Bridge Busting

Dec. 1, 1993

In time of war, bridges make attractive targets for air attack. They constitute seemingly vulnerable links in the enemy’s lines of communication. As targets go, they are easy enough to locate: Just follow the river, road, or railroad line they cross, and you are bound to find them.

In the history of aerial warfare, however, some of the most difficult actions and most gallant failures have centered on bridge attacks. From the ground, big bridges look enormous, but from an aircraft running in to bomb at, say, 20,000 feet, they show up as extremely thin lines across the landscape.

Moreover, bridges intended to carry lots of traffic are strongly constructed from steel, masonry, reinforced concrete, or a combination of these materials. They can take several hits on nonvulnerable parts of the structure and still stand.

To put a bridge fully out of action, one has to drop a span, and that usually takes detonation of one or more large explosive charges close to a vulnerable point. To achieve such accuracy with an unguided bomb, the aircrew usually has to carry out deliberate attacks from low altitude.

There’s the rub. If a bridge is important, it usually will be well defended. Accurate iron coming up invariably reduces the accuracy of iron going down, and if a bomb fails to score a direct hit, the bridge will usually remain in service. With most types of bombs, the bridge has to be attacked along its length or at a fine angle off it, which lessens the chance of tactical surprise.

The Stukas Strike

The first airplanes to carry out effective bridge-smashing operations as a matter of course were the German Junkers Ju-87 Stuka dive-bombers used during World War II. A fixed undercarriage gave this aircraft a decidedly dated look, and in horizontal flight its maximum speed was less than 250 mph. During its eighty-degree attack dive, however, with the dive brakes in high-drag position, the Ju-87 was an excellent aiming platform. Its terminal velocity never exceeded 350 mph.

German commanders expected Ju-87 pilots, on completion of training, to be able to put half their bombs within eighty feet of the target. The Stuka’s dive typically commenced at 11,000 feet and lasted about twenty seconds, allowing the pilot plenty of time to align his reflector sight on the target. For bridge attacks, the plane carried one 1,100-pound bomb. Bomb release was at 2,275 feet, at which altitude an automatic mechanism initiated a six-G pullup. The dive would bottom out at 1,000 feet above the ground

.These aircraft first demonstrated their bridge-smashing ability in Poland in September 1939 when they destroyed crossings over the Vistula River, preventing Polish troops from fleeing eastward to escape the Nazi invasion.

During the German blitzkrieg in the early days of World War II, the Luftwaffe invariably achieved air superiority over enemy rear areas, and its opponents were poorly equipped with antiaircraft artillery (AAA) to counter the dive-bombers. Thus the Stukas were able to carry out deliberate bridge attacks with near impunity.

For the Luftwaffe’s enemies, however, the story was quite different. Their bridge attacks, mounted in the face of German air superiority, proved extremely costly.

On May 12, 1940, two days after the German Army opened its all-out offensive in the west, its troops poured into Belgium over two bridges spanning the Albert Canal. Five light bombers of the RAF’s No. 12 Squadron set out to attack the bridges, with orders to destroy the structures at all cost. Two planes delivered shallow-dive attacks on a concrete bridge at Vroenhoven, and the other three pressed home low-level attacks on the steel bridge at Veldwezelt. Both targets were surrounded by strong flak defenses, and the attackers suffered accordingly. Four planes were shot down. The fifth, riddled with flak, crashed on the way home.

During softening-up operations preparatory to the 1944 Normandy invasion, Ninth Air Force opened its campaign of bridge attacks on May 7, when P-47s attacked four bridges spanning the Seine. The next day, B-26 medium bombers joined in the attack, launching pattern-bombing strikes while flying in group formation. Some bridges went down relatively easily; others did not. The rail bridge over the Seine at Rouen, for example, absorbed five separate assaults before it went down.

On May 31, B-24 bombers of the 458th Bomb Group delivered an experimental attack on the bridge at Beaumont-sur-Oise. They used Azon weapons, 1,000-pound bombs with radio guidance in azimuth. This first use of guided missiles against bridges was a failure: All fourteen weapons missed the target. The cause was judged to be lack of operator training.

By the time Allied troops landed in France on June 6, 1944, however, USAAF had learned enough about bombing bridges to destroy the Seine bridges almost completely. From the river’s mouth on the Channel to the gates of Paris, German troops could find only one usable bridge. The bridges over the River Loire south of the beachhead then suffered a similar fate, as the Allies sought to isolate the battle area.

Relearning in Korea

During the war in Korea, US Air Force and Navy attack planners had to relearn many of the lessons of World War II.

Repeated attacks by carrier planes on the much-repaired rail bridges between Kilchu and Songjin inspired the famous novel The Bridges at Toko-Ri. Initially, B-29s knocked out the undefended bridges using conventional 1,000-pound bombs dropped from 10,000 feet. Then the AAA defenses improved, and the bombers were forced to attack from above 20,000 feet, with a consequent reduction in accuracy.

