The Collapse of the Tecamachalco Bridge Near Mexico City - December 4, 1967 - An Engineer's Aspect


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Sunday, February 26, 2012

The Collapse of the Tecamachalco Bridge Near Mexico City - December 4, 1967

Engineering a structure in which someone will live, ride, fly, or work is a tremendous responsibility. Generally the first duty recognized by Professional and Chartered engineers is to the safety of the public. As with any profession, mistakes can happen. Unfortunately, in the case of engineering structures, a small mistake can prove to be fatal. 

Therefore, it is often instructive to study cases where mistakes were made in order to understand and never repeat the mistake.

The Collapse of the Tecamachalco Bridge 

On December 4, 1967, a giant concrete and steel bridge was under construction just outside of Mexico City in Tecamachalco. The 1,000-foot Tecamachalco Bridge was to span the Loma del Negro canyon, a 550-foot gorge.

The bridge was in the last stages of construction and most of the workers were in the canyon when tragedy struck.

Two workmen were reported to have seen a crack form in the center of the bridge as the final support was being placed. They both ran to the side as the center span of the bridge fell into the Loma del Negro canyon.

(NY22-Dec.5) AFTERMATH OF FATAL BRIDGE COLLAPSE--This is a view of the wreckage following the collapse of a bridge under construction on the outskirts of Mexico City.  Ten bodies were recovered and one survivor was pulled from beneath a pile of oak before search operations were suspended at midnight last night because of poor visibility and the danger of a further collapse.  The wreckage fell into a deep canyon.  (AP Wiephoto) 1967.

One other man reportedly survived by jumping into a tree on the canyon face. He was hospitalized with critical injuries.

Initially, the estimated number of deaths ranged from 30 to 70.   Two days later, reports from Mexico confirmed 21 deaths. Later that number was officially reduced to 17.

It was speculated that the collapse was due to faulty engineering of temporary supports. Others speculated that unstable earth below the supports was to blame.

Two engineers were arrested and charged with negligent homicide. Nearly a year later, they were cleared of guilt and no official cause was given for the bridge collapse.

I have transcribed newspaper articles that covered the tragedy in chronological order below.

The San Mateo Times and Daily News Leader, San Mateo, California, Tuesday, December 5, 1967, page 1.

Bridge Falls Into Gorge--Fear 50 Dead

Workers At Span Buried
 At Gorge West Of Mexico City

 MEXICO CITY (UPI) -- An estimated 20 to 50 workmen were entombed today under tons of concrete and splintered lumber after the collapse of a 1,000-foot bridge under construction over a deep gorge west of Mexico City.

A center support of the bridge gave way with a rumbling shudder last night sending an estimated 360 tons of debris into the 550-foot deep gorge.

Estimates of the number of dead varied greatly. Two bodies were recovered and workers said they saw 14 other bodies stuck in the wreckage.

An accurate death count was delayed when officials suspended rescue operations because they feared standing portions of the bridge also would collapse.
Authorities said it was believed 12 workmen were on the span and 50 others were working in the gorge 550 feet below when the bridge gave way. 

One member of the bridge crew was reported to have survived and was hospitalized in serious condition. 

Officials said it might take days for army and Red Cross workers to clear away enough debris to find all the bodies. They estimated that 360 tons of steel and concrete, some of it in huge blocks, had fallen into the gorge.

Two workmen, Benito Sanchez Garduno, 17, and Adolfo Sanchez Bernal, 15, reported seeing a crack form in the center of the bridge as a final support was being placed. 

"We both ran to one side just in time to hear a tremendous thunder behind our backs," Garduno said. When they looked back the

span and all the men on it had vanished in a huge cloud of concrete dust.

The bridge was being built over a gorge on the west side of the Mexican capital to connect two suburban neighborhoods. 

The Alton Evening Telegraph, Alton, Illinois, Wednesday, December 6, 1967, page 1.

Bridge Collapse
Buries Workers

MEXICO CITY (AP) -- Rescue workers probed gingerly in the wreckage of a collapsed bridge Tuesday in search of the bodies of 20 men believed buried below.  Officials expressed fears of a new collapse.

The center span of the bridge, which was under construction, fell 300 feet into a canyon Monday.

Estimates of the number trapped ranged from 30 to 70.  Fifteen bodies were recovered.

An official of the Public Works Ministry estimated more than 30 men died.  Some workers at the scene gave higher estimates.

Most of the workers were in the canyon when the span broke into its death-dealing cascade.  One worker atop the bridge, Angel Gutierrez Carroga, jumped into a tree on the canyon face.  He was hospitalized with critical injuries.

Cause of the collapse was not immediately determined.

Construction of the bridge, which was about 300 yards long and just north of the city line in Tecamachalco, is under supervision of a private Mexican firm.

BRIDGE COLLAPSES -- Rescue workers carrying out one of the 15 bodies so far recovered from debris at the scene of the collapse Monday of a bridge under construction at the state of Mexico.  At least 30 workers are believed to have perished in the accident.  (AP Wirephoto) (The Alton Evening Telegraph, Alton, Illinois, Wednesday, December 6, 1967, page 1.)

The Post-Tribune, Jefferson City, Missouri, Wednesday Afternoon, December 6, 1967, page 13.

Collapsed bridge 
death toll rises 
at Mexico City 

MEXICO CITY (AP) -- The toll in the collapse of a huge bridge under construction over a canyon just north of Mexico City stood at 21 confirmed dead today, but authorities predicted the toll would go higher.

Estimates of the number of workmen killed ranged from 30 to 70. The sole survivor, Angel Gutierrez Carroga, jumped into a tree on the canyon face at the collapse and was hospitalized in critical condition.

