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Engineers - River Crossings

Soviet military theorists placed great emphasis on high advance rates by armor-heavy columns in the offense. The Soviets stressed that this high advance rate would be important in the European theater with its "relatively small" operational depth. Such an offensive would be impossible without overcoming Europe's many north-south water obstacles. A 1965 Soviet study revealed that in the European theater, forces would encounter water obstacles up to 100 meters wide every 35 to 60 kilometers, between 100 and 300 meters wide every 100 to 150 kilometers, and greater than 300 meters wide, every 250 to 300 kilometers.

In the Russian textbook on General Tactics, it is written in black and white that for every 5 km of movement across Russian fields and weights, a water obstacle of at least 5 m wide is sure to be encountered. For every 10 km - at least 10 m, for 50 km - not 50 m, and for a 100 km march - a river with a width of more than 100 m. This postulate is known to all graduates of infantry, artillery and tank universities of Russia.

In response to these challenges, Soviet planners devoted tremendous resources to improving the river crossing capabilities of their combat equipment. They provided their ground forces with large stocks of specialized bridging and assault crossing equipment. River crossing figures prominently in most Soviet exercises.

To insure a rapid advance, the Soviets built river crossing capabilities into numerous types of ground force equipment. All Soviet armored personnel carriers, infantry and airborne fighting vehicles, and scout vehicles produced since the 1960s are amphibious, as were some self-propelled (SP) artillery and tactical surface-to-air missile (SAM) carriers.Soviet medium tanks have been provided with snorkels for crossing obstacles up to 5.5 meters in depth. As little as 15 minutes was required to prepare some Soviet tanks for underwater fording, although up to a half hour was required for older tanks.

Extensive tank snorkeling training was conducted. Tank crews trained for up to 2 months before their first underwater crossing. Tanks cross underwater in first gear and follow a predetermined azimuth with the aid of the on-hoard gyrocompass. This direction can be altered by instructions radioed to the tanks from the unit commander. If a tank stalled on the bottom, it must be flooded before crew members using their breathing apparatus can open the hatches and escape.

A snorkeling tank cannot cross a water obstacle if the entry slope exceeds 47 percent (25 degrees), if the exit slope is greater than 27 percent (I5 degrees), or if the current velocity is more than about 3 meters per second. Snorkeling is not feasible during winter, because drifting or unbroken ice could rip away the snorkel. It is also impossible if the water is deeper than 5.5 meters, if there are craters or large boulders on the river bottom, or if the bottom is too soft.

Unmanned tanks can be moved across a river by means of a winch system. This system permits a tank company of 10 tanks to be moved across a river up to 200 meters wide in about 35 minutes (excluding preparation). One pulley block and an anchoring unit are transported to the far bank in a tracked amphibian, armored personnel carrier (APC), or power boat. It must be installed 30 to 45 meters from the water's edge if three tanks cross simultaneously or 10 to 15 meters for a single tank. After tanks are prepared for underwater crossing, they are pulled across by two armored recovery vehicles while their crews cross in APCs or tracked amphibians.

The Soviets estimated that about 60 percent of all obstacles they would encounter in Europe are less than 20 meters wide. Accordingly, there were several models of both tank- and truck-launched gap bridges for rapidly crossing ravines, partially blown bridges, antitank ditches, road craters, and similar obstacles. Gap bridging is used frequently in combination with ponton bridges to provide shore-connecting spans or to extend the bridge to sufficient length.

Each Soviet motorized rifle and tank regiment had one tank-launched bridge (MTU) per tank battalion; i.e., one MTU per motorized rifle regiment and three per tank regiment. Mounted on a T - 54/55 tank chassis, the MTU assault bridge is 12.3 meters long. The folded ramp sections of the MTU-20 (which had become the Soviet standard) extend the bridges length 20 meters. Both spans have a 50-ton carrying capacity and can be launched in 3 to 5 minutes without crew exposure.

Some Soviet regiments received a Czech-designed scissors bridge (MT-55) with an electro- hydraulic control system that permits bridge emplace-ment in 1.5 minutes. The MT-55 span is 17 meters long and can support loads up to 50 tons. The launcher has a gap-measuring device and infrared equipment for bridge laying at night.

Each motorized rifle and tank regiment also had a set of four truck-launched scissors spans (TMM). The TMM set, with its four 10.5-meter spans, could erect 42 meters of class 60 (capable of supporting 60 tons) bridging in 20 to 40 mintues.

The engineer battalion organic to each Soviet tank and motorized rikle division provided the division commander with flexible river-crossing support. Equipment organic to the battalion included PMP ponton bridging (frequently used to make ferries), power boats, GSP self-propelled ferries, tracked amphibious transporters, tank-and truck-launched gap bridging, and limited stocks of fixed wooden bridges.

