TM 5-5420-209-12
Table 2-16. Ribbon Bridge Capacities.
Rating
Velocity (ft/sec)
(0-3)
4
5
6
7
8
9
10
NORMAL
75
75
70
70
70
60
45
30
(Track
96
96
96
96
82
65
45
30
Wheel)
CAUTION
85
85
80
80
80
65
40
35
105
105
100
100
96
75
50
35
Wheel)
RISK
95
90
90
90
75
65
40
(Track
110
110
105
105
100
82
65
40
Wheel)
*Notes:
1. These ratings apply for a bridge held in place with bridge erection boats. In current up to 5 ft/sec, one boat is required per four
bays. In 8 ft/sec, one boat is required every three bays. In 9 ft/sec, one boat is required every two bays. In currents above 9 ft/sec,
or if the bridge is to remain in place for long periods of time, bridge lines should be used (150° vertical angle).
2. Vehicle spacing criteria:
Rating
Normal
100 feet (Front-To-Back)
Caution
150 feet (Front-To-Back)
Risk
One vehicle only on bridge
3. Maximum Speeds for Normal Crossings:
On Ramps
Class 0 to Class 40-15 mph
Over Class 40-5 mph
On Bridge
Class 0 to Class 40-25 mph
Over Class 40-15 mph
c. Ramp Bay Controls. Prior to allowing vehicle traffic on bridge, the bridge NCO checks the ramp cylinder controls.
The ramp cylinder pump lever will be placed in the TRAFFIC position. This condition will allow the ramp bay to automatical-
ly adjust to any rise in water level. To compensate for falling water level, the pump lever must be placed in the PUMP
position until the ramp bay obtains the lower water level. When the ramp bay obtains the proper water level, place the
lever in TRAFFIC position before allowing traffic on bridge. The maximum angle the ramp bay can raise is 20 degrees.
Some vehicles, such as Armored Vehicle Launched Bridge (AVLB), must be guided onto the bridge because of the interfer-
ence of vehicle equipment with bridge deck.
2-93
Track
100
