Evaluation of the Performance of the Sydney Coordinated Adaptive Traffic System (SCATS) on Powell Boulevard in Portland, OR

The Sydney Coordinated Adaptive Traffic System (SCATS) is used to mitigate traffic congestion along urban arterial corridors. Although there has been research on SCATS\u27 performance, this report combines three different areas of research about SCATS that are not known to be represented in any research literature. These include: (a) the relationship between SCATS, traffic volumes, and Transit Signal Priority (TSP); (b) between TSP and traffic conditions; and (c) the correlation between signal timing and air quality; in particular, human exposure to the air pollutant PM2.5 at intersections. In addition, this research looked at the key factors affecting transit user exposure to traffic-related pollutants at bus shelters. All areas of study present the results of statistical tests and regressions to determine SCATS or traffic variables impacts. SCATS did show statistically significant improvements regarding traffic speeds at one minor intersection, even when traffic volumes showed a statistically significant improvement. At a major intersection, results were mixed and not conclusive. Overall, it was determined that the improvements available through SCATS vary depending on the time of day and the direction of travel. TSP was not negatively affected by SCATS. In controlling for both priority and traffic conditions, each were shown to have a distinguished and significant impact on bus travel time. Non-priority signals had a much greater impact on travel time than priority signals (11.0 and 0.6 seconds for the corridor model, respectively). In controlling for both priority and traffic conditions, each were shown to have a distinguished and significant impact on travel time. Utilizing a regression model, results in an intuitive ranking of the intersections’ delay was produced; major intersections with high traffic volumes on crossing streets are likely to not experience TSP benefits. To a high degree, this research has shown that pedestrian exposure can be considered as an outcome of traffic-signal timing decisions made by cities and counties. The statistical results have shown the high impact that signal timing and queuing have on pedestrian level exposure. Heavy vehicle volume was a significant variable as well as the presence of buses. The reduction of bus idling time through more efficient operations and transit-signal priority is likely to reduce pedestrian and transit users\u27 pollution exposure levels. Longer green times along the main corridor are able to significantly reduce particulate matter for transit users and pedestrians waiting at the sidewalk of the intersection, whereas time allocated to cross the street increases queuing and exposure along the main corridor. The impact of heavy-duty diesel engines is also clear. The reduction of bus idling time through more efficient operations and transit-signal priority is likely to reduce pedestrian and transit users\u27 pollution exposure levels. Transit agencies can also reduce pollution significantly by improving the efficiency and cleanliness of their engines. TriMet (the local transit agency) initiatives to improve fuel efficiency by installing EMP engine-cooling devices not only improve fuel efficiency, but also air quality. Finally, significant reductions in transit users’ exposure to traffic-related pollution can be made at bus stops by properly orienting the shelter and by reducing bus idling

Oregon Freight Data Mart

Increasing freight volumes are adding pressure to the Oregon transportation system. Monitoring the performance of the transportation system and freight movements is essential to guarantee the economic development of the region, the efficient allocation of resources, and the quality of life of all Oregonians. Freight data is expensive to collect and maintain. Confidentiality issues, the size of the datasets, and the complexity of freight movements are barriers that preclude the easy access and analysis of freight data. Data accessibility and integration is essential to ensure successful freight planning and consistency across regional partner agencies and planning organizations. In relation to Internet-based mapping technology in freight data collection and planning, the main objectives of this project are: (a) address implementation issues associated with data integration, (b) present a system architecture to leverage existing publically-available interfaces and web applications to accelerate product development and reduce costs, (c) describe an existing web-based mapping prototype and its capabilities, (d) state lessons learned and present suggestions to streamline the integration and visualization of freight data, and (e) discuss load-time and display quality issues associated with the visualization of transportation data on internet-based mapping applications. The strategies and methodologies described in this report are equally applicable to the display of areas such as states or counties as well as linear data such linear data such as highways, waterways, and railways. Despite data integration challenges, Internet-based mapping provides a cost effective and appealing tool to store, access, and communicate freight data as well as enhance our understanding of freight issues. Institutional barriers, not technology, are the most demanding hurdles to widely implementing a freight data web-based mapping application in the near future

Climate Change Impact Assessment for Surface Transportation in the Pacific Northwest and Alaska

WA-RD 772.