The assault crossing company of a Soviet division's engineer battalion had GSP tracked ferries and K-61 or PTS tracked amphibians. PKP amphibious trailers may be assigned to units equipped with PTS. Tracked amphibians were used primarily to transport artillery, air defense, or logistical elements across water barriers. (The Soviet 122-mm SP howitzer is amphibious.)

The assault crossing company's GSP ferries were used to transport armor across water obstacles that are impossible to ford or snorkel. Missile units and other organizations with heavy equipment also rely on the GSP. The Soviet PMP ribbon bridge was revolutionary both in its simplicity and rapid emplacement time. Its accordion-like pontons are launched when the trucks on which they are transported are braked at the water's edge. They were opened automatically by a torsion bar mechanism, rotated manually 90 degrees, and quickly joined to form a continuous strip of floating roadway. Soviet motorized rifle and tank divisions have a half set of 16 PMP and two end (ramp) sections in their engineer battalion.

The engineer battalion's PMP ponton bridge company could construct 119 meters of 60-ton bridging at a speed of 7 meters per minute. PMP pontons also may be split in half to form 281 meters of 3.27-meter-wide, class 20 bridging. Bank preparation is the critical factor for bridging operations. Erection times vary depending on enemy resistance, crew training, and conditions at each site. PMP pontons can be retrieved in about twice the time required to emplace them. Each ponton carrier had a jib, winch, and roller system to accomplish this.

If the water obstacle is wider than the unit's organic bridging capability, or if the site is not secure enough to build a bridge, a PMP company also could form either eight 40-ton rafts, five rafts of 60-ton capacity, four rafts of 80-ton capacity, three 1 10-ton rafts, or two 170-ton rafts. Configured as three 110-ton platforms, the PMP company could accomplish the simultaneous lift of nine medium tanks (three platoons). The PMP bridging company had six BMK power boats to assist in bridge emplacement or raft propulsion. Models ranging from 75 to 180 horsepower were in use, most of which were transported on retractable wheeled struts. The newest model, BMK-T, was transported and launched from the same truck that transports the PMP. All Soviet power boats are compartmented for bouyancy. Even if two of the BMK-T's four compartments were flooded, it would not sink.

A PMP bridge permits crossing by tanks at speeds up to 30 kilometers per hour. Speeds for wheeled vehicles are greater.The bridge can be built in water having a current velocity up to 2 meters per second. By attaching how and stem shields to PMP sections, the crew can emplace the bridge in currents of up to 2.5 or 3 meters per second without loss of stability. Army and front had river crossing capabilities in their organic engineer regiments or brigade. Ponton brigade regiments and assault crossing battalions also provide river crossing support. Each Soviet combined arms or tank army had one ponton brigade regiment, while two may be subordinate to a front.

Most PMP regiments were organized into two battalions of three companies each and have a total of 108 PMP pontons capable of bridging 681 meters. The regiment also has eight tracked amphibians (K-61 or PTS) or GSP ferries.

Assault crossing battalions that provide amphibious transport and ferry support to army or front elements could be allocated to divisions to speed up crossing operations. There was one battalion in each army, with up to three in a front. If equipped with the PTS and PKP trailer, the battalion's two tracked amphibious companies were able to transport two towed artillery battalions simultaneously. Each GSP ferry could transport one Soviet medium tank.

To provide the logistic support necessary for planned rapid offensives, the Soviets expended considerable resources to field a variety of line of communications (LOC) hridging. LOC bridges are essential for the orderly introduction of divisions and combat forces of successive echelons, as well as un-interrupted resupply of combat units. They are emplaced by troops of the Military Transportation Service. In anticipation of wartime interdiction of existing bridges, the Soviets and their allies stock-piled obsolescent bridging and prefabricated bridge sections near strategic crossings.

The NZhM-56,a combination railroad and vehicular floating bridge, has an estimated carrying capacity of 120 tons. Soviet engineers designed three new types of sectional bridging: MARM,SARM. and BARM (Soviet acronyms for small, medium, and large high-way sectional bridge). The major disadvantage of sectional bridging is its slower ection process. The average rate of construction is 20 meters per hour if the bridge is built from a single bank or 30 to 35 meters per hour if the engineers start from both banks. Sectional bridging freed tactical bridging for further use by combat forces. MARM was also used to create overpasses over key road junctions, thus all wiating congestion.

River barges were also used for LOC bridging. Large numbers of 600-ton barges are available throughout central Europe. They are placed end to end and con-nected with special ramps to form a "ribbon" bridge. Seven such barges would span a 400-meter-wide river and would take about 24 hours to construct.

The Soviets considered units engaged in a river crossing to be especially vulnerable to enemy aviation. They emphasized the need for tactical air defense at river crossing sites before a crossing is attempted. In some tactical situations they may choose to move part of their air defense assets across first to maximize the range of these weapons in protecting subsequent units making the crossing. Placement and movement sequence of air defense assets could vary as the Soviet commander assesses each new tactical situation.

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Page last modified: 14-09-2021 15:23:32 ZULU