The Improved Ribbon Bridge family of modular flotation bridge systems is a NATO wet-gap crossing asset evolved from a 1960s Soviet design, continues Carl Schulze.
The Ramp Bay and Interior Bay of the Improved Ribbon Bridge (IRB), or Faltschwimmbrücke Typ 2 (FSB2) in German service, are floating integral superstructures made of aluminium that function as pontoons and feature a roadway surface.
![](https://www.joint-forces.com/wp-content/uploads/2019/01/IRB-08.jpg)
The United States Marine Corps employs the Logistic Vehicle System Replacement MKR18 Cargo Truck as transporter for the components of the IRB [© Carl Schulze]
![](https://www.joint-forces.com/wp-content/uploads/2019/01/IRB-10.jpg)
M1977A2 HEMTT Common Bridge Transporter carrying an M16 Ramp Bay of the Improved Ribbon Bridge [© Carl Schulze]
![](https://www.joint-forces.com/wp-content/uploads/2019/01/IRB-11.jpg)
A M1977A2 HEMTT Common Bridge Transporter recovers a M17 Interior Bay of the Improved Ribbon Bridge at end of a bridging operation [© Carl Schulze]
Ferries and bridges are usually built with the SRB, IRB and FSB 2 in the same way and in the following this procedure is only briefly described. After a possible bridging or ferry site has been identified, first the Bridge Erection Boats (BEB) are launched in the same way as later on the bridge bays.
![](https://www.joint-forces.com/wp-content/uploads/2019/01/IRB-12.jpg)
When caution is exercised the FSB 2 can be crossed by tracked vehicles up to MLC 80 and wheeled vehicles up to MLC 96 [© Carl Schulze]
When launched the bridge bays are still folded, on hitting the water its pressure and the hinging arrangement of the bridge bay automatically ensure their opening. Once afloat, a BEB will now take care of the launched bridge bay and engineers climb onto the bay and lock the two centre pontoons and two side pontoons in place.
![](https://www.joint-forces.com/wp-content/uploads/2019/01/IRB-14.jpg)
An interior bay of the Faltschwimmbrücke Typ 2 (FSB 2) is recovered by a MAN 7-ton 6×6 KAT 1 Brückentransporter [© Carl Schulze]
![](https://www.joint-forces.com/wp-content/uploads/2019/01/IRB-16.jpg)
Once afloat BEBs take care of the launched bridge bays, engineers get on board and lock the pontoons in place [© Carl Schulze]
Technical Data FSB 2 and IRB*
- Interior bay total length: 6.92m
- Interior bay width folded: 3.3m
- Interior bay width unfolded: 8.63m
- Interior bay height folded: 2.35m
- Interior bay height unfolded: 1.3m
- Interior bay total weight: 6.350kg
- Ramp bay total length: 6.92m
- Ramp bay width folded: 3.19m
- Ramp bay width unfolded: 8.63m
- Ramp bay height folded: 2.35m
- Ramp bay height unfolded: 1.3m
- Ramp bay total weight: 6,350kg
- Payload ferry and bridge operation – single load: Tracked vehicles up to MLC 80 and wheeled vehicles up to MLC 96
- Usable deck width ferry and bridge operation, single lane loading MLC 80/MLC 96: 4.5m
- Usable deck width ferry and bridge operation, two lane loading MLC 20 tracked/MLC 14 wheeled: 6.75m
- Bridge bays required for a 100m long bridge: 13x Interior bays and 2x Ramp Bays
- Construction time for a 100m long bridge: approximately 30 minutes.
*Figures from a GDELS product brochure
{ images © Carl Schulze unless noted }