We have spent over 30 years developing SIDRA INTERSECTIONsoftware with one core philosophy in mind - to provide a powerfultool that helps you to save time and effort and enables production of effective solutions for your local traffic conditions.
We are proud to announce the release of SIDRA INTERSECTION 5.1 - loaded with more powerful and time-saving features:
"I have used SIDRA in USA, Asia and Australia for 20 years. It has continually improved and over the past six years I have found it extremely useful for analysis of roundabouts in California, Arizona, Oregon and Washington. It is quick and easy to use accurately and my clients respect the results."
Kevin Fehon / DKS Associates
"A great tool to enable students to undertake project work on live intersections as part of the academic syllabus"
Tom Mckune / Durban University of Technology
SIDRA INTERSECTION software (previously called SIDRA and aaSIDRA) is an advanced micro-analytical traffic evaluation tool that employs lane-by-lane and vehicle drive cycle models. SIDRA INTERSECTION is a renowned software package used worldwide for intersection (junction) capacity, level of service and performance analysis by traffic design, operations and planning professionals. SIDRA INTERSECTION incorporates leading analytical methodology based on Dr Akcelik's award-winning research and development work.
SIDRA INTERSECTION, essentially a mathematical model for traffic analysis, 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. Developed over 30 years, SIDRA INTERSECTION uses one of the most advanced methodologies of any traffic design package.
SIDRA INTERSECTION model can be used to evaluate and compare capacity, level of service and performance of alternative treatments involving signalised intersections, roundabouts, roundabout metering signals, two-way stop and give-way (yield) sign-control, all-way (4-way and 3-way) stop sign control, single-point urban interchanges, and signalised midblock crossings for pedestrians, all in one package . This is unlike other software such as ARCADY, PICADY and OSCADY from TRL (UK) which model different types of intersections in separate packages. Intersections with up to 8 legs (approaches), each as a two-way road, one-way approach or one-way exit can be modelled with ease. Templates are provided for analysis of zebra crossings, merging and basic freeway segments. Provision is made for analysis of closely-spaced intersections.
SIDRA INTERSECTION provides facilities to calibrate the traffic model for local traffic conditions which are easy to use and powerful:
HCM Version of SIDRA INTERSECTION
HCM 2010 Roundabout Model Option
SIDRA INTERSECTION offers an easy-to-use Microsoft Office 2007 style user interface with enhanced file management, input dialogs, error handling, a detailed input report, numerous output reports and graphical displays and a graphs facility.
SIDRA INTERSECTION offers graphics-based input dialogs. The intersection geometry and signal phasing data style of SIDRA INTERSECTION reflects the design process directly. Together with the use of Layout and Volume Summary displays for easy checking of data, the graphical data simplify the input preparation task to a great extent, and reduce data errors.
Use the Templates facility for common intersection layouts help to reduce data preparation time greatly. Over 100 TEMPLATES for roundabouts, signals, sign control and pedestrians are available including all MUTCD roundabout design examples.
SIDRA allows creation of intersection models with ease using time-saving intersection configuration and calibration methods. Pedestrian data are given in dedicated pedestrian input dialogs including enhanced pedestrian timing data. Movement priorities (opposed and opposing movements) are set automatically when diagonal legs, deleted approaches and banned movements are introduced, and when movement type (e.g. slip lane) or control (e.g. major road / stop sign) is changed.
SIDRA INTERSECTION output includes capacity, timing and performance results reported for individual lanes, individual movements, movement groupings (such as vehicles and pedestrians), and for the intersection as a whole. Estimates of capacity and performance characteristics (including annual sums) such as delay, queue length, stop rate as well as operating cost, fuel consumption and pollutant emissions are available for all intersection types.
SIDRA INTERSECTION contains comprehensive help facilities. Extensive documentation (500-page User Guide plus major supporting technical reports and papers) is available. Visit our eLearning Centre for great guides and video links.
We have been running highly successful SIDRA INTERSECTION training workshops to help you solve intersection evaluation and design problems effectively and reliably.
