Speed Bumps Ahead Post Mounted Sign - 557.1 R2/RA2 (Face Only)If you are installing speed bumps then it is recommended that signage is installed to give ample warning to road users that they need to slow down for the speed bump ahead in the road. Sign diagram 557. 1 is the official sign diagram to give the clear message that a speed bump is ahead in the road. These signs are most commonly found in areas where there is likely to be lots of pedestrian traffic. This may be around university campuses, schools,