Bayesian updating of simulated household travel survey data for small/medium metropolitan areas

This thesis tests an approach for generating simulated travel survey data that has local characteristics incorporated in it. Travel survey data are generally required for estimating and calibrating travel demand models for a region. The high cost associated with travel surveys puts them beyond the budget of most small/medium MPOs. Therefore simulation of travel survey data provides a viable alternative for these data starved regions to generate data. The simulated data is produced by combining socio-demographic data along with a national survey data set. Updating the simulated data distributions with the distributions obtained by surveying a small sample of local households, adds a local element to the simulated data set. The updating procedure using a small local sample of households is tested for two regions, which had previously conducted household travel surveys. The local sample was drawn from the travel survey and results obtained after updating were compared to those from the travel surveys in order to assess the performance of updating. Comparisons of trip attributes (trip rates, mode shares, departure times and trip lengths) in the two study areas show the updating has succeeded in bringing the updated values closer to the survey values in the majority of cases. The anomalies, which were seen in a few cases, were attributed to the lack of representativeness of the local sample, the inability of the simulation to capture all variations and the contextual differences between the regions. The concept of updating a simulated travel data set using local sample distributions in order to generate an updated simulated travel data set is explained here. While updating in general was found to move the updated trip attributes in the correct direction and towards the survey values, further testing such as comparing the population values estimated from the survey data and the updated simulated data need to be carried out in order to generate conclusive evidence on the benefit of updating. The main beneficiaries of this method are small/medium metropolitan areas who can use this method to produce synthetic travel data for running their travel demand models at a much lower expense

Multimodal Data at Signalized Intersections: Strategies for Archiving Existing and New Data Streams to Support Operations and Planning & Fusion and Integration of Arterial Performance Data

There is a growing interest in arterial system management due to the increasing amount of travel on arterials and a growing emphasis on multimodal transportation. The benefits of archiving arterial-related data are numerous. This research report describes our efforts to assemble and develop a multimodal archive for the Portland-Vancouver region. There is coverage of data sources from all modes in the metropolitan region; however, the preliminary nature of the archiving process means that some of the data are incomplete and samples. The arterial data sources available in the Portland-Vancouver region and that are covered in this report include data for various local agencies (City of Portland, Clark County, WA, TriMet and C-TRAN) covering vehicle, transit, pedestrian, and bicycle modes. We provide detailed descriptions of each data source and a spatial and temporal classification. The report describes the conceptual framework for an archive and the data collection and archival process, including the process for extracting the data from the agency systems and transferring these data to our multimodal database. Data can be made more useful though the use of improved visualization techniques. Thus as part of the project, a number of novel, online visualizations were created and implemented. These graphs and displays are summarized in this report and example visualizations are shown. As with any automated sensor system, data quality and completeness is an important issue and the challenge of automating data quality is large. Preliminary efforts to validate and monitor data quality and automate data quality processing are explored. Finally, the report presents efforts to combine transit and travel time data and signal timing and vehicle count data to generate some sample congestion measures