SIDRA INTERSECTION ensures model consistency in evaluating alternative intersection treatments. This applies to different types of intersection including signalised intersections, roundabouts, two-way stop and give-way /yield sign-control, all-way stop sign control, single-point urban interchanges, signalised pedestrian crossings and more.
Unique lane-by-lane capacity and performance analysis method is used allowing for exclusive lanes and unequal lane utilisation. This method is superior to approach-based and lane-group models used in other software packages.
Vehicle path estimation for drive-cycle (modal analysis) method for prediction of operating cost, fuel consumption, greenhouse gas (CO2) and pollutant (CO, NOX, HC) emissions, and vehicle delay components including stopped delay, acceleration - deceleration delay, queuing delay and geometric delay.
Calibrate traffic models for your local conditions. Carry out sensitivity analyses to evaluate the impact of changes on parameters representing intersection geometry and driver behaviour. Analyse oversaturated conditions making use of the time-dependent delay, queue length and stop rate models. Investigate implications of alternative capacity models using advanced model settings.
SIDRA INTERSECTION has an extensive defaults system that covers most input data and traffic model parameters. You can create your own customised model and edit the default parameters set for your own purposes, e.g. to calibrate some parameters for your local conditions.
Carry out a Design Life or Flow Scale analysis to assess impact of normal traffic growth or impact of developments. Allow for different growth rates for individual movements and use options for setting different analysis objectives including the Final Year, Worst Movement Level of Service Target, Worst Lane Level of Service Target, Capacity and Practical Capacity.
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 and continuous bypass lanes and turn bans as relevant. Design intersection geometry including lane use arrangements taking advantage of the unique lane-by-lane analysis method of SIDRA INTERSECTION. Analyse many design alternatives to optimise the intersection geometry. Analyse the impact of intersection flaring through short lanes (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 effects of heavy vehicles on intersection performance. Use heavy vehicle equivalents for model calibration to allow for very large vehicles in specific traffic streams. Use SIDRA INTERSECTION output on vehicle paths through intersection (negotiation distance, radius and speed) in checking your intersection design. Investigate driver characteristics including driver response time estimates associated with queue discharge. Use this information to calibrate microsimulation models.
SIDRA INTERSECTION provides a large number of intersection performance measures. Standard performance measures such as delay, queue length and number of stops as well as measures to help with environmental impacts and economic analysis are provided. The performance measures offered by SIDRA INTERSECTION include the following:
Performance and level of service results are given at various aggregation levels:
Performance and level of service results are given for:
SIDRA INTERSECTION offers a large number of alternative Level of Service (LOS) methods and LOS Target settings to determine acceptable design:
As an analytical tool, SIDRA INTERSECTION produces unique deterministic results for a given set of inputs while software packages based on microsimulation generally do not. This applies to the capacity, performance and level of service estimates for each lane, each movement, each approach and the intersection.
SIDRA INTERSECTION estimates the cost, energy and pollution implications of your intersection design using a unique vehicle path model (4-mode elemental model with detailed acceleration, deceleration, idling, cruise elements). This drive-cycle (modal analysis) method coupled with a power-based vehicle model helps to estimate operating cost, fuel consumption, greenhouse gas (CO2) and pollutant (CO, NOX, HC) emissions towards reducing environmental impacts of traffic congestion. The model includes estimates of acceleration and deceleration times and distances for light and heavy vehicles coupled with a polynomial model of acceleration-time profile.
The four-mode elemental model used in SIDRA INTERSECTION for fuel consumption and emission estimation includes the following features:
More information on SIDRA INTERSECTION pollutant emission and energy model
SIDRA INTERSECTION performance estimates (delay, number of stops, average speed, etc.) can be used as parameters in your economic analysis model, or the operating cost estimates of SIDRA INTERSECTION can be used directly, for Benefit - Cost analysis to evaluate intersection treatments. This is enhanced by the Demand Analysis (Design Life or Flow Scale) facility. Annual Sums for performance statistics such as total delay, total operating cost, total fuel consumption, total CO2 emission per year are also provided for this purpose.
