Search

Search Results

• 261. [Article] Consistent Estimation of Route Choice Models for Dynamic Transit Assignment

  Dynamic transit assignment models have the potential to improve local transportation agencies’ capability to forecast the demand for public transit facilities under conditions of limited capacity or varying ...

  Citation × Citation Citation Abstract Copy Title: Consistent Estimation of Route Choice Models for Dynamic Transit Assignment Author: Hood, Jeff Year: 2016 Dynamic transit assignment models have the potential to improve local transportation agencies’ capability to forecast the demand for public transit facilities under conditions of limited capacity or varying reliability. In order to be useful in practice, the simulated route choices of passengers in these models need to reflect the behavior of actual residents observed in local travel surveys. Most analysis methods of revealed route choice preferences developed to date have either (1) not been proven to provide consistent estimates or (2) required an untenable computation time for practical applications. Furthermore, no model of transit route choice has accounted for variability in both passenger behavior and vehicle arrivals. This seminar will focus on an econometric framework that Hood Transportation Consulting designed to overcome these limitations in partnership with the second FHWA Strategic Highway Research Program, the Metropolitan Transportation Commission of the San Francisco Bay Area, the San Francisco County Transportation Authority, and the Puget Sound Regional Council. The framework is based on a recursive logit model where the traveler makes a series of dynamic choices which maximize the conditional expected utility of travel to the destination, given the sequence of vehicles which have already arrived. The model also contains new size variables to correct for the correlations caused by route overlap. Application of the new correction formulas to illustrative examples demonstrates that predictions with the model more closely match theoretically correct results than existing methods. Title: Consistent Estimation of Route Choice Models for Dynamic Transit Assignment Author: Hood, Jeff Year: 2016 Dynamic transit assignment models have the potential to improve local transportation agencies’ capability to forecast the demand for public transit facilities under conditions of limited capacity or varying reliability. In order to be useful in practice, the simulated route choices of passengers in these models need to reflect the behavior of actual residents observed in local travel surveys. Most analysis methods of revealed route choice preferences developed to date have either (1) not been proven to provide consistent estimates or (2) required an untenable computation time for practical applications. Furthermore, no model of transit route choice has accounted for variability in both passenger behavior and vehicle arrivals. This seminar will focus on an econometric framework that Hood Transportation Consulting designed to overcome these limitations in partnership with the second FHWA Strategic Highway Research Program, the Metropolitan Transportation Commission of the San Francisco Bay Area, the San Francisco County Transportation Authority, and the Puget Sound Regional Council. The framework is based on a recursive logit model where the traveler makes a series of dynamic choices which maximize the conditional expected utility of travel to the destination, given the sequence of vehicles which have already arrived. The model also contains new size variables to correct for the correlations caused by route overlap. Application of the new correction formulas to illustrative examples demonstrates that predictions with the model more closely match theoretically correct results than existing methods. Close

• 262. [Article] Evaluation of Transportation Microenvironments Through Assessment of Cyclysts' Exposure to Traffic-Related Particulate Matter

  It is well established that vehicles powered by carbon-based fuels (e.g. gasoline, diesel) have a negative impact on air quality, especially in urban centers. Traditionally, air quality conformity studies ...

