ADVANCED SOFTWARE FOR SIGNAL ANALYSIS
SIDRA INTERSECTION is a powerful software package for timing, capacity, performance and level of service analysis of signalised intersections (junctions controlled by traffic lights) including signal coordination effects. It uses an advanced critical movement analysis method allowing for overlap movements and movements with two green periods per cycle.
Features of SIDRA INTERSECTION
TRAFFIC SIGNAL TIMING
SIDRA INTERSECTION uses powerful methods for determining signal timings using fixed-time (pretimed) and actuated signal analysis methods for any intersection geometry allowing for simple as well as complex phasing arrangements involving overlap movements. Practical cycle time, optimum cycle time, user-given cycle time and user-given phase times options are available. Advanced signal timing options available in SIDRA INTERSECTION include green split priority for coordinated movements, equal and unequal target degrees of saturation, cycle time optimisation for fixed-time / pretimed signals or coordinated actuated signals, and maximum green optimisation for actuated signals.
SIGNAL MODEL FEATURES
SIDRA INTERSECTION models for analysis of traffic signals include turn on red (RTOR or LTOR), semi-actuated signals, and allow for such features as undetected movements, dummy movements and phase transition data. Graphical input method can be used for easy specification of phasing and timing data including known phase times.
SCATS CONTROL
For intersections running under the SCATS control system, fixed-time / pretimed analysis method available in SIDRA INTERSECTION can be used to emulate equal degree of saturation method used by SCATS for green splits. SIDRA INTERSECTION output includes estimates of SCATS parameters maximum flow and headway, occupancy time and space time at maximum flow. These parameters, together with the SCATS lane flow data can be used for model calibration purposes where applicable.
CYCLE TIME & GREENSPLIT OPTIONS
SIDRA INTERSECTION offers different options to specify the desired method of cycle time calculation for traffic signals (subject to minimum and maximum cycle time constraints):
Practical Cycle Time: A cycle time (and green times) that satisfy the practical (target) degree of saturation for critical movements are determined.
Optimum Cycle Time: A cycle time that optimises a selected performance measure is determined for fixed-time (pretimed) or coordinated actuated signals. One of a large number of options can be chosen as the performance function to determine the best cycle time.
User-Given Cycle Time: The green times using the given cycle time are determined for fixed-time (pretimed) or coordinated actuated signals.
User-Given Phase Times: The phase times given for the selected sequence are used. In this case, the phase times are added to determine the cycle time.
The Green Split Priority option is available for the allocation of longer green times to coordinated movements while keeping other movements at their target (practical) degree of saturation levels.
Parameters for Actuated Signal timing analysis include Maximum Green Setting, Gap Setting and Effective Detection Zone Length. Actuated signal timings can be optimised by varying the Maximum Green Settings.
RESOURCES
Below are some useful resources relating to traffic signals.
Stops & Goes of Traffic Signals
Download (PDF 370KB)
Transfund New Zealand (now part of Land Transport New Zealand) funded the development of a signal audit methodology in order to examine the safety and efficiency of traffic signals. A representative number of signal installations across nine territorial local authorities (TLAs) were audited. Stops & Goes of Traffic Signals presents findings of this study. Targeted at engineers who design, construct, install, manage and maintain traffic signals, the booklet examines the key factors required for safe and efficient operation of signalised intersections. These include technical requirements of the signals such as phasing and operational issues, intersection and lane layout, placement of signal posts, road marking, conspicuity of signals and other factors influencing the environment at intersections.
AUSTROADS Traffic Signals Guide
ERRATA_AUSTROADS Traffic Signals Guide
The third edition of AUSTROADS Traffic Signals Guide (Guide to Traffic Engineering Practice Part 7) was published in June 2003. Rahmi Akcelik acted as the Technical Writer and Editor to implement this major revision of the 1993 edition under the directions of an AUSTROADS reference group during the last five years.
Reference
AUSTROADS (2003). Guide to Traffic Engineering Practice Part 7 - Traffic Signals. AP-G11.7. Sydney. 184 pages.
Contents (PDF 70KB)
Keywords
Bicycle, Cycle (traffic signals), Delay, Design, Design speed, Detection, Dividing line, Driver behaviour, Fixed time (signals), Gap acceptance, Junction (intersection), Interchange, Lantern, Layout, Level of service, Linked signals, Parking, Pavement marking, Pedestrian, Pedestrian crossing, Performance, Public transport, Queue, Road marking, Road user, Roundabout, Safety, Sight distance, Signalisation, Signalised crossing, Traffic control, Traffic flow, Traffic lane, Traffic island, Traffic management, Traffic sign, Traffic signal, Vehicle actuated, Vehicle spacing
Abstract
The AUSTROADS Guide to Traffic Engineering Practice provides a comprehensive coverage of traffic surveys, analysis, layout, design, traffic management, and road safety standards and practices in Australia. To date, 15 parts of the guide have been published. Part 7 - Traffic Signals (2003) is a major revision of the 1993 publication. It incorporates the latest practice in the safe and efficient design of traffic signal installations. Part 7 presents detailed information and provides guidelines on collection of design data, geometric elements, signal system and components, signal face layouts and display sequences, signal phasing, location of signal equipment, traffic detection, signal controllers, pavement markings, signs, electrical design, coordination of traffic signals, installation checks and maintenance, and special applications including advance warning signals, emergency vehicle facilities, public transport priority, bicycle facilities, roundabout metering signals, ramp metering signals, special intersection treatments, overhead lane-control signals, single-lane operation and portable signals, left turn on red, and metering signals at sign-controlled intersections. Appendices provide detailed discussions on human factors and vehicular traffic characteristics relevant to traffic signal control, provide guidelines for determining signal timings, and give a complete worked example. A glossary of terms is included.
Traffic Signal Photos
This collection of photos includes some unusual traffic signal arrangements.
Please download it for your personal use (permission required for commercial use).
Traffic Signal Photos (PDF 360KB)
Contact us for PowerPoint version