Fifteen bodies were recovered before operations were suspended for the night Tuesday, but searchers said they had located six more under the tangled steel, concrete and wood.

Mexico City newspapers speculated that faulty materials may have led to the collapse of the 395-foot "Universidad de Anahuac" bridge, but there was no official explanation of the cause.

The center span of the bridge, in Tecamachalco, just north of the Mexico City line, fell 300 feet into the Loma del Negro canyon Monday night.

 The Department of Public Works in the state of Mexico said it thought the Federal Ministry of Public Works was supervising the project, but the ministry said the bridge was a private project not supervised by it.

The Daily News, Hamilton, Ohio, Friday, December 8, 1967, page 32.

World News
At A Glance

MEXICO CITY (AP) -- Atty. Gen. Gilberto Suarez Torres of the Mexico City federal district said the bridge collapse that killed at least 15 workers Monday could have been avoided and "those responsible should be prosecuted for murder."

"You can be assured there will be an exhaustive investigation," said Leopoldo Velasco Mercado, attorney general for the State of Mexico.  "Officials of the company will be prosecuted if investigation shows them to be responsible."

The 985-foot bridge was under construction over a canyon just across the Northern City limits in Mexico State.  At least 17 workers apparently were killed when the center span gave way, and so far 15 bodies have been recovered.

The Coshocton Tribune, Coshocton, Ohio, Sunday, December 10, 1967, page 3.

Bridge Collapse Fatal
To Mexico's Travelers

"On a Friday noon, July the Twentieth, 1714, the finest bridge in all Peuu (sic) broke and precipitated five travelers into the gulf below."
--Opening lines of Thornton Wilder's "The Bridge of San Luis Rey"

MEXICO CITY (UPI)--Toluca is a cool city of fogs, high in the mountains 50 miles west of Mexico City, twice as high as Denver, ringed with pines.

Lauro Cruz Valdez, 22, and his older brother Benito, 35, usually went home to Toluca for the weekend, to spend some time with their families.

They didn't go last weekend.  Like Thornton Wilder's Travelers, they had a date with fate and a bridge.

The bridge of Tecamachalco over "Black Canyon" just west of Mexico City collapsed Monday, "in sudden thunder," as a survivor put it.  Bodies rained into the 550-foot-deep abyss below, entombing the workmen building it under an estimated 362 tons of crumbled concrete and spaghetti-twisted steel tubing.

Twenty-two were confirmed dead.  Officials said it appeared there were more bodies in the wreckage.

The Cruz Brothers decided [not] to go home last weekend.  They would stay in the city and pick up some money working on the bridge.  They only earned about $3 a day.

Maria de Jesus Cruz Valdez, their sister, stood waiting with a crowd of other Indian women about a half mile from the gaping death trap.  Police held them back.

They could not see the wreckage, but newspaper vendors offered the latest editors "with the best pictures."

The Register, Danville, Virginia, Sunday, December 10, 1967, page 13-A.

DIGGING FOR ENTOMBED WORKMEN -- Rescue workers dwarfed by huge slabs of concrete inch their way through a vast maze of steel scaffolding bars as they search for from 20 to 50 workmen entombed by a collapse of a 1,000-foot bridge being built over a deep gorge west of Mexico City.

Twin Falls Times-News, Twin Falls, Idaho, December 11-12, 1967, page 7.

2 Arrested In 
Bridge Collapse 

MEXICO CITY (AP) -- Local officials have arrested two construction officials in connection with the collapse of a partially completed bridge which killed at least 19 workers last Monday.

The two, field engineer Mario Perez Gonzalez and Juan Antonio Colunga, general manager of the firm which built temporary supports for the bridge, have said the collapse may have resulted from flaws in the earth beneath the structure.

Their attorney, Andres Iglesias Baillet, contended that two were scapegoats arrested to calm adverse public reaction.

The Brownsville Herald, Brownsville, Texas, Tuesday, December 12, 1967, page 16.


MEXICO CITY (UPI) -- A government construction expert today said it was not possible to determine the cause of the collapse of the Tecamachalco bridge which killed at least 18 workmen Dec. 4.

Seven engineers in charge of construction of the bridge will be freed or arraigned today, according to the decision of the courts in the state of Mexico.

Their responsibility has not been clarified.

Meanwhile, rescue brigades continued searching in the debris of the bridge for more victims.

The Brownsville Herald, Brownsville, Texas, Thursday, December 14, 1967, page 8a.

MEXICO CITY (UPI)--Five construction engineers were indicted Wednesday for negligent homicide in the collapse of a bridge that killed 17 laborers last week.

Two were jailed by authorities of the state of Mexico and three others remained at liberty under protection of injunctions against arrest.

The bridge of Tecamachalco, over the 550-foot-deep "black canyon" on the edge of Mexico City, collapsed with a roar Dec. 4, raining the workmen with tons of concrete and twisted steel into the gorge.

The Port Arthur News, Port Arthur, Texas, Sunday, November 17, 1968, page 7C.

Two Cleared of 
Mexican Bridge 
Collapse Deaths 

MEXICO CITY (AP) -- A Mexican judge has cleared two engineers of any guilt in a bridge collapse almost a year ago which killed 17 persons.

Ignacio Naime Abraham, public ministry agent for Tialnepantia near Mexico City, said expert study of the tragedy cleared the man in charge of the bridge's reinforcement of any guilt.

The engineers were Mario Antonio Colunga Reyna. The concrete and steel bridge across Tecamachalco canyon on the southern edge of the capital fell Dec. 4 while in the last stages of construction. Those who died were men working on the bridge and on its supports several hundred feet below in the canyon.

Experts said the flashwork done by the engineers was in accord with plans and specifications and the cause of the collapse lay elsewhere. They did not specify what may have caused the big bridge to fall.