  Citation × Citation Citation Abstract Copy Title: Evaluation of Transportation Microenvironments Through Assessment of Cyclysts' Exposure to Traffic-Related Particulate Matter Author: George, Linda A., Figliozzi, Miguel A., Monsere, Christopher M., Kendrick, Christine M., Bigazzi, Alexander Y, Moore, Adam Year: 2011 It is well established that vehicles powered by carbon-based fuels (e.g. gasoline, diesel) have a negative impact on air quality, especially in urban centers. Traditionally, air quality conformity studies analyze the macroenvironmental impact of transportation corridors, as they relate to regional air quality management concerns. Urban residents spend a considerable amount of outdoor time in transportation microenvironments as pedestrians, bicycle commuters, people waiting to use public transport, residents and workers situated along roadways, and commuters within vehicles. An emerging area of research has shown that human health impacts within transport microenvironments can be considerable, but have not been well-characterized. As urban public policies increasingly encourage the use of multi-mode commuting in dense urban centers, decisionmakers need reliable modeling tools to predict and mitigate the health consequences of vehicle-related emissions in transportation microenvironments. This project proposes unique integration of real-time multi-modal personal exposure monitoring with real-time detailed traffic monitoring in order to develop a computer model that links traffic characteristics, emissions, built environment configuration, mode of travel and health impacts. Existing emission and dispersion models do not take direct account of the dynamic nature of traffic and how emissions impact the health of the diversity of urban dwellers, bus commuters, pedestrians, and bicycle riders. Typical approaches use highly aggregated vehicle data and computed link speeds to assign an emission factor to the traffic, an assumed proportion of which is trucks. In addition, existing methods to assess environmental impacts tend to focus on the production source of the pollutant not the impacts, which require information on population activities and its proximity to vehicle flows. Personal exposure studies document significant air quality impacts within the transportation microenvironment but do not integrate dynamic traffic and emission analysis. Previous research argues for a comprehensive approach. From the perspective of mitigating transportation impacts, it is significant to understand: a) exposure to the pollution, which in turn requires assessment of where people are in relation to the source of the pollutant, and b) the relation between pollution and vehicle flows. This research will target highly polluted high exposure hotspots in Portland, e.g. high traffic flows running through a major trip destination area for shopping, entertainment, education, or health care highly dependent on mode of travel, traffic levels and type, and built environment characteristics. Our approach is to conduct field studies to measure personal exposure to particulate matter as a function of transportation mode through pre-determined routes in the city. Exposure levels, position, time and rate of travel will be recorded. Simultaneously we will collect detailed traffic data that will provide type/number of vehicle, speed of travel and start/stop behavior. GIS analysis of the urban form and land use characteristics will establish built environment parameters. These data will be integrated into a built environment-travel mode-exposure model. The major scientific innovations offered by this project are: 1) integration of detailed and real-time exposure/emissions with a real-time traffic measurement approach, and 2) development of an integrated emissions and transportation model that combines traffic characteristics, emissions, built environment configuration, mode of travel and predicted health impacts. The outcomes of the research will be of importance to the general public, urban communities, departments of transportation charged with managing urban traffic, and public health authorities. Title: Evaluation of Transportation Microenvironments Through Assessment of Cyclysts' Exposure to Traffic-Related Particulate Matter Author: George, Linda A., Figliozzi, Miguel A., Monsere, Christopher M., Kendrick, Christine M., Bigazzi, Alexander Y, Moore, Adam Year: 2011 It is well established that vehicles powered by carbon-based fuels (e.g. gasoline, diesel) have a negative impact on air quality, especially in urban centers. Traditionally, air quality conformity studies analyze the macroenvironmental impact of transportation corridors, as they relate to regional air quality management concerns. Urban residents spend a considerable amount of outdoor time in transportation microenvironments as pedestrians, bicycle commuters, people waiting to use public transport, residents and workers situated along roadways, and commuters within vehicles. An emerging area of research has shown that human health impacts within transport microenvironments can be considerable, but have not been well-characterized. As urban public policies increasingly encourage the use of multi-mode commuting in dense urban centers, decisionmakers need reliable modeling tools to predict and mitigate the health consequences of vehicle-related emissions in transportation microenvironments. This project proposes unique integration of real-time multi-modal personal exposure monitoring with real-time detailed traffic monitoring in order to develop a computer model that links traffic characteristics, emissions, built environment configuration, mode of travel and health impacts. Existing emission and dispersion models do not take direct account of the dynamic nature of traffic and how emissions impact the health of the diversity of urban dwellers, bus commuters, pedestrians, and bicycle riders. Typical approaches use highly aggregated vehicle data and computed link speeds to assign an emission factor to the traffic, an assumed proportion of which is trucks. In addition, existing methods to assess environmental impacts tend to focus on the production source of the pollutant not the impacts, which require information on population activities and its proximity to vehicle flows. Personal exposure studies document significant air quality impacts within the transportation microenvironment but do not integrate dynamic traffic and emission analysis. Previous research argues for a comprehensive approach. From the perspective of mitigating transportation impacts, it is significant to understand: a) exposure to the pollution, which in turn requires assessment of where people are in relation to the source of the pollutant, and b) the relation between pollution and vehicle flows. This research will target highly polluted high exposure hotspots in Portland, e.g. high traffic flows running through a major trip destination area for shopping, entertainment, education, or health care highly dependent on mode of travel, traffic levels and type, and built environment characteristics. Our approach is to conduct field studies to measure personal exposure to particulate matter as a function of transportation mode through pre-determined routes in the city. Exposure levels, position, time and rate of travel will be recorded. Simultaneously we will collect detailed traffic data that will provide type/number of vehicle, speed of travel and start/stop behavior. GIS analysis of the urban form and land use characteristics will establish built environment parameters. These data will be integrated into a built environment-travel mode-exposure model. The major scientific innovations offered by this project are: 1) integration of detailed and real-time exposure/emissions with a real-time traffic measurement approach, and 2) development of an integrated emissions and transportation model that combines traffic characteristics, emissions, built environment configuration, mode of travel and predicted health impacts. The outcomes of the research will be of importance to the general public, urban communities, departments of transportation charged with managing urban traffic, and public health authorities. Close

• 263. [Article] Factors Affecting Behavioral Changes in Response to Road Fees: Some Analyses of the Effect of Attitudes, Transit Access, and Fuel Efficiency on Changes in Miles Driven

  Objective The Oregon Department of Transportation conducted a test of an innovative technology to replace fuel taxes with mileage fees. In the test, some vehicles were charged a flat fee per mile and others ...

