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Truths and Myths about Traffic Data Truths and Myths about Traffic Data ITSA Presentation June 2007 AirSage Proprietary & Confidential
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A discussion about terminology and perspectives on traffic data #1: What is “Probe Data”? #2: Sensors verses “Probes” … Is that the right comparison? #3: What does Coverage mean? #4: Can Congestion be predicted? #5: Is carrier data free/cheap? … Easy to get? … Easy to work with? #6: What do GPS equipped vehicles do for traffic monitoring? #7: How do you define accuracy? #8: Do multiple data sources increase data quality?
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AirSage turns anonymous cellular signals into real-time, comprehensive traffic and transportation-related information Speeds Travel Times 911 Incident Detection Historical Data Congestion Detection Highways and Arterials Delivery of:
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# 1: “Probe Data” ----- Wireless Signal Extraction (WiSE) Probe Data: Specific units (e.g. delivery trucks, busses) reporting back speeds -Floating Car Data -Cell Probe Data -Fleet data (e.g. delivery trucks, 18-wheelers) GPS Data: GPS units collecting speed data Wireless Signal Extraction (WiSE) Data: -Anonymous cell phone signal data -GPS data from 50,000,000+ cell phones
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# 2: Sensors cover a limited number of roadways After billions of dollars in investment, less than 10,000 miles of roadways are covered by sensors According to self-reported state data, operate with a 20% down-time -Breakages require work zones and crews to repair Safety Deaths -Maintenance and periodic calibration of sensors is expensive
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# 3: Coverage is measured in many different ways Coverage is measured using different methodologies -Lane Miles -Directional Miles -Centerline Miles (industry standard) Coverage is measured using different data sets -Flow Data -Incident Data -Historical (”Predictive”) Data Coverage is measured using different market sizes
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A view of sensor data around Washington DC indicates limited flow coverage… Washington DC Sensor Coverage Map
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… And a historical and “predictive” coverage map indicates data from as far away as West Virginia… Washington DC Historical Coverage Map
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… While WiSE technology provides comprehensive coverage of highways and arterials (hundreds of thousands of centerline miles … several orders of magnitude more than current sources)
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# 4: Congestion can not be predicted… According to the FHWA and The Texas Transportation Institute: Between 55%-60% of congestion is non-recurring Accidents can not be predicted Impact and severity of accidents can not be predicted Historical data used as a basis for traffic information can not be modeled to “predict” the “unpredictable”
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#5: Is carrier data free/cheap? …. Easy to get? … Easy to work with? Wireless carriers are in an intensely competitive industry; they require a substantive return on their investment Formally supported programs take time but are essential -Long term contract and Service Level Agreements in place -Firewall approvals -Internal department and deployment approvals Wireless carriers use different equipment (e.g. Nortel, Motorola) -Provides different types of data -Requires unique data processing
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# 6: GPS equipped vehicles can not detect congestion # 6: GPS equipped vehicles can not detect congestion There are over 230 million vehicles on the road today; Probe fleets represent less than 0.3% of vehicles on the roads today Probe fleets are often comprised of commercial vehicles -Prohibited from many roadways during rush hours -Have different driving patterns -Often report back as little as once per hour General Motors (2005 study): >5% of vehicles, or 11,000,000, would be required to cover the major US roadways The International University of Monaco (2003 study): 2.4% of all vehicles, or 5.5 million, would provide only a 50% chance of detecting congestion
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# 7: “Accuracy” - What does it mean? Segment lengths – 1, 5, 15? Speed within 5, 10, 15 mph of GTD (Ground Truth Data) Average Accuracy: -Severe congestion -Moderate congestion -No congestion Overall Average Error (mph) Severe Misses (off by one category or 25mph)
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# 8: Do you need multiple data sources to ensure accuracy & reliability? In the past, aggregation of traffic data was necessary -15 to 20 different DOT sources -Minimal sensor coverage -No alternative sources of data Today, Wireless Signal Extraction (WiSE) technologies provide comprehensive coverage -All highways -All major arterials GPS fleets of 500,000 on top of 50,000,0000 does not increase the value of data More data sources are necessary only when current data quality is poor and/or fragmented
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A discussion on terminology and perspectives #1: Wireless Signal Extraction (WiSE) is a disruptive approach to traffic data collection efforts #2: Sensors cover a limited number of roadways #3: Coverage claims can be misleading #4: Congestion can not be predicted #5: Expertise and relationships in working with wireless carriers is a fundamental requirement for WiSE traffic data collection #6: GPS equipped vehicles offer little value today #7: WiSE data provides reliable and accurate traffic data #8: Multiple data sources do not necessarily mean better data quality
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Thank You Thank You ITSA Presentation June 2007 AirSage Proprietary & Confidential
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