FM 90-13/FMFM 7-26 Part Two. Detailed Procedures Chapter 7 Cr o s s i n g S i t e s SECTION I. CHARACTERISTICS GENERAL provide direct and indirect suppressive fires. Assault This section supplements the general descriptions of sites may or may not coincide with raft or bridge sites. acceptable crossing sites in Chapters 2 and 3. Selection When selecting swim sites, the goal is to pick those of crossing sites is primarily based on the that permit fighting vehicles to rapidly enter, swim " Existing situation and anticipated scheme of across, and exit the water with minimum assistance. maneuver. The goal for raft and bridge sites is to pick those that " Physical characteristics of the available sites, road support the greatest volume of vehicle traffic consistent networks, and surrounding terrain. with the scheme of maneuver. Raft and bridge sites are " Availability and capabilities of crossing means. usually on or near major roads to minimize route " Availability of engineer support. preparation and maintenance. When the raft and Conflicts between tactical and technical require- bridge sites are located close together, the bridge site ments frequently occur. Commanders evaluate the fac- must be upstream of the raft site. This will avoid poten- tors bearing on the problem to determine the best tial damage that may be caused by disabled rafts drift- overall solution. ing into the bridge. CROSSING SITE SELECTION Regardless of the crossing means, each site needs Each crossing means, except air assault, requires a engineers to cross early, reduce obstacles, and develop type of crossing site. They can be ford, assault boat, exit points on the far bank. River banks at otherwise swim, raft, or bridge sites. Assault battalions use either suitable crossing sites often need work for access to the a ford or an assault boat site (or sometimes a swim site) river. Most natural soil becomes unstable under heavy as an assault site. traffic. This condition worsens as fording, swimming, Both the desired scheme of maneuver and available and rafting activities carry water onto it. The required crossing means influence crossing-site selection. The engineer effort varies with soil type, crossing means, division assigns a crossing area to each lead brigade. and vehicle density. The brigade chooses which crossing sites to use within Natural conditions vary widely. Banks may require its area. When a particular site is important to the little preparation, or they maybe so restrictive that they division s tactical concept, such as for movement of limit feasible sites. Desirable site characteristics breakout forces, the division either coordinates with the include affected brigade to open that bridge site or moves a " Minimum exposure to threat direct-fire weapons. bridge to that site once the brigade hands over the " Covered and concealed access to the river s edge. crossing area to the division. " Gently sloping and firm banks allowing rapid entry Engineer intelligence identifies tentative locations and exit at multiple points. supportable with the available crossing means. Brigade Initial and subsequent entry points can vary. Avail- commanders select final crossing sites based on other able locations seldom have all the desired tactical and tactical intelligence and their desired schemes of technical characteristics. The best routes through the maneuver. Each site s physical characteristics, re- crossing area normally cross the river at the technically quired engineer support, and available crossing means best crossing sites. The best technical sites are not the influence the decision, but tactical requirements are the best tactical sites because they are well known and are most important. heavily defended by the threat. Forces initially crossing The goal when selecting assault sites is to pick those at less desirable locations are most likely to avoid detec- that allow lead battalions to cross unopposed and tion and gain surprise. Moving laterally along the exit rapidly seize far-shore lodgments. If unsuccessful at bank, they attack the flank or rear of threat units to seize finding undefended crossing sites, lead battalions cross the better crossing locations. Use of these sites then under threat fire while follow-on and overwatch units allows the most rapid buildup of combat power. Crossing Sites 7-1 FM 90-13/FMFM 7-26 Part Two. Detailed Procedures PLANNING Routes and Approaches Planners need information of potential crossing sites Units use the following routes and approaches: to evaluate their compatibility with proposed crossing " Fords. Dismounted forces may use approaches with plans. Generally, planners need to know steep slopes and heavy vegetation, while vehicle ford- " Friendly and threat capabilities and probable COAs. ing requires paths or roads to approach fording sites. " Site