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.
Determine 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. Select one of many cycle time options available. Use advanced signal timing options such as 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.
Analyse the effects of turn on red and semi-actuated signals. Make use of features such as undetected movements, dummy movements and phase transition data. Use the graphical input method for easy specification of phasing and timing data including known phase times.
For intersections running under SCATS control, use fixed-time / pretimed analysis method to emulate equal degree of saturation method used by SCATS for green splits. Make use of SCATS parameter estimates (maximum flow and headway, occupancy time and space time at maximum flow) given by SIDRA INTERSECTION for calibration purposes where applicable.
SIDRA INTERSECTION offers different options to specify the desired method of cycle time calculation (subject to minimum and maximum cycle time constraints):
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.
SIDRA INTERSECTION is the most popular traffic software for roundabouts and other intersections around the world. Multi-lane roundabouts and single-lane roundabouts with up to 8 legs (each as a two-way road, one-way approach or one-way exit) can be analysed with ease.
SIDRA INTERSECTION offers numerous TEMPLATES for roundabouts including all roundabout examples given in MUTCD 2009 and TRB 2010 Roundabout Informational Guide (NCHRP Report 672).
General information on SIDRA INTERSECTION for roundabouts
SIDRA INTERSECTION offers a unique Roundabout Metering analysis method which enables the evaluation of the effect of metering signals on roundabout capacity and performance with ease. This helps to solve the problem of excessive queuing and delays at approaches affected by unbalanced traffic streams at roundabouts.
As advanced software for roundabout analysis, SIDRA INTERSECTION provides powerful model calibration facilities. Calibration parameters such as Environment Factor, HCM 2010 roundabout capacity model calibration factors and the Sensitivity Analysis facility can be used to achieve observed capacity values.
SIDRA INTERSECTION uses empirical gap-acceptance models based on data collected at roundabouts in Australia and USA. The critical gap and follow-up headway parameters used in modelling the gap-acceptance behaviour of drivers entering a roundabout depend on roundabout geometry as well as the circulating flow rates. This allows drivers to accept shorter gaps at roundabouts as demand flow rates increase over time.
Capacity of roundabout entry lanes also depends on lane balance of circulating flows as well as balance of origin-destination demand patterns.
SIDRA INTERSECTION offers the HCM 2010 roundabout capacity model based on US research on roundabouts. The model is implemented as described in Highway Capacity Manual 2010 with numerous extensions. The Highway Capacity Manual (HCM) versions of SIDRA INTERSECTION use the HCM 2010 roundabout capacity model as the default model. The software also continues to offer the SIDRA Standard model with a default Environment Factor of 1.2 to match the lower capacity estimates based on US roundabout research.
HCM 2010 roundabout model in SIDRA INTERSECTION
General information on the HCM Version of SIDRA INTERSECTION
SIDRA INTERSECTION also offers several additional roundabout capacity models for comparison with its main model. These include the FHWA 2000 roundabout model which is similar to the UK TRL linear regression ("empirical" model) used in the UK roundabout software packages (ARCADY and RODEL).
Pedestrian effects on roundabout entry lane capacity and exit lane capacity (vehicles giving way to pedestrians on exit) are modelled in SIDRA INTERSECTION. Staged movements are used to correspond to the approach and exit sides of the roundabout leg. Output relevant to the effect of pedestrians at roundabouts is given in output.
SIDRA INTERSECTION allows detailed modelling of slip and continuous bypass lanes at roundabouts. Slip lanes can be give-way / yield or stop controlled. Both shared and exclusive slip lanes can be modelled.
The Highway Capacity Manual (HCM) version of SIDRA INTERSECTION offers options for US Customary and Metric units. SIDRA INTERSECTION is compatible with the Highway Capacity Manual. However, unlike other software packages, the HCM version of SIDRA INTERSECTION does not claim to be a simple replication of the HCM procedures. Instead, SIDRA INTERSECTION offers various extensions on the capabilities HCM offers.
