Focus
Land-use decisions and the network on the same page.
A plot’s use, density and land-use mix determine how many trips it will generate, when and by which mode. A 200-home estate and a shopping centre of the same floor area generate traffic at entirely different times and with different users. We therefore treat a traffic impact assessment as the transport consequence of a planning decision, not as a vehicle count.
We assess three situations: today’s conditions (existing), the expected situation once the current plan is built out (future without project) and the situation once the proposed plan or project is built (future with project). The project’s real impact is the difference between the last two.
Zoning changes
The transport case for a zoning change, with evidence.
Converting residential land to commercial or mixed use, increasing floor area ratio or introducing a mix of uses changes not only total trips but also their distribution through the day. Visitors, staff and deliveries are added to residents’ morning and evening trips, often at midday and in the evening with a different directional split.
In mixed-use schemes, internal trips between uses are not counted as load on the external network; we estimate this internal capture with justification. Walking distance to public transport and the quality of pedestrian links also directly affect car mode share.
- Plan decisions: current and proposed use, floor area ratio, coverage, height and mix
- Travel demand: trip generation by use, peak hours and mode split
- Access and operation: site access, car park entrances, servicing and pedestrian access
- Network effects and measures: junction capacity, queues and delay, public transport links
Key questions
Which questions does this study answer?
- How much does the proposed change alter travel demand and access needs compared with the current plan?
- At what times, by which modes and in what volume will the project generate trips?
- How do access points, servicing and parking affect surrounding roads and pedestrian safety?
- At what level of service will junctions operate in the future with the project, and how far will queues extend?
- Which measures can offset the difference between the without- and with-project futures?
Workflow
How we work
- 01
Scope and study area
We review plan and project data and the authority’s expectations, and set the study area, junctions, assessment year and peak hours.
- 02
Measure the existing situation
We survey turning movements, pedestrians and journey times where needed, and derive the peak hour and peak hour factor from site data.
- 03
Estimate demand and build scenarios
We calculate trip generation by use, adapted to local conditions, apply mode and directional split, assign demand to the network and build without- and with-project scenarios.
- 04
Assess performance and propose measures
We compare capacity, delay, level of service and queue lengths, and propose signal, turning pocket, access and pedestrian measures with their effect.
Deliverables
What you receive
- Transport comparison of the current and proposed plan decisions
- Study area, count data and existing conditions
- Trip generation, mode and directional split assumptions with sources
- Capacity, delay, level of service and queue comparison for all scenarios
- Assessment of access, parking, servicing and pedestrian access
- Mitigation measures and mitigated performance
- A traffic impact report with transparent method and assumptions, ready for submission
Report scope depends on the nature of the change, the study area, data availability and the authority’s requirements. The report is a technical input; the approval decision rests with the authority.
Getting started
What we need to get started
- Site location: parcel number or a map link
- Current and proposed plan decisions: land use, floor area ratio, site coverage, height
- Land-use mix and floor areas: number of homes, retail area (m²), bed or student capacity
- Site layout and proposed vehicle and pedestrian access, if available
- The authority’s letter or requested report scope, if available
We can start the first call even if not all documents are ready.
FAQ
Questions about this service
What is a traffic impact assessment and when is it needed?
A traffic impact assessment evaluates the trips a new development or plan change will generate and their effect on surrounding roads, junctions, pedestrian routes and public transport. It is usually requested by the municipality or transport authority for changes of use, density increases or large retail, residential, healthcare, education and logistics developments. Its scope is set by the authority’s request and the nature of the change.
How long does a traffic impact report take?
Duration depends on the size of the study area, the number of junctions to count and the modelling required. Because counts must be made in a representative period, school holidays and public holidays can affect the programme. We confirm the programme in writing once scope is agreed.
How is the fee determined?
By the study area and number of junctions, count locations and durations, the type of model needed (junction analysis, microsimulation or demand model) and the report scope requested by the authority. We provide an itemised quote once scope is clear.
Do you guarantee approval of the report?
No. The approval decision rests with the authority. We prepare a report that sets out its method, assumptions and findings transparently and can answer the authority’s questions with technical justification, and we support revisions during review.