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Powerful SIDRA Network Model for performance results based on strong traffic research foundations
Analytical models for traffic design, operations and planning practice facilitate better knowledge and understanding of the laws that rule traffic movements (as distinct from, but based on, the behaviour of individual vehicles and their relationships) and the interactions of those movements in a complex traffic system.
The power of analytical models and lane-based analysis in traffic design and planning
Watching an animation, even if it is a perfect replication of the real-life conditions, does not reveal those laws to a modeller who does not have adequate knowledge based on concepts developed by decades of traffic science.
Lane-based algorithms in SIDRA INTERSECTION
The unique NETWORK model in our SIDRA INTERSECTION software package uses lane-based algorithms for traffic and transport planning, management, design and operations purposes.
These algorithms provide extensive capacity, level of service and performance output for multimodal traffic analysis allowing the modelling of all transport users (pedestrians, cyclists, buses, tram / light rail, cars and freight vehicles), traffic impact assessments, geometric design of roundabout corridors with other types of nearby intersections, efficient operation of traffic signal control systems, environmental assessments and development of balanced Movement and Place solutions.
SIDRA Model Features
Read a summary of the powerful SIDRA Model features in SIDRA INTERSECTION.
Main features
Research base
The SIDRA INTERSECTION network model is a culmination of 40 years of research and development - 20 years at the Australian Road Research Board and more than 20 years at SIDRA SOLUTIONS.
Refer to over 100 research papers and reports on our Publications Page.
Dr Rahmi Akçelik also publishes his work on ResearchGate. His research papers and reports on ResearchGate enjoyed approximately 85,000 reads and about 2,600 citations in eight years.
Lane-based model
A unique lane-based micro-analytical model differs from traditional link, lane group or approach-based models. This coupled with lane-based vehicle path (drive-cycle) models and an iterative approximation method to solve complex mathematical models provides an advanced micro-analytical traffic evaluation tool.
Highway Capacity Manual Setup
The Highway Capacity Manual (HCM) Setup in SIDRA INTERSECTION with options for US Customary and Metric units complements the HCM as a lane-based intersection and network analysis tool. Unlike other software packages, the SIDRA HCM Setup does not claim to be a simple replication of the HCM procedures. Instead, it complements the HCM by providing various extensions on the capabilities HCM offers.
SIDRA capacity and performance models are generally compatible with the HCM models in their basic structures and principles. In the HCM Setup, model parameters are calibrated using the HCM defaults.
Refer to HCM articles in our Publications section.
Easy to configure
Sites connected to form a Network; up to 50 Sites per Network;
contra-flow lanes allowed; easy to clone and modify Networks to test alternative treatments.
Routes
User-defined Routes for travel performance reports and displays, and Signal Offset calculations.
All Site types and Network configurations
Signals, roundabouts, sign control, signalised and unsignalised pedestrian crossings
Site and Network templates available including templates for alternative intersections, interchanges, paired intersections, roundabouts and staged crossings
Map Extract tool for new Sites to be created from map data
Movement Classes
Light vehicles, heavy vehicles, buses, bicycles, large trucks, light rail/trams and six user-configured classes with different vehicle characteristics (including queue space, speed, acceleration, mass, etc) can be allocated to different lanes, lane segments and signal phases, and signal platoon patterns can be tracked separately.
Special Movement Classes
Used for estimation of unequal lane use at closely-spaced intersections and interchanges; intersection turning volumes layered so as to identify external approach through movements that become turning movements at downstream internal approaches and the dogleg movements between side roads.
Fuel consumption and emission models (CO2, CO, HC, NOx)
Environmental impacts of proposed traffic design, operations and planning schemes can be assessed.
Models calibrated for modern vehicles.
Highly accurate four-mode elemental model (acceleration - cruise - deceleration -idle) applied to vehicle paths of queued and unqueued vehicles in individual lanes.
Demand and Sensitivity analysis
Design Life, Flow Scale and Parameter Sensitivity analysis for Sites and Networks.
SIDRA API
SIDRA API provides a programming interface that enables external applications to communicate with SIDRA INTERSECTION to achieve more.
VOLUMES utility helps users as a simple application of SIDRA API.
Network model
Queue Spillback (backward spread of congestion)
Analytical model based on the probability of blockage of upstream lanes by downstream queues at all types of facilities.
