tracking bluetooth ids to measure travel time & origin/destination how does it work? what...
TRANSCRIPT
Tracking Bluetooth IDs
To Measure Travel Time
& Origin/Destination
How does it work?
What information does it give?
With California law requiring hands free cell phone use, we see less of this . . .
And more hands free cell phone use like this
These ‘hands free’ devices use Bluetooth communications
Bluetooth operates in 2.4 GHz ISM radio bandEach Bluetooth device has an unique 48 bit ‘MAC’ addressThere are 3 Bluetooth device classes based on emitted power
Class 1 up to 100 mW, range up to 100 metersClass 2 up to 2.5 mW, range up to 22 metersClass 3 up to 1 mW, range up to 6 meters
These ‘hands free’ devices use Bluetooth communications
Bluetooth operates in 2.4 GHz ISM radio bandEach Bluetooth device has an unique 48 bit ‘MAC’ addressThere are 3 Bluetooth device classes based on emitted power
Class 1 up to 100 mW, range up to 100 metersClass 2 up to 2.5 mW, range up to 22 metersClass 3 up to 1 mW, range up to 6 meters
High gain antennas can extend therange at which these devices are ‘read’ when they are discoverable
The process starts with reading a Bluetooth ID at one site
And continues with reading the same ID at a 2nd site
The time between the 2 reads is the travel time
Bluetooth IDs can be read from vehicles 300 feet away
Including those on roadways which may not be of interest
Shielding can limit reception to the area of interest
This roadway area will be ignored
How are Bluetooth IDs
Read?
Electronics in aweatherproof caseat roadside sends
out an inquiry to Bluetooth devices in
the vicinity every few seconds . . . .
Bluetooth devices nearby respond with their IDsBluetooth devices nearby respond with their IDs which are recorded with date and timewhich are recorded with date and time
GPSDate
GPSTime
BluetoothID (hex)
BluetoothID (decimal)
# ofreads
Dwell TimeAt Site
Non-reversible encryption can be done by erasing1 bit in each Bluetooth ID
Even on urban and suburban streets, many Bluetooth IDs will be read
Over 11,000 IDs were read in 4 days on a small arterial
Data record when ID passed first BluFaxData record when ID passed first BluFax
Data record when ID passed second BluFaxData record when ID passed second BluFax
Travel time for this Bluetooth IDTravel time for this Bluetooth ID
Bluetooth IDs + GPS time measure travel time directlyBluetooth IDs + GPS time measure travel time directly
The travel time is the difference in GPS times
Urban/Suburban street travel times look like this
Interrupted Trips
Uninterrupted Trips
The travel times are a mix of uninterrupted + interrupted trips
Only uninterrupted trips characterize traffic system performance
Identifying the Uninterrupted Trips Is Easy
The interrupted trips are all those travelers who stopped to shop, get gas, visit the bank - - - extending their trip time arbitrarily.
Interrupted Trips
Despite filtering, uninterrupted trip times still vary
What Can We Do With BluFax?
Measure travel time along a corridorBluFax at beginning, end, and key entry/exit points
Confirm benefits of signal coordinationMeasure origin and destination of travelers
Requires BluFax at all boundary entry/exit pointsMeasure delay on approaches to a signal
BluFax on each approach ~200’ back from stop line Identify causes for congestion Identify influence of traffic management on travel demand
Some Examples of Actual Usage
Temecula: confirm signal coordination benefitsMurrieta: confirm signal coordination benefitsPleasanton: track cut-through traffic from freewaysCCIT: measure travel times on urban streetsPATH: measure travel times on freewaysOmni-Means: origin/destination in downtown NapaQuality Traffic Data: corridor travel time in Walnut CreekStantec: origin/destination on freeways for SANDAGDKS: origin/destination + travel time on freeways for RCTC
A Specific Example: Origin/Destination + Travel Time on the 91 Freeway
Each pushpin symbol was a BluFax unitA total of 13 BluFax units were deployed
Typical Site Mounted BluFax on an Existing Pole
A
B
BluFax at site A read 60% of IDs read by a BluFax at site BBoth directions on most freeways can be monitored with 1 unit
A simplified diagram of measurementsFor just one movement of traffic
Here are some ofthe results found for one 3 hourtime period
Here is the 6AM Caltrans Traffic Map from IE511
Traffic from 71 Southbound enters the 91 Westbound and congestion spills back Eastward
BluFax – the tool used for data collectionA portable unit in a weatherproof case
Internal GPS for location + precise time Internal GSM modem for data communications
Can send email with data collected each day Can operate as a real time unit also
Battery provides up to 2 weeks of operation2 GB memory stores all data collectedBluFax can be purchased or rentedBluStats PC software included (batch software)
Processes data into chartsExports data to EXCELVery is easy to use Windows 7 or XP compatible
Real Time Usage
This is the next step after using BluFax as a “study tool”Firmware allows any BluFax to do real time monitoringServer is required to receive and process the data
BluFaxWeb is available as a rental service on Traffax’ server BluFaxWeb software is available as licensed software on user’s server Either way, results are delivered as an XML feed Requires a communication network to all BluFax sites
Data security is a solvable challenge BluFax can encrypt Bluetooth MAC IDs as they are read The encryption used is non-reversible (and simple)
Traffax has real time systems in place in US & Australia
Solar Power Supports A Real Time Site in Maryland
Where are we going?
Fostering acceptance of new technology Engineers learn it in school and carry concept into employment Researchers use it and develop applications practices Practicing engineers learn about it in projects
We have moved beyond the technology Implement user applications
Provide accurate travel time information Measure origin/destination movements Measure movements along a corridor
Focus on user needs (financial and technical) Rent equipment allow low cost evaluations and study projects Rent server/software to facilitate transition to real time
It takes 10+ years for new technology to be widely accepted
BluFax makes travel time and traveler origin/destination directly observable
On Freeways . . .
as well as Arterial Streets
Making it easy to show stakeholders the value of improvements
Further information is available at www.traffaxinc.com
Traffax, Inc. is the manufacturer of BluFax
Or, feel free to contact: Mike Juha
Tel: 951-600-9499
Cell: 949-310-5106