Port Isabel Memorial Causeway

[roadman65]

I was checking out GSV and noticed that on the only bridge to link South Padre Island, TX to the US Mainland there are gates at each end of the bridge.  In addition there are two section red signal heads strategically placed at regular intervals along the 2.37 mile bridge. Some of the signals have a red DANGER along with both English and Spanish informing motorists to stop when flashing.

I cannot find too many articles on this, so I was wondering if anyone knows what the red flashers on the bridge are for and what their purpose serves.  I imagine the gates on the shores of the causeway are for high wind conditions and it would be obvious to not allow any vehicles across the open roadway.  However, I do not see any reason why anyone would want any vehicles to stop on the middle of the crossing.  It is unique I must say, even the 7 Mile Bridge in the Florida Keys does not even have these.

[Brian556]

It is probably to warn drivers in case a section of bridge collapses due to a ship/barge strike. I think these systems have a wire running under the entire length of the bridge, and if the wire is broken it activates the signals. A bridge on the Texas coast (not sure if it was this one) had a section collapse due to a ship strike during the last decade. Also, there was the Sunshine Skyway disaster in FL in 1980. Due to these incidents, they probably thought this was a prudent safety measure.

[roadman65]

It is probably to warn drivers in case a section of bridge collapses due to a ship/barge strike. I think these systems have a wire running under the entire length of the bridge, and if the wire is broken it activates the signals. A bridge on the Texas coast (not sure if it was this one) had a section collapse due to a ship strike during the last decade. Also, there was the Sunshine Skyway disaster in FL in 1980. Due to these incidents, they probably thought this was a prudent safety measure.

Actually it was this one back in 01 just days after 9/11.  Eight people died when they drove over the missing segment, hence the name "Memorial" in the bridge's name in memory of those who perished. 

You know, I never thought of that.  Your theory has merit as it would indeed give notice to motorists as those eight did not.  The bridge collapsed at its highest point where it was hidden to motorists.  This also helps at night like the Connecticut I-95 collapse near Stamford back in the 1980's where some drivers could not see the missing road.