The 1,000-pound Razon weapon, a development of the earlier Azon but with guidance in both range and azimuth, was used to some effect. Far more impressive was the monster 12,000-pound Tarzon radio-guided bomb. Thirty of these weapons were dropped during the conflict, knocking out six bridges and damaging a seventh.

The Vietnam War was the arena for one of history’s famous bridge attacks. Flying into North Vietnamese defenses, US forces mounted several major raids on the Paul Doumer highway and rail bridge over the Red River at Hanoi. The bridge was more than a mile long and contained nineteen spans. Of great strategic importance, it carried the only rail link between Hanoi and the main port of Haiphong.

The first attack was carried out on August 11, 1967. [See “Valor: A Bridge Downtown,” January 1992, p. 90.] Thirty-six F-105 Thunderchiefs each delivered two 3,000-pound bombs in a shallow-dive attack and dropped three of the spans. All of the planes returned safely. Soon, however, the spans were repaired and, in early October, traffic resumed.

On October 21, 1967, an attack by twenty-one F-105s put the bridge out of action again, but within a month it had been returned to normal operations. During December 1967, two heavy attacks involving a total of fifty F-105 sorties dropped five consecutive spans. The bridge remained out of use until the bombing pause of March 1968. By May, repairs were complete, and the bridge was in use once more.

Smacked With “Smart” Bombs

For the next four years, the Paul Doumer Bridge was left alone, but when attacks on Hanoi resumed on May 10, 1972, it was targeted. Sixteen F-4 Phantoms of the 8th Tactical Fighter Wing delivered shallow-dive attacks using new, first-generation “smart” bombs. The four planes in the lead flight each carried two 2,000-pound Electro-Optical Guided Bombs (EOGBs), and each of the rest carried two 2,000-pound laser-guided bombs (LGBs).

Modern EOGBs are highly accurate, but the same could not always be said for their predecessors. During the initial attack all eight weapons missed the target, some by wide margins. The LGBs did much better, scoring several direct hits that displaced one span without dropping it but rendered the bridge impassable to wheeled traffic. The following day, a flight of four F-4s, concentrating their LGBs on the damaged section, dropped the span into the river.

The Doumer Bridge remained out of use until after the cessation of air attacks on North Vietnam in January 1973. Then repair work progressed rapidly, and the bridge was ceremoniously reopened for traffic March 4, 1973.

During the 1991 Persian Gulf War, Air Force F-111Fs, with their nighttime, precision-attack capability and heavy bomb capacity, bore the brunt of the initial coalition air offensive against key Iraqi bridges. Other USAF aircraft, notably F-16s, plus British and French planes, also contributed.

USAF Maj. Gen. John A. Corder was director of air operations for US Central Command Air Forces. In a postwar interview excerpted in the 1992 book Airpower in the Gulf, by James P. Coyne, he recalled the campaign. “We hit a few bridges here and there during the first couple of days,” said General Corder. “After about the fourth day of the war, we started going hard against bridges, to seal everything off. . . .

“ The F-111s were in after bridges at night, and the British and the French were in there in the daytime, dropping precision guided bombs. . . . Only occasionally would you see a miss. And that took care of the Iraqi bridge system.”

The F-111Fs of the 48th Tactical Fighter Wing achieved a major success on the night of January 29, 1991, with a successful attack on the bridge over the Hawr al Hammar Lake northwest of Basra. By then, the coalition had secured air supremacy over Iraq, and F-111Fs were able to mount set-piece attacks with LGBs and EOGBs.

The usual attack force comprised four planes that established a “race track” pattern over the target at altitudes around 20,000 feet. The lead plane ran in and released one or two bombs, then turned through a semicircle and flew around the race track while the Weapon System Officer guided the weapons to impact. At intervals, the remaining planes in the force followed the initial attacker, each flying the same track.

When the lead aircraft completed its trip around the race track, it delivered a second attack, and the process was repeated until every plane had expended its ordnance or the structure was destroyed. It was a textbook example of the sort of deliberate action that is possible with air superiority but almost inconceivable without it.

Still Standing

Even when hit by 2,000-pound precision guided weapons, however, the bridges did not always fall. Spectacular television footage was broadcast of bridges first seen under aiming reticles and then disappearing in great clouds of dust and debris as bombs exploded. The bottom line for such attacks is what the bridges looked like after the dust had settled.

Lt. Dave Giachetti, the 48th TFW’s specialist in bridge attacks, recalled the situation: “I thought that bridges would be pretty easy to knock out with PGMs [precision guided munitions]—until I tried it. We would attack a bridge and get several hits, and then we’d discover—holy mackerel!—the bridge was still standing.

With PGMs, hitting the bridge was not a problem. The problem was hitting it at a weak part, a point where the weapon would cause structural damage and drop a span. If you didn’t hit it exactly on the abutment at either end, or where the supports were, the bomb would often go through the pavement leaving a neat round hole that they could easily repair.”

