17 research outputs found
Using Connected Vehicle Trajectory Data to Evaluate the Effects of Speeding
Speeding has been and continues to be a major contributing factor to traffic
fatalities. Various transportation agencies have proposed speed management
strategies to reduce the amount of speeding on arterials. While there have been
various studies done on the analysis of speeding proportions above the speed
limit, few studies have considered the effect on the individual's journey. Many
studies utilized speed data from detectors, which is limited in that there is
no information of the route that the driver took. This study aims to explore
the effects of various roadway features an individual experiences for a given
journey on speeding proportions. Connected vehicle trajectory data was utilized
to identify the path that a driver took, along with the vehicle related
variables. The level of speeding proportion is predicted using multiple
learning models. The model with the best performance, Extreme Gradient
Boosting, achieved an accuracy of 0.756. The proposed model can be used to
understand how the environment and vehicle's path effects the drivers' speeding
behavior, as well as predict the areas with high levels of speeding
proportions. The results suggested that features related to an individual
driver's trip, i.e., total travel time, has a significant contribution towards
speeding. Features that are related to the environment of the individual
driver's trip, i.e., proportion of residential area, also had a significant
effect on reducing speeding proportions. It is expected that the findings could
help inform transportation agencies more on the factors related to speeding for
an individual driver's trip
EVALUATE PROBE SPEED DATA QUALITY TO IMPROVE TRANSPORTATION MODELING
Probe speed data are widely used to calculate performance measures for quantifying state-wide traffic conditions. Estimation of the accurate performance measures requires adequate speed data observations. However, probe vehicles reporting the speed data may not be available all the time on each road segment. Agencies need to develop a good understanding of the adequacy of these reported data before using them in different transportation applications. This study attempts to systematically assess the quality of the probe data by proposing a method, which determines the minimum sample rate for checking data adequacy. The minimum sample rate is defined as the minimum required speed data for a segment ensuring the speed estimates within a defined error range. The proposed method adopts a bootstrapping approach to determine the minimum sample rate within a pre-defined acceptance level. After applying the method to the speed data, the results from the analysis show a minimum sample rate of 10% for Kentucky’s roads. This cut-off value for Kentucky’s roads helps to identify the segments where the availability is greater than the minimum sample rate. This study also shows two applications of the minimum sample rates resulted from the bootstrapping. Firstly, the results are utilized to identify the geometric and operational factors that contribute to the minimum sample rate of a facility. Using random forests regression model as a tool, functional class, section length, and speed limit are found to be the significant variables for uninterrupted facility. Contrarily, for interrupted facility, signal density, section length, speed limit, and intersection density are the significant variables. Lastly, the speed data associated with the segments are applied to improve Free Flow Speed estimation by the traditional model
Using Crowdsourced Vehicle Braking Data to Identify Roadway Hazards
Modern vehicles know more about the road conditions than transportation agencies. Enhanced vehicle data that provides information on “close calls” such as hard braking events or road conditions during winter such as wheel slips and traction control will be critical for improving safety and traffic operations. This research applied conflict analyses techniques to process approximately 1.5 million hard braking events that occurred in the state of Indiana over a period of one week in August 2019. The study looked at work zones, signalized intersections, interchanges and entry/exit ramps. Qualitative spatial frequency analysis of hard-braking events on the interstate demonstrated the ability to quickly identify temporary and long-term construction zones that warrant further investigation to improve geometry and advance warning signs. The study concludes by recommending the frequency of hard-braking events across different interstate routes to identify roadway locations that have abnormally high numbers of “close calls” for further engineering assessment
Performance-Based Operations Assessment of Adaptive Control Implementation in Des Moines, Iowa RB09-016, August 2018
Maintaining optimal mobility on high-volume arterial traffic corridors is important to transportation agencies and the public.
Corridor performance often can be enhanced by updating traffic signal timing, but most agencies find it necessary to prioritize
their retiming efforts based on resource constraints. To facilitate prioritization, a set of arterial corridor performance measures
was developed using INRIX probe vehicle data. These commercially available data are derived from in-vehicle global positioning
system (GPS) observations transmitted wirelessly, eliminating the need for supplemental traffic observation infrastructure to be
installed in the field.
The main objective of this study was to present a methodology to compare arterial corridors in terms of mobility-based
performance measures. This process can help agencies select the corridors that are in need of signal retiming and can help
identify corridors suited for adaptive signal control implementation. The two-step methodology began by identifying the number
of days in a year with abnormal traffic patterns and comparing the volume-normalized performance of the remaining segments to
identify corridors that are problematic on normal days.
The proposed methodology was applied to 12 corridors in Des Moines, Iowa, and 1 in Omaha, Nebraska. Three corridors were
found to have a high number of anomalous days. Among the remaining corridors, three were identified as under-performing on
normal days. In addition, the impact of implementing an adaptive signal control system on one corridor (University Avenue) was
evaluated, where small improvements in travel rate and daily variation were observed, but the overall variability increased
Regional Data Archiving and Management for Northeast Illinois
This project studies the feasibility and implementation options for establishing a regional data archiving system to help monitor
and manage traffic operations and planning for the northeastern Illinois region. It aims to provide a clear guidance to the
regional transportation agencies, from both technical and business perspectives, about building such a comprehensive
transportation information system. Several implementation alternatives are identified and analyzed. This research is carried
out in three phases.
In the first phase, existing documents related to ITS deployments in the broader Chicago area are summarized, and a
thorough review is conducted of similar systems across the country. Various stakeholders are interviewed to collect
information on all data elements that they store, including the format, system, and granularity. Their perception of a data
archive system, such as potential benefits and costs, is also surveyed. In the second phase, a conceptual design of the
database is developed. This conceptual design includes system architecture, functional modules, user interfaces, and
examples of usage. In the last phase, the possible business models for the archive system to sustain itself are reviewed. We
estimate initial capital and recurring operational/maintenance costs for the system based on realistic information on the
hardware, software, labor, and resource requirements. We also identify possible revenue opportunities.
A few implementation options for the archive system are summarized in this report; namely:
1. System hosted by a partnering agency
2. System contracted to a university
3. System contracted to a national laboratory
4. System outsourced to a service provider
The costs, advantages and disadvantages for each of these recommended options are also provided.ICT-R27-22published or submitted for publicationis peer reviewe