2011 IR&D Annual Report

Investigation into the Usage of Bluetooth® Signals for Roadway Speed Calculations, 10-R8164

Principal Investigators
Lynne Randolph
Adam Clauss
Meredith Wright

Inclusive Dates:  07/02/10 – 11/02/10

Background — With Bluetooth®-enabled devices becoming more prevalent in vehicles, a few companies have developed proprietary solutions for determining travel times over roadway segments. While Florida and Texas Departments of Transportation (DOT) districts are interested in obtaining this functionality, a turnkey solution is undesirable. The DOTs require data be incorporated into their existing traffic management software rather than invest in multiple solutions that are not integrated. However the DOTs are under some pressure from the various districts to implement a solution that can be put in place where little to no infrastructure exists.

Approach — The objective of this project is to investigate potential issues with Bluetooth technology used for the purpose of traveler information. Some of the concerns with using Bluetooth technology for this purpose include validating that an adequate number of data points can be gathered from devices at high speeds and what mode a device must be in to read a signal.

This research includes investigating various Bluetooth device capabilities. The assortment of evaluated devices includes end-user products such as cell phones, personal digital assistants (PDAs), MP3 players, headsets and cars with Bluetooth technology. The other end of the product spectrum includes Bluetooth adapters for connecting to devices and range extending antennas. Scanning capabilities were ascertained to determine the feasibility of using this technology for the purpose of determining traffic speeds and travel times.

Accomplishments — One of the initial limitations investigated was whether the end-user devices must be in discoverable mode to be detected. Prototype software was developed to scan for devices. Bluetooth adapters were used in conjunction with both focused and omni-directional antennas to determine effective ranges. Some adapters are capable of ranges up to 250 feet without an attached antenna, which is adequate for scanning end-user devices on roadways with 20 lanes of traffic. Determination was made that only discoverable devices can be detected, which limits the use of this technology for the purpose of travel time generation.

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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 9 technical divisions.