Junctions 10 Features

Junctions 10 is the latest version of TRL Software’s industry-standard package for the modelling of roundabout and priority intersections, consisting of ARCADY (the Roundabout Module), PICADY (the Priority Intersection Module), and OSCADY (the Signalised Intersection Module).

Driven by our customers, Junctions 10 incorporates several new modelling capabilities, a collaboration portal and various user interface enhancements all designed and implemented to make this latest version of Junctions more capable, easier to use, and easier to collaborate.


As many of you will know, it has been frustrating not to be able to apply site-specific adjustments at priority junctions in a number of scenarios, such as when you have blocking of the main road by right-turners, pedestrian crossings, or flares on the minor arm.   After much investigation, Junctions 10 now allows you to define capacity adjustments for any of the movements within the junction.  For example, if you have a two-lane minor road or one lane flaring to two, you can now define an adjustment to the B-C (left turn movement) capacity that the model calculates.  Similarly, you can apply adjustments to all the other movements through your junction.  Adjustments are made to the initially calculated capacity only, i.e. it will be subject to further adjustments as and when necessary, due to the presence of various features, such a flare, pedestrian crossing, etc.

 Multiple adjustments can be applied:

  • Adjustments are reported clearly in the HTML report
  • As always, we recommend any adjustments are made only when enough good quality observed data exists, to compare the model results to

Direct capacity adjustment of +30 PCU/hr for the B-C movement

Chicane showing queueing traffic

Typical chicane, Bracknell

Modelling Chicanes, Narrowings and Kerb Build-outs

Many roads contain restrictions where traffic in one direction gives way to traffic from the opposite direction, sometimes with each direction giving way to each other.  Examples include unsignalled shuttle working, traffic-calming build-outs, unsignalised roadworks, narrow bridges/tunnels and so on.  These can now be modelled in Junctions 10.  The requirement to model may not be particularly common, but there are various scenarios where it is needed, such as when the effect of the narrowing affects a more important adjacent junction’s performance.

  • Model the above scenarios using new ‘obstructions’ on lanes in simulation mode
  • Easy to set up by defining opposing lanes as both having ‘obstructions’ to represent opposite traffic directions
  • Accounts for the traversal time through the obstruction
  • Gives a good approximate indication of the impact of the obstruction, although certain real-life effects such as drivers different levels of aggression/courtesy are not modelled

Modelling a Wider Range of Scenarios

A key focus of Junctions 10 is the expansion of the product to allow it to model several scenarios than it could not model before at all, and to more easily model some scenarios that it has been used to model but was not designed explicitly to model, such as one way entries and exist.

  • Explicitly define one-way minor roads into and out of modelled at priority junctions
  • Explicitly define one-way roads into and out of roundabouts
  • Model no give-way line scenarios at roundabouts
  • Model reverse priority approaches at roundabouts
  • Model a variety of more complex approaches, such as where an approach diverges into two physically-distanced entries for left and right turners.

Example of a diverging priority approach

Other Modelling Improvements

In addition to the major new feature, Junctions 10 includes a few other modelling changes driven by customer feedback. These are listed below:

  • Calculation of ratio of flow to capacity (RFC) values while in Lane Simulation mode
  • Reconciled circulating flows for HCM roundabouts
  • Modelling in lane simulation mode of occasional blocking of major road by larger vehicles

Measuring separation distance at large/grade separated roundabouts

Extended Geometric Measurement Tool

The ability to store Junctions measurements in the form that they were measured, such as the four individual measurements taken to measure the major road width of a T-junction with a ghost island, is important as it allows better scrutiny and reproducibility of the measurements, no matter what is used to take these measurements.  Therefore, we have improved Junctions 10 so that it now captures all the ‘component’ measurements and, where it is appropriate to do so, can be measured using an enhanced geometric measurement tool.

