Software for Smart Traffic Engineering


The following is a summary of the new features of SIDRA INTERSECTION 8:

More Powerful and Efficient Processing

Substantial increases are achieved in computing speeds for the iterative network analysis method enabling introduction of facilities for optimum timings as well as demand and sensitivity analysis for networks. Average computing speeds about 5 to 10 times faster than previous versions can be expected in Network analysis

Increased efficiency of database operations have also been achieved and memory management enhancements have been introduced.

Enhanced User Interface

Significant user interface improvements introduced for ease of use of the software include:

  • graphical displays of Layout, Volumes, Phase Sequence and Movement IDs within most Site input dialogs for assisting the input data entry process and allowing direct in-display data entry;
  • various commands that were hidden in right-click menus in previous versions made available in the Site / Network / Route ribbon or in Site Output sections;
  • right-clicking an output report or display to open the relevant Site / Network / Route input menu and some display commands;
  • double-clicking Site / Network / Route name to open the relevant layout picture;
  • modified processing icon animation according to the new structure for Network model iterations;
  • where Network parameters override Site data, no need to process the Network again if any of the corresponding parameters are changed in Sites that constitute the Network;
  • improved Import Volume Data function;
  • simplified Volume Data Settings for Pedestrians;
  • various improvements in the CCG Phasing & Timing and the Network Data dialogs;
  • cancelling processing of multiple Sites and Networks;
  • option to include or exclude suffixes (Copy, Conversion, Import, Reversed) when Clone, Import, Convert, Reverse functions are used for Sites, Networks, Routes and Sequences;
  • improved Zoom Slider including a dialog to set exact zoom values.

Better Output Reports and Displays

These have been enhanced significantly. New Site, Network and Route output reports and displays include:

  • Project Summary report using the new Site Category and Network Category parameters;
  • User Report facility based on user-defined report templates;
  • enhanced Input Comparison and Output Comparison facilities using results from different Projects;
  • Lane Changes, Lane Flows, Network Flows and Midblock Flows displays for the whole Network with pop-up boxes showing demand and arrival flows by movement class;
  • Approach Distances display for Networks;
  • Numerical values shown in all Network and Route Displays;
  • Signal Coordination displays in the form of Lane Displays for Sites, Networks and Routes, and Movement Displays for Sites;
  • Route Travel Performance report;
  • Saturation Flows report for signalised Sites;
  • Critical Movements display for signalised Sites with a phase - movement timings bar display and an ARR 123 style critical movement diagram;
  • Movement Timing display for Common Control Groups (CCGs) showing all movements of the CCG together;
  • Gap Acceptance Cycle Parameters included in the Sign Control Analysis and Roundabout Analysis reports.

Significant Network Model Improvements

Important model improvements have been made including:

  • Optimum Cycle Time for Networks;
  • Optimum Cycle Time and Optimum Maximum Green Settings for Common Control Groups;
  • new Phase Time calculation options;
  • improved treatment of Uncoordinated and Unconnected Sites for signal timing calculations;
  • Network Demand and Sensitivity analysis methods for design life, flow scale and parameter sensitivity;
  • Queue at Start of Green and Average Number of Cycles to Depart for signalised Sites;
  • enhanced methods used for stopping conditions in Network and Site model iterations with Network Model Variability Index and Site Model Variability Index parameters given in various output reports and displays;
  • improvements to the iterative method used for Site capacity and timing analyses resulting in fewer cases of unsettled results.


The SIDRA INTERSECTION software is for use as an aid for design and evaluation of individual intersections and networks of intersections. It can be used to analyse signalised intersections (fixed-time / pretimed and actuated), signalised and unsignalised pedestrian crossings, roundabouts (unsignalised), roundabouts with metering signals, fully-signalised roundabouts, two-way stop sign and give-way / yield sign control, all-way stop sign control, single point interchanges (signalised), freeway diamond interchanges (signalised, roundabout, sign control), diverging diamond interchanges. It can also be used for uninterrupted traffic flow conditions and merge analysis.

SIDRA INTERSECTION allows modelling of separate Movement Classes (Light Vehicles, Heavy Vehicles, Buses, Bicycles, Large Trucks, Light Rail / Trams and two User Classes) with different vehicle characteristics. These movements can be allocated to different lanes, lane segments and signal phases, for example for modelling bus priority lanes at signals.

Signal timing calculations for single intersections and network timings including signal offsets for signal coordination are carried out. A unique method is used to determine signal timings for a number of intersections operating under a single signal controller (common control groups).

SIDRA INTERSECTION is an advanced micro-analytical traffic evaluation tool that employs lane-by-lane and vehicle path (drive-cycle) models coupled with an iterative approximation method to provide estimates of capacity and performance statistics (delay, queue length, stop rate, etc). All input and output data and modelling is based on Origin-Destination movements. This improves handling of movements at intersections with diagonal legs and U turns.