  Citation × Citation Citation Abstract Copy Title: Factors Affecting Behavioral Changes in Response to Road Fees: Some Analyses of the Effect of Attitudes, Transit Access, and Fuel Efficiency on Changes in Miles Driven Author: Rufolo, Anthony M. Year: 2009 Objective The Oregon Department of Transportation conducted a test of an innovative technology to replace fuel taxes with mileage fees. In the test, some vehicles were charged a flat fee per mile and others were charged differential fees that were higher for travel in the Portland metropolitan area during weekday peak hours and lower for other travel. I was charged with developing the database for the project and analyzing the behavioral responses of the participants. The database is quite extensive, including responses to three surveys as well as information on mileage in various categories. The experiment ended on April 1, 2007 and the final report on the project is due June 30, 2007. This is also the time when funding for the project will end. The final report will include information on key behavioral changes, such as the reduction in miles traveled per day during the peak for the congestion charge group. However, the database has the potential for much more extensive analysis. In addition, a different type of congestion charging experiment was conducted by the Puget Sound Regional Council, and a public use dataset from that experiment is expected to become available within the next six months. The objective of this proposal is to extend the analysis of changes in behavior by subjects in the ODOT Road User Fee Pilot Project, and to draw on other sources, such as the Puget Sound project, to compare the behavioral changes observed in this experiment with those found in other contexts. Scope A substantial amount of data was collected on participants in the Oregon Road User Fee Pilot Project. Basic analysis of the data is being conducted as part of the project. However, there is potential to gain further information on characteristics that caused or prevented changes in participants’ driving patterns. For example, participants were asked the distance from their home to the nearest transit stop, but that was the only information on transit service that was available for analysis. It would be possible to use the participant’s address to generate much more comprehensive measures of transit service availability to determine whether these other dimensions of transit service affected the response to road pricing. In addition, information on day of week and morning versus evening peak travel is being aggregated for the existing study, but this data holds the potential for further information on the nature of the responses. Methodology A variety of statistical analyses will be conducted to evaluate both the extent of response to a vehicle mileage fee and the interaction with both demographic and attitudinal characteristics of the participants. A GIS analysis will be used to link household location with better measures of transit service. Results Results would include a better understanding of how pricing interacts with other factors in affecting driving patterns and in particular in affecting driving during peak periods. It would also provide a better understanding of the revenue potential from such charges. Title: Factors Affecting Behavioral Changes in Response to Road Fees: Some Analyses of the Effect of Attitudes, Transit Access, and Fuel Efficiency on Changes in Miles Driven Author: Rufolo, Anthony M. Year: 2009 Objective The Oregon Department of Transportation conducted a test of an innovative technology to replace fuel taxes with mileage fees. In the test, some vehicles were charged a flat fee per mile and others were charged differential fees that were higher for travel in the Portland metropolitan area during weekday peak hours and lower for other travel. I was charged with developing the database for the project and analyzing the behavioral responses of the participants. The database is quite extensive, including responses to three surveys as well as information on mileage in various categories. The experiment ended on April 1, 2007 and the final report on the project is due June 30, 2007. This is also the time when funding for the project will end. The final report will include information on key behavioral changes, such as the reduction in miles traveled per day during the peak for the congestion charge group. However, the database has the potential for much more extensive analysis. In addition, a different type of congestion charging experiment was conducted by the Puget Sound Regional Council, and a public use dataset from that experiment is expected to become available within the next six months. The objective of this proposal is to extend the analysis of changes in behavior by subjects in the ODOT Road User Fee Pilot Project, and to draw on other sources, such as the Puget Sound project, to compare the behavioral changes observed in this experiment with those found in other contexts. Scope A substantial amount of data was collected on participants in the Oregon Road User Fee Pilot Project. Basic analysis of the data is being conducted as part of the project. However, there is potential to gain further information on characteristics that caused or prevented changes in participants’ driving patterns. For example, participants were asked the distance from their home to the nearest transit stop, but that was the only information on transit service that was available for analysis. It would be possible to use the participant’s address to generate much more comprehensive measures of transit service availability to determine whether these other dimensions of transit service affected the response to road pricing. In addition, information on day of week and morning versus evening peak travel is being aggregated for the existing study, but this data holds the potential for further information on the nature of the responses. Methodology A variety of statistical analyses will be conducted to evaluate both the extent of response to a vehicle mileage fee and the interaction with both demographic and attitudinal characteristics of the participants. A GIS analysis will be used to link household location with better measures of transit service. Results Results would include a better understanding of how pricing interacts with other factors in affecting driving patterns and in particular in affecting driving during peak periods. It would also provide a better understanding of the revenue potential from such charges. Close

• 264. [Article] Commute-Friendly, Gas-Electric Hybrid Vehicle Testing

  Overview: Green Lite Motors is a Portland-based company building a hybrid commuter vehicle targeted for urban and suburban areas. The vehicle is a front/back, two-seat configuration with three wheels (two ...

  Citation × Citation Citation Abstract Copy Title: Commute-Friendly, Gas-Electric Hybrid Vehicle Testing Author: Long, James, Currin, Hugh, Wang, Xin Year: 2013 Overview: Green Lite Motors is a Portland-based company building a hybrid commuter vehicle targeted for urban and suburban areas. The vehicle is a front/back, two-seat configuration with three wheels (two front and one rear-drive wheel). The vehicle is classed as a motorcycle, giving it all the advantages of a smaller footprint in parking and highway travel; however, the advanced roll-cage design and fairing give the vehicle safety and comfort advantages of a standard passenger car. The unique combination of internal combustion engine and electric motor give the vehicle mileage possibilities greater than 100 mpg as well as the convenience and advantages of a plug-in hybrid. The current vehicle has been developed with a gas-electric hybrid drive system as result of a prior Oregon BEST Commercialization Grant. The coverage of the OTREC grant effort relates to the dynamometer and highway testing for verification of mechanical operation, computer hardware and software integration, and control algorithm operational efficiency as well as implementation of resulting modifications related to initial system issues. Mechanical System: The mechanical system involves the testing of the hybrid interface system proving seamless utilization and control of the internal combustion engine and electric motor. The configuration will be analyzed and tests will be designed for validation and verification of mechanical system integrity. Embedded Control System Objective: The embedded control system consists of a real-time computer system tasked with calculation and application throttle control to the internal combustion engine and electric motor. The control system acquires real-time data from the internal combustion engine propulsion system, the electric motor propulsion system, and the vehicle user. From this input, both propulsion systems will be digitally controlled with the goal of optimizing power plant operation to get the most efficient use of the provided energy stores for moving the vehicle at the users desired performance levels. This system must be exhaustively tested for fault conditions and commissioned for optimal operation. Integrated System: The vehicle will be dynamometer tested as a fully functional system. Different driving scenarios will be tested for vehicle performance, handling, and control system behavior. Mileage factors will be derived with a goal of 100 mpg under normal operation. Title: Commute-Friendly, Gas-Electric Hybrid Vehicle Testing Author: Long, James, Currin, Hugh, Wang, Xin Year: 2013 Overview: Green Lite Motors is a Portland-based company building a hybrid commuter vehicle targeted for urban and suburban areas. The vehicle is a front/back, two-seat configuration with three wheels (two front and one rear-drive wheel). The vehicle is classed as a motorcycle, giving it all the advantages of a smaller footprint in parking and highway travel; however, the advanced roll-cage design and fairing give the vehicle safety and comfort advantages of a standard passenger car. The unique combination of internal combustion engine and electric motor give the vehicle mileage possibilities greater than 100 mpg as well as the convenience and advantages of a plug-in hybrid. The current vehicle has been developed with a gas-electric hybrid drive system as result of a prior Oregon BEST Commercialization Grant. The coverage of the OTREC grant effort relates to the dynamometer and highway testing for verification of mechanical operation, computer hardware and software integration, and control algorithm operational efficiency as well as implementation of resulting modifications related to initial system issues. Mechanical System: The mechanical system involves the testing of the hybrid interface system proving seamless utilization and control of the internal combustion engine and electric motor. The configuration will be analyzed and tests will be designed for validation and verification of mechanical system integrity. Embedded Control System Objective: The embedded control system consists of a real-time computer system tasked with calculation and application throttle control to the internal combustion engine and electric motor. The control system acquires real-time data from the internal combustion engine propulsion system, the electric motor propulsion system, and the vehicle user. From this input, both propulsion systems will be digitally controlled with the goal of optimizing power plant operation to get the most efficient use of the provided energy stores for moving the vehicle at the users desired performance levels. This system must be exhaustively tested for fault conditions and commissioned for optimal operation. Integrated System: The vehicle will be dynamometer tested as a fully functional system. Different driving scenarios will be tested for vehicle performance, handling, and control system behavior. Mileage factors will be derived with a goal of 100 mpg under normal operation. Close

