BS EN 1340 kerb profiles, upstand heights, vehicle overrun requirements, and UK highway specification — complete 2026 reference
A complete guide to concrete kerb mountability standards covering barrier kerbs, mountable kerbs, dropped kerbs, half-battered profiles, upstand dimensions, vehicle overrun clearances, pedestrian accessibility requirements, and compliance with BS EN 1340, Manual for Streets, and the Highways England Design Manual for Roads and Bridges (DMRB) in 2026.
Kerb mountability determines whether a vehicle can overrun or mount a kerb — a critical factor in highway safety, drainage design, accessible route planning, and carriageway edge definition. Getting the upstand height and profile right is a legal and technical requirement on all UK highway schemes in 2026.
Kerb mountability describes the ease or resistance with which a vehicle tyre can ride over a kerb. It is primarily governed by the upstand height — the vertical distance between the carriageway surface and the top of the kerb — and the kerb face profile (vertical, battered, or splayed). A barrier kerb with a 125 mm upstand prevents most vehicles from mounting; a mountable kerb at 25 mm upstand allows controlled vehicle overrun in specific situations such as ghost islands, bus boarders, and tracking margins.
Concrete kerbs in the UK are manufactured to BS EN 1340:2003 — the European standard for concrete kerb units covering dimensions, strength, water absorption, and freeze–thaw resistance. Highway specification is governed by the Highways England DMRB (Design Manual for Roads and Bridges), Manual for Streets (MfS), and local authority highway design guides. Dropped kerbs for accessibility must comply with BS 8300:2018 and the Equality Act 2010.
The upstand height is the single most important mountability parameter. Too high and an errant vehicle striking the kerb suffers a sudden directional change — potentially causing loss of control. Too low and the kerb provides no edge containment, allowing uncontrolled vehicle overrun onto footways, verges, and drainage channels. The standard UK highway upstand of 100–125 mm balances containment with safety for most applications, but specific locations — bus stops, crossings, ghost islands — require carefully selected reduced upstands per the appropriate design guide.
Upstand height governs mountability. Flush and dropped kerbs permit pedestrian and wheelchair access; barrier kerbs provide vehicle containment. Each profile has a defined application per UK highway design standards.
Concrete kerb mountability standards in the UK are defined by a combination of BS EN 1340 (product standard), highway design guidance documents, and accessibility legislation. The key principle is that the kerb upstand height and face profile must be matched to the specific function of each location — a one-size-fits-all approach to kerb upstands creates both safety hazards and accessibility barriers on the same scheme. Understanding the relationship between kerb profile, upstand height, vehicle speed, and pedestrian need is fundamental to competent highway and urban realm design in 2026.
The Manual for Streets (MfS) and its successor guidance documents recognise that residential streets require a different kerb treatment to primary distributor roads. At low-speed environments (20–30 mph), lower upstands and more forgiving profiles are acceptable because vehicle impact energy is lower. On high-speed rural roads, the DMRB requires robust barrier kerbing to prevent errant vehicles from mounting footways or drainage channels at speed. Specifiers must select the appropriate kerb type, upstand, and bedding specification for each individual location and speed environment.
Standard high-upstand containment kerb — BS EN 1340
The barrier kerb is the standard UK highway kerb — a near-vertical or slightly splayed face with a 100–125 mm upstand above the finished carriageway surface. It provides maximum edge containment, clearly delineates the carriageway from the footway, and channels surface water to gullies. The most common profiles are HB1 (half-batter top, vertical face) and BN (bullnose) — both specified extensively in UK local authority and Highways England schemes. Standard unit length is 900 mm; depths 150–300 mm to suit bedding depth and stability requirements.
Low angled face — permits controlled vehicle overrun
Mountable kerbs have a splayed or angled face — typically 1:3 to 1:5 gradient — and a low upstand of 25–45 mm. The angled face allows vehicle tyres to ride over the kerb without the sudden deflection caused by a vertical face, enabling controlled overrun at ghost islands, central reservations, bus boarder kerbs, and junction tracking margins. The SP (splayed) profile is the most common UK mountable kerb type. Mountable kerbs must never be used where pedestrian protection from vehicle encroachment is required.
Accessibility crossing — 6 mm max upstand at tactile zone
Dropped kerbs reduce the kerb upstand to 6 mm maximum at the crossing point — the threshold required by BS 8300:2018 for wheelchair users, mobility scooter users, and pushchair access. The dropped section transitions from full upstand via transition units (dished kerbs) on each side. A correctly graded footway behind the dropped kerb must slope at no more than 1:20 longitudinally and 1:40 crossfall. Blister tactile paving (400 × 400 mm minimum) is mandatory at all dropped kerb crossings on public highways under UK guidance.
