Bridge Approaches

Rigid barriers are typically used where there is no available space to accommodate barrier deflection. They are constructed from concrete or heavy-duty steel sections and are predominately used on bridges.

In many instances the areas either side of a bridge is shielded with a longitudinal barrier such as w-beam guardrail.

Whilst connecting a semi-rigid guardrail barrier to a rigid barrier installed on a bridge provides barrier continuity, the transition between the two barrier types requires careful consideration.

thrie beam bridge approaches
hot dip galvanised bridge approaches
thrie beam bridge transition

The transition area must gradually increase the lateral stiffness of the semi-rigid guardrail barrier and reduce the potential for vehicle pocketing at the connection with the rigid concrete barrier.

Transition designs are contained within road authority specifications and vary from state to state. A transition area will typically incorporate one or more of the following techniques to provide the gradual increase in stiffness;

  • Reducing the spacing between supporting posts;
  • Nesting (double layering) of the standard w-beam rail elements; or
  • Transition from w-beam rail to a thrie-beam (triple corrugation) rail.