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  • Windows XP/Vista/7/8

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Assessment of Roundabout Capacity and Delay

Prediction of capacities, queues, delays and accidents at roundabouts

"TRL has emerged as a leader in training and software, INDOT was very fortunate to adopt ARCADY. We now have 50 INDOT engineers trained and fully engaged in investigating all of our upcoming projects for the feasibility of using a roundabout." John Wright, Indiana Department of Transportation.

ARCADY is based on three decades of research and development by TRL and is used for predicting capacities, queues, delays (both queueing and geometric) and accident risk at roundabouts. ARCADY is an easy-to-use and essential tool for the busy traffic engineer designing new roundabouts and assessing the effects of modifying existing sites.

It is now available as the ARCADY (roundabout) component within Junctions 8.

Roundabouts are modelled using the well-established TRL/Kimber capacity relationships (the ARCADY Model), which take into account key roundabout geometries such as entry width, approach width, flare length, conflict angle, inscribed circle diameter and entry radius. This empirical framework intrinsically links roundabout geometry to driver behaviour and in turn to predicted capacities, queues and delays. 

ARCADY has been successfully used to design and improve tens of thousands of roundabouts throughout the world. It has a host of satisfied customers including governments, multi-national organisations and universities. Its simple interface means that it can be used effectively by small consultancy companies.

ARCADY 8, can model:

  • Roundabouts
  • Mini Roundabouts
  • Linked Roundabout Networks
  • Grade Separated Roundabouts
  • Motorway (Interstate) Roundabouts
  • Pedestrian Crossings (Signalled, Unsignalled and Adaptive)

Different traffic profiles can be analysed and simple calibration options are available to account for local considerations at different sites.

ARCADY encourages "what if?" scenarios and direct comparison of results makes it simple to compare different geometries, models or performance side by side.

A small change in entry width or flare length will often have a great effect on performance, this can be explored effortlessly using ARCADY's sensitivity analysis.

Entry Lane Simulation

ARCADY 8’s Entry Lane Simulation tool enables full simulation of individual entry lanes to be performed on existing ARCADY models. The user can quickly see where unbalanced queuing may occur and if lane starvation may take place. The simulation takes into account the geometric layout of the roundabout, turning proportions and user-specified lane designations.  Lane movements can then be altered easily using the roundabout diagram to explore and identify the optimum lane configuration.

Other new roundabout features in ARCADY 8

The ARCADY-AutoTrack Link is now free to all users of ARCADY 8 to enable on-the-go analysis of roundabout CAD designs on one single screen, as the design evolves. With Autodesk® acquiring Savoy Computers, the vendors of AutoTRACK, ARCADY 8 has been updated to support the new product called Autodesk® Vehicle Tracking.

The HCM 2010 Roundabout Capacity Model has been included in ARCADY 8 for international customers needing to submit analysis using different analysis models, making ARCADY 8 the only tool necessary.

Options for the modelling of linked roundabouts (first introduced in ARCADY 7) have been simplified.

Bypass flows at roundabouts can now be explicitly specified.

Residual Capacity mode quantifies the ‘spare’ capacity at any roundabout.

Junction results show demand-weighted delay and LOS for the whole roundabout. 

It is now easier to distinguish between original turning counts, the scaled demand used in the model, and the final calculated entry flows.  These can be seen in the Turning Count screen and in the Junction Diagram, which now also shows circulating flows.

ARCADY 8 also includes many more enhancements that make data entry easier. For example, in recognition of the fact that this is the most commonly used option, the default traffic profile type is now set to ONE HOUR (ODTAB) with a 90-minute modelled period. More options can now be saved in individual data files as well as user preferences.  Some data items, options and screens have been simplified, renamed or moved, again to simplify the data entry process.  The Analyser Screen now has some common graphs built-in, to save having to set them up each time.

Further details about the individual versions of ARCADY can be found in the support section.

Forthcoming Training Courses

  Course Dates Location Cost*  
View Details TRANSYT 15 Upgrade Workshop 13 May 2014 Crowthorne £290 Add to Basket
View Details ARCADY / PICADY Workshop 20 May 2014 Crowthorne £290 Add to Basket
View Details ARCADY / PICADY Workshop 07 Jul 2014 Crowthorne £290 Add to Basket
View Details TRANSYT 15 Upgrade Workshop 08 Jul 2014 Crowthorne £290 Add to Basket
View Details TRANSYT 15 Two day Workshop 09 Jul 2014 - 10 Jul 2014 Crowthorne £570 Add to Basket
View Details TRANYST 15 Upgrade Workshop 09 Sep 2014 Crowthorne £290 Add to Basket
View Details ARCADY / PICADY Workshop 16 Sep 2014 Crowthorne £290 Add to Basket
View Details TRANYST 15 Two day Workshop 08 Oct 2014 - 09 Oct 2014 Crowthorne £570 Add to Basket
View Details ARCADY/PICADY Workshop 04 Nov 2014 Crowthorne £290 Add to Basket
View Details TRANSYT 15 Upgrade Workshop 11 Nov 2014 Crowthorne £290 Add to Basket
* The cost is per delegate and excludes VAT.

Forthcoming Webinars

There are no webinars currently planned but please check this page regularly