Officers with the 48th TFW said that the wing used only 2,000-pound bombs in its antibridge operations, though it used many different types. These included the GBU-24 with a hardened bomb body, the GBU-10, and the GBU-15. The officers said the wing developed a number of different attack techniques and conducted many multiple bomb attacks, using two bombs per pass.

The most difficult spans to destroy were the two Basra Highway bridges, side by side over the Tigris River. Before the bridges were put out of action, the Air Force had to mount attacks over several days.

One F-111 pilot recalls that he first attacked the Basra complex on February 3, 1991, when it was “a virgin target.” Since the bridges did not drop then, he went back against them two days later and again four days later, when the bridges finally fell into the river. Strangely, they were not well defended, having AAA emplacements but no surface-to-air missiles.

After a period of trial and error, the wing leaders found that the best technique usually was to use two GBU-24 LGBs to destroy the abutments at either end of a bridge, then hit the middle support sections with GBU-15 EOGBs. In several cases, this method succeeded in demolishing the structures.

Initially, the F-111s concentrated on a large number of bridges in the area around Basra. When these had fallen, they worked their way north and west. Once a bridge span had been dropped, the Iraqis usually did not attempt to make repairs because the war was still in progress. One exception was Iraq’s frequent refurbishment of the bridge spanning the Hawr al Hammar Lake. It was, in fact, more of a dirt causeway and proved fairly easy to repair. The F-111s had to return several times to renew the damage and prevent the causeway from being brought back into use.

When coalition air forces dropped a bridge along a particularly important route, Iraqi engineers would usually erect a pontoon bridge alongside to carry the traffic. These flimsy structures posed little challenge to the F-111 crews. They did not need to use a penetrating weapon, just the GBU-10. They simply hit one end of the pontoon bridge, and, because it lacked strength, the whole thing would break apart.

General Corder recalled in his Airpower in the Gulf interview, “For three or four nights, [the Iraqis] were putting up pontoon bridges as fast as we could knock them down. Then they began to run out of bridges. So they’d put one up for a few hours at night and then take it down. To counter that, we put patrols every thirty minutes over the Tigris and the Euphrates and we’d catch them and . . . knock the bridges down.”

New Tactics

About two weeks into the war, Royal Air Force crews joined in the attacks on Iraqi bridges. At that time, the Tornado GR. Mk. 1 force did not possess its own laser-designation capability, so elderly Buccaneers fitted with daytime-only AVQ-23E Pave Spike pods had to be flown into the theater to provide it.

The standard six-plane raiding force consisted of two elements, each comprising a Pave Spike Buccaneer and two Tornados, each carrying three 1,000-pound LGBs. If one Buccaneer became unserviceable, the other was to designate the targets for all four Tornados.

The new tactics were tested in action on February 2 against the As Samawah Road bridge over the Euphrates River. “The weather forecast was grobbley,” recalled Wing Cmdr. Bill Cope, commander of the Buccaneer force and pilot of the leading designator. “It was touch and go whether we would even see the target. In fact, I had to go into Iraq . . . close on the first Tornado’s wing, until we reached the IP [initial point]. There we were, over Iraq in cloud, listening to the RHWR [radar homing warning receiver] and thinking, ‘This is one hell of a way to go to war for the first time!’ But then the weather magically cleared, and there was our target.”

The Tornados in each element flew in trail at altitudes around 20,000 feet, with their attendant Buccaneers behind and above. After releasing their bombs in salvos, the first two Tornados turned away from the target while the Buccaneer entered a shallow turn to keep the target within view of the Pave Spike pod under the port wing.

The second attack element followed the first with the laser designating the same point on the bridge. Of the twelve LGBs dropped, nine scored direct hits. One bomb failed to explode, but the detonation of eight 1,000-pounders within a few feet of each other was sufficient to demolish the central span.

During this and subsequent bridge attacks by RAF airplanes, the 1,000-pound LGBs were fitted with electronically programmed multifunction bomb fuses, which permitted highly accurate timing of detonation after impact and greatly increased the effectiveness of the weapons. Tornado-Buccaneer teams took out several bridges along the Tigris and Euphrates Rivers.

Several months after the war, the Air Force released a white paper that provided some details of the bridge-busting campaign. It said that, when hostilities commenced, there were fifty-four railroad and highway bridges in Iraq, most of them on roads running from Baghdad to Basra and Kuwait. By the end of the war, coalition aircraft had destroyed forty-three of these bridges. Most of those remaining were deemed of little military significance and had not been targeted. Coalition attackers also had dropped thirty-two temporary pontoon bridges built as replacements. By the third week of the war, said the paper, supplies reaching Basra, the major transshipment point for the Iraqi army in Kuwait, were insufficient to maintain combat effectiveness.

Alfred Price flew with the Royal Air Force for sixteen years. He has published some three dozen books, including Instruments of Darkness, The History of US Electronic Warfare (two volumes), and Air Battle Central Europe. His most recent article for Air Force Magazine was “Against Regensburg and Schweinfurt” in the September 1993 issue.