• 265. [Article] Combined Traction and Energy Recovery Motor for Electric Vehicles

  Electric vehicle manufacturers are looking for ways to optimize energy use for vehicle range extension and reduction of battery capacity. Electric motors have lower efficiencies at very low speed and high ...

  Citation × Citation Citation Abstract Copy Title: Combined Traction and Energy Recovery Motor for Electric Vehicles Author: Long, James, Wang, Xin, Kansaku, Claude, Moravec, Brian Year: 2014 Electric vehicle manufacturers are looking for ways to optimize energy use for vehicle range extension and reduction of battery capacity. Electric motors have lower efficiencies at very low speed and high torque. This is typically at vehicle launch from standstill, at very low speeds, and during energy regeneration at lower speeds and approaching standstill. The KersTech solution is a breakthrough technology allowing supplement of the electric drive with a hydraulic drive, active in lower speeds ranges, dropping out as the electric motor takes over in its higher efficiency range of operation. The report consists of four parts. Part I presents novel the hybrid vehicle simulations in MATLAB. Both the Diesel-Hydraulic Hybrid Vehicle and Electric-Hydraulic Hybrid Vehicle have been simulated and compared in this report. Part II deals with the electrical system control design. Permanent magnet synchronous motors have been widely used in hybrid electric vehicle applications. Permanent magnet synchronous motors have a small size, high efficiency and high performance. This report presents a mathematical model of permanent magnet synchronous motor. Power switching electronics are used to generate the desired voltage/current from DC source. A pulse width modulation technique controls the switching power electronic by creating a control signals which are applied to their gates. The whole circuit of the inverter based on space vector pulse width modulation is simulated in MATLAB/Simulink and its results are presented. Field-oriented control is implemented via digital signal processors to control the permanent magnet synchronous motor. Clarke and Park transformations are applied to “abc" coordinate frame of the permanent magnet synchronous motor model to get the “qd" coordinate frame used in the field oriented control technique. Hence, the developed torque and the magnetizing the flux component are controlled separately. PI controller is used to control the motor speed and torque. PI controllers are designed using frequency response method and a symmetric optimum method. The whole system is simulated based on the mathematical model of PMSM and field oriented control method with designed PI controllers. Simulation results show the PMSM to have perfect dynamic response. A digital signal processor can be used to implement the field oriented control algorithms and compute the parameters in real time. Implementation of field oriented control of a permanent magnet synchronous motor shows that the motor has satisfactory response in terms of torque ripple and speed response. Nonlinear control, including Sliding Mode Controller and State Dependent Linear Matrix Inequality Controller, are also proposed as a powerful control technique to govern the speed of the permanent magnet synchronous motor in hybrid vehicle applications. In Part III, we discuss the hydraulic system design. Finally, in Part IV, the dSPACE hardware controller is used for the overall control system design. Title: Combined Traction and Energy Recovery Motor for Electric Vehicles Author: Long, James, Wang, Xin, Kansaku, Claude, Moravec, Brian Year: 2014 Electric vehicle manufacturers are looking for ways to optimize energy use for vehicle range extension and reduction of battery capacity. Electric motors have lower efficiencies at very low speed and high torque. This is typically at vehicle launch from standstill, at very low speeds, and during energy regeneration at lower speeds and approaching standstill. The KersTech solution is a breakthrough technology allowing supplement of the electric drive with a hydraulic drive, active in lower speeds ranges, dropping out as the electric motor takes over in its higher efficiency range of operation. The report consists of four parts. Part I presents novel the hybrid vehicle simulations in MATLAB. Both the Diesel-Hydraulic Hybrid Vehicle and Electric-Hydraulic Hybrid Vehicle have been simulated and compared in this report. Part II deals with the electrical system control design. Permanent magnet synchronous motors have been widely used in hybrid electric vehicle applications. Permanent magnet synchronous motors have a small size, high efficiency and high performance. This report presents a mathematical model of permanent magnet synchronous motor. Power switching electronics are used to generate the desired voltage/current from DC source. A pulse width modulation technique controls the switching power electronic by creating a control signals which are applied to their gates. The whole circuit of the inverter based on space vector pulse width modulation is simulated in MATLAB/Simulink and its results are presented. Field-oriented control is implemented via digital signal processors to control the permanent magnet synchronous motor. Clarke and Park transformations are applied to “abc" coordinate frame of the permanent magnet synchronous motor model to get the “qd" coordinate frame used in the field oriented control technique. Hence, the developed torque and the magnetizing the flux component are controlled separately. PI controller is used to control the motor speed and torque. PI controllers are designed using frequency response method and a symmetric optimum method. The whole system is simulated based on the mathematical model of PMSM and field oriented control method with designed PI controllers. Simulation results show the PMSM to have perfect dynamic response. A digital signal processor can be used to implement the field oriented control algorithms and compute the parameters in real time. Implementation of field oriented control of a permanent magnet synchronous motor shows that the motor has satisfactory response in terms of torque ripple and speed response. Nonlinear control, including Sliding Mode Controller and State Dependent Linear Matrix Inequality Controller, are also proposed as a powerful control technique to govern the speed of the permanent magnet synchronous motor in hybrid vehicle applications. In Part III, we discuss the hydraulic system design. Finally, in Part IV, the dSPACE hardware controller is used for the overall control system design. Close

