The Hong Kong Apartment Complex Fire

 

In the afternoon of Wednesday, November 26, it was windy in the part of Hong Kong where eight 31-story apartment towers called Wang Fuk Court were undergoing renovations.  As has been the custom for hundreds of years, exterior scaffolding made of bamboo was erected around the towers.  To prevent damage to the single-pane windows of the complex, workers had covered the windows with foam-plastic sheets.  Nylon safety nets surrounded the scaffolding.  What could go wrong?

 

The world found out when an unknown cause started a fire in the lower level of one of the scaffolds.  The flames quickly spread from high winds to the flammable plastic sheets over the windows.  Burning debris and flames spread from tower to tower until seven of the eight towers were engulfed.  About 40% of the residents were over 65, and the fire alarms in many of the buildings were later found to be out of order.

 

For the next day or so, the fire defeated efforts of thousands of firefighters to control it.  As of this writing, the confirmed death toll stands at 146, with dozens more missing.  About 4,600 people lived in the complex, so many got out alive.  But many others, probably including most of those who needed mobility assistance to escape, didn't make it.

 

News reports are calling this tragedy a "man-made disaster," and I couldn't agree more.  Authorities have arrested several officials of the construction company in charge of the renovations, Prestige Construction and Engineering Company, and have halted the firm's work on all other projects in order to conduct safety inspections. 

 

Whoever made the choice of protective window panels may have chosen low cost over safety.  In any event, that choice directly contributed to the fire perhaps more than anything else, although final conclusions will have to await a thorough investigation.  The use of nylon for safety netting and bamboo for scaffolding are also questionable, although China has a centuries-old tradition of bamboo scaffolding that has only recently come into question as metal scaffolding gradually supplants it.  Photos of the scene after the disaster seem to indicate that the scaffolding largely stayed in place, but was charred to the point of being structurally unsound.

 

As soon as I learned of this fire, I thought of the 2017 Grenfell Tower fire in London.  In that disaster, a refrigerator caught fire in a lower apartment and the flames spread to flammable exterior insulating sheathing that had been installed in an upgrade some years before.  The fire propagated behind the sheathing and was difficult to extinguish, and before it was all over, 72 people died and many more were injured.  Again, negligent planning and a failure to take account of the flammability of exterior sheathing was at fault, just as it appears to be in the Wang Fuk Court fire.

 

Engineering ethics requires imagination of a particularly informed type:  imagination bolstered by in-depth technical knowledge.  Engineers sometimes have a reputation for being dour pessimists who always jump to the worst-case scenario of a given situation.  But in the case of the Hong Kong fire, engineers were not pessimistic enough.  Nobody apparently imagined what would happen if one of the plastic window-sheathing panels caught fire, especially if it was on a lower floor of a building that happened to be upwind of most of the others on a blustery day. 

 

It's possible that workers were instructed not to smoke or to engage in operations that might lead to a fire.  That's all very well, but not everybody follows instructions. And even the best-intentioned workers can be using equipment that shorts out or otherwise becomes a source of ignition.  Good safety practitioners imagine that something statistically unlikely will nevertheless go wrong, and then draw conclusions from that premise. 

 

Judging from the number of residents listed and the casualty list, it's possible that about 5% of the listed residents died in the fire.  That means that 95% escaped either with no injuries or non-life-threatening ones, while however losing most of their worldly possessions.  No one I know would like to go through an unplanned experience that will strip you of your things and lead to a one-in-twenty chance of death.  So while fire escapes and other built-in safety features allowed most residents to escape the flames, over a hundred didn't.

 

Major renovation projects are routinely inspected by civil authorities, and I can't imagine that this project was an exception.  If a construction firm neglects to take due safety precautions, it is the civil authority's responsibility to step in and halt work if necessary in order for safety hazards to be addressed.  This obviously wasn't done. 

 

I don't know the nature of safety inspection services in Hong Kong, but among those to be held accountable should be whoever permitted the work to proceed.  Such officials can be subject to corruption pressures, and until a tragedy like this occurs, no light is shed on the fact that corners are being cut by paying off inspectors.  I have no reason to believe that this was the case here, but it is certainly an avenue worth investigating.

