The high water levels have heightened awareness of the air gaps for all LMR Bridges between New Orleans and Baton Rouge.
There have been some conflicts regarding which numbers should be used.
Research has shown up to 4 different bridge measurement references from the:
  1. USCG
  2. NOAA PORTS
  3. 2015 USACE Map Books
  4. NOBRA Pilots Bridge Card
Recently NOAA conducted a complete survey of the LMR from Baton Rouge to SWP.  
New measurements were taken during those surveys.  Accurate air gap numbers should be available once the measurements and the datum numbers are computed.
Also, efforts are underway to have air gap sensors installed on all bridges.
 
But, until any new measurements are provided, currently the NOBRA’s Pilot Card provides the pilots with their best assumption of the safest measurements that have worked for them.
Accordingly, LAMA’s air gap computations will now reference those numbers.
 
I have provided a table that shows the change in the calculations.
 
Additionally, the NOBRA Bridge Card is attached.
Bridge Name

Mississippi River Mile

Was

Now

Referenced River Guage

Baton Rouge HWY Bridge

229.3

174.0

172.5

Baton Rouge

Interstate Route10

Ascension • St. James HWY Bridge

167.4

171.0

168.0

Donaldsonvile

Sunshine Bridge

_

Gramercy Bridge

145.9

164.0

164.9

Reserve

Hale Bogs Bridge

121.6

158.0

158.4

Reserve

Interstate Route 310

 

 

Huey P. Long RR and HWY Bridge

106.1

152.3 153.8

Carrollton

Crescent City Connection Bridges

95.7 & 95.8

171.0

170.0

Carrollton