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Calling all cars: cell phone networks and the future of trafficPresentation by Scott CoreyArticle written by Haomiao HuangThe Future of CarsSelf-driving cars?Boosting the brainpower of the environment cars drive inTraffic monitoring has been revolutionizedAn intelligent highwayReducing the effect of traffic jams and accidentsTraffic control schemes to react to real time dataAid in planning for the future

SensorsMonitor trafficParking availabilityAir pollutionHave traditionally been static sensorsInductive Loop DetectorsTraffic CamerasRFID tags

ProblemsExpensive to deploy, operate, repairPlaced only at key locations

Mobile sensors are a necessity

Mobile PhonesEquipped with GPS and Internet accessSmartphones enable more widespread source of data

Worldwide, there are more cell phones in use than toothbrushes

Mobile MillenniumOne of the first large-scale phone-based traffic monitoring projects in the USRun by Nokia, NAVTEQ, and UC Berkeley

Gathering data, but privatelyUser privacy is key for user acceptanceTwo main needs:Preventing the path of a vehicle to be reconstructedSeparating the identification of the phone from the dataAnonymityData from phones is tagged with user informationThe data packet is encrypted at transmissionProxy server cannot decrypt packet, but can strip identifying informationSent to traffic servers after information strippedReconstructing pathsUses virtual trip lines instead of constant reportingVTL spacing varies based on speed to maximize number of carsRandomizing measurements

Making sense of it allUC Berkeley tasked to fuse all the data togetherGPS from phonesGPS data from dedicated vehiclesStatic 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 mapsGPS tracks are useless alone need to combine with maps to know what road network you are monitoringMeasurements have to use machine-learning methods to correct for people walking with phones, parked cars

The flow of trafficTracking thousands of cars individually is difficult and expensiveTraffic researchers treat movement of cars as liquid flowing through tubes

Fluid DynamicsRequires initial conditions and rate of cars entering/leaving roadwayFluid dynamics model works well with fixed sensorsCameras can determine initial conditionsSensors attached to on and off rampsDisruptionsDrivers are not perfectAccidentsUnnecessary slow-downs

Adding GPS dramatically increases the versatility of the fluid modelGPS incorporated as internal conditions for the flow to satisfy

Mobile CenturyProof of concept test100 cars with mobile phones mixed into trafficRan for 10 hours with 150 student driversDespite 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 minuteTill all are oneConcepts and technology are now widespreadMobile sensors used to identify potholes in roadsConnections to vehicle sensorsMobile sensing is the future