The SIDRA NETWORK model determines the backward spread of congestion as queues on downstream lanes block upstream lanes (queue spillback), and applies capacity constraint to oversaturated upstream lanes, thus limiting the flows entering downstream lanes. These two elements are highly interactive with opposing effects. A network-wide iterative process is used to find a solution that balances these opposing effects.

Unlike traditional network models that use aggregate models of "links" or "lane groups", SIDRA INTERSECTION uses a lane-based model to create second-by-second platoon arrival and departure patterns for signalised Sites (at-grade intersections, interchanges, pedestrian crossings) to calculate signal coordination effects as a function of signal offsets for internal approaches in network analysis.

The model takes into account midblock lane changes that apply to signal platoon patterns. This is particularly important in evaluating closely-spaced (paired) intersections with high demand flows where vehicles have limited opportunities for lane changes between intersections. These lane-based modelling requirements are important in emulating the forward movements of platoons for estimating performance measures (delay, back of queue, stop rate) at an individual lane level.

SIDRA INTERSECTION provides various facilities for calibration of its traffic models for local conditions. The US HCM version of SIDRA INTERSECTION is based on the calibration of model parameters against the US Highway Capacity Manual (see the section titled About the HCM Setup of SIDRA INTERSECTION).

In the USA, SIDRA INTERSECTION is recognised by the US Highway Capacity Manual, TRB Roundabout Guide (NCHRP Report 672) and various local roundabout guides. In Australia and New Zealand, SIDRA INTERSECTION is endorsed by AUSTROADS and various local guidelines (the Association of Australian State, Territory and Federal Road and Transport Authorities).

Since its first release in 1984, the use of SIDRA INTERSECTION has grown steadily over the years to make it a best-selling software package. In April 2016, the latest versions of the software were in use by over 1900 organisations with about 8300 licences in 86 countries. The countries where SIDRA INTERSECTION was used most extensively were (with the approximate number of organisations shown) USA (650), Australia (440), Europe (200), New Zealand (70), South Africa (110), Canada (100), Malaysia & Singapore (110), Arabian Peninsula (90) and Latin America (60).

On-going development

SIDRA INTERSECTION has been a valuable technology transfer tool based on extensive research carried out in Australia, USA and elsewhere. It has been developed continuously in response to feedback from practising traffic engineers and planners. This feedback has improved the methods used in SIDRA INTERSECTION and expanded its functionality to cover a wider range of problems. SIDRA INTERSECTION now uses one of the most advanced methodologies of any traffic design package.



  • analyse a large number of intersection types including signalised intersections
    (fixed-time / pretimed and actuated), signalised and unsignalised pedestrian crossings, single point interchanges (signalised), roundabouts (unsignalised), roundabouts with metering signals, two-way stop sign and give-way / yield sign control, all-way stop sign control, give-way / yield sign-control and merge analysis;
  • analyse any network with up to 20 Sites including roundabout corridors, a mixture of signalised intersections, roundabouts and sign control, and so on;
  • using the network model, analyse paired (closely-spaced) intersections including staggered T intersections, freeway signalised diamond interchanges, freeway roundabout interchanges, fully-signalised roundabouts (including signalised circulating roads), large signalised intersections with wide median storage areas, staged crossings at sign-controlled intersections, pedestrian crossings near intersections, and alternative intersection and interchange configurations such as diverging diamond interchanges (signalised), continuous flow intersections, restricted cross street U turns, and so on;
  • use diverse movement classes including Standard Movement Classes (Light Vehicles and Heavy Vehicles, Buses, Bicycles, Large Trucks, Light Rail / Trams) and User Classes to analyse bus lanes and phases, bicycle lanes and phases, the effect of heavy vehicles on intersection capacity and performance, and so on;
  • obtain estimates of capacity and performance characteristics such as delay, queue length, stop rate as well as operating cost, fuel consumption and pollutant emissions for all intersection types;
  • analyse many design alternatives to optimise the intersection and network geometry, signal phasing and timings specifying different strategies for optimisation;
  • handle intersections with up to 8 legs, each with one-way or two-way traffic, one-lane or multi- lane approaches, and short lanes, slip /bypass lanes, continuous lanes, turn bans, U turns, contra flow lanes as relevant;
  • determine signal timings (fixed-time / pretimed and actuated) for any intersection geometry allowing for simple as well as complex phasing arrangements;
  • carry out a design life analysis to assess impact of traffic growth;
  • carry out a parameter sensitivity analysis for calibration, optimisation, evaluation and geometric design purposes;
  • design intersection geometry including lane use arrangements taking advantage of the unique lane-by-lane analysis method of SIDRA INTERSECTION for individual Sites and Networks;
  • determine short lane lengths (turn bays, lanes with parking upstream, and loss of a lane at the exit side);
  • analyse complicated cases of shared lanes and opposed turns (e.g. permissive and protected phases, slip lanes, turns on red);
  • analyse oversaturated conditions making use of the time-dependent delay, queue length and stop rate models used in SIDRA INTERSECTION. 