• 266. [Article] Freight Distribution Problems in Congested Urban Areas: Fast and Effective Solution Procedures to Time-Dependent Vehicle Routing Problems

  Congestion is a common phenomenon in all medium to large cities of the world. Reliability of freight movement in urban areas is an important issue to manufacturing or service companies whose operation ...

  Citation × Citation Citation Abstract Copy Title: Freight Distribution Problems in Congested Urban Areas: Fast and Effective Solution Procedures to Time-Dependent Vehicle Routing Problems Author: Figliozzi, Miguel A. Year: 2011 Congestion is a common phenomenon in all medium to large cities of the world. Reliability of freight movement in urban areas is an important issue to manufacturing or service companies whose operation is based in just-in-time approaches. These companies tend to provide high value or time sensitive products/services. As congestion increases, carriers face increasing challenges to satisfy their time sensitive customers in an economical way. Route designs or schedules which require long computation times or ignore travel time variations will result in inefficient and suboptimal solutions. Poorly designed routes that lead freight vehicles into congested arteries and streets not only increases supply chain and logistics costs but also exacerbate externalities associated with freight traffic in urban areas such as greenhouse gases, air pollution, noise, and accidents. Whilst it is rarely possible to entirely avoid the impacts of congestion, it is feasible to schedule operations so that the effects of congestion are minimized. Better scheduling can be effectively supported by the advent of inexpensive and ubiquitous Information and Communication Technologies (ICT). The use of mobile phone technology and on-board routing devices allows fluid communication between truck drivers and fleet operators in real-time. In such a real time operation it becomes possible to dynamically reassign vehicles, including modifying the order in which customers are served and diverting a vehicle already en-route to service another customer. However, without fast routing methods that can take advantage of real time congestion information carriers cannot reap the benefits of real-time information. From the operational point of view, congestion creates a substantial variation in travel times during peak morning and evening hours. This is problematic for all vehicle routing models which rely on a constant value to represent vehicle speeds. And while the ubiquitous availability of real time traffic information allows drivers to reactively alter routes and customer service sequences to better cope with congestion, static routing models are unable to take advantage of these advances in real-time information provision in order to proactively find adequate routing solutions. In addition, changes in travel time caused by congestion cannot be accurately represented in static models. Research in time-dependent vehicle routing problem is comparatively meager and current solution methods are inadequate for practical carrier operations which need to provide fast solutions for medium to large instances. Even faster solution methods are essential to take advantage of real time information. The major aim of this proposal is to develop and evaluate new methods for vehicle routing in congested urban areas. The emphasis will be placed on improving the running time of the existing methods. Title: Freight Distribution Problems in Congested Urban Areas: Fast and Effective Solution Procedures to Time-Dependent Vehicle Routing Problems Author: Figliozzi, Miguel A. Year: 2011 Congestion is a common phenomenon in all medium to large cities of the world. Reliability of freight movement in urban areas is an important issue to manufacturing or service companies whose operation is based in just-in-time approaches. These companies tend to provide high value or time sensitive products/services. As congestion increases, carriers face increasing challenges to satisfy their time sensitive customers in an economical way. Route designs or schedules which require long computation times or ignore travel time variations will result in inefficient and suboptimal solutions. Poorly designed routes that lead freight vehicles into congested arteries and streets not only increases supply chain and logistics costs but also exacerbate externalities associated with freight traffic in urban areas such as greenhouse gases, air pollution, noise, and accidents. Whilst it is rarely possible to entirely avoid the impacts of congestion, it is feasible to schedule operations so that the effects of congestion are minimized. Better scheduling can be effectively supported by the advent of inexpensive and ubiquitous Information and Communication Technologies (ICT). The use of mobile phone technology and on-board routing devices allows fluid communication between truck drivers and fleet operators in real-time. In such a real time operation it becomes possible to dynamically reassign vehicles, including modifying the order in which customers are served and diverting a vehicle already en-route to service another customer. However, without fast routing methods that can take advantage of real time congestion information carriers cannot reap the benefits of real-time information. From the operational point of view, congestion creates a substantial variation in travel times during peak morning and evening hours. This is problematic for all vehicle routing models which rely on a constant value to represent vehicle speeds. And while the ubiquitous availability of real time traffic information allows drivers to reactively alter routes and customer service sequences to better cope with congestion, static routing models are unable to take advantage of these advances in real-time information provision in order to proactively find adequate routing solutions. In addition, changes in travel time caused by congestion cannot be accurately represented in static models. Research in time-dependent vehicle routing problem is comparatively meager and current solution methods are inadequate for practical carrier operations which need to provide fast solutions for medium to large instances. Even faster solution methods are essential to take advantage of real time information. The major aim of this proposal is to develop and evaluate new methods for vehicle routing in congested urban areas. The emphasis will be placed on improving the running time of the existing methods. Close

• 267. [Article] Analyses of Bus Travel Time Reliability and Transit Signal Priority at the Stop-To-Stop Segment Level

  Transit travel time is affected by many factors including traffic signals and traffic condition. Transit agencies have implemented strategies such as transit signal priority (TSP) to reduce transit travel ...

