Back to the drawing board

It was yet another spectacular structural failure in Boston.

On Jan. 25, 1971, one side of an unfinished 16-story Brighton apartment building collapsed, killing four construction workers. The tragedy at 2000 Commonwealth Ave. exposed major engineering and construction flaws in the building's concrete floors. The deaths sparked the city to tighten oversight of construction projects and the state to eventually develop a statewide building code.

If history is any guide, there are similar, important lessons embedded in the failure last week of a concrete section of ceiling in the Interstate 90 connector tunnel, which fell and killed a Jamaica Plain woman. Early indications were that a bolt that held the ceiling panels into place failed, possibly because of the epoxy that was supposed to hold it in place.

In Boston and beyond, infamous failures have allowed engineers and designers to unmask serious mistakes that can result in better building methods. But despite the best intentions, many failures are repeated because they have more to do with politics, maintenance, management, construction mistakes, or corruption than with engineering. ``The tendency is to look at the engineer, and that is not always where the blame should go," said Stephen Banzaert, a Massachusetts Institute of Technology instructor who teaches a course in spectacular engineering failures. ``Most of the time it's a whole system of events that brings about" the problems.

Consider the 1981 Hyatt Regency Hotel walkway collapse in Kansas City that killed 114 people during a weekend dance. The year-old Hyatt had a dramatic atrium with three suspended concrete walkways, each designed to carry its own weight. A change during construction resulted in the fourth-floor walkway carrying the weight of the second-floor bridge as well -- far more than it could handle, especially, as it turned out, with lots of people on it.

Investigators ultimately concluded that the collapse was caused by two mistakes: First, a communication error between the design engineer and the contractor meant that no one verified the strength of critical connections. Second, the change during construction doubled the amount of load those connections had to bear. Two engineers lost their licenses over the tragedy, and the story remains a classic cautionary tale in the engineering field.

``You need that deliberate review," said Glenn Bell, chief executive officer of Simpson, Gumpertz & Heger Inc., a national design and consulting engineering firm headquartered in Waltham. In addition to engineering design, his company performs forensic engineering -- or the investigation of structural failures such as the Hyatt accident.

Bell's company also investigated the mysterious case of the falling windows from Boston's 60-story John Hancock Tower in the early 1970s. Four-by-11-foot windows on the newly built tower would come crashing down in high winds with such regularity that police cordoned off the streets around the mirrored building on windy days.

Investigators later realized that while the technology of the double-paned windows was well known, it was largely used with panels much smaller than the Hancock windows. The increased size of the Hancock panels along with the introduction of a new reflective coating contributed to severe stresses along the windows' edges during high winds, causing them to blow out.

The problem was a reminder: In adapting a design, engineers have to make sure that previous experiences are truly comparable. And the example also shows why the realities of the engineering and construction professions sometimes make it hard to learn from their failures.

In airplane crashes, the Federal Aviation Administration investigates all accidents and distributes lessons to the industry. But engineers, although they have industry standards and professional organizations, have no such centralized command. The brand of windows used in the Hancock Tower was eventually pulled from the market -- but not until it was used in other buildings. Because the window failures ultimately resulted in a lawsuit, a gag order was placed on all parties as to the cause of the problem. The reason for the window failures only came out years later in the course of another lawsuit.

``We don't have a robust, coordinated way to learn from our failures," said Bell. ``Most of our investigations are done during the process of litigation."

Sometimes, a potential problem just never occurred to the engineers involved. In 1940, the four-month old Tacoma Narrows Bridge in Washington collapsed as spectators watched in horror. On a windy day, the suspension bridge began undulating like a twisting ribbon, ultimately ripping apart and crashing into Puget Sound. Several motorists abandoned their cars and crawled to safety. No one died.

The bridge had earned the nickname ``Galloping Gertie" because of its normal tendency to sway and buckle, but it was deemed safe in part because engineers had used that kind of design before, even on longer bridges. But the Tacoma bridge had a narrower, thinner design than those other bridges, causing an aerodynamic instability that no one had anticipated. The twisting movement of the bridge that November day amplified the problem, and the bridge's suspender cables snapped.

Politics and policy are also blamed, at least in part, for some fatal flaws. Prior to launching the space shuttle Challenger in 1986, engineers said they couldn't guarantee the safety of the shuttle's O-ring seals. Their concern was eventually overruled. NASA was under great pressure to fly the shuttle because of dwindling political support for the program and mounting publicity surrounding the voyage of Christa McAuliffe, the first ``teacher in space."

Other times, improper maintenance may be at fault. In 1979, an American Airlines jet crashed in Chicago after one of its engines broke off. All 271 people on board died. Airplanes' engines are periodically removed for inspection, but according to a federal review, maintenance workers had incorrectly detached the engine and the apparatus that affixes it to the wing -- setting in motion a series of events that caused the crash.

``Maintenance is important," said Henry Petroski, a Duke University civil engineering professor and author of the book ``Success through Failure: The Paradox of Design." ``Engineers could design a perfect system, but it needs to be constructed and maintained properly in order to work."

Of all the lessons in Boston, there are few that resonate as much as a scandal 25 years ago, publicized by the Ward Commission report. Corrupt oversight of public construction projects led to flooded athletic fields and a new Salem State College library that could not support the weight of its books, among other problems. Rampant patronage and payoffs were eventually halted, and the problems were fixed through millions more in public spending.

``You need redundancy not only in design, but in process and oversight," said MIT's Banzaert. When you don't have that, ``you see what happens."

Beth Daley can be reached at bdaley@globe.com.