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Highways Visibility and Sight Lines Calculator
Calculate required visibility splays and assess compliance with MfS and DMRB standards.
Road and Access Characteristics
Additional Considerations
Visibility Splay Calculation Results
Stopping Sight Distance (SSD) Required
Required Y-Distance (metres)
Adjusted for gradient; represents forward visibility requirement
Required Visibility Splay (Triangle)
X × Y dimensions for visibility triangle
Pedestrian Visibility Splay
Curve Visibility Adjustment
Compliance Assessment
Planning Condition Template
Suggested condition for decision notice
Standards Reference
Manual for Streets (MfS), Manual for Streets 2 (MfS2), Design Manual for Roads and Bridges (DMRB)
About this tool: Highways Sight Lines
Visibility splay calculator — X/Y sight-line distances for a new or altered access using Manual for Streets / DMRB stopping-sight-distance methodology.
When to use it
Use whenever you propose a new or altered vehicular access onto the public highway, or change the use intensity of an existing one.
Policy and guidance it draws on
Manual for Streets, DMRB CD 123
Part of Site Intelligence
Use these tools early in your project to understand what environmental, heritage, and ecological constraints affect your site. The results will determine which technical reports you need and shape your application strategy.
Related tools
Flood Risk AssessmentFlood ScreeningContaminationGround StabilityEcologyBNG CalculatorTreesHeritageGuidance to help you prepare — not formal planning advice. Check the current policy text and your council's local plan before relying on it.