 

Disasters like this one can have the silver lining of making future safety regulations and inspections much more rigorous.  As the investigations proceed and the chain of causation is revealed, Hong Kong engineers, construction firms, and officials can all learn valuable lessons that are driven home by the horrible example of what can go wrong if safety measures are neglected.  My sympathy is with those who lost loved ones in the fire.  And my hope is that nobody anywhere in the world puts flammable sheathing on high-rises ever again.

 

Sources:  I referred to a BBC report at https://www.bbc.com/news/articles/cdxe9r7wjgro, a report from the news outlet livemint.com at https://www.livemint.com/news/world/hong-kong-apartment-fire-death-toll-climbs-to-146-probe-reveals-fire-code-violations-11764496767266.html, and the Wikipedia article "Grenfell Tower fire.

The Lahaina Fire: A Failure to Communicate

 

We think of Hawaii as being the stereotypical island paradise, where the weather is always ideal and nothing major can go wrong.  But on Monday, Aug. 7, the weather forecast on the island of Maui for Tuesday included near-hurricane-force winds of up to 65 mph (105 kph).  Combined with an unusually dry summer, this forecast meant that any fires which might start would spread, well, like wildfire.

 

Sure enough, shortly after Tuesday began, a little after midnight a fire in Maui's central Upcountry region was reported, and emergency management officials ordered some evacuations.  This fire attracted the attention of safety and fire officials throughout most of the day Tuesday.

 

In comparison to most other parts of the U. S., Hawaii is well equipped to notify its residents of emergency situations such as fires, hurricanes, and volcanic eruptions.  An extensive network of alert sirens blankets the occupied parts of the islands, as well as electronic notifications that can be given through legacy media such as radio and TV as well as social media (Facebook, X—ex-Twitter‚ and so on).  So one would think that even a rapidly-spreading wildfire would not be able to keep residents from evacuating promptly.

 

Think again.  The historic town of Lahaina sits on the western coast of Maui and is accessible by only three main roads that go along the coastline.  Nestled between the ocean and the mountains, Lahaina was an attractive tourist destination with historic structures.  The following timeline was reported by the Associated Press.

 

When a second fire started near Lahaina before 7 A. M. Tuesday, firefighters converged on it and reported that it was contained by 11 A. M.  However, the fires had knocked out power to much of Lahaina and surrounding areas, which may have included cell towers.

 

The Upcountry fire continued to occupy the attention of officials even after the Lahaina fire escaped containment some time after noon.  By 3:30 PM, the fire's progress made officials decide to close the Lahaina Bypass road, one of the three main routes out of Lahaina. 

Around that time was when the Lahaina fire exploded.  Very few residents reported receiving any warning about the fire before it showed up at their doorstep.

 

Survivors describe cars in the downtown area being surrounded by flames, smelling smoke one minute and seeing their houses engulfed the next, and fleeing along the Lahaina Bypass only to be turned back by the roadblock.  Up until 4:30 PM, virtually nothing appeared about the Lahaina fire on any communications medium, and residents report that the sirens never sounded. 

 

At 4:30 P. M., residents of an inland subdivision of Lahaina were instructed by the Hawaii Emergency Management Agency to evacuate to a civic center north of town.  But by then, much of the damage had been done, and the fire continued to spread toward the coastline.  By 5:20, the Lahaina Bypass roadblock was lifted, but by then many residents of Front Street near the coast had fled to the shoreline and were either treading water in the ocean or hiding on the shore away from the worst of the flames.  More announcements came warning residents of Lahaina to shelter in place, but if your place is going up in flames, that's not good advice. 

 

At this writing (Sunday morning Aug. 13), the death toll stands at 80, making this natural disaster one of the worst in Hawaii's recent history.  While it is too soon to make a thorough assessment of what went wrong, experience and the little we know now can help us make some preliminary judgments.

 

First, the Lahaina fire wasn't the only emergency happening that day.  The earlier Upcountry fire engaged the attention of emergency management personnel to the extent that information from Lahaina may not have been acted upon as fast as it might have been otherwise.

