Scuppers in median barriers shall not be used in the following situations:
• Passing runoff from one side of a median barrier to a drainage structure or curb-and-gutter section on the other side (downstream) of the median barrier
• Passing runoff through the median barrier so that the runoff continues to flow across highway lanes on the other side (downstream) of the median barrier
For the above scenarios, flows shall be captured by placing inlets on each side of the median barrier as shown in Standard Plan B-95.20-02, allowing runoff to pass between the structures in a pipe.
In locations where a scupper barrier is used specifically to pass stormwater to flow across highway lanes on the other side of the median barrier, the scuppers shall be analyzed for potential plugging and consider site-specific details such as accumulation of debris or maintenance sand as well as impacts or risk associated with snow and ice obstructing the passage of stormwater. In sag profile locations, the project shall consider secondary means of removing stormwater, should scuppers be plugged, by installation of drainage structures. To analyze the hydraulic capacity of scuppers or curb-opening inlets, refer to HEC-22 Section 4-4.4.2 for guidance. Instead of using equation 4-22 in HEC-22 for the length of the curb-opening inlet required for total interception, use the recommended equation (8) for the curb-opening length from FHWA-HRT-22-061 Curb-Opening Inlet Interception On Grade Technote.
Contact the RHE to determine the appropriate level of consideration and analysis appropriate for a specific project or design.