Back of queue extending upstream at intermediate locations with continuous lanes including major roads at sign-controlled intersections modelled.
Saturation flow and capacity reduction
Dynamic saturation flow estimation to allow for upstream lane capacity losses due to lane blockage with effect on signal timing calculations.
Capacity constraint
Exit flow rates from oversaturated upstream lanes entering downstream lanes are limited to capacity flow rates (arrival flow rates differ from demand flow rates).
Iterative method
Network-wide iterative process to find a capacity - performance solution that balances the opposing effects of queue spillback (lane blockage) and capacity constraint, with corresponding signal timing solution where applicable.
Lane movements
Flow proportions for lane movements from each approach lane to each exit lane can be specified; relevant to modelling forward movement of platoon patterns and backward effect of lane blockages.
Traffic volumes
Site turning volumes (approach-movement demand flow rates) used.
Midblock inflow and outflow rates
Determined from Site approach-movement demand flow rates; significant effect on signal platoon modelling.
Midblock lane changes
Determined from upstream and downstream lane flow rates to allow the user to calibrate external approach lane use.
Basic model elements
Back of queue model (average and percentile queues)
Key parameter to estimate lane-based probabilities of blockage or overflow in queue spillback and short lane models with percentile queue modelling; used for signals as well as gap-acceptance processes (roundabouts and sign control).
Short lane model
Complex multiple short lane configurations modelled.
Blockage of upstream intersection lanes by short lane queues that overflow into full-length lanes at a downstream intersection modelled.
Shared lane model
Blockage of movements with different signal control characteristics blocking each other in shared lanes modelled using the free queue method.
Merge model
Merge Model for exit short lanes at any type of intersection with Priority Merge and Zipper Merge operations.
U-Turns
Available at all Site types; U-Turn before intersection available at signalised and unsignalised Sites.
Continuous lanes
Continuous movement (uninterrupted flow) model with detailed performance estimates.
Pedestrians
Extensive treatment of signalised and unsignalised (zebra) pedestrian crossings at intersections and midblock locations.
Effect of pedestrian movements on signal timings (including pedestrian actuation feature).
Delays and other performance estimates for pedestrian movements at signalised intersections.
Effect of pedestrians on capacity and performance of vehicle movements.
Staged pedestrian crossings with selectable elements (approach or exit side crossing can be specified as not existing)
Unsignalised (zebra) crossings on slip / bypass lanes at all types of intersection.
Roundabouts
Roundabout capacity and performance
Roundabout capacity and performance models developed as part of an integrated performance modelling framework developed considering all types of intersection allows comparison of roundabout design with signalised and sign-controlled intersections in one package using consistent methodology.
Roundabouts with 2 or more entry and circulating lanes with any configuration.
Roundabout corridors and networks with signals, sign-controlled intersections and pedestrian crossings.
Roundabout Level of Service option.
Negotiation speeds and distances and geometric delays estimated.
Capacity constraint
Capacity constraint method applied to oversaturated lanes as an essential element of roundabout analysis.
Unbalanced flow conditions
Roundabout is treated as an interactive system for modelling of unbalanced flow conditions.
Upstream signals
Effect of upstream signals on capacity is taken into account by determining extra bunching in circulating flows.
Roundabout metering signals
Unique method for analysis of metering signals on one leg of the roundabout.
SIDRA Standard Roundabout Capacity Model Features
Environment Factor parameter for easy model calibration for different local conditions.
The effects of driver yield behaviour and roundabout geometry factors on capacity and level of service are taken into account using a unique lane-by-lane analysis method combined with gap-acceptance parameters that are empirically based.
The effect of roundabout geometry parameters (roundabout size, circulating road width, entry radius, entry angle, etc.) on capacity included.
Critical Gap and Follow-Up Headway Reduction with increasing demand flows in design life analysis.
Effect of Heavy Vehicles and other Movement Classes on capacity taken into account using the Gap Acceptance Factor and Opposing Vehicle Factor parameters.
Highway Capacity Manual Roundabout Capacity Model Options
The US HCM Software Setup in SIDRA INTERSECTION uses the HCM Edition 6 roundabout capacity model as the default model, continues to offer the HCM 2010 roundabout capacity model option, and offers the SIDRA Standard (HCM) roundabout capacity model option calibrated for HCM with default Environment Factors of 1.05 for single-lane roundabouts and 1.20 for two-lane roundabouts to match the lower capacity estimates based on US roundabout research. Roundabout Capacity Model in HCM Edition 7 is the same as the model in HCM Edition 6.
