I request the professionals on this board to paint a spatial and temporal picture of some combat situations for the benefit of civilians like me. If the size of the units likely to be involved in these actions are outrageous, please correct those too:

1. A river crossing by an armored regiment (~ 55 tanks), assuming a span of 500 m and greater than fording depth:

- What will be the spatial dimensions of the bridgehead, including engineering and supply vehicles - 2 km x 2 km??

- How many crossing points at a minimum?

- How many hours will it take to cross, including bridge-laying?

- What defensive measures will be taken if they come under fire?

2. Minefield - breaching operations: Assuming a minefield of 5 km (width) x 1 km (depth) needs to be breached by a mechanized infantry company that is the lead element of an armored brigade level thrust, how would it proceed? My guess follows:

- Sappers' platoons identify approx. 5 gaps along the width of the minefield? How is this identification done?

- Mineclearing vehicles travel along those paths, paving the way for follow-on IFVs and jeeps?

- Recovery vehicles follow?

- How much time does all this take assuming no enemy artillery?

- What additional measures are needed to allow the crossing of the tank regiments coming up in the rear?

Thanks in advance.

I was with the 299th Muli Roll Bridging company in Iraq, so I can fill you in on the bridging questions. First off, here is the pict of the bridge we built in Iraq.

http://community.webshots.com/photo/...75932709SWkzSI

Here are some basics about the float bridge. Each bridge piece is about 22 ft long. A bridging company normally has about 30 interior bays and 14 ramp bays. In Iraq, the Army issued us a bunch more to fit the nature of the mission. Each bay is carried by a Hemmit. I believe my company had over 110 vehicles. That made for one big convoy.

As for the actually bridging, here are the facts on that. Before a bridge is put in, the leaders recon the area. There is no specifics on where a bridge can be emplaced. The bank must be between 0 and 20 deg for the bridge to work. The 299th had C trucks and dozers to make a site or improve an existing site. The staging area can be anywhere from at the bridge site to kilometers away. The one in Iraq was about 5km away from the actual bridge. The size of the actual bridge head is only the size needed to back a truck into the water to release the boats and bays. No bridge can be placed in water that is faster than 10 feet per second. A good reference for bridge building is about 200 meters an hour under good conditions and no hostile fire. At night, things take a lot slower.

In combat, the friendly forces secure the near side of the bridge site and provide covering fire. Then infantry are ferried across by zodiacs provided by the bridging company. Then the boats are put in. The company starts to build rafts that can ferry 1 M1 or up to 3 Hummers. The raft consists of 3 interior bays and 2 ramp bays. 2 boats will ferry the tanks to the other side. Once there is enough security on the far side, the actual bridge is made. The rafts are taken apart and used for the bridge. Once the bridge is emplaced, the bridge is anchored using boats and the hemmits.

There is no standard for crossing a bridge. There has to be at least a 2 bay space between each tank. With lighter vehicles, they can cross without any limitations. Tanks with the anti mine teeth must cross the bridge backwards. Speed depends on the drivers. The tanks gun must be straight ahead and cannot fire. Crew served weapons can be fired

I hope I was able to answer your questions.

Sgt. Doody,

I greatly appreciate your detailed and comprehensive response. Thank you.

A few questions:

1. In the US Army, would a Bridging Coy like yours support an entire armored brigade's operations? With at least 44 HEMTT vehicles and being capable of crossing a nearly 100 ft river at 7 different locations (going by the 14 ramp bays and the 22 ft span of each bay), it appears to be a significant support element. Would the Bridging Coy travel/act as a single unit or be divided among the brigade's tank battns?

2. Usually how much depth into the other river bank is sanitized before taking a decision to cross? I'd think it would be at least a few kms, considering that you would have to account for enemy reaction for at least half-hour (the time it would take to lay a bridge across a 100 ft river and transport significant number of tanks to repulse enemy action).

3. In your opinion is the greater danger to river crossing from enemy air or its artillery? I mean, what does such such a Bridging Coy prepare for - is it usually accompanied by air-defence artillery and/or field artillery?

Once again, thank you for the nuggets of information in your post - I learnt things I'd have had difficulty finding in books.

In a major bridging operation, I do believe a bridging company can only support one bridge...maybe 2. The limitation to bridging is the boats used to hold the bridge in place. In the pict of my bridge, you see that the boats are parallel to the bridge. There is only 7 or 8 boats in a bridging company. Every other boat must be running to counter the effects of the river flow. A nother consideration would be a broken bridge. When we were building our bridge, one bay wouldn't open so we let it float down river and got it the next day. If there were a second bridge down stream, the down stream bridge could be damaged.

As the extent of far side security, I do not think much is needed. The survival of a bridge head is getting a lot of forces into the fight fast. ferrying takes a lot of time and does not aid in building a bridge. The manuals say little more than a company ferried over. Ultimately, that decision is left up to the maneuver commander.

I would say Artillery is a greater threat for US forces. Our airforce does a good job of getting control of the skies. We never really had any AAA protection. Since we were a Corps asset, we were kept close but never really in the fight. I heard the 459th Bridging Company saw some nasty fighting in their travels with the Marines. Artillery can be fired from up to 30 km away and there is generally more artillery on the battle field than air craft. In Iraq, there were several artillery rounds that landed near by. I do not think it was directed at us, but still came damn close.