capacity for crossing of troops, equipment, and " Assault or swim routes. Assault boat crossings may supplies using various crossing means. use more rugged approaches than amphibious " Engineer support required to develop, improve, and vehicles. maintain each site. " Rafts. Multiple approach routes to rafting sites per- mit relocation of rafting up- or downstream. More specifically, planners need to know the " Bridges. Bridge sites require developed road net- " Bank, bottom, and water conditions of the river. works to sustain the crossing capacity. " Impact of forecast or historical seasonal weather conditions. Vehicles use the following routes and approaches: " Defensible terrain, cover and concealment, and " Wheeled vehicles. In general, wheeled vehicles re- natural or threat-emplaced obstacles on both sides quire 3.5-meter path widths and 3.5 meters of over- of the river. head clearance. Dry, hard slopes of 33 percent can " Time and effort required to develop sites, assemble be negotiated; however, slopes less than 25 percent rafts, and construct bridges. are desired. " Entry/exit routes and off-road trafficability. " Tracked vehicles. Tracked vehicles require up to " Road networks. 4-meter path widths and 3.5 meters of overhead " Capability to deny observation, suppress fires, and clearance. Tanks can climb 60-percent (31-degree) provide site protection. slopes on dry, hard surfaces; however, slopes less than 50 percent are desired. REQUIREMENTS Entry and Exit Waiting Areas A desired feature of all sites is readily accessible Numerous waiting areas are required for equipment entry/exit routes or paths on either bank. Approaches and troops preparing and protecting sites and for to banks are checked for their ability to support the troops and vehicles preparing and/or waiting for cross- requirements of the crossing element (width, slope, and ing. These areas should be dispersed, provide cover and trafficability) for wheeled and tracked vehicles. concealment, and be accessible to road networks near Covered and concealed approaches enhance surprise the sites. and survivability; however, multiple routes, free from River Conditions obstruction, will increase crossing speed and flexibility. In general, currents less than 1.5 meters per second Exit-bank conditions often take precedence over entry- (MPS) are desired. Narrow segments of the river bank conditions until equipment and troops can be decrease equipment requirements, crossing time, and crossed to develop and improve the site. See Figure 7-1 exposure. However, resulting increased current for depth requirements. . . velocities may offset any advantage. 7-2 Crossing Sites FM 90-13/FMFM 7-26 Part Two. Detailed Procedures Banks TC 5-210 contain details for the conduct and reporting Ford banks may be steep and rugged for dismounted of site reconnaissance.) From these and other detailed troops. Vehicles require less than 33 percent slopes and reports, planners may develop charts or overlays to firm soil conditions. Assault or swim banks may be compare alternate sites. Unit SOPs may prescribe specific comparative methods. See Figure 7-3 for an steep when using assault boats for dismounted troops. Amphibious vehicles may be able to enter over low, example. l-meter vertical banks, but they require sloped exits. Vertical banks of approximately 1 to 2 meters maybe accommodated by bridge or raft ramps (see Figure 7-2). Vertical bank heights for bridges using the equipment listed in the figure do not change for light tactical raft (LTR) or ribbon bridges. For M4T6 and Class 60, the height of the bridge deck can be adjusted to accept a difference in bank heights; however, the limiting factor may become the longitudinal slope of the bridge. Bottoms Ford bottoms must be free from obstacles, firm, and uniform. Riverbeds may be improved with rock fill or grading equipment. Guide stakes ease crossing. Assault FIELD CALCULATIONS or swim site bottoms must be free from obstructions Some common relationships and expedients useful that interfere with boats or tracks of amphibious during a ground reconnaissance include determining
