NED data in GridFloat format
From PathlossWiki
This is the same NED data except in Grid float format. These files are twice as big as the BIL format. They will run a bit slower for generating network backgrounds. The files are named by the North West corner having the following syntax:
NXXWYYY.zip where XX = the latiude in degrees and YYY = longitude in degrees
Links to Prepackaged GridFloat files. Each file is 1degree X 1 degree and is named by the north west corner.
1" GridFloat files:
ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/NED/1/GridFloat/
1/3" GridFloat files:
ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/NED/13/GridFloat/