Showing papers by "Brian L. Smith published in 2009"

Kalman Filter Approach to Speed Estimation Using Single Loop Detector Measurements under Congested Conditions

Abstract: The ability to measure or estimate accurate speed data are of great importance to a large number of transportation system operations applications. Estimating speeds from the widely used single inductive loop sensor has been a difficult, yet important challenge for transportation engineers. Based on empirical evidence observed from sensor data collected in two metropolitan regions in Virginia and California, this research developed a Kalman filter model to perform speed estimation for congested traffic. Taking advantage of the coexistence of dual loop and single loop stations in many freeway management systems, a calibration procedure was developed to seed and initiate the algorithm. Finally, the paper presents an evaluation that illustrates that the proposed algorithm can produce acceptable speed estimates under congested traffic conditions, consistently outperforming the conventional g-factor approach.

Modeling Single Occupant Vehicle Behavior in High-Occupancy Toll (HOT) Facilities

Abstract: High-occupancy toll (HOT) lanes are in operation, under construction, and planned for in several major metropolitan areas. The premise behind HOT lanes is to allow single occupant vehicles (SOVs) to access high occupancy vehicle (HOV) lanes (and theoretically, a higher level of service) if they are willing to pay a toll. To maintain a high level of service in the HOT lanes, the toll rate is set dynamically to restrict the number of SOVs which access the facility as it nears capacity. Thus, HOT facilities provide operators of transportation systems with an additional tool: pricing. In order to effectively use pricing, it is critical to understand driver behavior when faced with a set of traffic conditions and toll levels. This thesis presents the results of an empirical investigation into the relationship between toll rate, traffic conditions, and SOV driver behavior, based on data from the dynamically-tolled I-394 HOT facility in Minneapolis, Minnesota. Analysis of the empirical data indicated that of the SOVs using the HOT lanes, 87.5% use the HOT lanes at predictable rates throughout the AM peak period, even when there is no clear travel time advantage. After accounting for these “regular” users, the remaining “price-sensitive” SOV drivers utilize the HOT lanes at greater rates when the cost per hour of commute time saved is lowest. A model was developed that incorporates both of these findings, predicting HOT lane usage rates based on time savings, time of day, and toll rates with an R value of 0.684, n = 27831. When compared to the historic HOT utilization rates only, i.e. assuming all HOT lane SOVs are “every day” drivers, the resulting model has an R value of 0.675, n = 27831. Thus, the pricing structure as in place at this facility, appears to have a negligible influence on behavior. This may indicate serious implications, as many HOT facilities are

Analysis of Standard Operating Procedures for Enhanced Regional Transportation Systems Operations

Abstract: Traditionally, transportation system operations have been constrained by jurisdictional and administrative boundaries. Local governments and state agencies have operated facilities for which they are responsible with little coordination. As surface transportation mobility challenges continue to increase, it is evident that although different localities and agencies may still operate their own systems, there is a need for coordinated regional operations. An important component of enabling such coordination is the achievement of consistency in the standard operating procedures (SOPs) used by the individual transportation operations centers (TOCs). Historically, each TOC has developed its own SOPs, suited to its own unique needs and the resources available. Although these individual SOPs have served their TOCs well, such customized operations procedures of a TOC are often not compatible with its neighboring TOCs. As such, establishing regional coordination, especially to manage large-scale incidents or emergencies, is difficult. In this research effort a methodology was developed to analyze TOC SOPs to find opportunities to increase regional consistency. This methodology was applied in a case study to analyze the SOPs of the five TOCs and the statewide emergency operations center in the state of Virginia. The results of this study indicate that several differences indeed hamper coordination among the centers. At the same time a number of procedures with the potential for increased consistency are also identified. Information contained in this paper will benefit systems integrators, planners, researchers, and other transportation professionals involved in regional integration efforts and in policy and procedures review.