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