades there has been a significant increase in using real-traffic data for car-following models calibration. The most widely used way of microscopic trajectory data collection utilizes digital cameras for recording the video of vehicles on the road and subsequent digital image processing to extract vehicle trajectory data. Unfortunately, this method of data collection is not perfect and obtained trajectories contain multiple forms of errors and noise due to both method of data collection and the algorithms used for processing digital data. Such data, however, is widely used in the transportation community for developing and calibrating various models. Some researchers use data post-processing prior to calibration to address the problem noisy while others do not. From this arises a question of measurement errors influence on the quality of results of calibration using real-traffic data. The objective of this study is to compare quantitative results of calibration of two car-following models performed using raw data versus post-processed data, and provide recommendations on post-processing data prior to calibration. Calibration of two car-following models is first performed on the raw data and then on several datasets that filtering techniques had been applied to in order to reduce measurement errors. Two smoothing methods utilized in this study include moving average with a Gaussian kernel and exponential moving average; data frequency reduction is also considered as an alternative. Calibration is performed for Tampere model (stimulus-response model) and Gibbs model (belongs to safe-distance models). The study examines and compares the results of calibration using raw and filtered data; the recommendation is made to perform post-processing of the raw data prior to using the data for calibration procedures.Publication Route Choice Behavior in a Driving Simulator With Real-time Information(2010-09) Tian, HengliangThis research studies travelers' route choice behavior in a driving simulator with real-time information en-route. We investigate whether travelers plan strategically for real-time information en-route or simply select a fixed path from origin to destination at the beginning of a trip, and whether network complexity and a parallel driving task affect subjects' strategic thinking ability. In this study, strategic thinking refers to a traveler's route choice decision taking into account future diversion possibilities downstream enabled by information at the diversion node. All of the subjects in this study participated in driving-simulator-based tests while half of the subjects participated in additional PC-based tests. Three types of maps were used. The first type required a one-time choice at the beginning of a trip to test the traveler's risk attitude. The other two types offered route choices both at the beginning of and during a trip to test the traveler's strategic thinking. The study shows that a significant portion of route choice decisions are strategic in a realistic driving simulator environment. Furthermore, different network complexities impose different cognitive demands on a subject and affect his/her strategic thinking ability. A subject tends to be more strategic in a simple network. Lastly, a parallel driving task does not significantly affect a subject's strategic thinking ability. This seemingly counterintuitive conclusion might be caused by the simplicity of the tested network.Publication Investigation of the Behavior of Open Cell Aluminum Foam(2010-05) Veale, Patrick JThe study investigates the behavior open cell aluminum foam in scenarios applicable to potential use in structural applications. Behavior was examined through mechanical testing, computer modeling and analytic expressions. Existing assumptions about the foam characteristics that define the elastic properties were expanded to include contributions of axial and shear deformations in addition to bending and were rewritten in terms of the axial and bending stiffness ratios of ligaments. Compressive and tensile tests were performed to gain a measure of the elastic properties of the foam as well as the behavior and failure mechanisms in both loading conditions. The materials used in testing were manufactured and supplied by ERG Duocel with defined porosities of 20 and 40 ppi and relative density of 6-8%. Fatigue tests were performed on open cell foam samples to determine the strain to fatigue life relationship for the material at high applied strain amplitudes. Finally, finite element models were created in ADINA for both ordered and random networks. The changes in elastic properties due to relative density, defined by ligament geometry, cell anisotropy and joint connectivity were measured for ordered networks, while irregular, random networks were used to investigate the forces developed within ligaments. Conclusions from this study provide insight on the behavior of open cell foam and promote further research in an effort to determine the viability of structural use of the material.Publication Route Choice Behavior in Risky Networks with Real-Time Information(2010) Razo, Michael DThis research investigates route choice behavior in networks with risky travel times and real-time information. A stated preference survey is conducted in which subjects use a PC-based interactive maps to choose routes link-by-link in various scenarios. The scenarios include two types of maps: the first presenting a choice between one stochastic route and one deterministic route, and the second with real-time information and an available detour. The first type measures the basic risk attitude of the subject. The second type allows for strategic planning, and measures the effect of this opportunity on subjects' choice behavior. Results from each subject are analyzed to determine whether subjects planned strategically for the en route information or simply selected fixed paths from origin to destination. The full data set is used to estimate route choice models that account for both risk attitude and strategic thinking. Estimation results are used to assess whether models that incorporate strategic behavior more accurately reflect route choice than do simpler path-based models.Publication A Quantitative Analysis of the Impacts from Selected Variables Upon Safety Belt Usage in Massachusetts(2010) Gregorio, Samuel WSafety belts are the most effective safety device in vehicles in terms of preventing injuries (1). Every year, safety belt