  • Geometric data measuring tool extended to include priority intersection (PICADY) data
  • Measuring tool extended to include separation distance at large/grade-separated roundabouts

“Follow Me” Licensing

A licensing system for the 21st century: Over the past decade or so, where and how employees work has changed a lot, with many working from multiple sites or from home.  This change has accelerated because of Covid-19.  To account for this increased mobility of staff, Junctions 10 now offers user world-wide licencing, instead of the previous less flexible equipment-based site licencing system.  Here is a list of some of its benefits:

  • Personal user licensing
  • Log in and use wherever there is the Internet
  • Planned off-line use available when you know you won’t have internet access
  • Licences automatically switched to the device you are using
  • Simple subscription licensing, including support
  • Freedom to reallocate licences to staff yourself, to accommodate organisational changes

Junctions 10 User login screen

Main screen of the Collaboration Portal

  • Access to portal and its contents includes a grace period if Junctions 10 licence ends
  • Option to reactivate while in grace period
  • Planned additional portal capabilities will be added over time


Most companies have seen a significant shift to working remotely and an ever-increasing need to conveniently share files. Often these files are numerous enough or big enough to fall outside of what is permitted to be simply emailed to clients, or to colleagues even.  This results in delays and difficulties trying to share material.  In recognition of this, all Junctions 10 subscription licences now include access to your own personal cloud-hosted collaboration storage area.  Listed below is some of the collaboration portal’s attributes:

  • Available as part of having an active maintenance contract
  • Can store up to 5GB of files per organisation
  • Create your own folder structure
  • File versioning system
  • Share files or folders within your organisation or outside of it (i.e. with clients)
  • Key data from within Junctions 10 files displayed within portal, to assist with identification

Adaptive Traffic Control and Signalled Roadworks

Many Junctions operate under some form of adaptive signal control, so Junctions 10 when in simulation mode, now offers to model this method of control.  It does not represent a specific form of adaptive traffic control.  It is intended to be fairly generic, and as such can be used to evaluate junctions running a variety of systems, such as the UK’s “System D”, and should give a reasonable representation of the benefits or disbenefits of running an adaptive control system compared with, say, optimised fixed timings. Some of its capabilities are listed below:

  • Allows you to compare adaptive control with fixed time control or priority control
  • Modelling of Signalled shuttle working at roadworks (1,2,3,4-way control)
  • Option of modelling an explicitly defined all-red stage, or an implied one
  • Define behaviour when zero demand exist, e.g. revert to all-red, or to a specific main road stage
  • Specific performance metrics calculated to enhance your understanding of junction performance and behaviour:
    • Adaptive mean cycle time (per time segment)
    • Maximum stage length (within modelled time period)
    • Mean stage durations (per time segment)
    • Percentage stage skipped (per time segment)

Junctions 10’s representation of two-way signal control (Adaptive)

Selection of Adaptive traffic control with reversion to main road stage when there is zero demand

User Interface and Reporting Improvements

Despite the maturity of Junctions, the desktop product user-interface has had a few functional improvements and has been given a fresh makeover so that it looks a bit different and now offers a choice of Light and Dark themes. The report has had a few tweaks as well. Here is a taste of a few of the improvements made:

  • Dynamic link to Excel: New option to cater for multiple Demand Flows stored within the one worksheet
  • Option to report Queue lengths metres/feet instead of PCU/Veh
  • For convenience, the “Run All Sets” dropdown is promoted to having its own button!
  • Estimation of large roundabout circulating flow across all sets in one go
  • Data grid “Edit All” enhanced so that it ignores disabled fields
  • Extended Diagram right-click menus to provide easier access to geometric data screen, etc.
  • Lane Simulation: When adding additional lane levels, default storage length set automatically
  • Easy reporting of product ideas using TRL Software’s Ideas Portal
  • Reporting of queries to TRL software support staff directly from the product
Junctions 10 Light Theme
  • Lane Simulation: Easier to set Animation speed
  • Virtually all user interface screens given a modernised look
  • Various other small UI changes to improve user experience


Update to the Highway Capacity Manual model:  An optional facility is now available which when activated will reconcile the circulating and entry flows around the roundabout being modelled, i.e. it recognises their interdependence.  This is process has been adopted from the UK ARCADY roundabout model which has had this capability for some time.  When this new option is switched off the flows are trivially summed values, which of course can lead to inconsistencies in the flows, and hence in the results.

ARCADY ‘Runner’ (on-line ARCADY model)

This is an cloud-based experimental ARCADY model provided to Junctions 10 maintenance holders, which is accessed from within the new collaboration portal.  As a concept feature it does not represent in any way a fully functional product, but instead gives you the opportunity to glimpse into one possible future.  Whether or not you love the ‘concept’ or hate it, please let us know your thoughts on it, using any one of the many channels that now exist to provide us with feedback.

ARCADY ‘Runner’