In using SIDRA INTERSECTION, you can:

  • prepare data and inspect output with ease due to the graphical nature of SIDRA INTERSECTION input and output, and use extensive templates supplied with the software;
  • obtain output including capacity, timing and performance results reported for individual lanes, individual movements, movement groupings (such as vehicles and pedestrians), and for the intersection and network as a whole;
  • obtain network displays for graphical representation of network performance;
  • use options to set up output reports and displays;
  • in your reports, present your data and results in picture and graphs form;
  • carry out sensitivity analyses to evaluate the impact of changes on parameters representing intersection geometry and driver behaviour;
  • calibrate the parameters of the operating cost , fuel consumption and emission models for your local conditions allowing for factors such as the value of time and resource cost of fuel;
  • set User Setups for default systems that reflect your local traffic conditions;
  • use Excel VOLUMES and ANNUAL SUMS utilities provided using the SIDRA INTERSECTION Application Programming Interface.

› What can SIDRA NETWORK Model Do?

SIDRA INTERSECTION employs a unique lane-based micro-analytical network model unlike traditional link-based network models where links represent lane groups in which traffic conditions of individual lanes are aggregated and therefore lost in more aggregated traffic units. Such link-based (lane-group based) and approach-based network models cannot identify backward spread of congestion for closely-spaced intersections adequately.

SIDRA INTERSECTION allows you to evaluate the performance of a Network with interactions between component Sites. The SIDRA INTERSECTION network model will:

  • allow the user to configure a detailed lane-based Network including signalised and sign-controlled intersections and roundabouts with ease;
  • allow user-specified Route definitions for performance reports and displays, and for signal offset calculations;
  • provide detailed Network and Route performance estimates in a variety of output reports and displays (including Route travel time and distance);
  • determine blockage of upstream lanes by downstream queues;
  • estimate capacity reduction of upstream lanes due to lane blockage;
  • emulate backward spread of congestion (queue spillback);
  • apply capacity constraint to oversaturated upstream lanes to determine exit flow rates and limit the flows entering downstream lanes;
  • take into account midblock inflow and outflow rates implied by user input of Site volumes;
  • allow the user to control lane movement flow proportions to determine the exit lane use;
  • determine midblock lane changes implied by upstream and downstream lane flow rates so that the user can calibrate external approach lane use patterns;
  • use a network-wide iterative process to find a solution that balances the opposing effects of lane blockage and capacity constraint;
  • determine network cycle time, phase times and signal offsets for coordinated signal systems;
  • determine signal timings for Common Control Groups (several signalised intersections operating under a single signal controller);
  • use second-by second arrival and departure flow patterns as a function of signal Offsets to model forward movement of signal platoons for coordinated signal Sites including a unique platoon dispersion model;
  • apply midblock lane changes when moving second-by second signal platoon patterns between intersections;
  • use the extra bunching parameter determined by the program to allow for the effect of upstream signals on gap-acceptance capacity of roundabouts and two-way sign-controlled intersections;
  • allow the use of Special Movement Classes to represent Through movements at external approaches which become turning movements at downstream internal approaches, and the dogleg movements between side roads of two closely-spaced intersections; allocate these movements to specific approach lanes according to movement through the network; and track second-by-second signal platoons for these movements separately.

› Benefits of using SIDRA INTERSECTION

The benefits of the SIDRA INTERSECTION software include the following:

  • a unique lane-based analytical road traffic Network model
    • helps the traffic engineering profession to find and implement measures to alleviate congestion and handle complicated network design, planning and operation cases with greater confidence and in an efficient way;
    • helps to achieve road network performance improvements that will deliver large economic and community benefits;
    • provides the functionality to model movement classes to enable the traffic engineering and transport planning profession design and assess such measures as bus priority lanes, bicycle lanes, tram /light rail lanes and signals;
  • energy and emission models help to assess environmental impacts of proposed traffic design, operations and planning schemes with a practical calibration method that enables the SIDRA INTERSECTION models to be used for modern vehicles;
  • a method that takes into account the intersection geometry and flow conditions automatically in determining capacity of sign-controlled intersections;
  • a method that allows for the effects of vehicle bunching caused by upstream traffic signals in determining capacity of roundabouts;
  • a Network model that includes detailed movements of vehicle platoons with lane changes between signalised intersections for assessing the efficiency of signal coordination systems and optimising signal timings for signalised intersection networks to allow signal timing plans to be prepared for existing networks and used as part of assessment of proposed networks;
  • enhanced network timing calculation methodology to determine network cycle time, phase time and signal offsets for signal coordination in signalised intersection networks, and to determine timings for common control groups (several signalised intersections controlled by a single signal controller);
  • a timing method that differs from existing methods in being derived from a lane-based network model that allows for queue spillback effects of signal timings;
  • a method to enable preparation of route-based signal coordination plans that are suitable for use in existing signal control systems such as SCATS used in Australia and worldwide.

For further information please visit:


Traffic Engineering

Adem Aslan
(Dipl. -Ing. Civil Engineering / Transportation)

Erzbergerallee 65
52066 Aachen