High vertical upstand — 160–200 mm — for level bus boarding
Bus boarder kerbs — also known as Kassel kerbs — have an upstand of 160–200 mm and a profiled face designed to guide bus tyres to within 25 mm of the kerb face, achieving near-level boarding for passengers including wheelchair users. The angled tyre guide face prevents tyre scuffing while the high upstand keeps the bus close to the platform. Specified on all new bus stops on UK trunk roads and many local authority bus priority schemes. The upstand must be maintained precisely — incorrect road surfacing levels post-laying are the most common cause of boarding gaps exceeding the 75 mm DDA maximum.
Drainage edge definition — flush with carriageway
Edging kerbs and channel units are laid flush with or slightly above the carriageway surface — primarily to define edges of footways, cycle tracks, grass verges, and drainage channels rather than to provide vehicle containment. Channel kerbs form the V or U-shaped drainage channel at the carriageway edge, collecting surface water runoff and directing it to gullies. In rural highway cross-sections, channel blocks replace the kerb/gully system, allowing water to flow off the edge of the carriageway into a roadside drain or verge without kerbing.
Curved units for junctions, radii, and turning heads
Radius kerbs are pre-curved concrete units manufactured to specific radii (typically 305 mm to 20 m+) for use at junctions, roundabouts, turning heads, and any location where the kerb alignment follows a curved path. Available in the same profile types (HB1, BN, SP) as straight units, and must be specified with the correct radius and chord length to achieve a smooth kerb line without joints opening excessively on the outside of the curve. Tighter radii require shorter chord lengths to maintain joint width below 10 mm. For radii below 1 m, in-situ concrete kerb haunching allows a continuous curved profile.
The table below sets out the standard concrete kerb mountability upstand heights for each kerb type and application, per BS EN 1340, DMRB, Manual for Streets, and BS 8300:2018.
| Kerb Type | Profile | Upstand Height | Mountability | Primary Application | Standard / Reference |
|---|---|---|---|---|---|
| HB1 / BN / CS | 100–125 mm | Non-mountable | Primary / distributor roads, footways | BS EN 1340 / DMRB | |
| Half-Battered | HB2 / HB3 | 50–75 mm | Semi-mountable | Residential streets, estate roads | BS EN 1340 / MfS |
| Mountable | SP / ET | 25–45 mm | Mountable | Ghost islands, central reservations, bus boarders | BS EN 1340 / DMRB TD 16 |
| Dropped Kerb | Dished / Transition | 6 mm max | Fully accessible | Pedestrian crossings, access points | BS 8300 / Equality Act 2010 |
| Bus Boarder | Kassel / BB | 160–200 mm | Non-mountable (tyre-guided) | Bus stop platforms | DMRB / DDA / LTN 1/20 |
| Edging / Channel | EC / SC / VC | 0–25 mm | Fully mountable | Verge edges, drainage channels, cycle tracks | BS EN 1340 |
| Transition Unit | Dished | 125 mm → 6 mm | Transition | Dropped kerb approach ramps | BS 8300 / BS EN 1340 |
BS EN 1340:2003 is the product standard for concrete kerb units — covering all precast concrete kerbs, channels, edgings, and quadrants used on UK highways and public spaces. It specifies dimensional tolerances, compressive strength classes, water absorption limits, slip/skid resistance, and freeze–thaw durability requirements that all kerb units must meet before use on adoptable highway schemes.
BS EN 1340 defines three compressive strength classes for concrete kerb units. Class 1 (≥ 35 N/mm²) is the minimum for all highway kerbing. Class 2 (≥ 49 N/mm²) is required for high-traffic locations, bus lanes, and areas subject to heavy vehicle overrun. Class 3 (≥ 55 N/mm²) is used in the most demanding environments including HGV-trafficked areas and locations where salt spray or freeze–thaw cycling demands maximum durability. All highway kerb units in the UK are specified to Class 2 minimum on adoptable roads.
BS EN 1340 limits water absorption to a maximum of 6% by mass for Class F (freeze–thaw resistant) kerbs — mandatory for all external highway use in the UK. Low water absorption reduces the risk of freeze–thaw spalling that can destroy the kerb face and upstand geometry over successive winters. Air-entrained concrete with a minimum cement content of 370 kg/m³ and w/c ratio ≤ 0.45 typically achieves BS EN 1340 Class F requirements. All kerb units supplied for UK highway use must carry CE marking confirming BS EN 1340 compliance.
