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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 software setups (Customary and Metric units) of SIDRA INTERSECTION is based on the calibration of model parameters against the Highway Capacity Manual.

In the USA, SIDRA INTERSECTION is recognised by the US Highway Capacity Manual, TRB Roundabout Guide (NCHRP Report 672) and various local roundabout guides. SIDRA INTERSECTION is the most widely-used software tool in the USA for roundabout capacity and performance analysis.  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 February 2017, the latest versions of the software were in use by about 1930 organisations with about 8200 licences in 84 countries. The countries where SIDRA INTERSECTION was used most extensively were (with the approximate number of organisations shown) USA (650), Australia (440), Europe (190), New Zealand (70), South Africa (120), 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.



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  • 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 templatessupplied 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, and also obtain output for Routes that you define;
  • obtain approach, movement and lane displays for graphical representation of site, network and route performance;
  • use options to manage output reports and displays;
  • carry out Input Comparison and Output Comparison, and produce Project Reports that summarise results for Sites, Networks and Routes;
  • prepare your own User Report templates that include your preferred report and display elements, and produce output reports using these templates;
  • in your reports, present your data and results in picture and graphs form;
  • calibrate key performance parameters such as saturation flow rate, critical gap and follow-up headway, queue space, and so on for the SIDRA traffic models to represent your local traffic conditions;
  • 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 the Excel VOLUMES utility provided using the SIDRA INTERSECTION Application Programming Interface;
  • prepare your own programs using the SIDRA INTERSECTION Application Programming Interface.

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