Exploring Pedestrian Responsive Traffic Signal Timing Strategies in Urban Areas

The role of walking in the development of healthy, livable communities is being increasingly recognized. In urban areas, intersections represent locations where different modes converge, and are often viewed as deterrents to walking. This is due to the unwarranted and often unnecessary delays imposed by signal timing policies for pedestrians and increased potential for conflicts. Traditional signal timing design prioritizes vehicles over pedestrians leading to undesirable consequences such as large delays and risky pedestrian behaviors. Pedestrians are accommodated in a manner that is designed to cause least interruption to the flow of motor vehicles. This lack of pedestrian accommodation at signalized intersections is the focus of this dissertation. Understanding pedestrian attitudes and perceptions is important because it offers insights into actual crossing behavior at signalized intersections. An intercept survey of 367 crossing pedestrians was undertaken at four signalized intersections in Portland, Oregon, and binary logistic regression models were constructed to quantify the impacts of demographics, trip characteristics and type of infrastructure on pedestrian perceptions and attitudes regarding delay, crossing time and motivators for crossing decisions. Safety was found to have a larger effect than compliance on the decision to cross the street. Pedestrians at recall intersections expressed higher satisfaction with delay than at actuated intersections. Novel methods to measure pedestrian delay using 2070 signal controllers and Voyage software were developed. These methods have been adopted by the City of Portland to record actuation trends and delays at various intersections. In the absence of demand data, pedestrian push button actuations can be considered as a proxy for crossing demand. The micro-simulation software VISSIM was used to analyze delays resulting from varying pedestrian and vehicle volumes on a network of three intersections in Portland, Oregon. From a pedestrian perspective, free operation was found to be always beneficial due to lower pedestrian delays. However, from a system wide perspective, free operation was found to be beneficial only under low-medium traffic conditions from an overall delay reduction viewpoint, while coordinated operation showed benefits under heavy traffic conditions, irrespective of the volume of pedestrians. Control strategies were developed to identify the best mode of signal controller operation that produced the lowest overall average delay per user. A procedure to identify the optimal control strategy based on user inputs (major street volume to capacity ratios and rate of pedestrian phase serviced for the minor street) was developed. The procedure was applied to a network of three intersections in east Portland, OR and the findings were verified. This research offers significant contributions in the field of pedestrian research. The findings related to attitudes and perceptions of crossing pedestrians offer greater insights into pedestrian crossing behavior and add to the body of existing literature. The methods developed to obtain pedestrian actuations and delay data from signal controllers represent an easy and cost-effective way to characterize pedestrian service at intersections. The results pertaining to signal timing strategies represent an important step towards incorporating pedestrian needs at intersections and demonstrate how control strategies employed to benefit pedestrians could benefit the entire system

Assessment and Refinement of Real-Time Travel Time Algorithms for Use in Practice

The Federal Highway Administration (FHWA) has set a high priority on the use of existing dynamic message signs (DMS) to provide travel time estimates to the public. The Oregon Department of Transportation (ODOT) currently has three DMS in the Portland metropolitan area configured to display travel time information. In the near future, ODOT would like to make travel time estimates available on additional DMS, over the Internet on tripcheck.com and via 511. Travel time estimates are valuable to the traveling public; however, the estimates must be accurate to be useful. The FHWA indicates that 90% accuracy is ideal and suggests a minimum accuracy of 80%. Thus, in order to display travel time estimates, it is essential to understand the accuracy of the estimates. The purpose of this study is to extend prior travel time research conducted at Portland State University with additional data collection and analysis to provide statistical confidence in travel time estimates and to determine the best travel time estimation approach for ODOT. Ground truth data in the form of probe vehicle runs will be collected and travel time estimates will be evaluated using that data. Several travel time estimation algorithms will be evaluated and modifications to existing algorithms will be proposed. In addition, this project will provide analysis to help understand the reliability and performance of the algorithms under various conditions (free-flow, congestion, incidents). A methodology will be developed for determining if travel time estimates fall within an acceptable accuracy limits. At the conclusion of the project, it is desired that a methodology can be recommended that will provide accurate measures of travel time for use with DMS, the Internet and 511 applications

Assessment and Refinement of Real-Time Travel Time Algorithms for Use in Practice, Phase II

The Federal Highway Administration (FHWA) has put a high priority on the use of existing dynamic message signs (DMS) to provide travel time estimates to the public. The Oregon Department of Transportation (ODOT) has three DMS in the Portland metropolitan area configured to display travel time information. In the near future, ODOT would like to make travel time estimates available on additional DMS, over the Internet on tripcheck.com and via 511. Travel time estimates are valuable to the traveling public; however, the estimates must be accurate to be useful. The purpose of this study is to extend prior travel time research conducted by Portland State University with additional analysis to provide statistical confidence in travel time estimates and to determine the best travel time estimation approach for ODOT. The initial ODOT-funded phase of this project gathered a large amount of ground truth data and analyzed the performance of the current algorithms and current infrastructure using that data. However, additional work remains to be done. OTREC Phase I of this project will focus on using the existing data to understand the conditions under which travel time estimation algorithms are not accurate. This extension will build on that work to investigate improvements to travel time estimation algorithms and to identify a set of metrics for travel time accuracy and guidelines for when travel time estimates should be provided. At the conclusion of the project, it is desired that a methodology can be recommended that will provide accurate measures of travel time for use with DMS, the Internet and 511 applications