usage data across the nation is collected by the individual states, the District of Columbia, and U.S. territories in a probability-based observational survey. Using this survey, Massachusetts, a secondary seat belt law state, ranked last in safety belt usage in 2008. This percentage was approximately a 2 percent decrease from 2007. This value was not an aberration as within the recent past, Massachusetts, a secondary safety belt law state, has consistently ranked at or near the bottom of the 50 states. The foremost issue with safety belt usage is the inherent disregard of the safety related benefits for both drivers and passengers, alike. While there is a significant amount of literature documenting the safety related benefits, there is still a need for continued study of the persistent attributes that are associated with those vehicle occupants who make the decision to not buckle up. The scope of this research encompasses the use of the collected data in the 2009 Massachusetts Safety Belt Usage Observation Study to determine what demographic variables; such as age, gender, race, occupant location, community median income, community population density, community education level, and combined demographics, are at high and low ends of the safety belt usage spectrum. Using this data, along with Massachusetts safety belt usage data from the immediate past observational studies, usage based on these and additional demographic information was quantified and analyzed. An outcome of this research was to identify specific strategies, such as increased education and concentrated enforcement, aimed at increasing safety belt usage amidst those targeted subsections of the population that are not buckling up.Publication Analytical Modeling of Tree Vibration Generated during Cutting Process(2009) Karvanirabori, PaymanThere are several ways to cut down a tree. The piece by piece cutting method is studied in this research. By modeling the cutting process into simple dynamic models and obtaining governing equations of motion of tree and cut piece in each model, the forces during cutting process were calculated. The method was then applied to a set of real data and tree vibrations were compared with field measurements. The study is very rare in the case of the variety of the topics it covers from dynamics and mechanics to finite element modeling of a biological system.Publication Computer-Assisted Emergency Evacuation Planning Using TransCAD: Case Studies in Western Massachusetts(2009) Andrews, Steven PDisasters, ranging from manmade events to natural occurrences, can happen anywhere on the planet, and their consequences can range from economic loss to catastrophic loss of life. Determining how the transportation system fares in the face of these disasters is important so that proper planning can take place before, rather than after, an event has happened. Modeling the transportation system gives operators the ability to discover bottlenecks, to determine the possible benefit of using lane reversals, and to find out the influence of evacuation speed on system efficiency. Models have already been created that are able to model some of these types of disasters with some level of accuracy. These models range from microscopic simulation to regional, macroscopic models. This research examines how an off-the-shelf regional modeling software package, TransCAD, can be used to model emergency evacuations. More specifically, this thesis presents four case studies involving three different types of disasters in Western Massachusetts. Because this research documents a first-hand experience using TransCAD in emergency evacuation planning, the results give regional modelers the ability to modify their models to fit their specific region. These case studies demonstrate how the modified inputs and existing portions of the four-step transportation planning model can be used in place of the usual data demands of the software. Dynamic traffic assignment is used in three of the case studies while the fourth case study uses static traffic assignment. An evaluation of the software package along with lessons learned is provided to measure the performance of the software.Publication Optimal Adaptive Departure Time Choices with Real-Time Traveler Information Considering Arrival Reliability(2009) Lu, XuanWhen faced with an uncertain network, travelers adjust departure time as well as route choices in response to real-time traveler information. Previous studies on algorithm design focus on adaptive route choices and cannot model adaptive departure time choices (DTC). In this thesis, the optimal adaptive departure time and route choice problem in a stochastic time-dependent network is studied. Travelers are assumed to minimize expected generalized cost which is the sum of expected travel cost and arrival delay costs. The uncertain network is modeled by jointly distributed random travel time variables for all links at all time periods. Real-time traveler information reveals realized link travel times and thus reduces uncertainties in the network. The adaptive departure time and route choice process is conceptualized as a routing policy, defined as a decision rule that specifies what node to take next at each decision node based on realized link travel times and the current time. Waiting at origin nodes is allowed to model DTCs that are dependent on traveler information. Departure time is a random variable rather than fixed as in previous studies. A new concept of action time is introduced, which is the time-of-day when a traveler starts the DTC decision process. Because of the efforts involved in processing information and making decisions, a cost could be associated with a departure made after the action time. An algorithm is designed to compute the minimum expected generalized cost routing policy and the corresponding optimal action time, from all origins to a destination for a given desired arrival time window. Computational tests are carried out on a hypothetical network and randomly generated networks. It is shown that adaptive DTCs lead to less expected generalized cost than fixed DTCs do. The benefit of adaptive DTC is larger when the variance of the travel time increases. The departure time distribution is more concentrated with a larger unit cost of departure delay. A wider arrival time window leads to a more dispersed departure time distribution, when there is no departure penalty.
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