Junction & Signal Design

Modelling and evaluation tools

Junction & Signal Design Software

Junctions

Modelling and analysis of roundabouts, priority junction and signalised junctions

TRANSYT

Signal design for network and junctions

PCMOVA

MOVA simulation tool for use in PC environment

The Science of Traffic

About Junction & Signal Design

Signal timings at road junctions have an important effect on levels of traffic congestion, both at the junction itself and at surrounding junctions which may be signalised or priority-controlled. Ensuring traffic signals are timed effectively is one of the most cost-effective methods for reducing congestion.

Based on over three decades of research and development, Junctions 11 is used to model and predict capacity, queues and delays at roundabouts, priority intersections and isolated (uncoordinated), traffic signal-controlled junctions.

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Junction & Signal Design News

Junctions & Signal Design

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Public Roads, Private Benefit: #1 An Introduction

21 May 2025
TRANSYT

TRL Software Launches Latest Version of TRANSYT Software: Revolutionising Traffic Signal Modelling

2 April 2025
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Junction & Signal Design Webinars

Junctions & Signal Design
Hands on with Junctions 10
January 29, 2021 12:30 am
Junctions & Signal Design
Junctions 10: The Next Step in Junction Signal Design
November 26, 2020 12:30 pm
hong kong, city, traffic-1990268.jpg
Junctions & Signal Design
Introduction to TRANSYT
September 30, 2020 12:30 pm
Junctions & Signal Design
Introduction to OSCADY
July 30, 2020 12:30 pm
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Junction & Signal Design Videos

TRANSYT 17 Modelling demand dependent scenarios

TRANSYT 17 Corridor Optimisation

Junctions 11 Quick Start Guide

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Junction & Signal Design Knowledge Base

If, when logging in you, you get an error message starting with the phrase “Unable to connect to the login service” this could be due to a number of reasons:

(A) It could be a temporary blip to our own cloud-based licensing service, in which case simply try again in a minute or two to see if you can log in

(B) If you are trying to log into either Junctions or TRANSYT, it might be due to the fact that you are registered on the TRL Software Portal under your organisation, but you have not yet been allocated a Junctions or TRANSYT licence.  In which case you can check by logging into the TRL Software Portal.  If that works, you should contact your local administrator to allocate you a licence to the product you wish to use.   (TRL can provide you with a list of local admins, if you don’t know any.)

(C) If you cannot access the product nor the TRL Software Portal, then it is most likely that your device’s configuration is blocking access to the required internet addresses required for the TRL licensing system to function correctly.  The following address should be white-listed if there is any issues of access.  (Cybersecurity and antivirus solutions can sometimes block access unless these addresses are white-listed.)

If none of the above works, then please contact TRL Software for support in the usual way.

View FAQ
If, when logging in you, you get an error message starting with the phrase “Unable to connect to the login service” this could be due to a number of reasons:(A) It could be a temporary blip to our own cloud-based licensing service, in which case simply try again in a minute or two to see if you can log in(B) If you are trying to log into either Junctions or TRANSYT, it might be due to the fact that you are registered on the TRL Software Portal under your organisation, but you have not yet been allocated a Junctions or TRANSYT licence.  In which case you can check by logging into the TRL Software Portal.  If that works, you should contact your local administrator to allocate you a licence to the product you wish to use.   (TRL can provide you with a list of local admins, if you don’t know any.)(C) If you cannot access the product nor the TRL Software Portal, then it is most likely that your device’s configuration is blocking access to the required internet addresses required for the TRL licensing system to function correctly.  The following address should be white-listed if there is any issues of access.  (Cybersecurity and antivirus solutions can sometimes block access unless these addresses are white-listed.) If none of the above works, then please contact TRL Software for support in the usual way.
View FAQ

If this message (or similar) starts to pop up when you try to log into either TRANSYT or Junctions, it is likely due to a known issue that can affect some older versions of Junctions 10, Junctions 11 and TRANSYT 16.

image.png

Please switch to using the most recent version of the product you are trying to log into, which you can download from https://my.trlsoftware.com/download.
If you’re already using the most recent version, or if updating doesn’t make any difference, please let us know.

View FAQ
If this message (or similar) starts to pop up when you try to log into either TRANSYT or Junctions, it is likely due to a known issue that can affect some older versions of Junctions 10, Junctions 11 and TRANSYT 16.image.pngPlease switch to using the most recent version of the product you are trying to log into, which you can download from https://my.trlsoftware.com/download. If you’re already using the most recent version, or if updating doesn’t make any difference, please let us know.
View FAQ

In non-Simulation mode the RFCs can be calculated analytically – The whole approach is regarded as a single entity, making this possible. 