vehicles. Raft sites must be free from obstructions that unit measures of speed, measuring river velocity, deter- could interfere with boat operations. Bridges emplaced mining slopes and degrees, measuring river width, and for lengthy periods (4 hours or more) or in strong calculating downstream drift. currents require suitable riverbeds for anchorage. Divers from theater army may be used to conduct Determining Unit Measures of Speed river-bottom reconnaissance to ensure the success of Correlating the desired maximum stream velocity of the operation. 1.5 MPS with a familiar comparative unit of measure may help estimate current. The quick-time march rate Threat Situation of 120 steps per minute, with a 30-inch step, equates to Sites masked from threat observation enhance 1.52 MPS. Other approximate correlations of 1.5 MPS surprise and survivability. The use of existing sites include reduces preparation time but requires caution in that " 5 feet per second (fps) the threat may have emplaced obstacles and registered " 3.5 miles per hour (mph) artillery on the site. " 5.5 kilometers per hour (kph) Measuring River Velocity SITE ANALYSIS A ground reconnaissance refines and confirms The current of the river is critical to effective and safe information gathered from other sources. (FM 5-36 and operation. A reasonable estimation involves measuring Crossing Sites 7-3 FM 90-13/FMFM 7-26 Part Two. Detailed Procedures a distance along the riverbank and noting the time a require vehicles to operate in a lower gear). Slope, floating object takes to travel the same distance. Divid- usually expressed as a percentage, is the amount of ing the distance by the time provides the water s speed change in elevation (rise or fall) over a ground (see Figure 7-4). (horizontal) distance (see Figure 7-5). Vehicle capabilities to climb or descend terrain are Determining Slopes and Degrees commonly expressed in percent of slope. For example, The slope of terrain is significant (for example, tanks can negotiate slopes of 60 percent, based on ideal slopes of 7 percent or more slow movement and may conditions such as dry, hard surfaces. Rocks, stumps, and loose soil degrade capabilities. Wheeled vehicles are generally limited to a maximum slope of 33 percent. Means to determine percent of slope include " Clinometers. These instruments measure percent of slope and are organic to most engineer units. " Maps. In this method, one must first measure the horizontal distance along the desired path, then determine the difference in elevation between the starting and ending points of the path. The next step is to ensure that both figures are the same unit of measure (such as feet or meters). The final step is to divide the elevation (rise) by the distance (run) and multiply the result by 100 to get percent of slope (see Figure 7-6). " Line of sight and pace. This method uses eye-level height above ground (usually from 1.5 to 1.75 meters) and length of standard pace (usually 0.75 meter). While standing at the bottom of the slope, the individual picks a spot on the slope while keeping his eyes level. He paces the distance and repeats the procedure at each spot. Adding the vertical and horizontal distances separately provides the total rise and run. Slope may also be expressed in degrees; however, this provides angular measurements. The method is not commonly used because the relationships are more 7-4 Crossing Sites FM 90-13/FMFM 7-26 Part Two. Detailed Procedures complex than desired for field use. Figure 7-7 lists some relationships of percent and degree of slope. Measuring River Width A field-expedient means of measuring river width is with a compass. While standing at the waterline, sight on a point on the opposite side. Note the magnetic azimuth. Move upstream or downstream until the azimuth to the point on the opposite bank is 45 degrees different than the original reading. The distance from the original to the final point of observation is equal to the stream width (see Figure 7-8). Crossings with amphibious vehicles and pneumatic Calculating Downstream Drift boats must compensate for the effect of river current. The river current causes all surface craft to drift The following examples show methods: downstream. Each vehicle has a different formula for Example 1. Entry is usually made upstream of the calculating downstream drift. Amphibious vehicles and desired exit point. The vehicle or boat is aligned, or assault boats drift more than powered boats and rafts; aimed, straight across the river, creating a head-on the latter have a greater capability to negate the effect orientation that is perpendicular to the exit bank. How- of river velocity by applying more power. ever, the current produces a sideslip, downstream for- Amphibious vehicles and nonpowered assault boats ward movement (see Figure 7-10). This technique are generally limited to water speeds of 1.5 to 2 MPS requires operator training in continual adjustment to and 1 MPS respectively (see Figure 7-9). reach the objective point on the exit bank. This tech- nique results in a uniform crossing rate in the least amount of time and is usually the desired technique. Crossing Sites 7-5 Part Two. Detailed Procedures FM 90-13/FMFM 7-26 Example 2. If the operator continues to aim the vehicle at the desired exit point, the orientation of the craft at the exit point will approximate an upstream heading. The craft path is an arc in proportion to the speed of the river (see Figure 7-11). Example 3. To exit at a point directly across from the