Generally (for all types of intersection), SIDRA INTERSECTION uses more advanced models and methods, including lane-by-lane analysis (rather than analysis by lane groups ), modelling of short lanes, detailed modelling of geometric delays, and the use of drive cycles (cruise, acceleration, deceleration and idling) for detailed modelling of delay and travel time components as well as operating cost, fuel consumption and emission estimation.
SIDRA INTERSECTION includes various configuration options to allow the user to choose between the HCM and standard SIDRA model options, e.g. the HCM Delay and Queue model options.
Some HCM models or methods are used in all versions of SIDRA INTERSECTION, including the HCM Level of Service method and criteria, the delay and queue progression factors for signal coordination effects, and All-Way Stop Control (AWSC) analysis method (the SIDRA AWSC model is currently based on the HCM 1994 edition, and there are some differences between the SIDRA and HCM two-way stop control models).
For signalised intersections, in addition to the general features mentioned above, advanced signal timing methods are available, and the use of two green periods for modeling slip lanes, RTOR and permitted-protected left-turns provides more accurate capacity estimates.
The HCM version of SIDRA INTERSECTION is based on the calibration of most model parameters using the HCM defaults as applicable.
TRB Highway Capacity Manual 2010 (HCM 2010) has been published recently, and a full implementation of the new roundabout capacity model described in the manual is now available in SIDRA INTERSECTION 5.1. This new version of the software offers powerful extensions to the HCM 2010 methodology to enhance your roundabout design capabilities.
The roundabout capacity model is the only analysis method in HCM 2010 which uses lane-by-lane analysis, and as such it is best implemented by SIDRA INTERSECTION which has been using a lane-by-lane methodology for all types of intersection since 1980s.
The Highway Capacity Manual (HCM) versions of SIDRA INTERSECTION use the HCM 2010 roundabout capacity model as the default model. It also continues to offer the SIDRA Standard model with a default Environment Factor of 1.2 to match the lower capacity estimates based on US roundabout research.
HCM 2010 acknowledges the need to use alternative models in view of various shortcomings it lists about the HCM 2010 roundabout capacity model. SIDRA INTERSECTION is one of the alternative tools referred to in HCM 2010. The limitations listed in HCM 2010 are addressed by SIDRA INTERSECTION through extensions to the HCM 2010 model option or as part of the SIDRA Standard model option.
For detailed information on major extensions to the capacity and performance estimation method offered by the HCM 2010 roundabout model integration in SIDRA INTERSECTION, see: HCM 2010 Roundabout Capacity Model
Also see: General information on the HCM version of SIDRA INTERSECTION
While SIDRA INTERSECTION is a single-intersection analysis software, its model does not assume isolated operations. Thus, it can be used for analysing closely-spaced intersections, pedestrian crossings near intersections, or any number and type of multiple intersections. This applies to both undersaturated and oversaturated cases, i.e. whatever the degrees of saturation (v/c ratios) are. The important aspects of modelling closely-spaced intersections are:
SIDRA INTERSECTION has the following provisions for multiple intersection analysis as in the case of closely-spaced intersections and network applications.
It is important to specify the approach and exit lane lengths and number of lanes (including any approach and exit short lanes) for all intersections realistically, especially for internal approaches between intersections so that queue storage problems can be identified.
Lane underutilisation is an important issue at closely-spaced intersections. Lane flow estimates of SIDRA INTERSECTION should be inspected and lane utilisation specifications should be given if necessary.
For platooned arrivals at roundabouts and sign-controlled intersections (due to upstream signals), the Extra Bunching parameter is used. Platooned arrivals are not as important at roundabouts unless the extra bunching is very high and the proportion queued is very low. This is because roundabout capacity is determined by the circulating flow, and the headway distribution of circulating flow is affected by queues on roundabout approaches which filter out platooning depending on the amount of queuing. All this is modelled by SIDRA INTERSECTION.
The effect of upstream roundabouts or sign-controlled intersections on the arrival pattern at a roundabout or sign-controlled intersection approach is minimal since the departure patterns from upstream unsignalised intersections are randomised due to the gap-acceptance process.