In Simulation Mode, RFCs are not calculated regardless of junction type.  The reason for this is that RFCs are difficult to measure/define and interpret when using simulation mode, as the capacity calculated required to establish an RFC is influenced by turning proportions, flare/lane lengths and lane designations, unlike the non-Simulation model.  It is these influences on the results that make the simulation model effective in accounting for substantial lane starvation and allows different designs to be compared.  

 Please note that, if you drill down into the individual LANE results you can see that RFCs values are calculated.  These can be misleading though, as low values can be indicative of either good performance, or that traffic is unable to reach the lane you are examining the results for.  

 In Junctions 10.1 and later, there is now an option to calculate lane-based RFC values.  The runs times can be considerable, so there is an option to mitigate that by calculating the RFC for specific arms only.  TRL Software have endeavoured to ensure that the RFC’s can be regarded in a similar way to those calculated in non-sim mode.  

In the rare situations the program does not calculate arm-based RFCs in simulation mode (such as internal approaches within linked junctions), instead we recommend looking at the results which are measured and reported from the simulation, such as mean queues, percentile queues, and delays.  You can also ‘stress-test’ a network by using the Analyser screen to plot a graph of queue/delay against flow scaling factor. 

(Added April 2025)

View FAQ
In non-Simulation mode the RFCs can be calculated analytically – The whole approach is regarded as a single entity, making this possible. In Simulation Mode, RFCs are not calculated regardless of junction type.  The reason for this is that RFCs are difficult to measure/define and interpret when using simulation mode, as the capacity calculated required to establish an RFC is influenced by turning proportions, flare/lane lengths and lane designations, unlike the non-Simulation model.  It is these influences on the results that make the simulation model effective in accounting for substantial lane starvation and allows different designs to be compared.   Please note that, if you drill down into the individual LANE results you can see that RFCs values are calculated.  These can be misleading though, as low values can be indicative of either good performance, or that traffic is unable to reach the lane you are examining the results for.   In Junctions 10.1 and later, there is now an option to calculate lane-based RFC values.  The runs times can be considerable, so there is an option to mitigate that by calculating the RFC for specific arms only.  TRL Software have endeavoured to ensure that the RFC’s can be regarded in a similar way to those calculated in non-sim mode.  In the rare situations the program does not calculate arm-based RFCs in simulation mode (such as internal approaches within linked junctions), instead we recommend looking at the results which are measured and reported from the simulation, such as mean queues, percentile queues, and delays.  You can also ‘stress-test’ a network by using the Analyser screen to plot a graph of queue/delay against flow scaling factor. (Added April 2025)
View FAQ

The latest versions of both TRANSYT 16 and TRANSYT 17 can be found in the Downloads section inside the TRL Software Portal. Note that a subscription licence for TRANSYT allows you to use either TRANSYT 16 and TRANSYT 17.  Both can reside on your device, and you simply use the same login credentials for both versions.  This gives flexibility for situations where a client is using or wanting you to use a specific version of TRANSYT.

(Updated April 2025)

View FAQ
The latest versions of both TRANSYT 16 and TRANSYT 17 can be found in the Downloads section inside the TRL Software Portal. Note that a subscription licence for TRANSYT allows you to use either TRANSYT 16 and TRANSYT 17.  Both can reside on your device, and you simply use the same login credentials for both versions.  This gives flexibility for situations where a client is using or wanting you to use a specific version of TRANSYT.(Updated April 2025)
View FAQ

A comprehensive user guide is included with every installation of Junctions and TRANSYT, assessible via the F1 key, or the Help button on the top toolbar.

Frequently Ask Questions (FAQs) are also available inside our website’s Knowledge Base.

If you still require assistance, you can:

  • Contact us via software@trl.co.uk 
  • If you wish to send us a model data file as part of your enquiry, the most direct way is by navigating to the Main Menu of Junctions or TRANSYT, selecting the ‘Help’ dropdown, and selecting “Email data file to TRL…”

(Updated April 2025)

View FAQ
A comprehensive user guide is included with every installation of Junctions and TRANSYT, assessible via the F1 key, or the Help button on the top toolbar. Frequently Ask Questions (FAQs) are also available inside our website’s Knowledge Base. If you still require assistance, you can:
  • Contact us via software@trl.co.uk 
  • If you wish to send us a model data file as part of your enquiry, the most direct way is by navigating to the Main Menu of Junctions or TRANSYT, selecting the ‘Help’ dropdown, and selecting “Email data file to TRL…”
(Updated April 2025)
View FAQ
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