entry point requires an upstream heading to compen- sate for the river s speed (see Figure 7-12). In all three examples, the craft speed relative to the river speed is constant, assuming the engine revolutions per minute (RPM) or paddling rate remains constant. Terrain conditions may restrict the location of entry and/or exit locations. Threat situations may require alternate techniques. For example, when aiming at the downstream exit point, the craft moves at a greater speed relative to the banks after entry than it does as it nears the exit. The cause is the river current speed. Use of this technique may be favored when the threat has better observation of the entry bank than the exit bank. Watercraft moving fast and at a changing rate are more difficult to engage effectively. Section II. Operations RAFTS Rafts are usually the initial means for crossing non- swimming vehicles, particularly tanks, on wide, unfor- Sites dable rivers. It maybe possible to bridge immediately Assault battalions seize a far-shore lodgement and after the assault across the river phase; however, rafting then clear in zone to secure the crossing sites from is normally first because direct fire. Quick reinforcement with armored fighting " Rafts are less vulnerable to threat air and indirect fire vehicles is critical when the initial assault is dismounted. due to their size and maneuverability. They have the weapons needed to defeat determined " Rafts are quicker to assemble. threat counterattacks and can rapidly move units to " Rafts offer more flexibility in operation, particularly subsequent objectives. Fighting vehicles cross by swim- in site selection and subsequent movement between ming or rafting. sites. Given the vital need to rapidly build combat power " Rafts can use existing road nets and banks where on the far shore, the lead brigades should swim fighting access and exit routes are not aligned opposite each vehicles of follow-on battalions whenever practical to other. save rafts for tanks. Raft assembly begins on order, not according to a preplanned schedule, even though the crossing plan has 7-6 Crossing Sites FM 90-13/FMFM 7-26 Part Two. Detailed Procedures an estimated start time. Unless the division commander Each lead brigade should have at least two raft sites, directs otherwise, the brigade commander, advised by each of which has one to three raft centerlines. Terrain, his engineer, decides when to begin rafting. This is routes, and the tactical plan determine their location. always after eliminating threat direct fire on the site and However, they should not be closer together than 300 usually after neutralizing observed indirect fire. meters to avoid congestion and the risk that threat (Massed threat indirect fire can cover an entire raft artillery concentrations will impact on more than one site.) The force neutralizes observed indirect fire by site during a barrage. Engineers prepare alternate sites suppressing it and obscuring the crossing sites. as soon as possible to permit relocation in case of threat The brigade commander also decides when bank action or bank deterioration. preparation can begin, or he may delegate this decision Additional control measures are necessary on the to his engineer. This is a matter of judgement, based on river and bank approaches at night. Chemical lights and the estimated time required to secure the area. Extra other discreet markers help drivers find and load onto time and effort initially spent on bank preparation rafts. Rehearsals include divers, who practice driving avoids interruptions for maintenance later while rafting on and off of rafts at night. Engineers may need addi- is in progress. tional communication and night-vision devices to con- The key to rapid and effective bank preparation is trol their operation. good engineer reconnaissance, which permits en- Raft sites include centerlines crossing the river gineers to arrive at the site early, organized and where the rafts operate, the approaches to the center- equipped to perform specific tasks to improve the lines on each shore, and the control and operation approach. The same is true on the exit bank. Poor bank structure necessary to conduct rafting operations. conditions require early priority for raft movement of Figure 7-13 illustrates a typical raft site with three engineer equipment across the river. Time spent centerlines. preparing the exit banks before passing heavy traffic An engineer company commander (normally from greatly reduces maintenance of the crossing site and the bridge company) is the crossing-site commander. speeds force buildup later. Two entry and exit points He is in command of crossing-site activities from the per centerline make it possible to alternately use one call-forward area to the far-shore attack position. He while maintaining the