The Application of Smart Phone, Weight-Mile Truck Data to Support Freight-Modeling, Performance Measures and Planning

Oregon is one of the few states that currently charge a commercial truck weight-mile tax (WMT). The Oregon Department of Transportation (ODOT) has developed a data-collection system – Truck Road Use Electronics (TRUE) – to simplify WMT collection. The TRUE system includes a smart phone application that collects and records Global Positioning System (GPS) data. The TRUE data has enormous advantages over GPS data used in previous research due to its level of geographic detail and the potential to also integrate trip origin and destination, vehicle class, and commodity-type data. This research evaluates the accuracy of the TRUE data and demonstrates its use for significant ODOT ancillary applications. Specifically, ancillary applications that address ODOT freight modeling, performance measures, and planning needs are explored. The use of the data for highly accurate trip-generation rates and mobility performance measures is demonstrated. In addition, it is shown that the TRUE data has strong potential to be used for safety, accessibility and connectivity, system condition and environmental stewardship performance measures. The potential use of the TRUE data for emissions estimates that take into account truck-type details, truck weight and detailed speed profiles is considered. Results indicate that TRUE data, integrated with ODOT weigh-in-motion (WIM) data, will greatly improve the accuracy of emission estimates at the project and regional level. This research confirms the potential use of the TRUE data for significant ancillary applications and demonstrates the regional value of the TRUE data to enhance existing freight modeling, performance measures and planning

Emission model sensitivity analysis: The value of smart phone weight-mile tax truck data

This research serves to evaluate the potential use of a system developed by the Oregon Department of Transportation (ODOT) for emission estimates. The data collection system developed by ODOT – Truck Road Use Electronics (TRUE) – includes a smart phone application with a Global Positioning System (GPS) device and microprocessor. Previous research with the TRUE data served to demonstrate its use for important ancillary applications such as highly accurate trip generation rates and m obility performance measures. In addition, it was shown that the TRUE data has strong potential use for safety, accessibility and connectivity, system condition and environmental stewardship performance measures. This new research builds on that past work and evaluates the potential use of the TRUE data for emissions estimates that take into account truck type details, truck weight and detailed speed profiles. A sensitivity analysis using the U.S. Environmental Protection Agency's (EPA) Motor Vehicle Emissi on Simulator 2010b (MOVES2010b) is performed in order to understand the level of error that might be encountered when such detailed data are not available. The impact of grade on emissions estimates is also considered. Results indicate that TRUE data in in tegration with Oregon Department of Transportation (ODOT) weight - mile tax (WMT) data will greatly improve the accuracy of emissions estimations at the project and regional level

Value of Travel Time Reliability Part II: A Study of Tradeoffs Between Travel Reliability, Congestion Mitigation Strategies and Emissions

Capacity, demand, and vehicle based emissions reduction strategies are compared for several pollutants employing aggregate US congestion and vehicle fleet condition data. We find that congestion mitigation does not inevitably lead to reduced emissions; the net effect of mitigation depends on the balance of induced travel demand and increased vehicle efficiency that in turn depend on the pollutant, congestion level, and fleet composition. In the long run, capacity-based congestion improvements within certain speed intervals can reasonably be expected to increase emissions of CO2e, CO, and NOx through increased vehicle travel volume. Better opportunities for emissions reductions exist for HC and PM2.5 emissions, and on more heavily congested arterials. Advanced-efficiency vehicles with emissions rates that are less sensitive to congestion than conventional vehicles generate less emissions co-benefits from congestion mitigation

