Transport statement or transport assessment: the cost difference

The document is decided by the scale of the traffic effect, and the cost follows from the scoping response rather than from the label. A transport statement for a small scheme is a short piece of work: a site visit, accessibility review, trip generation from a recognised database, a parking and servicing section and an access safety review. A transport assessment for the same site with 60 dwellings instead of six adds junction capacity modelling, future year assessments and mitigation design, and that is where the money goes.

So the question worth answering before you commission anything is not which document is needed. It is which junctions the highway authority wants modelled.

The thresholds that decide which document applies

There is no single national threshold any more. National guidance asks for the scope of transport evidence to be agreed with the local highway authority, in proportion to the likely impact, and the numbers now sit in local validation lists and highway design guides.

Two figures appear repeatedly in practice: around 50 dwellings or around 2,500 m² of floorspace as the point where an assessment rather than a statement is expected. Those are also the thresholds PlanScope uses to flag a Transport Assessment in its report recommendations, and the council's own validation list and the highway authority's view take precedence over any rule of thumb.

Below that, a Transport Statement is normally proportionate. Well below it, for a handful of units with an existing access, a transport note or a short section within the planning statement may be all that is asked for.

What each document contains

The step change is the middle three rows. Once distribution, modelling and future years are in scope, the work stops being descriptive and becomes analytical, and the analysis has to be built, checked and defended.

Trip generation and the cost of data

Trip rates normally come from a recognised trip rate database, and consultants hold the licence for it. The cost you feel is the survey work around it: automatic traffic counts on the affected links, manual classified turning counts at the junctions to be modelled, and sometimes a queue length survey to validate the model.

Counts have to be taken in neutral periods, which means avoiding August, the Christmas and New Year fortnight, school holidays and any week with local disruption. Miss the window and the survey waits for the next neutral month, which is a programme cost rather than a fee.

Where the access is being altered, the safety review has to show the recorded position rather than assert that the access is safe. Collision data comes from the highway authority for a defined study area and period, usually five years, and it is used to show whether the access has a recorded problem. Ask for it early, because authorities take time to supply it.

Junction modelling as the main cost driver

Each junction modelled is a discrete piece of work: build the model, validate it against observed queues, run the base year, run the future year with and without development, and report the results. The number of junctions in scope therefore sets the fee, and that number is set by the highway authority in scoping.

This is where a scoping conversation pays for itself. A study area of two junctions and one assessment year is a different commission from five junctions and two assessment years, and the difference is not marginal. Authorities will often narrow the scope when asked to justify each junction.

Where a county or strategic model has to be run, the authority may do the work and recharge it, and the timescale is theirs rather than yours. Ask about that specifically, because it is the item most likely to sit outside your consultant's fee and outside their control.

Scoping the work with the highway authority first

Send a one page scoping note before instructing anyone. It should set out:

1. The development description, quantum and proposed access arrangement.
2. The trip rate source and the site categories proposed, with the reasoning.
3. The proposed study area and the junctions suggested for assessment.
4. The assessment years and the growth assumptions.
5. The survey dates proposed and the periods being avoided.
6. Whether a travel plan is offered, and at what level.

Then ask for written confirmation or amendment. The response is your specification, and it converts a variable cost into a defined one. Without it you are paying a consultant to guess, and paying again when the authority disagrees.

Travel plans, monitoring and the cost that arrives later

The transport work has a tail. A travel plan secured by obligation usually carries monitoring surveys and a monitoring fee, and those sit in the post-consent budget rather than in the application budget.

Two things keep that tail short. Time the first survey to a stated occupancy level rather than a calendar date, and cap any obligation to implement further measures at an agreed sum. A Travel Plan drafted with measurable targets and a defined end point costs less to live with than one drafted loosely.

Physical measures are often the better trade. Secure cycle parking and a charging point provided by condition need no annual monitoring, and they cost a known amount once.

Setting the budget from the scoping response

Build the budget in this order: the scoping response, then the survey schedule, then the modelling scope, then the reporting, then the post-consent tail. Every line then has a reason attached to it, which is what a client or a lender wants to see.

Fees for individual technical reports commonly fall in the range of £1,000 to £5,000 each, and transport work sits at the upper end once modelling is involved, which is why the scoping stage has more effect on the total than any other decision. Budget the survey contingency too, because a count taken in the wrong week has to be repeated.

Drafting the document is a separate cost from the analysis behind it. PlanScope drafts transport statements and assessments structured to the sections a highway authority expects, with missing site facts flagged rather than invented, and PlanScope pricing is one free report, £50 per report, or £150 a month on the Professional tier. The analysis, the surveys and the modelling still need a transport planner, and councils expect a suitably qualified author for assessment level work.

One honest uncertainty. Highway authorities differ considerably in what they ask for at the same scheme size, and a neighbouring authority's scoping response is not a guide to yours. Budget on the response you receive, not on the last scheme you did. Other evidence lines behave the same way, as we set out in budgeting the daylight and sunlight evidence base and in utility connection costs in a development budget.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required. This is general guidance rather than legal advice, so agree the transport scope with your local highway authority before commissioning work.