other. Crossing Sites 7-7 FM 90-13/FMFM 7-26 Part Two. Detailed Procedures reports to the CAE. His company headquarters coor- company s capability, this is the normal maximum dinates the following site activities: employed. On any centerline, rafts must be the same " Site layout. type and configuration. " Raft assembly, operation, and maintenance. Centerlines are marked to guide vehicles approach- " Opening and closing of raft centerlines. ing and leaving the water and to guide rafts to the " Layout of the call-forward area, operation of the correct landing points. Marker stakes or panels are ERP, and organization of crossing units into raft used during daylight, and dim lights (covered loads. flashlights or chemical lights) are used at night (see " Route marking from the call-forward area to raft Figure 7-14). Markers include the following: centerlines. " Raft guide markers, at a 45-degree angle upstream, " Movement of raft loads from the call-forward area to guide the raft to the embarkation or debarkation raft centerlines, across the river, and into the far- point. The two markers are 3 feet apart, and the shore attack position. marker farthest from the river is 2 feet higher than " Bank and route maintenance. the other. The raft has the correct approach to the " Vehicle movement within the site. bank when the markers appear to be in a straight line, " Movement of return traffic from the far shore. with one above the other. " Liaison from the crossing unit. " Raft landing markers depict the left and right limits of the embarkation or debarkation point. The CAE provides corps combat engineers, normal- " Vehicle guide markers align raft loads with the raft ly a platoon or more, to the crossing-site commander to and are visible to both the raft and the vehicles. use for ERPs, route and bank maintenance, and other tasks beyond the capability of the bridge company. Each raft site contains at least one safety boat, nor- The CSC designates an engineer bank master, who mally a bridge-erection boat, for troop and equipment maintains traffic flow as directed by the CSC or his recovery. The bridge company provides the crew of the headquarters. His functions are to safety boat, including the boat operator, the boat com- " Tell the ERP at the call-forward area when to send mander, medic, and lifeguard (two, if possible), The raft loads to the river. lifeguard-qualified swimmer does not wear boots or " Direct each raft load to a centerline. load-bearing equipment (LBE). The safety boat also " Divert vehicles off the road when necessary to a has a float with an attached line for rescuing troops in maintenance recovery point, casualty collection the water, a boat hook, rocket-propelled lifelines (if point, or small holding area. available), and night-vision goggles for at least the boat commander. It has a radio on the bridge company net. Each raft site has one to three active centerlines The safety boat maintains its station 50 meters spaced 100 to 300 meters apart. The 100-meter downstream of the safety line. minimum distance avoids collisions between rafts on When possible, a safety line should be run across the adjacent centerlines and reduces the effects of artillery, river 100 meters downstream from the last centerline, while spacing centerlines farther than 300 meters apart This line is fastened to the banks and kept afloat by life stretches the ability of one unit to control both land jackets attached to the line every 30 meters. This rope approaches and water operations. Each crossing site acts as a catch rope for troops who may fall overboard has at least one alternate centerline. The CSC switches during rafting operations. to the alternate centerline when necessary due to threat Each crossing site requires an EEP located where fire or bank maintenance. the equipment will have easy access to the crossing site. A platoon leader of the bridge company is in charge Traffic between the EEP and the riverbank should use of each centerline. A centerline has an embarkation a separate route to avoid congestion with the crossing. point on the near bank, a debarkation point on the far Each raft site requires a place along the friendly bank, and rafts operating between these two points. The shore, downstream of the centerlines, for immediate number of rafts on a centerline depends on river width raft repairs, The maintenance area requires an access and unit control. Appendix B gives the number of rafts point to the river for removal and launching of bays and per centerline based on river width. Maintaining bridge boats. Additional equipment desired at the main- unit integrity on centerlines and crossing sites is critical. tenance area includes It simplifies maintenance and operation of rafts and " A bridge boat to move damaged bays and serve as a significantly improves control