LVIA or Townscape and Visual Impact Assessment

LVIA vs TVIA is not a choice between two methodologies. Both are built on the same chassis, the Guidelines for Landscape and Visual Impact Assessment third edition published by the Landscape Institute and IEMA in 2013, and both separate effects on the resource from effects on views and visual amenity. What differs is the baseline they characterise, the receptors they identify, the way viewpoints get agreed, and how cumulative effects are handled.

Understanding those four divergences is what stops a consultant commissioning the wrong assessment, or worse, receiving a rural landscape assessment for a city centre site with the word "townscape" substituted throughout.

The same chassis, two different baselines

GLVIA3 asks for two linked but separate assessments. Landscape effects are effects on the landscape as a resource: its character, its elements, its qualities. Visual effects are effects on specific views and on the visual amenity of people. That structure holds whether the receiving environment is a chalk downland escarpment or a Victorian terraced street.

A landscape and visual impact assessment characterises landscape character areas and types, then assesses the effect of the proposal on them. A townscape and visual impact assessment characterises townscape character areas, urban grain, streetscape, public space and the setting of heritage assets, then does the same.

The methodology for scoring is common to both. Sensitivity combines susceptibility to the particular change with the value attached to the receptor. Magnitude combines size and scale, geographical extent, duration and reversibility. Significance follows from professional judgement applied transparently, which is a requirement rather than a courtesy. The mechanics of that scoring are set out under sensitivity and magnitude and how significance is scored.

Where the methodology diverges

Four divergences matter in practice.

The receptor set. In a rural assessment the visual receptors are residents, users of public rights of way, road and rail users and recreational users, and they are often few and widely spread. In a townscape assessment they are pedestrians in named streets and public spaces, workers, residents at specific storey heights, and users of designated views, and they are numerous and concentrated.

The scale of analysis. Rural work uses a zone of theoretical visibility generated from terrain data, often across several kilometres. Urban work uses a three-dimensional model of the surrounding buildings, because the buildings rather than the terrain control visibility, and a zone of theoretical visibility built from bare terrain in a city is meaningless.

The treatment of heritage. Townscape assessment overlaps heavily with the setting of listed buildings and conservation areas, so the Historic England guidance on assessing the setting of heritage assets runs alongside GLVIA3 and the two conclusions have to be consistent. Rural assessment touches heritage less often, though registered parks and scheduled monuments pull it in.

And the vertical dimension. Urban assessment has to deal with views from upper floors, from roof terraces and along framed street vistas. Rural assessment is largely a ground-level exercise.

Character assessment baselines

The published baseline material is different in kind, and knowing what exists saves survey time.

For a rural site: Natural England's National Character Areas at the strategic level, then the county or district Landscape Character Assessment for character types and areas, plus any local landscape designation, seascape character assessment on the coast, and the special qualities statement for a National Park or National Landscape where one applies.

For an urban site: the conservation area appraisal, any townscape or urban character study adopted by the council, a tall buildings study or view management framework where one exists, the local plan's character policies, and the National Heritage List for the assets in the study area.

Where nothing has been published for the immediate area, the assessment has to establish its own character areas, and that judgement then becomes the weakest link in the whole report. State the method, walk the study area, and define the boundaries on a plan with a reasoned description of each area. An objector who can show that your character areas were drawn to suit the proposal has a strong line of attack.

Viewpoint selection and agreement

This is where the two practices differ most, and where the greatest saving sits.

Urban viewpoints are usually agreed formally. In London the designated views in the Mayor's view management framework fix both the location and the assessment point, and there is no discretion. Outside London, many authorities with tall building policies keep a list of townscape views, and the officer will expect the assessment to use them plus a set agreed at scoping.

Rural viewpoints are more often proposed by the applicant and negotiated. The schedule should give, for each viewpoint, a grid reference, the receptor type, the distance and direction to the site, the reason it was selected, and the visualisation type produced. Send the schedule and a plan before the photography, because re-shooting a season later is a real cost.

Two points that apply to both. Include viewpoints that show the proposal badly, because an assessment that only contains flattering views loses credibility on the first site visit. And record the photography conditions: date, time, weather, and whether the trees were in leaf. The practice of agreeing and reporting these schedules is covered under TVIA viewpoint schedules.

Photomontage and wireline standards

Visualisations are the part of either assessment that a committee actually looks at, and the standards are specific.

The Landscape Institute technical guidance on the visual representation of development proposals sets out visualisation types running from an annotated baseline photograph through wirelines to a photomontage rendered to show materials and finishes. It specifies the camera and lens characteristics, the requirement to record camera position and height, the projection to be used, and the printed size and viewing distance at which the image is intended to be read.

Three failures recur.

• Images printed at a size that does not match the stated viewing distance, which makes the proposal look smaller than it will appear.
• A wireline supplied where the effect turns on materials and reflectivity, or a fully rendered montage supplied where the geometry is still in flux.
• No baseline photograph at the same station point, so the before and after cannot be compared.

For a rural scheme, wirelines over baseline photography are often enough for distant viewpoints, with photomontages reserved for the close and mid-range views. For an urban scheme, accurate visual representations from the designated views are normally required at the higher visualisation types, and the verification method has to be described.

Sites on the urban fringe

A site at the edge of a town sits in a published landscape character area while being seen mainly by urban receptors. Running two separate assessments duplicates the viewpoint work and produces two sets of conclusions that have to be reconciled.

The better approach is a single assessment with two baseline chapters, one landscape and one townscape, a single viewpoint set that covers both receptor groups, and a combined effects chapter that reports landscape effects, townscape effects and visual effects separately. Say in the methodology why you structured it that way.

Where the site is allocated in the local plan, check what the site assessment said about landscape sensitivity, because that document sets the terms of the argument and an assessment that ignores it looks evasive. The choice between the two report types on a given site is covered under choosing the right visual assessment.

Cumulative assessment in each

Cumulative assessment means different things in the two settings.

In a rural context, the cumulative case usually concerns other schemes of the same type: wind turbines, solar arrays, or successive housing allocations around one village. The analysis needs a defined list of schemes by status, combined zones of theoretical visibility, cumulative viewpoints showing both proposals, and a sequential assessment along the routes people travel.

In an urban context, the cumulative case usually concerns consented tall buildings that have not yet been built. The analysis needs a consented baseline model, an emerging baseline including schemes at application stage, and views showing the proposal in each. State the date the cumulative list was compiled, because it changes monthly in a busy borough.

In both settings, the list of cumulative schemes should be agreed with the authority in writing. It is the single most common reason a visual assessment is sent back for further work, and it costs nothing to settle at scoping.

Councils normally expect this work to be done by a landscape professional with the relevant competence, and professional review before submission is strongly advised. PlanScope drafts the report structure, the methodology narrative and the policy framing, and marks every figure it cannot source as to be confirmed. Browse all 66 report types and start a draft.

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