Transit Bus Fleet Age and Replacement Type Optimization

Due to recent budget and fiscal constraints, it is ever more imperative for transit agencies to manage their fleets in an optimal way. Fleet data have consistently shown that bus operational and maintenance (O&M) per-mile costs increase as buses age. From a purely economic perspective, there is a cost tradeoff between the lower O&M costs of newer fleets and their higher initial capital costs. This tradeoff has a significant impact on the optimal timing of purchase and replacement decisions. Utilizing realistic cost data and an optimization modeling framework, we analyze (a) the impact of purchase timing decisions on fleet per-mile costs and (b) the key factors and variables affecting the optimization of transit diesel and hybrid bus fleets. Given uncertain and hard-to-forecast market variables, multiple scenarios are examined and sensitivity analyses are performed to study the impacts of key variables on optimal replacement policies and costs. In terms of the impact of purchase timing decisions on fleet per-mile costs (a), results indicate that: 1) increases in diesel prices do not affect total bus fleet costs as much as increases in maintenance costs; 2) increases in maintenance costs and utilization per year reduce the optimal replacement age; 3) increases in utilization and fuel economy have a similar impact in terms of total fleet costs; and 4) bus purchase-price changes have a significant impact on the optimal replacement age. In terms of the key factors and variables affecting the optimization of transit diesel and hybrid bus fleets (b), results indicate that: 1) the Federal Transit Administration (FTA) purchase cost subsidy has the highest impact on the optimal replacement policies; 2) without the FTA subsidy, the optimal policy is to choose the diesel bus unless the purchase cost difference is larger than 10%; 3) with an 80% FTA purchase cost subsidy, the hybrid bus is always the best choice unless fuel economy difference between the hybrid and diesel buses is substantial; 4) maintenance costs affect the optimal replacement age but are unlikely to change the optimal bus type when comparing diesel and hybrid technologies; and 5) greenhouse gas emissions costs are not significant and affect neither bus type nor replacement age

Value of Travel-Time Reliability: Commuters’ Route-Choice Behavior in the Twin Cities

Travel-time variability is a noteworthy factor in network performance. It measures the temporal uncertainty experienced by users in their movement between any two nodes in a network. The importance of the time variance depends on the penalties incurred by the users. In road networks, travelers consider the existence of this journey uncertainty in their selection of routes. This choice process takes into account travel-time variability and other characteristics of the travelers and the road network. In this complex behavioral response, a feasible decision is spawned based on not only the amalgamation of attributes, but also on the experience travelers incurred from previous situations. Over the past several years, the analysis of these behavioral responses (travelers’ route choices) to fluctuations in travel-time variability has become a central topic in transportation research. These have generally been based on theoretical approaches built upon Wardropian equilibrium, or empirical formulations using Random Utility Theory. This report focuses on the travel behavior of commuters using Interstate 394 (I-394) and the swapping (bridge) choice behavior of commuters crossing the Mississippi River in Minneapolis. The inferences of this report are based on collected Global Positioning System (GPS) tracking data and accompanying surveys. Furthermore, it also employs two distinct approaches (estimation of Value of Reliability [VOR] and econometric modeling with travelers’ intrapersonal data) in order to analyze the behavioral responses of two distinct sets of subjects in the Minneapolis-Saint Paul (Twin Cities) area

Bicycle-Specific Traffic Signals: Results from State-of-the-Practice Review

This poster presents the results of a survey of North American jurisdictions with known installations of bicycle-specific traffic signals and a review of available engineering guidance. Surveys were sent to agencies in 21 jurisdictions (19 in the United States and two in Canada) that requested detailed engineering aspects of the signal design such as placement, mounting height, lens diameter, backplate color, type of actuation, interval times, use of louvers, and performance. We reviewed guidance documents produced by the National Association of City Transportation Officials (NACTO); American Association of State Highway and Transportation Officials (AASHTO); Transportation Association of Canada (TAC); the CROW design manual for bicycle traffic; and the Canadian, U.S. and Californian manuals on uniform traffic control devices. Responses were received for 63 intersections and 149 separate signal heads. The survey results highlight the current treatments and variations of similar designs. A subsequent review of the documents generally revealed consistent guidance with regard to the design of bicycle-specific traffic signals. The guidance on bicycle signals has grown substantially in recent years, and it is likely that there will be less variety in future designs

Finding least fuel emission paths in a network with time-varying speeds

This article considers the problem of finding a route and schedule for a vehicle starting from a depot, visiting a set of customers, and returning to the depot, in a time-dependent network where the objective is to minimize the greenhouse gas emissions. In this formulation, the speeds of the vehicle as well as the routes chosen are decision variables subject to limits determined by the level of congestion on the roads at the time. Two methods are proposed to find the optimal strategy for a single route. One is a time-increment-based dynamic programming method, and the other is a new heuristic approach. In addition, a case study is carried out, which compares the performances of these methods, as well as the least polluting routes with the shortest time routes between two customer nodes