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Floating car data
Driving a vehicle in the traffic stream, trying to maintain an "average" position in the traffic stream, i.e:
passing only as many vehicles as pass you.
Inductive loop detectors
The most widely used sensors (for TM)
easy to install, inexpensive
time occupancy (%)
flow (number of vehicles)
speed (for double loops)
Calling and extension detectors
call for green (presence)
ask for green extension (queue)
Utilized in many cities with advanced management systems
Traffic lights exist to control the flow of traffic and are expected to bring benefits:
Minimize accident frequency and severity
If properly timed, a traffic signal increases the traffic handling capacity of an intersection
Manage traffic and travel times
Provide directions to drivers
Phase, Stage, Cycle
Phase: The sum of the displayed green, yellow and red times for a movement or combination of movements that receive the right of way simultaneously during the cycle.
Stage: A group of phases that receive the right of way simultaneously during the cycle for an intersection.
Cycle: The sum of the phase lengths is the cycle length.
Protected movement: A movement that has the right of way and does not need to yield to conflicting movements, such as opposing vehicle traffic. Through movements, which are always protected are given a green indication.
Permitted movement: A movement that must yield to opposing traffic flow. This movement is made during gaps.
Can be determined by using the cross-product.
Cross product rule
Cross product rule helps us identify if a movement should be protected or permitted. The cross-product is a simple approach that is only dependent on the peak-hour traffic flows\(\nu\).
Generally, we take the peak-hour traffic flow value of the traffic movement we want to check on protected movement and the opposing traffic movements. The determined values are checked against thresholds.
Cross product exceeds 50'000 vehicles during peak-hour for one opposing lane
Cross product exceeds 90'000 vehicles during peak-hour for two opposing lanes
Cross product exceeds 110'000 vehicles during peak-hour for three or more opposing lanes