Two two-bay pultruded glass fibre reinforced polymer (GFRP) post and rail safety barriers have been fabricated. One, a modular barrier, was fabricated from circular cross-section tubes, bolted sheet moulded composite (SMC) two-part multi-way connectors and bases. The other, a custom barrier, was fabricated from three profiles: square cross-section tubular posts, a circular cross-section tubular knee rail and a C-section hand rail. Rivets connected the hand rail to the tops of the posts and bolted bases connected the posts to the foundation. The continuous knee rail was located by means of holes in the posts’ walls. Both barriers were loaded incrementally up to the general duty load applied to the hand rail and then unloaded. Their load–deformation responses were monitored and both barriers were able to support the general duty load undamaged. After unloading the maximum residual deflection of the hand rail was about 5 mm. The barriers’ mean transverse stiffnesses were evaluated and the custom barrier’s stiffness was about 46% greater than that of the modular barrier. The custom barrier was re-tested up to the heavy duty load and was able to support the load without visible signs of damage.