In 1953 Sparkman & Stephens was commissioned by the U.S. Navy's Bureau of Yards and Docks to prepare design studies of a Ship to Shore Causeway. Here were some basic parameters:
a) Maximum length - one mile
b) To transport on a LST
c) To be able to carry 60 ton track vehicles (tanks) one way and truck traffic two ways
d) To erect the first 3,000 ft in two hours
f) To erect the balance if 2,280 ft in another four hours
g) Adaptability to an irregular bottom at low tide
h) Provide support on a miry or marshy bottom
i) Not to be overstressed in waves 80' long and 4' high
That's a pretty impressive wish list. This study followed on the heels of a previous study by the firm for a light tactical pontoon bridge the previous year, design #1000. The report is extensive but in summary the solution consisted of aluminum decking sections over rubber pneumatic floats with a ramp at the terminal (shore) end. The sections were connected using threaded rods, cables and springs. The floats were made up of multiple chambers in case a float was breached by gunfire.
The causeway assembly was tank tested at the Stevens Institute of Hoboken, New Jersey. Here are a couple of images from that testing.
The report and associated plan work includes diagrams regarding assembly and storage aboard a LST.
Height (Over Floats) 7'-0"
Number of Pontoons Per Section 20
Float Spacing 9'-0" and 13'-0"
Roadway Width 19'-0"
Weight Per Section 55.25 Short Ton
Length (Width of Bridge) 22'-0"