NPSBS – Non-Proprietary Safety
Barrier Systems (UK)

OBB/DROBB Barriers


OBB is approved to EN1317 as N2W4 and N2W5 single and double-sided with a post spacing at 1.2m and 2.4m respectively.

Open Box Beam is also suitable for use at the road edge or in the central reservation of motorways or high speed roads.

The strength of the barrier lies in the section of the rails, which are normally supplied in 4.8m and 2.4m lengths. These are connected together by fishplates which match the profile of the rail and sit inside, bridging adjoining beams.

There is no limitation on the length of run which can be installed, but both the approach and departure ends should be anchored at ground level to strong SHS posts, or to full height anchor frames (a departure from standard is required).

Due to the rigid nature of OBB some allowance must be made for the effects of temperature change, therefore a special expansion assembly must be fitted every 100m.

Heavier duty ‘Z’ section posts are used for mounting OBB in double height format (DROBB), where a potential hazard exists for vehicles with a higher centre of gravity and mass.

Helpful Links


If you have any queries please feel free to contact us.
Telephone: +44 (0) 1902 499400

xtratech Technical Support

Visit our Xtratech technical web site for advice and support on the Hill and Smith product range.

Hill & Smith Holdings PLC

Headquartered in the UK, the Group employs some 3,600 staff across 51 sites, principally in 7 countries.

Varley & Gulliver

The UK's premier manufacturer of both steel and aluminium bridge parapets to the civil engineering industry.

Asset VRS

The leading supplier of temporary safety barriers in the UK.

Highways Agency

Managing, maintaining and improving England's motorways and trunk roads.

National Roads Authority

Securing the provision of a safe and efficient network of national roads.

Terms & Conditions

For further information on Hill & Smith terms and conditions please call: +44 (0) 1902 499400