Webinar: Improving Walkability at Signalized Intersections with Signal Control Strategies

The goal of signal timing at an intersection should be to maximize efficiency for all users. In many jurisdictions, however, traffic signals are timed mostly with the goal of reducing vehicular delay. Other road users, such as pedestrians, deserve similar focus. In legacy transportation systems, pedestrians experience delays much in excess of those that would be deemed acceptable for a motor vehicle at the same location. Excessive delay can lead to pedestrian frustration, non-compliance and ultimately decreased safety. In the North American context, implementation of strategies to address pedestrian service varies greatly across jurisdictions, and there has been limited research on incorporating alternative pedestrian treatments at signalized intersections. Recent updates to the Highway Capacity Manual (HCM 2010) have included specific multimodal delay modeling techniques offering a bit more accommodation to pedestrians, but still remain heavily vehicle-centric. While strategies such as an exclusive pedestrian phase and leading pedestrian intervals can help improve the safety of pedestrian operations, legacy service of pedestrians requires that they still must wait for their turn. This webinar will present the details of alternative pedestrian strategies, as well as the results of recent research into the impact on delay that these treatments have on all users. At the conclusion, practitioner recommendations will be presented developed from the results of a user survey, field implementations of strategies, and software-in-the-loop (SITL).https://pdxscholar.library.pdx.edu/trec_webinar/1016/thumbnail.jp

Exploring Thresholds for Timing Strategies on a Pedestrian Active Corridor

Traditional signal timing policies have typically prioritized vehicles over pedestrians at intersections, leading to undesirable consequences such as large delays and risky crossing behaviors. The objective of this paper is to explore signal timing control strategies to reduce pedestrian delay at signalized intersections. The impacts of change in signal controller mode of operation (coordinated vs. free) at intersections were studied using the micro-simulation software VISSIM. A base model was developed and calibrated for an existing pedestrian active corridor. A hypothetical network of three intersections was used to explore the effects of mode of operation and measures of delay for pedestrians and all users. From a pedestrian perspective, free operation was found to be more beneficial due to lower delays. However, from a system wide (all user) perspective, coordinated operation showed the greatest benefits with lowest system delay under heavy traffic conditions (v/c \u3e 0.7). In the off-peak conditions when traffic volumes are lower, free operation resulted in lowest system delay (v/c \u3c 0.7). During coordination, lower cycle lengths were beneficial for pedestrians, due to smaller delays. The results revealed that volume to capacity (v/c) ratios for the major street volumes coupled with pedestrian actuation frequency for the side street phases, could be used to determine the signal controller mode of operation that produces the lowest system delay. The results were used to create a guidance matrix for controller mode based on pedestrian and vehicle volumes. To demonstrate application, the matrix is applied to another corridor in a case study approach