  Citation × Citation Citation Abstract Copy Title: Analyses of Bus Travel Time Reliability and Transit Signal Priority at the Stop-To-Stop Segment Level Author: Feng, Wei Year: 2014 Transit travel time is affected by many factors including traffic signals and traffic condition. Transit agencies have implemented strategies such as transit signal priority (TSP) to reduce transit travel time and improve service reliability. However, due to the lack of empirical data, the joint impact of these factors and improvement strategies on bus travel time has not been studied at the stop-to-stop segment level. This study utilizes and integrates three databases available along an urban arterial corridor in Portland, Oregon. Data sources include stop-level bus automatic vehicle location (AVL) and automatic passenger count (APC) data provided by the Tri-County Metropolitan Transportation District of Oregon (TriMet), the Sydney Coordinated Adaptive Traffic System (SCATS) signal phase log data, and intersection vehicle count data provided by the City of Portland. Based on the unique collection and integration of these fine granularity empirical data, this research utilizes multiple linear regression models to understand and quantify the joint impact of intersection signal delay, traffic conditions and bus stop location on bus travel time and its variability at stop-to-stop segments. Results indicate that intersection signal delay is the key factor that affects bus travel time variability. The amount of signal delay is nearly linearly associated with intersection red phase duration. Results show that the effect of traffic conditions (volumes) on bus travel time varies significantly by intersection and time of day. This study also proposed new and useful performance measures for evaluating the effectiveness of TSP systems. Relationships between TSP requests (when buses are late) and TSP phases were studied by comparing TSP phase start and end times with bus arrival times at intersections. Results show that green extension phases were rarely used by buses that requested TSP and that most green extension phases were granted too late. Early green effectiveness (percent of effective early green phases) is much higher than green extension effectiveness. The estimated average bus and passenger time savings from an early green phase are also greater compared to the average time savings from a green extension phase. On average, the estimated delay for vehicles on the side street due to a TSP phase is less than the time saved for buses and automobiles on the major street. Results from this study can be used to inform cities and transit agencies on how to improve transit operations. Developing appropriate strategies, such as adjusting bus stop consolidation near intersections and optimizing bus operating schedules according to intersection signal timing characteristics, can further reduce bus travel time delay and improve TSP effectiveness. Title: Analyses of Bus Travel Time Reliability and Transit Signal Priority at the Stop-To-Stop Segment Level Author: Feng, Wei Year: 2014 Transit travel time is affected by many factors including traffic signals and traffic condition. Transit agencies have implemented strategies such as transit signal priority (TSP) to reduce transit travel time and improve service reliability. However, due to the lack of empirical data, the joint impact of these factors and improvement strategies on bus travel time has not been studied at the stop-to-stop segment level. This study utilizes and integrates three databases available along an urban arterial corridor in Portland, Oregon. Data sources include stop-level bus automatic vehicle location (AVL) and automatic passenger count (APC) data provided by the Tri-County Metropolitan Transportation District of Oregon (TriMet), the Sydney Coordinated Adaptive Traffic System (SCATS) signal phase log data, and intersection vehicle count data provided by the City of Portland. Based on the unique collection and integration of these fine granularity empirical data, this research utilizes multiple linear regression models to understand and quantify the joint impact of intersection signal delay, traffic conditions and bus stop location on bus travel time and its variability at stop-to-stop segments. Results indicate that intersection signal delay is the key factor that affects bus travel time variability. The amount of signal delay is nearly linearly associated with intersection red phase duration. Results show that the effect of traffic conditions (volumes) on bus travel time varies significantly by intersection and time of day. This study also proposed new and useful performance measures for evaluating the effectiveness of TSP systems. Relationships between TSP requests (when buses are late) and TSP phases were studied by comparing TSP phase start and end times with bus arrival times at intersections. Results show that green extension phases were rarely used by buses that requested TSP and that most green extension phases were granted too late. Early green effectiveness (percent of effective early green phases) is much higher than green extension effectiveness. The estimated average bus and passenger time savings from an early green phase are also greater compared to the average time savings from a green extension phase. On average, the estimated delay for vehicles on the side street due to a TSP phase is less than the time saved for buses and automobiles on the major street. Results from this study can be used to inform cities and transit agencies on how to improve transit operations. Developing appropriate strategies, such as adjusting bus stop consolidation near intersections and optimizing bus operating schedules according to intersection signal timing characteristics, can further reduce bus travel time delay and improve TSP effectiveness. Close

• 268. [Article] Travel Mode Choice Framework Incorporating Realistic Bike and Walk Routes

  For a number of reasons--congestion, public health, greenhouse gas emissions, energy use, demographic shifts, and community livability to name a few--the importance of walking and bicycling as transportation ...

