Signal timings from simple to complex signal phasings
DIVERSITY OF APPLICATION
Signal timing analysis methods in SIDRA INTERSECTION cover an extensive area of application including single intersections and networks (cycle time, green splits and offsets), pretimed, SCATS-like EQUISAT, actuated and semi-actuated signals, variable phasing, pedestrian and minor vehicle phase actuation (phase skipping), turn on red, yield-controlled and continuous bypass lanes, and so on.
The SIDRA INTERSECTION network model uses lane-based signal platoon movements to determine second-by second arrival and departure flow patterns as a function of signal offsets for signal coordination assessment.
SIDRA INTERSECTION Version 9.1 includes tools to enable calibration for local conditions and presents many detailed signal timing output reports and displays.
Powerful traffic signal timing analysis for intersections, interchanges and networks
UNIQUE SIGNAL TIMING METHODOLOGY
Signal timing analysis methods in SIDRA INTERSECTION 9.1 cover an extensive area of application including single intersections, interchanges and networks, pretimed, actuated and semi-actuated signals, variable phasing, pedestrian and minor vehicle phase actuation, turn on red, yield-controlled and continuous bypass lanes, and so on.
SIDRA INTERSECTION 9.1 includes many signal timing features:
- NEMA Phase Numbering Scheme for US applications.
- Unique critical movement identification method.
- Network signal timings (cycle time, phase times and offsets) for signal coordination.
- Signal timings for multiple intersections operating under one signal controller.
- Graphical Interactive Offsets function.
- Unique Green Split Priority method for coordinated movements.
- Second-by-second modeling of platoon movements using the
SIDRA lane-based network model with midblock lane changes. - Detailed signal timing output reports and displays.
Unique Methodology Built On Strong Research Foundations
SIDRA was first developed implementing Dr Rahmi Akçelik’s well-known Research Report ARR 123 (Traffic Signals: Capacity and Timing Analysis. This was published by the Australian Road Research Board in 1981 and had a strong influence on signal analysis methods in the 1985 Highway Capacity Manual - an influence that continues today.
The original ARR 123 critical movement analysis method is the core element of the timing analysis method in SIDRA INTERSECTION. This method is built to handle simple to very complex phase sequences. The timing analysis methodology in SIDRA was further developed introducing many unique methods including the green split priority method, and more recently, the common control group method for multiple sites controlled by a single signal controller. The latter is important for timing analysis of traditional as well as innovative (compound) intersections and interchanges.
Example of Critical Movement Display using US NEMA Phase Numbering Scheme
Powerful Network Signal Timing Analysis
Network timing for signal coordination involves Network Cycle Time and Site Phase Time calculations as well as Signal Offsets calculated for Routes defined by users. Network Cycle Time, Site Phase Times and Signal Offsets can be specified by the user. Signal timings for Common Control Groups (CCGs), i.e. several signalised intersections operating under one signal controller, are calculated using a unique method that treats each CCG as a single entity.
Interactive Offsets function allows the user to modify Offsets manually towards achieving desired two-way signal progressions.
Displayed signal timings for vehicle and pedestrian movements
There is a useful feature in SIDRA INTERSECTION which is an option to show "displayed signal timings" for vehicle and pedestrian movements in the Movement Timing display. These are signal timings (red, green, yellow, flashing don't walk) as drivers see them as opposed to "effective timings" used in performance calculations. The improved display visualises the timing data given in tables included in the Timing Analysis and Pedestrian Analysis reports (see image below). Blue box in the timing bar indicates the effect of pedestrian actuation or minor phase actuation for vehicles.