 

Second, the widespread power failure may have crippled a number of electronic communications systems.  Sirens may or may not have backup power sources so that they will work when utility power fails.  If the ones in Lahaina didn't have backup power and the power was out, this would explain why no one heard sirens before the fire.  Also, although most cell tower stations have some form of backup power, the emergency power source doesn't always work properly.  And a cell tower with its ground-level equipment engulfed in flames is unlikely to be of much help anyway.

 

Third, it is pretty clear that some well-intentioned actions of officials actually made things worse.  Closure of a road that has smoke from fires crossing it is a prudent measure, as tragic traffic accidents on interstates suddenly enveloped in smoke attest.  But when the people needing to use the road are fleeing for their lives, that should take precedence over lesser considerations, if the officials in charge know what is going on.  It looks like the Lahaina fire moved so fast that it was hard for officials (or anyone else) to know what was happening. 

 

One reason that overall global deaths from natural disasters have been declining for the last several decades is that electronic communications can give advance warning to people who would otherwise be in harm's way.  Tornado fatalities in the U. S., for example, can be averted by timely warnings of specific storms that include likely localities to be affected.

 

Unlike tornadoes, fires can't be tracked by radar, at least not yet.  Until such technology is available, fire and safety officials have to rely on eyewitness reports to take appropriate actions, whether that consists of warnings, evacuation orders, or dispatch of fire-fighting resources.  The speed with which the high winds spread the Lahaina fire is unusual, but not unprecedented.  Clearly, the system of fire warning and protection was unprepared for what happened. 

 

Lessons learned from the 9/11 World Trade Center attacks about the failure of electronic emergency communications led to widespread improvements in interoperability and design of first-responder communications systems, as I wrote in a paper published in 2007.  We can hope that the sad lessons learned from the Lahaina fire will lead to upgrades in equipment and changes in policies that will make the emergency response to the next wildfire in Hawaii more robust, leading to more lives and property saved.

 

Sources:  I referred to an AP report published by PBS at https://www.pbs.org/newshour/nation/as-death-toll-of-maui-wildfires-rises-to-80-a-timeline-of-failed-communications-emerges and a map of the fire extent at

https://www.cbsnews.com/news/satellite-images-show-scale-hawaii-wildfires-devastation/.  My paper "We've Got to Talk:  Emergency Communications and Engineering Ethics" was published in IEEE Technology and Society Magazine, vol. 26, no. 3 pp. 42-48, Fall 2007.

Sandwich Panels and the Dubai Hotel Fire

If you were watching TV on New Year's Eve, amid all the spectacular fireworks displays in cities around the world you might have also seen an unplanned spectacle:  the blaze climbing up one side of the 63-story Address Hotel in Dubai, the largest city of the United Arab Emirates (UAE).  While the Address Hotel is not the tallest skyscraper in the world (that honor goes to the Burj Khalifa, also in Dubai), it's tall enough to attract global attention as it was enveloped in flames during the night.  Amazingly, no fatalities were reported, although numerous people suffered smoke inhalation or minor injuries while the hotel was being evacuated.  The main reason for the absence of serious casualties was that the fire was confined almost entirely to the "sandwich panels" or cladding on the outside of the building.  Why they could catch fire—and why entire buildings are covered with flammable material in the first place—are topics worth pursuing.

As most people know, modern skyscrapers depend on a hidden steel skeleton for mechanical strength, not on the exterior surfaces, which can be chosen for properties other than their ability to support the building.  At first, high-rise architects stuck to the traditional stone, concrete, and brick for facades, but in the 1950s, they began to experiment with lighter-weight and cheaper materials, such as glass and aluminum. Properly handled and mounted, aluminum makes a fine, long-lasting sheathing material, and so does glass.  Then a couple of decades ago, someone had the idea of sandwiching a few millimeters of plastic—polyethylene or some other heat-softening—between two thin  foil-like claddings of aluminum, making something cheaper and lighter but just as good-looking as solid aluminum.  Thus the sandwich panel was born.

Now, most heat-softening (thermoplastic) plastics can burn very easily, and some attempts were made to introduce fire-retardant materials into the plastic core of sandwich panels to make them fire-resistant.  Apparently, these attempts did not convince U. S. building-code authorities that the new sandwich panels were safe enough to use in high-rises.  A comment on an architect's chatroom I found indicates that these types of panels are prohibited in the U. S. for use on buildings taller than about four stories.  But other countries either had no such laws, or came to realize the potential for disaster too late.

