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to the pontons, and four tread way sections. Each tread way was 15 feet (4.6 m) long

with high guardrails on either side of the 2 feet (0.61 m) wide track.

The truck was mounted with a 4 short tons (3.6 t) hydraulic crane that was used to

unload the 45 inches (110 cm) wide steel tread ways. A custom designed twin boom
arm was attached to rear of the truck bed and helped unroll and place the heavy

inflatable rubber pontoons upon which the bridge was laid. The 220 inches (560 cm)
wheelbase chassis included a 25,000 pounds (11,000 kg) front winch and extra-large

air-brake tanks that also served to inflate the rubber pontoons before they were placed
in the water.

A pneumatic float was made of rubberized fabric separated by bulkheads into 12 airtight
compartments and inflated with air. The pneumatic float consisted of an outer perimeter

tube, a floor, and a removable center tube. The 18 short tons (16 t) capacity float was

8 feet 3 inches (2.51 m) wide, 33 feet (10 m) long, 2 feet 9 inches (0.84 m) deep.

3.7. SOLID PONTON

Solid aluminum-alloy pontons were used in place of pneumatic floats to support heavier

bridges and loads. They were also pressed into service for lighter loads as needed.

3.8. TREADWAY

A tread way bridge was a multi-section, prefabricated floating steel bridge supported by

pontoons carrying two metal tracks (or "tread ways") forming a roadway. Depending on its
weight class, the Treadway Bridge was supported either by heavy inflatable pneumatic

pontons or by aluminum-alloy half-pontons. The aluminum half-pontons were 29 feet

7 inches (9.02 m) long overall, 6 feet 11 inches (2.11 m) wide at the gunwales, and 3 feet
4 inches (1.02 m) deep except at the bow where the gunwale was raised. The gunwales

were 6 feet 8 inches (2.03 m) center-to-center. At 6 inches (150 mm) freeboard, the half-

ponton has a displacement of 26,500 pounds (12,000 kg). The sides and bow of the half-
ponton sloped inward, permitting two or more to be nested for transporting or storing.

A tread way bridge could be built of floating spans or fixed spans. An M2 tread Way Bridge

was designed to carry artillery, heavy duty trucks, and medium tanks up to 40 short tons

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