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Calling all cars: cell phone networks and the future of trafficPresentation by Scott CoreyArticle written by Haomiao Huang
The Future of Cars Self-driving cars? Boosting the brainpower of the
environment cars drive in Traffic monitoring has been
revolutionized
An intelligent highway Reducing the effect of traffic jams and
accidents Traffic control schemes to react to real
time data Aid in planning for the future
Sensors Monitor traffic Parking availability Air pollution Have traditionally been static sensors
Inductive Loop Detectors Traffic Cameras RFID tags
Problems Expensive to deploy, operate, repair Placed only at key locations
Mobile sensors are a necessity
Mobile Phones Equipped with GPS and Internet access Smartphones enable more widespread
source of data
Worldwide, there are more cell phones in use than toothbrushes
Mobile Millennium One of the first large-scale phone-based
traffic monitoring projects in the US Run by Nokia, NAVTEQ, and UC Berkeley
Gathering data, but privately User privacy is key for user acceptance Two main needs:
Preventing the path of a vehicle to be reconstructed
Separating the identification of the phone from the data
Anonymity Data from phones is tagged with user
information The data packet is encrypted at
transmission Proxy server cannot decrypt packet, but
can strip identifying information Sent to traffic servers after information
stripped
Reconstructing paths Uses virtual trip lines instead of
constant reporting VTL spacing varies based on speed to
maximize number of cars Randomizing measurements
Making sense of it all UC Berkeley tasked to fuse all the data together GPS from phones GPS data from dedicated vehicles Static sensors
Given all of the measurements being gathered and a stretch of road of interest, what is the best estimate of the number of cars on that road, and how fast they're going?
Combining data with maps GPS tracks are useless alone – need to
combine with maps to know what road network you are monitoring
Measurements have to use machine-learning methods to correct for people walking with phones, parked cars
The flow of traffic Tracking thousands of cars individually
is difficult and expensive Traffic researchers treat movement of
cars as liquid flowing through tubes
Fluid Dynamics
Requires initial conditions and rate of cars entering/leaving roadway
Fluid dynamics model works well with fixed sensors
Cameras can determine initial conditions
Sensors attached to on and off ramps
Disruptions Drivers are not perfect
Accidents Unnecessary slow-downs
Adding GPS dramatically increases the versatility of the fluid model
GPS incorporated as internal conditions for the flow to satisfy
Mobile Century Proof of concept test 100 cars with mobile phones mixed into
traffic Ran for 10 hours with 150 student drivers Despite accounting for 2-5% of cars on
the highway, speed and density of cars measured at a high resolution
Accident was detected and reported in less than a minute
Till all are one Concepts and technology are now
widespread Mobile sensors used to identify potholes
in roads Connections to vehicle sensors Mobile sensing is the future