on the water, as all raft spare boat. commanders and boat operators have trained together. As six rafts on one centerline are within one bridge 7-8 Crossing Sites FM 90-13/FMFM 7-26 Part Two. Detailed Procedures it to the appropriate centerline. The bank master con- " A crane to remove nonrepairable equipment from trols the flow of traffic to the centerlines to ensure that the water. " A bridge truck to transport damaged equipment to there is a smooth flow of traffic and that centerlines are neither congested nor underused. He establishes the the EEP. " A heavy-expanded mobility tactical truck timing required so that raft loads leave the call-forward (HEMMT). area and match up with a returning empty raft, When a raft load reaches the river bank, it is met by " One interior and exterior bay to use as replacement an engineer centerline guide. He stops the raft load 10 parts. feet from the edge of the water and holds it there for The maintenance area is continuously manned the raft commander. The raft commander guides the with vehicles of the raft load onto the raft. The raft crew " Two mechanics with tool boxes. chocks the vehicles and issues life jackets to passengers, " Two fuel handlers. who dismount from their vehicles (with the exception " Operators of the various pieces of equipment. of the operator and vehicle commander), don life jack- " A site supervisor. ets, and move to the rear of the vehicles. Upon reaching Operation the debarkation point, the raft crew guides the vehicles When ordered to begin rafting, the CSC directs the off the raft, collects the life jackets from the passengers, ERP at the call-forward area to begin sending raft loads and directs them off the raft. After the raft load forward. Units proceed from a staging area to the debarks, the raft commander checks with the centerline call-forward area, where engineers at the ERP organize guide for any return vehicles and returns to the em- them into raft loads and send them down to the river. barkation point. Any points along the route that may cause confusion, Once on the far shore, the centerline guide directs such as intersections, are either manned with a guide or the raft load to the far-shore attack position, where the are marked to ensure that the vehicles do not get lost. unit re-forms. Once a raft load nears the river, the bank master directs Crossing Sites 7-9 FM 90-13/FMFM 7-26 Part Two. Detailed Procedures Maintenance and Refueling soon as possible, while keeping other raft sites in opera- During raft operations, rafts require stops for refuel- tion until a second bridge is in place. Bridges have ing, preventive maintenance, and minor repairs. The greater traffic flow rates than rafts. Ribbon is the efficiency of the crossing depends on all rafts having preferred initial bridge, since it is faster to assemble and enough fuel and on minimal lost time for refueling and easier to move than other types. Once assembled, all normal maintenance. This efficiency requires the float bridges have a crossing rate of 200 vehicles per bridge company to intensely manage raft maintenance hour, with vehicle speed at 15 miles per hour. As with and to operate the maintenance area like a pit crew in rafts, bridge assembly begins on order, not according an automobile race. When directed, a raft pulls off the to a preplanned schedule. Since vehicles cross rivers centerline and moves to the crossing-site maintenance much faster on bridges than on rafts, early bridge as- area. sembly is desirable but must be weighed against the risk With the raft secured, the crew begins refueling and that the threat can still bring indirect fires down on an maintenance operations. Mechanics assess and repair immobile bridge. The bridgehead force brigade com- any minor damages to the raft and the boats. Fuel mander decides when to begin, with advice from his handlers run fuel lines from the fuel HEMMT to both engineer. He may delegate this decision to his engineer. bridge boats and fuel them simultaneously. If no major Bridges need protection. Air defense, counterfires, deficiencies are identified, the entire process requires and ground-security elements are necessary to defeat 20 minutes. If major deficiencies are identified, the threat attacks. Booms on the river protect bridges from damaged equipment is removed from the raft and collision damage caused by floating and submerged replaced with a spare. The damaged equipment will objects. then be removed from the water and sent back to the Bridges are vulnerable to threat long-range artillery EEP for repair. When finished, the raft returns to its fire and air attack even after the assault clears threat centerline and another raft is directed in for main- forces from the exit bank. For this reason, ribbon tenance and refueling. bridges operate for a limited period of