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Erstellt / Aktualisiert 20.06.2021 / 10.08.2022
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0 Exakte Antworten 78 Text Antworten 0 Multiple Choice Antworten
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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.

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Inductive loop detectors

  • The most widely used sensors (for TM)
    • magnetic field
    • easy to install, inexpensive
  • Measurements:
    • time occupancy (%)
    • flow (number of vehicles)
    • speed (for double loops)
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Calling and extension detectors

  • Detectors that
    • call for green (presence)
    • ask for green extension (queue)
  • Utilized in many cities with advanced management systems
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Traffic Lights

Traffic lights exist to control the flow of traffic and are expected to bring benefits:

  • Increased safety
  • 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
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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.

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Protected/Permitted movement

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.

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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

Cross Product:    \(CP_{\phi_i,\phi_j} = v_i \cdot v_j\)

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Traffic Signal - Stage

A stage is a group of phases (i.e. movements) that don't create conflicts and are compatible, i.e. they can operate together.