Improving Walkability Through Control Strategies at Signalized Intersections

As cities and communities nationwide seek to develop Complete Streets that foster livability and accommodate all modes, signal timing control strategies that include pedestrians in the operational decision process are gaining importance. This research tested several efficiency-focused pedestrian treatments – coordination, actuated-coordination, free operation, short cycle lengths – and safety-focused treatment including leading pedestrian intervals and Barnes Dance. Using a software-in-the-loop simulation, the operational impacts of these treatments on all users (vehicles, heavy vehicles, bicyclists and pedestrians) at an intersection were evaluated. Results showed that among the efficiency-based treatments, free operation was most beneficial for reducing minor-street pedestrian delays. Both safety treatments increased major-street vehicle delays. A new pedestrian priority algorithm is proposed and developed, which is designed to prioritize pedestrian service under certain traffic conditions. The algorithm is designed to analyze field data and change the user-defined operational strategy to match the conditions in the field. The developed algorithm was deployed at three separate locations, two of which used a Raspberry Pi device and one used the onboard logic processor of the ASC/3 controller. Before-and-after data analysis showed that the algorithm was successful in reducing pedestrian delay. While this research provides field-implementable solutions for reducing pedestrian delays, there is no one right solution . Ultimately, choice of a control strategy may rest on operational objectives and geometric characteristics of an intersection. The findings from this research may benefit cities that are looking to create safe, sustainable streets capable of accommodating multiple modes

Accuracy of Bicycle Counting with Pneumatic Tubes in Oregon

Interest in counting bicycles and establishing nonmotorized counting programs is increasing, but jurisdictions still struggle with how to integrate bicycle counting into standard practice. In this paper, the authors share findings and recommendations for how to minimize error for bicycle counting from tests conducted in conjunction with the Oregon Department of Transportation. This research studied three types of off-the-shelf pneumatic tube counters for counting bicycles, including equipment from five manufacturers: two bicycle-specific counters, three varieties of motor vehicle classification counters, and one volume-only motor vehicle counter. Tests were conducted both in a controlled environment and in on-road mixed traffic to better identify problems in accuracy. Equipment studied generally undercounted cyclists, especially those in groups. Results from the controlled test with standard bicycles showed that within 10 ft of the counter, the undercounting error ranged from 0% to 212%. In the mixed-traffic test, all the equipment tested tended to undercount with mean percent error ranging from 210% to 273%. Each counter type has pros and cons, but in general, counting accuracy decreased with increases in bicycle and motor vehicle traffic and longer tube lengths. Higher accuracy can be achieved by careful selection of equipment type, classification scheme, and tube configuration. Bicycle speeds given by off-the-shelf pneumatic counting equipment were accurate

Improved Safety Performance Functions for Signalized Intersections

For this effort, the research team developed new safety performance functions (SPFs) for signalized intersections in Oregon. The modeling dataset consisted of 964 crashes from a total of 73 intersections that were randomly selected based on the presence of a traffic signal (identified through the crash data records). The SPFs were developed using a Poissonlognormal Generalized Linear Mixed model framework for total crashes and severe injury crashes (coded as KAB). Three SPFs were developed: 1) an SPF for total crashes, which relies on both major and minor AADTs to predict the expected number of crashes; 2) an SPF for KAB crashes, whose predictions derive from both AADTs as well as from the speed limit on the major road; and (3) a severity model to predict the proportion of KAB crashes to be used in combination with the SPF for total crashes. The research analyses determined that the speed limit variable significantly improved the quality of the SPFs and severity model, and as expected, suggests increasing severity with speed differentials. The models were validated spatially and temporally based on additional sites and using an additional year of data. The models all performed well during the validation; however enhanced models to improve model reliability were developed based on the larger dataset. As part of the model development, this research also explored a variety of rules to identify crashes as intersection-related based on the crash geo-location (including the common 250 feet rule). Crashes were manually classified from the combined data available from the geo-location of crashes, the geometric database, and the various fields in the Oregon crash database. These classifications were then compared to a number of rule options for classifying them as intersection crashes. The analysis revealed that the best performing rule is to use crashes that were geo-located within 300 feet of the centerline intersection at signalized locations plus crashes where the crash report indicates that they were associated with a traffic control device (i.e. traffic signal). Finally, this research effort developed models to estimate to estimate minor road AADT for use in safety analysis where this exposure information is not available. These models were developed from data from 66 intersections with known minor and major AADT volumes and validated with data from another 25 intersections. Significant model variables included major AADT, number of approach lanes, functional class, presence of a two-way leftturn lane, and parallel road AADT