Standard straight kerb units are 900 mm long × 150 mm deep × 125 mm wide (HB1 profile) for most UK highway applications. Deeper units (200–300 mm) are used on primary roads and bus routes where greater bedding depth and stability are required. Width varies by profile — bullnose (BN) is typically 150 mm wide; half-battered (HB) 125–150 mm; splayed (SP) 125–200 mm depending on the degree of splay. Dimensional tolerances per BS EN 1340 are ± 3 mm for length and width, ± 5 mm for depth.
Kerb units must be bedded on a minimum 100 mm thickness of ST2 (Gen 0.5) concrete — never on compacted granular material alone, which allows settlement and upstand variation. Concrete haunching is applied to the back of the kerb unit to a minimum height of two-thirds of the kerb depth. Haunching prevents rotation, maintains upstand geometry, and protects the joint from vehicle impact. Haunching concrete must be placed the same day as the kerb is laid — leaving haunching overnight leads to loss of fines under the kerb base and poor bedding contact.
Joints between kerb units are typically 3–5 mm wide — achieved using temporary spacers during laying. On curved alignments, the outer joint may open to 10 mm maximum. Joints are pointed with a 1:3 cement:sand mortar flush with the kerb face after haunching has set. On high-speed roads and bus routes, joints may be sealed with a flexible polyurethane sealant to prevent ingress of de-icing salt solution, which accelerates carbonation of the backing concrete and corrosion of any reinforcement in the haunching.
Standard UK highway kerbs are natural grey. Buff, red, and charcoal kerbs are available for urban realm, pedestrianisation, and shared surface schemes — specifying coloured kerbs at pedestrian priority zones and crossings improves legibility for visually impaired users. Surface texture of the kerb top must achieve a minimum slip resistance value per BS EN 1340 Annex F — a smooth-topped kerb creates a slipping hazard for cyclists and pedestrians who may ride or walk along the kerb edge.
The finished upstand height must be achieved within ± 6 mm of the specified dimension per most UK highway authority specifications. This means that on a nominal 125 mm upstand barrier kerb, the acceptable range is 119–131 mm. Upstand variation beyond this tolerance creates trip hazards for pedestrians, causes drainage problems, and in the case of bus boarder kerbs, results in boarding gaps that exceed the permitted 75 mm maximum — triggering expensive remedial re-laying works.
BS 8300:2018 requires a maximum 6 mm upstand at the centre of dropped kerb crossings. The transition from full upstand (125 mm) to dropped (6 mm) is achieved over a minimum distance of 1200 mm using purpose-made dished transition units. The footway behind the dropped kerb must be minimum 1800 mm wide, slope at no more than 1:20 along the direction of travel, and be free of obstacles. Blister tactile paving (red at controlled crossings, buff at uncontrolled) must cover the full width of the dropped section.
The table below summarises the BS EN 1340 classification requirements for concrete kerb units used on UK adoptable highway schemes.
| Property | Class 1 | Class 2 | Class 3 | UK Highway Minimum | Test Method |
|---|---|---|---|---|---|
| Compressive Strength | ≥ 35 N/mm² | ≥ 49 N/mm² | ≥ 55 N/mm² | Class 2 (49 N/mm²) | BS EN 1340 Annex C |
| Water Absorption | ≤ 6% (Class F) | ≤ 6% (Class F) | ≤ 6% (Class F) | Class F (≤ 6%) | BS EN 1340 Annex D |
| Freeze–Thaw Resistance | Class F (required for UK) | Class F | Class F | Class F mandatory | BS EN 1340 Annex E |
| Slip Resistance (SRV) | ≥ 45 SRV | ≥ 45 SRV | ≥ 45 SRV | ≥ 45 SRV | BS EN 1340 Annex F |
| Length Tolerance | ± 3 mm | ± 3 mm | ± 3 mm | ± 3 mm | BS EN 1340 cl.4 |
| Depth / Width Tolerance | ± 3 mm | ± 3 mm | ± 3 mm | ± 3 mm | BS EN 1340 cl.4 |
| Warpage | ≤ 3 mm | ≤ 3 mm | ≤ 3 mm | ≤ 3 mm | BS EN 1340 cl.4 |
The definitive European product standard for concrete kerb units — covering compressive strength classes, water absorption, freeze–thaw resistance, slip resistance, dimensional tolerances, and CE marking requirements for all UK highway kerbing in 2026.
BSI Standards →BS 8300 governs accessible design of the built environment — including dropped kerb dimensions, upstand limits, tactile paving requirements, and footway geometry at crossing points. Compliance is a legal obligation under the Equality Act 2010 on all public highways.
Equality Act Guidance →Manual for Streets provides kerb selection guidance for residential and local roads. The DMRB covers trunk road applications including ghost island kerbing, bus boarder specifications, and roundabout kerb profiles. Both are essential references for UK highway designers in 2026.
Retaining Wall Guide →