Who should prepare a Transport Assessment and why it matters

A Transport Assessment is read by a highway officer who will form a view about the author within the first few pages. That view then colours everything that follows, because the document is built almost entirely on assumptions that cannot be checked without redoing the work. Who prepares a Transport Assessment therefore affects the outcome in a way that is hard to quantify and easy to observe.

The practical question for a developer is not whether the author has a particular qualification. It is whether they have the data access, the modelling competence and the working relationship with the highway authority to make the document stick.

What the assessment has to demonstrate

A Transport Assessment sets out the transport effects of a development and the measures proposed to deal with them. National guidance on travel plans, transport assessments and statements describes the scope, and the local highway authority sets the detail through a scoping exercise.

That normally means establishing existing conditions from survey data, forecasting trips generated by the proposal, distributing those trips across the network, assessing junction capacity in the relevant peak periods, testing accident records, evaluating accessibility by non-car modes, and proposing mitigation where the results require it.

Each of those steps rests on a choice. The survey period chosen, the trip rate site selection, the distribution method, the growth factors applied and the modelling parameters used all involve judgement, and any of them can be challenged. An author who cannot defend those choices in a meeting has produced a document that will be tested to destruction.

Professional body membership and what it signals

There is no statutory licence for transport planners in the way there is for ecologists handling protected species. Competence is evidenced through professional body membership, chartered status and demonstrable project experience.

The routes that carry weight with highway authorities include membership of the Chartered Institution of Highways and Transportation, membership of the Chartered Institute of Logistics and Transport, and chartered transport planning status. Chartered civil engineering status is common among authors who came through a highway engineering route.

What matters more than any single set of letters is the pattern behind them: a named author, an identified reviewer, and a professional indemnity position that covers the advice. Ask who will sign the document, not which firm is instructed. The wider question of what competence means across different planning regimes is covered in what competent person means in planning legislation.

Data access is a real barrier

Trip generation on most schemes comes from the TRICS database, which is a subscription service. An author without a current subscription cannot select sites, cannot document the filters used and cannot produce the output an officer expects to see.

That constraint is more absolute than it sounds. A document quoting trip rates without the supporting site selection cannot be reviewed, and the officer's only reasonable response is to ask for the underlying data. Where that data does not exist, the assessment has to be redone.

Other data sources matter too:

• Personal injury collision records, obtained from the highway authority or the national dataset, for the standard five year study period.
• Traffic count data, either commissioned or obtained from the authority, collected in neutral months.
• Census travel to work data for mode share, at the right geography.
• Public transport service data, checked at the date of the assessment rather than copied from a previous report.
• Parking surveys where parking stress is in issue, using a recognised methodology and the correct survey periods.

Ask a prospective author which of these they hold or will obtain, and what is excluded from the fee. The exclusions are where budgets are lost.

Junction modelling competence

Capacity modelling is the part of a Transport Assessment that separates authors most clearly. Priority junctions, roundabouts and signalised junctions are each modelled with different tools and different conventions, and the highway authority will usually specify which it accepts.

A model is only as good as its inputs and its calibration. Saturation flows, geometric measurements, lane allocations, signal timings and the base year flows all have to reflect the junction as it exists, and a model calibrated against observed queue lengths carries far more weight than one built from drawings alone.

Expect the authority to ask for model files rather than summary tables. An author who cannot supply them, or who supplies them in a form the authority cannot open, creates a delay that has nothing to do with the merits of the scheme.

Where the strategic road network is engaged, National Highways applies its own standards and expects modelling consistent with them. That is a different expectation from a local authority's, and identifying it early avoids a wasted round.

Knowing the authority's expectations

Highway authorities publish parking standards, design guidance and, in some cases, their own transport assessment requirements. They also have settled positions on questions the national guidance leaves open, such as which growth factors they accept, how they treat internal trips on mixed use schemes, and what they expect from a travel plan.

An author who has worked with the authority recently knows those positions. An author who has not will discover them through consultee responses, which costs a determination period.

That is not an argument for a local monopoly. It is an argument for asking the question directly at appointment: which schemes has this team taken through this authority, and what did the highway officer ask for that was not in the national guidance.

A Travel Plan is often secured alongside the assessment and is usually prepared by the same team, so scope it at the same time rather than as an afterthought.

Scoping the appointment properly

Councils usually expect a suitably qualified author for transport work, and professional review is strongly advised even on smaller schemes. The appointment should say so in writing.

1. Agree a scoping note with the highway authority before the assessment starts, and make the agreed scope part of the appointment.
2. Specify which surveys and datasets are included, and which will be charged separately.
3. Specify the junctions to be modelled, the peak periods and the assessment years.
4. Name the author and the reviewer, and confirm the professional indemnity position.
5. Include an allowance for responding to consultee comments, because the first response almost always asks for something.
6. Agree who attends meetings with the highway authority and whether that time is included.

Where an assessment already exists from an earlier scheme, check its currency before reusing it. Survey data ages, networks change and standards move, and the test applied to older evidence is the same one described in checking whether a survey is still valid.

An AI-assisted draft can carry the structure, the policy references, the site description and the accessibility narrative, and it gives the transport planner a document to correct rather than a blank page. The modelling, the data selection and the professional judgement remain with them. Where you need an independent reviewer to check a draft before submission, the professional directory is the route to one.

Ask for the author's name on the appointment letter. It changes the conversation, and it changes the document.

This is general guidance, not legal advice. Check the position with your local highway authority, your local planning authority or a qualified professional before relying on it.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.