Roundabout Capacity Model Comparison
Articles comparing the features of SIDRA Standard model, HCM model described in Highway Capacity Manual Edition 6, and the UK TRL model implemented in the RODEL and ARCADY software can be found under Publications.
The features compared include methodology, model level of detail (lane-based or approach-based), parameters used in the model to represent driver behaviour and roundabout geometry, and model calibration methods.
Signal Timings
Network timing for signal coordination
Cycle time and phase times:
Practical cycle time, optimum cycle time and user-given cycle time with program-determined and user-given phase times.
Offsets for signal coordination:
Calculated for Routes defined by users.
Interactive Offsets function allows the user to modify Offsets manually towards achieving desired two-way signal progressions.
Offset calculations and platoon progression with continuous lanes between two signalised intersections
Common Control Groups (CCGs)
Signal timing method for several signalised intersections operating under one signal controller as a single entity.
Signal timing (general)
Timing analysis using group control methodology treating vehicle turning movements by Movement Class (light and heavy vehicles, buses bicycles, and so on) and pedestrian movements individually.
Fixed-time / pretimed, SCATS-like EQUISAT, actuated and semi-actuated signal analysis methods.
Simple and complex phasing arrangements; variable phasing analysis.
ARR 123 critical movement identification method.
Green split priority for coordinated movements.
Undetected movements and phase transition methods.
Pedestrian actuation (variable pedestrian minimum time effects).
Minor phase actuation (phase skipping); phase frequency adjustments.
Late start and early cut-off.
Red arrow drop off.
Give-way / yield controlled and continuous slip / bypass lanes.
Turn On Red (gap acceptance method for capacity estimation).
SCATS parameters output.
Signal platoons
Signal platoons
Lane-based method to determine second-by second arrival and departure flow patterns as a function of Signal Offsets including a unique platoon dispersion model.
Midblock lane changes and midblock inflows and outflows taken into account when moving signal platoon patterns between intersections.
Second-by-second signal platoons modelled and tracked for each Movement Class separately.
Extra bunching
Effect of upstream signals on gap-acceptance capacity of roundabouts and two-way sign-controlled intersections modelled by increased bunching.
Routes
Route as a series of movements in one direction of travel
Routes can be defined in a very flexible way for travel performance results and signal offset calculations.
Route travel time
Route travel time and average travel speed estimates can be used for model calibration.
Route travel times include geometric delays, acceleration and deceleration delays for oversaturated conditions, travel times include delays experienced until all vehicles arriving during the analysis period have departed.
Site, network and route output
User Reports
Users can define User Report Templates to include selected output report and display elements (tables, graphical displays).
Customised output
Users can select the elements (tables, graphical displays) that they wish to include in standard reports and displays.
PDF Output
PDF Output function is available to save the output reports and displays in a PDF report.
Consistent displays for Sites, Networks and Routes
Approach Displays, Lane Displays, Movement Displays, Lane Flows, Movement Flows displays for Sites, Networks and Routes, and Midblock Flow and Lane Changes displays for Networks and Routes presented consistently. Other reports are listed below.
Network reports and displays
Diagnostics, Network Summary, Network Graphs, Network Variable Run Phase Timings, Signal Offsets.
Route reports and displays
Route Summary, Route Travel Performance, Time-Distance diagram (one or two directions).
Site reports and displays (individual Sites and Network Sites)
Diagnostics, Detailed Output, Intersection Summary, Movement Summary, Lane Summary, Fuel, Emissons & Cost, Queue Analysis, Lane Blockages, Lane Changes, Graphs, Variable Run, Lane LOS, Demand Flows.
Signal Timing reports for Sites (individual Sites and Network Sites)
Phasing Summary, Timing Analysis, Movement Timing, Saturation Flows Signal Coordination, Multiple Sequence Analysis, Pedestrian Analysis.
Roundabout and Sign Control reports
Roundabout Analysis, Roundabout Metering, Sign Control Analysis.
Other reports
Input Comparison reports for Sites and Networks.
Output Comparison reports for Sites, Networks and Routes.
Project Summary report.