Transport consultancies use traffic management software to design signal-controlled junctions, assess the impact of new developments and demonstrate that proposed schemes can accommodate future traffic demand.
The process usually begins with TRANSYT, which is used to model and justify a proposed traffic signal installation during the planning stage. The outputs from TRANSYT support the Traffic Impact Assessment (TIA), helping consultants demonstrate how the junction is expected to perform.
Once the scheme is approved, the signals are installed and connected to TRL’s Urban Traffic Control (UTC) platform, before adaptive systems such as SCOOT® or MOVA are added to optimise performance.
Together, these systems support the full journey from planning and approval through to live network management.
How is traffic management software used during planning?
When a new development or highway scheme is proposed, consultants need to understand it could affect the surrounding road network.
This is usually assessed through a Traffic Impact Assessment, or TIA, which considers:
- Existing and future traffic demand
- Junction capacity
- Queue lengths and delays
- Saturation levels
- The impact of additional vehicle movements
- Whether mitigation measures are required
For signal-controlled junctions, consultants can use TRANSYT to model current and forecast traffic conditions, test alternative layouts and optimise proposed signal timings.
The outputs provide evidence that can be included within the TIA to support the proposed junction design or signal installation.
Using TRANSYT to design and justify traffic signals
TRANSYT allows consultants to assess how a proposed signal-controlled junction or linked network is likely to perform before any physical changes are made.
Consultants can use it to:
- Test proposed traffic signal installations
- Compare junction layouts
- Assess queues, delays and capacity
- Optimise signal timings
- Model future traffic demand
- Review saturation levels
- Compare mitigation options
- Support planning submissions
This helps identify whether the scheme is viable and which design is most likely to provide the required performance.
TRANSYT modelling also gives planning and highway authorities a clearer evidence base for reviewing the proposal.
Demonstrating capacity and saturation
A key part of many Traffic Impact Assessments is demonstrating that the proposed junction has enough capacity to accommodate forecast demand.
Consultants may need to show that saturation levels remain within acceptable limits and that queues and delays can be effectively managed.
Where a junction is expected to operate close to capacity, adaptive traffic control may form part of the proposed solution.
Adaptive control can help demonstrate how signal timings could respond to changing traffic demand rather than relying only on fixed-time plans. This may improve the effective capacity of the junction and help achieve the saturation figures required to justify the TIA.
It can be particularly useful when widening the road, adding lanes or making major physical changes is not practical.
However, any adaptive control benefits included within the assessment should reflect a realistic operational solution. Consultants should consider how the proposed junction will be connected, managed and optimised once installed.
This is where TRL’s UTC, SCOOT® and MOVA become central to the process.
What happens once the scheme is approved?
Once the Traffic Impact Assessment has been accepted and the signal scheme has been approved, the project moves into implementation.
The traffic signals are installed and connected to the relevant communications infrastructure.
The junction is then added to TRL’s UTC.
TRL’s UTC provides the communication link between the roadside signal equipment and the central traffic management system. It allows the junction to be monitored and managed as part of the wider urban network.
This turns the scheme from a planning-stage model into a live, connected traffic signal installation.
The role TRL’s UTC
TRL’s UTC provides a central platform for communicating, monitoring and managing signal-controlled junctions.
It enables traffic operators to:
- Monitor traffic signals and roadside equipment
- Manage junctions from a central location
- Coordinate signal plans across a network
- Respond to incidents and changing conditions
- Access network and operational information
- Support bus priority and wider transport strategies
- Manage different forms of adaptive signal control
For transport consultants, TRL’s UTC is the bridge between the junction assessed during the planning stage and the scheme operating on the live network,
TRANSYT helps design and justify the junction. TRL’s UTC then provides the platform through which the installed signals are connected and managed.
Considering UTC requirements during the planning stage can also help consultants create a more realistic and deliverable proposal.
Adding SCOOT® for coordinated networks
Once the signals have been connected to TRL’s UTC, SCOOT® can be introduced where adaptive optimisation is required across a coordinated urban network.
SCOOT® uses live traffic information to adjust signal timings in response to changing demand.
It is typically used where several junctions need to work together across a corridor, town or city network.
SCOOT® can help:
- Coordinate signals across multiple junctions
- Respond to changing traffic demand
- Improve the use of available road capacity
- Reduce unnecessary delays
- Improve journey time reliability
- Support congestion and incident management
TRL’s UTC provides the central environment for monitoring and managing the network, while SCOOT® continuously optimises signal timings.
For consultants, this provides an operational basis for any adaptive control benefits included within the Traffic Impact Assessment.
Adding MOVA for individual junctions
Where optimisation is required at an individual junction or smaller group of junctions, MOVA may be used.
MOVA responds to live traffic demand and adjusts signal timings locally.
It can help:
- Increase effective junction capacity
- Reduce delays
- Make better use of available green time
- Respond to fluctuating traffic levels
- Improve junction performance
- Reduce the need for major infrastructure changes
Once connected to TRL’s UTC, MOVA-controlled junctions can still be centrally monitored and managed as part of the wider urban network.
The choice between SCOOT®and MOVA will depend on the junction, its location, surrounding traffic conditions and the Local Authority’s operational requirements.
How the full process works
Traffic management software supports each stage of a traffic signal scheme:
- Model the junction with TRANSYT
Consultants assess existing conditions, forecast future demand and test the proposed signal installation. - Support the Traffic Impact Assessment
TRANSYT outputs are used to demonstrate capacity, saturation, queues, delays and expected junction performance. - Include adaptive control where appropriate
SCOOT®orMOVA may be considered to show how responsive signal control could improve performance and make better use of available capacity. - Secure approval
Planning and highway authorities review the evidence, assumptions and proposed mitigation. - Install the traffic signals
Once approved, the signal equipment is installed and connected. - Add the junction to UTC
TRL’s UTC provides communication, central monitoring and ongoing network management. - IntroduceSCOOT®or MOVA
The appropriate adaptive control system optimises the junction or wider network using live traffic demand.
Why this connected approach matters
A traffic model is not the final outcome.
The real objective is to deliver a junction that can operate effectively one it becomes part of the live road network.
By linking TRL’s TRANSYT, UTC, MOVA and SCOOT®, consultants and Local Authorities can create a clearer journey from design through to operation.
This supports:
- Stronger Traffic Impact Assessments
- More defensible signal design decisions
- Clearer capacity and saturation evidence
- More realistic adaptive control assumptions
- A smoother transition from planning to implementation
- Central monitoring and management through UTC
- Ongoing optimisation using SCOOT® or MOVA
- Greater confidence in long-term network performance
It helps demonstrate not only that the scheme works within a model, but that it can be connected, controlled and optimised once operational.
From modelling to live network control
The process can be summarised simply:
TRANSYT models and justifies the traffic signal installation.
The Traffic Impact Assessment supports planning approval.
UTC connects and manages the installed traffic signals.
SCOOT® or MOVA optimises performance using live traffic conditions.
Together, these systems provide transport consultants and Local Authorities with a connected approach to designing, delivering and managing urban traffic networks.
Discover TRL’s traffic management software
TRL provides traffic modelling, control and optimisation software for transport consultancies, Local Authorities and network operators.
Our solutions support the complete traffic signal lifecycle:
- TRANSYT for traffic signal modelling, design and Traffic Impact Assessments
- TRL’s UTC for communication, central monitoring and urban network management
- SCOOT® for adaptive optimisation across coordinated networks
- MOVA for responsive optimisation at individual junctions
From justifying a new signal installation to managing and optimising it on the live network, TRL’s software helps consultants and authorities make better-informed decisions and deliver better-performing urban traffic schemes.