  Citation × Citation Citation Abstract Copy Title: Travel Mode Choice Framework Incorporating Realistic Bike and Walk Routes Author: Broach, Joseph Paul Year: 2016 For a number of reasons--congestion, public health, greenhouse gas emissions, energy use, demographic shifts, and community livability to name a few--the importance of walking and bicycling as transportation options will only continue to increase. Currently, policy interest and infrastructure funding for nonmotorized modes far outstrip our ability to model bike and walk travel. To ensure scarce resources are used most effectively, accurate models sensitive to key policy variables are needed to support long-range planning and project evaluation, and to continue adding to our growing understanding of key factors driving walk and bike behavior. This research attempts to synthesize and advance the state of the art in trip-based, nonmotorized mode choice modeling. Over the past fifteen years, efforts to model the decision to walk or bike on a given trip have been hampered by the lack of a comprehensive behavioral framework and inconsistency in measurement scales and model specification. This project develops a mode choice behavioral framework that acknowledges the importance of attributes along the specific walk and bike routes that travelers are likely to consider, in addition to more traditional area-based measures of travel environments. The proposed framework is applied to a revealed preference, GPS-based travel dataset collected from 2010-2013 in Portland, Oregon. Measurement of nonmotorized trip distance, built environment, tour-level variables, and attitudinal attributes as well as mode availability are explicitly addressed. Route and mode choice models are specified using discrete choice techniques, and predicted walking and bicycling routes are tested as inputs to various mode choice models. Results suggest strong potential for predicted route measures to enhance walk and bicycle mode choice modeling. Findings also support the specific notion that bicycle and pedestrian infrastructure contribute not only to route choice but also to the choice of whether to bike or walk. For decisions to bicycle, availability of low-traffic routes may be particularly important to women. Model results further indicate that land use and built environments around trip ends and a person’s home still have important effects on nonmotorized travel when controlling for route quality. Both route and area travel environment impacts are mostly robust to the inclusion of residential self-selection variables, consistent with the idea that built environment differences matter even for households that choose to live in a walkable or bikeable neighborhood. The combination of area and route-based built environment measures alongside trip context, sociodemographic, and attitudinal attributes provides a new perspective on nonmotorized travel behavior relevant to both policy and practice. Title: Travel Mode Choice Framework Incorporating Realistic Bike and Walk Routes Author: Broach, Joseph Paul Year: 2016 For a number of reasons--congestion, public health, greenhouse gas emissions, energy use, demographic shifts, and community livability to name a few--the importance of walking and bicycling as transportation options will only continue to increase. Currently, policy interest and infrastructure funding for nonmotorized modes far outstrip our ability to model bike and walk travel. To ensure scarce resources are used most effectively, accurate models sensitive to key policy variables are needed to support long-range planning and project evaluation, and to continue adding to our growing understanding of key factors driving walk and bike behavior. This research attempts to synthesize and advance the state of the art in trip-based, nonmotorized mode choice modeling. Over the past fifteen years, efforts to model the decision to walk or bike on a given trip have been hampered by the lack of a comprehensive behavioral framework and inconsistency in measurement scales and model specification. This project develops a mode choice behavioral framework that acknowledges the importance of attributes along the specific walk and bike routes that travelers are likely to consider, in addition to more traditional area-based measures of travel environments. The proposed framework is applied to a revealed preference, GPS-based travel dataset collected from 2010-2013 in Portland, Oregon. Measurement of nonmotorized trip distance, built environment, tour-level variables, and attitudinal attributes as well as mode availability are explicitly addressed. Route and mode choice models are specified using discrete choice techniques, and predicted walking and bicycling routes are tested as inputs to various mode choice models. Results suggest strong potential for predicted route measures to enhance walk and bicycle mode choice modeling. Findings also support the specific notion that bicycle and pedestrian infrastructure contribute not only to route choice but also to the choice of whether to bike or walk. For decisions to bicycle, availability of low-traffic routes may be particularly important to women. Model results further indicate that land use and built environments around trip ends and a person’s home still have important effects on nonmotorized travel when controlling for route quality. Both route and area travel environment impacts are mostly robust to the inclusion of residential self-selection variables, consistent with the idea that built environment differences matter even for households that choose to live in a walkable or bikeable neighborhood. The combination of area and route-based built environment measures alongside trip context, sociodemographic, and attitudinal attributes provides a new perspective on nonmotorized travel behavior relevant to both policy and practice. Close

• 269. [Article] Cyclist Path Choices Through Shared Space Intersections in England

  In the last several years, there has been growing worldwide interest in making streets safer for all users--pedestrians, cyclists, and motorists. One approach, shared space, is a traffic calming technique ...

  Citation × Citation Citation Abstract Copy Title: Cyclist Path Choices Through Shared Space Intersections in England Author: Duncan, Allison Boyce Year: 2016 In the last several years, there has been growing worldwide interest in making streets safer for all users--pedestrians, cyclists, and motorists. One approach, shared space, is a traffic calming technique as well as urban design concept. This technique strives to fully integrate the roadway into the urban fabric by removing elements such as lane markings, curbs, and traffic signs. By removing these elements and creating a more plaza-like space, these sites become ambiguous and no user group as priority. The technique is relatively new, and the majority of existing research concerns pedestrians only. This mixed methods research focused on six intersections in England with the goal of understanding how bicycle riders perceive and travel through shared space intersections. Using video observations of the six sites in three cities, three shared and three control, this project analyzed the variations in the paths cyclists rode through the intersections. Data were collected on several variables related to both the cyclists and their interactions with the site itself such as helmet use and riding through crosswalks. Path analysis required the development a new evaluative variable in order to compare individual paths by how much deviation there was in each path ridden as compared to other cyclists. Site-specific surveys addressed the perceptions, bicycling experience, demographics, and path and route preferences by cyclists at both shared space and control intersections. The analysis indicated that cyclists rode similarly through both shared and control intersections, and that a large percentage of riders preferred to ride farther from motor vehicles when given the space to do so. This project offered further insight in how to best design shared space projects for nonmotorized users by looking at the spatial layout and the elements that most influenced a rider’s path choice. Results indicated that, in these cases, shared space was not the panacea for nonmotorized users as some literature suggests, but nonetheless appeared to be a valid form of traffic calming. This research offered further insight in how to best design shared space projects for nonmotorized users by looking at the spatial layout and the elements that most influenced a rider’s path choice. Title: Cyclist Path Choices Through Shared Space Intersections in England Author: Duncan, Allison Boyce Year: 2016 In the last several years, there has been growing worldwide interest in making streets safer for all users--pedestrians, cyclists, and motorists. One approach, shared space, is a traffic calming technique as well as urban design concept. This technique strives to fully integrate the roadway into the urban fabric by removing elements such as lane markings, curbs, and traffic signs. By removing these elements and creating a more plaza-like space, these sites become ambiguous and no user group as priority. The technique is relatively new, and the majority of existing research concerns pedestrians only. This mixed methods research focused on six intersections in England with the goal of understanding how bicycle riders perceive and travel through shared space intersections. Using video observations of the six sites in three cities, three shared and three control, this project analyzed the variations in the paths cyclists rode through the intersections. Data were collected on several variables related to both the cyclists and their interactions with the site itself such as helmet use and riding through crosswalks. Path analysis required the development a new evaluative variable in order to compare individual paths by how much deviation there was in each path ridden as compared to other cyclists. Site-specific surveys addressed the perceptions, bicycling experience, demographics, and path and route preferences by cyclists at both shared space and control intersections. The analysis indicated that cyclists rode similarly through both shared and control intersections, and that a large percentage of riders preferred to ride farther from motor vehicles when given the space to do so. This project offered further insight in how to best design shared space projects for nonmotorized users by looking at the spatial layout and the elements that most influenced a rider’s path choice. Results indicated that, in these cases, shared space was not the panacea for nonmotorized users as some literature suggests, but nonetheless appeared to be a valid form of traffic calming. This research offered further insight in how to best design shared space projects for nonmotorized users by looking at the spatial layout and the elements that most influenced a rider’s path choice. Close