The following are important steps when using SIDRA INTERSECTION for closely-spaced signalised intersections with signal coordination.
An Application Programming Interface (API) is available to interface other programs to SIDRA INTERSECTION offering the potential for a limitless range of applications.
The SIDRA INTERSECTION API provides the following capabilities:
Various API applications and other programs are available as part of the SIDRA UTILITIES group of products. These small-sized programs and Excel applications help to enhance capabilities provided for SIDRA INTERSECTION users and may serve as sample applications for programmers who want to develop API applications for SIDRA INTERSECTION.
Detailed information about SIDRA UTILITIES and API can be found in SIDRA INTERSECTION User Guide, Part 2, Section 3.
SIDRA UTILITIES based on SIDRA INTERSECTION API require a licenced version of SIDRA INTERSECTION. The API will not work with a Trial Version of the software.
Various documents are available for programmers who want to develop API applications for SIDRA INTERSECTION in the SIDRA UTILITIES and API page
The following SIDRA UTILITIES are available for download from the
SIDRA UTILITIES and API page:
SIDRA INTERSECTION API will facilitate linking to:
"SIDRA INTERSECTION is a very powerful and useful tool for experienced traffic engineers. Its reputation is often tarnished when not used correctly, i.e. when a calibrated base model reflecting current observations is not created. It is user friendly for experienced traffic engineers, especially with reference to the detailed manuals provided. Unfortunately, in large organisations, SIDRA modelling is often assigned to graduates with little knowledge or experience on real life observations and traffic behaviour. The three 'C's to successfull modelling are "Calibrate" "Calibrate" and "Calibrate"."
David Wilkins / i3 consultants WA
"When our agency was tasked to perform a benefit/cost analysis for nearly twenty projects within a months' time, we did not know of any software that could help us. When we were informed of SIDRA software and how it could be applied to our tasks, we immediately used the available trial version, and completed our tasks within a three-week timeframe. I'm sold on the software, and I'm encouraging the North Carolina Department of Transportation to partner with the other metropolitan planning organizations throughout the state to purchase SIDRA under one contract to allow statewide usage."
Kenneth Withrow / North Carolina Capital Area Metropolitan Planning Organization
"Sidra is a wonderful tool for assessing individual intersections"
Edmond Platon / RTA
"User friendly, combines a sound theoretical background with results verified in the field."
Argiris Mamais / Athens international airport (ATH)
"SIDRA is still our standard for roundabout analysis because of its solid basis in gap acceptance theory that has shown to be more reliable in the USA than empirical models based in other countries."
James Dunlop / NCDOT
"I have been using SIDRA for the past 8 years and found all versions are intuitive and the output are very useful and concise for reporting."
Robert Kwok / Worley Parsons
"I have found SIDRA INTERSECTION to be a very reliable, versatile and effective tool for analysing intersection performance. The ability to calibrate the model to accurately represent existing intersection characteristics has been of significant benefit for both intersection design and future planning purposes."
Rob Day / RTA (NSW)
"I have found SIDRA to be a valuable tool to assist in traffic analysis; the model is able to reflect existing operating site conditions accurately and this in turn gives confidence in the SIDRA predictions for future traffic scenarios when assessing project proposals. The professional support from the SIDRA Team adds value to a user friendly product."
Terry KEATING / TPK & ASSOCIATES PTY LTD
"I thoroughly enjoy working with the new Sidra 5 Version and find that the traffic engineering tasks are easier to complete with the new product. Thanks to the team at SIDRA SOLUTIONS."
Bertie Phillips / Kantey & Templer
"SIDRA leads the way! It is easy to use and adaptable to local conditions. The output can easily be used in reports. I would recommend SIDRA to all traffic engineers!"
Liesel Vogel / EFG Engineers
"SIDRA provides reliable results and presents the results in formats that are great for public understanding and for including within design reports. SIDRA provides a very simple, quick and understandable way to analyze nearly all intersection types - especially roundabouts."
Howard Mcculloch / NE Roundabouts
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