A growing problem on the Western Rivers is vertical bridge clearance. It is always on the minds of passenger vessel operators like me that operate boats with tall stacks. However, vertical clearance is also becoming a problem for operators that haul containers and similar types of cargo with height issues.
At an industry meeting recently, experts predicted an increase in container traffic on the rivers and many Midwest ports are gearing up to handle this expected increase in container business. While this is great news for the shipping industry it raises some important operational questions. For example, how many containers can be safely stacked on a barge before vertical bridge clearance becomes an operational problem? Also, how will container vessels and barges handle high water conditions and will they be able to accurately estimate bridge clearance while underway?
In the last few years there have been several accidents involving commercial vessels and bridges during high water. Last year, a cargo vessel collided with a bridge in my home state of Kentucky causing severe damage to the bridge. Even though high water was not involved, the National Transportation Safety Board determined that bridge navigation lights were not functioning and that a crew navigation error contributed to the cause of the accident.
The National Oceanographic and Atmospheric Administration (NOAA) is working to reduce the incidence of vessel collisions with bridges using a laser-based system that measures “air gap.” Air gap is the distance between the water’s surface and the lowest point of a bridge. The system also measures the vessel’s clearance as it passes under a bridge. Data is updated every few minutes and measurements include changes in water level, bridge height due to bridge traffic and air temperature. These and other factors are communicated directly to vessels so crews can quickly make important navigation decisions. NOAA has installed air gap measurement systems in nine U.S. ports.
I hope that technology such as NOAA’s air gap system can provide us with a good starting point to begin to solve this growing problem.