Section 4: Bridge Railing Design Exceptions

Possible Design Exception

Occasionally, an upgrade to railing on an existing structure could degrade rather than improve bridge safety. A District should consult with the Bridge Division about a possible design exception if it is planning a bridge-widening or rehabilitation project in which raising the railing to meet current standards will reduce overall safety. Factors to consider include the following:
  • Speed of traffic in the bridge location.
  • Resistance to impact of the existing railing.
  • Whether the bridge ends are intersections protected by stop signs or stop lights.
  • Whether the geometry is straight into, along, and out of the bridge.
  • Whether traffic on the bridge is one-way or two-way.
  • Accident history on the bridge, including damages to and repairs of the railing.
  • Risk of fall over the side of the bridge.
  • Whether the bridge has a lower roadway.
  • Whether a railing upgrade will further narrow an already narrow lane width.