This paper describes the collection and use of 1.4 million travel time records that were collected over a 12-week period in 2009 to evaluate and communicate quantifiable travel mobility metrics for a rural interstate highway work zone along I-65 in northwestern Indiana. The effort involved the automated collection and processing of Bluetooth probe data from multiple field collection sites, communicating travel delay times to the motoring public, assessing driver diversion rates, and developing proposed metrics for a state transportation agency to evaluate work zone mobility performance. Collected travel time profiles were compared with traditionally measured hourly flows in both incident and nonincident conditions. Through the 12-week period over which work zone performance was measured, the work zone had 422 h of congested conditions in which travel time delay was greater than 10 min. Despite the display of real-time delay measurements to the motoring public through portable dynamic message signs, a negl...

Real-Time Measurement of Travel Time Delay in Work Zones and Evaluation Metrics Using Bluetooth Probe Tracking:

The consumer electronics industry has made extensive use of the Bluetooth wireless protocol in many portable devices. A substantial number of these Bluetooth devices broadcast a unique identifier in the form of the media access control (MAC) addresses. These MAC addresses can be captured electronically and the same matching algorithms used in traditional license plate studies can be used to estimate segment travel time and origin-destination matrices. This paper briefly illustrates how these data can be used to estimate arterial link travel times and empirically illustrates the sensitivity of sample size to sensor placement. A controlled experiment with fixed lateral mounting and varying vertical mounting heights is then conducted to develop design recommendations for mounting Bluetooth monitoring devices. The paper concludes by recommending a Class I Bluetooth detector mounting height of at least 8 ft above the pavement grade. Based on a 24-h empirical data set on I-65 in Indianapolis, we found that 7.4%...

Influence of Vertical Sensor Placement on Data Collection Efficiency from Bluetooth MAC Address Collection Devices

Traffic accidents impart both economic and social costs upon communities around the world, hence the desire for accident rates to be reduced. For this reduction to occur, the factors influencing the occurrence of accidents must be understood. The role of congestion in modifying accident risk has been widely studied, but consensus has not been reached, with conflicting results leaving open questions. An inverse relationship between accidents and congestion would imply a benefit of congested conditions for road safety, posing a difficult situation for traffic management. This paper assesses articles that reveal the shape of the relationship between traffic accidents and congestion. We find a positive linear response to dominate the literature. However, studies with higher numbers of statistical units tend to show a U-shaped relationship. This suggests an important role of high spatio-temporal traffic data in understanding factors causing accidents and identifying the combination of real-time conditions which may lead to increased accident risk. Modern advancements in traffic measurement systems provide the ability for real-time alleviation of accident-prone conditions before they can fully develop.

https://www.mdpi.com/1660-4601/16/18/3400/pdf

Current Understanding of the Effects of Congestion on Traffic Accidents.

An anonymous Bluetooth tracking system was deployed at the new Indianapolis International Airport in Indiana from May 8 to June 2, 2009, to measure the time for passengers (a) to move from the nonsterile side of the airport (presecurity), (b) to clear the security screening checkpoint, and (c) to enter the walkway to Concourse B on the sterile side. The maximum passenger transit time between these checkpoints was observed on Monday mornings at approximately 0600, when it could take passengers up to 20 min to transit the security queue and screening and to walk to Concourse B. Depending on the day of the week, this approach was demonstrated to sample between 5% and 6.8% of passengers. This modest sample size provides a more robust measurement of screening times than the current system of manually distributing time-stamped cards as passengers enter the queue and collecting them where passengers pass through the magnetometer. Furthermore, because the final passenger reference point used in this study is on the sterile concourse, it captures the time associated with passengers repackaging their belongings and redonning their shoes. The data from this pilot study suggest the feasibility of using an automated system to provide quantitative information to managers for more effective allocation of scarce resources, as well as providing the traveling public with necessary information about the amount of time they should allocate for transiting the security screening process. The paper concludes by suggesting that additional pilot studies should be performed at several airports with alternative checkpoint configurations to develop a consensus on best practices for locating sensors to measure passage times at airport security screening.

Automated Measurement of Wait Times at Airport Security: Deployment at Indianapolis International Airport, Indiana

Vehicle origin-destination (O-D) data has traditionally been a resource-intensive and expensive collection process. This paper reports on the passive observations of Bluetooth protocol devices embedded in vehicles and motorists' mobile devices to collect the O-D data. Bluetooth media access control address data has been used widely in the last few years to collect speed and travel time data; however, the use of media access control (MAC) address data for O-D surveys is not well documented. Several MAC O-D trials were performed for the Queensland Department of Transport and Main Roads. The Bluetooth MAC data are shown to compare favourably to both video and automated number plate recognition (ANPR) O-D data, however more research is needed to refine the expansion methodology. Despite expansion limitations, the MAC data collection is a cost effective way to collect O-D data in small and controlled networks. For more extensive networks the daily fluctuations indicated by MAC O-D data can be used to supplement traditional methods where collection over a longer period of time is cost prohibitive. (a) For the covering record of this conference, please refer to ITRD abstract no E220725.

Travel Time and Origin-Destination Data Collection using Bluetooth MAC Address Readers

This article attempts to assist survey planners in both the practical issues involved in conducting license plate matching surveys, and the needed statistical considerations for designing the survey and analyzing the survey results. Planning and conducting the survey is described including site visit, survey plan, manpower, weather, equipment, training, and data processing. The several mathematical/statistical considerations that should be evaluated are reviewed: selection of time interval to record data; number of plate characters to record; survey design; and the number of plates required for statistical analyses. Data analysis techniques are also discussed.

M C Schaefer

Papers

License plate matching surveys: practical issues and statistical considerations