time, normally Since the maintenance and refueling operation is two hours, before the engineer bridge units break them continuous and requires the removal of a raft from the apart and move them to other sites. When the division operation for up to 30 minutes, it is important to ac- uses this pulse-bridging tactic, its units wait to cross in count for this reduction in capabilities when planning staging areas and surge across when bridges are in the operation. As a general rule, it is unnecessary to place. refuel for the first two hours after rafting begins. Once Threat air superiority over the river may prohibit raft maintenance and refueling begin, one of the six bridge assembly. Sustained threat air attack forces en- rafts in each bridge company is unavailable for carrying gineers to break established float bridges into rafts. vehicles across the river. This minimizes destruction of scarce bridge assets yet In the event that a raft becomes damaged and needs enables the crossing to continue, though at a slower immediate repair, the raft commander moves the raft pace. Engineers prepare alternate sites and position to the maintenance area. If the raft loses a boat and spare equipment nearby in case of threat action. cannot make it to the maintenance area without As the danger from threat action lessens, engineers assistance, the raft commander contacts the main- use the more slowly assembled LOC, M4T6, and Class tenance supervisor, who sends the maintenance boat 60 bridges to augment and then replace the tactical out to assist. If the raft is still carrying a load, the raft bridges (ribbon or armored vehicle launched bridge commander decides which bank he will disembark the (AVLB)). They do this as soon as possible to move load on. Once in the maintenance area, mechanics ribbon bridges forward on other crossing operations. determine the extent of the damage. If the damage Threat bridges captured by the lead brigades are a requires significant repair, the damaged equipment will bonus and speed the crossing. Engineers with the lead be removed and replaced with a spare. Lengthy equip- brigades neutralize explosive devices and reinforce ment repairs are done at the EEP. weak or damaged bridge structures. Commanders rare- ly base the success of an operation solely on the seizure BRIDGES of intact bridges. General Site Organization Bridges replace or supplement rafts once threat-ob- A bridging operation requires a continuous traffic served indirect fire is eliminated. Each lead brigade flow to the river. Units must be quickly briefed and should convert at least one raft site to a bridge site as moved to the crossing site. To accomplish this, units 7-10 Crossing Sites FM 90-13/FMFM 7-26 Part Two. Detailed Procedures receive briefings in the staging areas from the traffic- chemical lights to prevent them from driving over the control personnel. There is no intermediate call- side of the bridge and to cause them to maintain cross- ing speed. forward area. In order to control crossing vehicles, the engineers from the bridge unit set up an ERP at the Actions Under Fire bridge access points on each side of the river. These If the unit comes under fire while on the bridge, those engineers guide vehicles onto and across the bridge, vehicles on the bridge continue moving to the other side ensure proper speed and spacing of vehicles on the and leave the area. Vehicles that are not yet on the bridge, and prevent vehicles too heavy for the bridge bridge stop and go into a herringbone formation or take from trying to cross. A recovery team is stationed on the up concealed positions. Once all vehicles have cleared far shore to remove any damaged vehicles from the the bridge, the bridge crew will break the bridge into bridge. The recovery team consists of a medium or rafts and disperse them to reduce vulnerability to in- heavy recovery vehicle and crew, with sufficient winch coming fire. cable to reach across the bridge. A typical site setup is shown in Figure 7-15. Vehicle Recovery If a vehicle breaks down on the bridge, the bridge Any method can be used to mark the route to the crew will immediately attach a winch cable from the far bridge, as long as markers are visible to the operators side and drag the vehicle off the bridge. The recovery of the vehicles and are masked to observation from vehicle will not move onto the bridge and tow the above. As the vehicle approaches the bridge edge, disabled vehicle off, since the critical requirement is to markers are spaced 100 feet apart to assist operators in clear the bridge and maintain traffic flow, loss of the visualizing the required vehicle interval on the bridge. vehicle is far less important. Operations At night and during limited visibility, the left and right limits of the bridge treadway are marked with Crossing Sites 7-11