• 270. [Article] Assessing Transit Fare Equity in Utah Using a Geographic Information System

  The goal of this study is to develop and apply a new method for assessing social equity impacts of distance-based public transit fares. Shifting to a distance-based fare structure can disproportionately ...

  Citation × Citation Citation Abstract Copy Title: Assessing Transit Fare Equity in Utah Using a Geographic Information System Author: Farber, Steven, Batholomew, Keith, Li, Xiao, Paez, Antonio, Nurul Habib, Khandker M. Year: 2014 The goal of this study is to develop and apply a new method for assessing social equity impacts of distance-based public transit fares. Shifting to a distance-based fare structure can disproportionately favor or penalize different subgroups of a population based on variations in settlement patterns, travel needs, and most importantly, transit use. According to federal law, such disparities must be evaluated by the transit agency, but the area-based techniques identified by the Federal Transit Authority for assessing discrimination fail to account for disparities in distances travelled by transit users. This means that transit agencies currently lack guidelines for assessing the social equity impacts of replacing flat fare with distance-based fare structures. Our solution is to incorporate a joint ordinal-continuous model of trip generation and distance travelled into a GIS Decision Support System. The system enables a transit planner to visualize and compare estimated distances travelled and transit-cost maps for different population profiles and fare structures. We apply the method to a case study in the Wasatch Front, Utah, where the Utah Transit Authority is exploring a switch to a distance-based fare structure. The analysis reveals that overall distance-based fares benefit low-income, elderly, and non-white populations. However, the effect is geographically uneven, and may be negative for members of these groups living on the urban fringe. The research discusses a potential conflict between policies designed to promote equity and those intended to increase discretionary ridership. For example, increasing fares for longdistance discretionary riders travelling from suburban light-rail stations to the central business district may have a negative impact on ridership, despite being economically more efficient through cost-recapturing. At the same time, reducing fares for short-distance trips that are currently too expensive compared to private automobile travel may attract new riders. A full cost-benefit analysis sensitive to heterogeneous price elasticity is recommended for future research. It is also noted that the research findings are dependent on the current spatial distributions of population segments and travel patterns. The equity benefits of distance-based fares are primarily derived from residential clustering of low-income and minority groups in more compact urban areas near the center of the city. Demographic trends, such as inner-city gentrification and suburban aging-in-place, may impose increased travel demands on low income and elderly riders, nullifying future equity gains made by a transition to distance-based fares. Title: Assessing Transit Fare Equity in Utah Using a Geographic Information System Author: Farber, Steven, Batholomew, Keith, Li, Xiao, Paez, Antonio, Nurul Habib, Khandker M. Year: 2014 The goal of this study is to develop and apply a new method for assessing social equity impacts of distance-based public transit fares. Shifting to a distance-based fare structure can disproportionately favor or penalize different subgroups of a population based on variations in settlement patterns, travel needs, and most importantly, transit use. According to federal law, such disparities must be evaluated by the transit agency, but the area-based techniques identified by the Federal Transit Authority for assessing discrimination fail to account for disparities in distances travelled by transit users. This means that transit agencies currently lack guidelines for assessing the social equity impacts of replacing flat fare with distance-based fare structures. Our solution is to incorporate a joint ordinal-continuous model of trip generation and distance travelled into a GIS Decision Support System. The system enables a transit planner to visualize and compare estimated distances travelled and transit-cost maps for different population profiles and fare structures. We apply the method to a case study in the Wasatch Front, Utah, where the Utah Transit Authority is exploring a switch to a distance-based fare structure. The analysis reveals that overall distance-based fares benefit low-income, elderly, and non-white populations. However, the effect is geographically uneven, and may be negative for members of these groups living on the urban fringe. The research discusses a potential conflict between policies designed to promote equity and those intended to increase discretionary ridership. For example, increasing fares for longdistance discretionary riders travelling from suburban light-rail stations to the central business district may have a negative impact on ridership, despite being economically more efficient through cost-recapturing. At the same time, reducing fares for short-distance trips that are currently too expensive compared to private automobile travel may attract new riders. A full cost-benefit analysis sensitive to heterogeneous price elasticity is recommended for future research. It is also noted that the research findings are dependent on the current spatial distributions of population segments and travel patterns. The equity benefits of distance-based fares are primarily derived from residential clustering of low-income and minority groups in more compact urban areas near the center of the city. Demographic trends, such as inner-city gentrification and suburban aging-in-place, may impose increased travel demands on low income and elderly riders, nullifying future equity gains made by a transition to distance-based fares. Close