What can happen is this.  If you have a whole building encased in this stuff, and one panel near the bottom happens to catch fire somehow (fireworks seem to be a popular way to do this), you are in big trouble.  Aluminum has a low melting point and melts away from the plastic cladding as soon as the flame reaches it, exposing more plastic to air and letting the fire feed on itself.  Hot air and flames travel upward to the next panel and so on, and in the case of a 63-story building, there's plenty of upward to travel through.  This is what happened, apparently, not only to the Address Hotel, but to several other similarly-clad high-rises in Dubai and elsewhere in the last few years.  The architect-chatroom website where this problem was discussed has numerous pictures of burned-over building exteriors in Dubai, China, and elsewhere—all fires in which sandwich panels played a critical role.

Fortunately, the fires that these panels support tend to stick to the outside, and most of the time, people inside the buildings have time to evacuate before anyone gets killed.  But nobody wants to leave a building under duress while dodging falling pieces of burning plastic and metal on your way out.  And it's very costly to clean up the resulting mess and re-cover the structure with something that won't burn as easily next time.

Both Australia (where such a fire happened in Melbourne in 2014) and the UAE have changed their building codes to require sandwich panels to pass certain fire-retardant tests.  There are two problems with this, however.  One, it's not clear exactly how fire-retardant a panel has to be in order to resist spreading a fire on a tall building.  The only sure way to know is to build such a building and try to set fire to it, and this experiment is beyond the resources of most building-code-writing organizations.  Second, such codes generally apply only to new construction, and are not retroactive.  So anyone who's already built a skyscraper with flammable cladding doesn't have to take the cladding down and replace it with something better.  That is, until it catches fire.  Judging by the fact that the Address Hotel fire was the third such conflagration in Dubai in three years, it may be only a matter of time until the others light up too.

Modeling how fires start and spread is still an inexact science, and it is understandable that pressures from the building industry allowed dangerous sandwich panels to be installed in many places around the world, despite the hazards involved.  But it takes only one or two fires like this to demonstrate that there's a serious problem.  The almost universal tradition of not making building codes retroactive makes sense, because taking stuff out of an existing building to replace it can be more expensive than the original building cost.  Better in that case simply to condemn the thing and tear it down, but that's an extreme measure too. 

So what's the best that can be done in the present situation?  There may be some lower-cost ways to reduce the chances that a fire in existing sandwich panels will spread, possibly by installing some kind of fire-break strip at selected heights.  But that would be pretty speculative and might not work.  Another proposal has been to install fire sprinklers on balconies near sandwich panels, because many of the buildings are high-rise apartments, and I bet there has been more than one numskull who's tried to light a barbecue grill on his balcony and let the fire get out of hand.  If a building has potentially flammable sandwich panels, the owners better make sure that all the fire alarms and protection systems are operational, and conducting regular fire drills might not be a bad idea either.  But owners will be reluctant to advertise the fact that their building is a giant firework waiting for someone to light the fuse.

We can also be thankful that U. S. building codes flat-out prohibit the use of sandwich panels in high-rise structures.  Yes, it forces builders to use more expensive materials, and drives the cost up compared to construction costs in other countries.  But we've had enough towering infernos in this country to last us a long time, and we don't need any more.

Sources:  I referred to a Reuters report by Andrew Torchia carried on Jan. 2, 2016 on the Yahoo News website http://news.yahoo.com/dubai-blaze-raises-questions-over-gulf-skyscraper-design-160747983--finance.html#.  The architect's chatroom with a comment about the U. S. prohibition of sandwich panels and photos of similar fires in other countries is at http://www.skyscrapercity.com/showthread.php?t=1801571.  A report of a sandwich-panel-fueled fire in a Melbourne building in 2014 appeared on the Australian website http://www.architectureanddesign.com.au/news/non-compliant-cladding-fuelled-melbourne-apartment on Apr. 28, 2015.  I also referred to the Wikipedia article on sandwich panels.