The Importance of U.S. Patent 31,128

The elevator is to the city what paper is to reading.


Without the elevator, there would be no verticality, no density, and none of the urban advantages of energy efficiency and economic productivity.


Ask a vertical-transportation-industry professional to recall an episode of an elevator in free fall—the cab plummeting in the shaftway, frayed rope ends trailing in the dark—and he will say that he can think of only one.


That would be the Empire State Building incident of 1945, in which a B-25 bomber pilot made a wrong turn in the fog and crashed into the seventy-ninth floor, snapping the hoist and safety cables of two elevators.


Both of them plunged to the bottom of the shaft.


One of them fell from the seventy-fifth floor with a woman aboard— an elevator operator. (The operator of the other one had stepped out for a cigarette.)


By the time the car crashed into the buffer in the pit (a hydraulic truncheon designed to be a cushion of last resort), a thousand feet of cable had piled up beneath it, serving as a kind of spring.


A pillow of air pressure, as the speeding car compressed the air in the shaft, may have helped ease the impact as well.


Still, the landing was not soft.


The car’s walls buckled, and steel debris tore up through the floor.


It was the woman’s good fortune to be cowering in a corner when the car hit.


She was severely injured but alive.


Nonetheless, elevators are extraordinarily safe - far safer than cars, to say nothing of other forms of vertical transport.


Statistics are elusive but the claim, routinely advanced by elevator professionals, that elevators are ten times as safe as escalators seems to arise from fifteen-year-old numbers showing that, while there are roughly twenty times as many elevators as escalators, there are only a third more elevator accidents.


The Otis Elevator Company, the world’s oldest and biggest elevator manufacturer, claims that its products carry the equivalent of the world’s population every five days.


***


Elevatoring


The term “elevatoring” refers to the discipline of designing a building’s elevator system in the most efficient and effective manner: how many, how big, how fast, and so on.


You need to predict how many people will be using the elevators, and how they’ll go about their business.


In elevatoring, the essential variables are time and space.


A well-elevatored building gets you up and down quickly, without giving up too much square footage to elevator banks.


Especially with super-tall towers, the amount of core space that one must devote to elevators, in order to convey so many people so high, can make a building architecturally or economically infeasible.


This limitation served to stunt the height of skyscrapers until, in 1973, the designers of the World Trade Center introduced the idea of sky lobbies. A sky lobby is like a transfer station: an express takes you there, and then you switch to a local.


Elevatoring Metrics


There are two basic elevatoring metrics.


One is handling capacity: your aim is to carry a certain percentage of the building’s population in five minutes. Thirteen per cent is a good target.


The other is the interval, or frequency of service: the average round-trip time of one elevator, divided by the number of elevators.


In an American office building, you want the interval to be below thirty seconds, and the average waiting time to be about sixty per cent of that.


Any longer, and people get upset.


In a residential building or a hotel, the tolerance goes up, but only by ten or twenty seconds.


An over-elevatored building wastes space and deprives a landlord of revenue.


An under-elevatored building suffers on the rental or resale market.


***


Elevatoring Market Research


Otis has conducted research to find out whether people might better enjoy their time in elevators if it were more of an experience - if it would somehow help to emphasize that they’re in an elevator, hurtling up and down a shaft.


Otis found, to little surprise, that people would rather be distracted from that fact.


Even elevator music, designed to put passengers at ease, is now so closely associated with elevators that it is no longer widely used.


*** Elevatoring Design


Elevator design is rooted in deception - to disguise not only the bare fact of the box hanging by ropes but also the tethering of tenants to a system over which they have no command.


In most elevators, at least in any built or installed since the early nineties, the door-close button doesn’t work.


It is there mainly to make you think it works. (It does work if, say, a fireman needs to take control. But you need a key, and a fire, to do that.)


Once you know this, it can be illuminating to watch people compulsively press the door-close button.


That the door eventually closes reinforces their belief in the button’s power.


Recently a new style of elevator has emerged – the destination dispatch system.


Destination dispatch assigns passengers to an elevator according to which floors they’re going to, in an attempt to send each car to as few floors as possible.


You enter your floor number at a central control panel in the lobby and are told which elevator to take.


With destination dispatch, the wait in the lobby may be longer, but the trip is shorter. Smart elevators are strange elevators, because there is no control panel in the car; the elevator knows where you are going.


People tend to find it unnerving to ride in an elevator with no buttons.


Helplessness may exacerbate claustrophobia.


The biggest drawback of destination dispatch, besides the anxiety of novelty, is that once you are in an elevator you cannot change your mind.


To amend your floor choice, you must disembark, and start again.


*** The original Otis patent (US Patent 31,128 “Improvement in Hoisting Apparatus”) can be found at www.pat2pdf.org/patents/pat31128.pdf


Extract from The New Yorker “Up and Then Down – The Lives of Elevators” by Nick Paumgarten. April 21st, 2008.

The Market for Red Fire Trucks

These markets only grow at about 1-3 per cent a year … we need to think differently in order to increase our market share.


Anyone who thinks "fire engine red" is a standard colour would be surprised by the paint laboratory at the back of the Pierce factory in Appleton, Wisconsin.


On the wall are 125 metal plates, each painted a slightly different reddish hue.


"If you're going to spend half a million dollars on a fire truck, you've got to be able to choose the exact colour you want," jokes Jim Michal, vice-president of manufacturing for Oshkosh Corporation, the heavy truck maker that acquired Pierce in 1996.


Many western manufacturers have tried to stay competitive in the face of low-cost overseas competition by closely tailoring products to their customers' needs.


Oshkosh takes this approach to the extreme, customising its trucks according to individual buyers' needs and collaborating with customers on redesigning its vehicles.


Its experience shows how such a strategy can pay off: in the past decade, Pierce has grown at an average rate of more than 11 per cent a year.


With revenues last year of $600m - up from $180m when it was bought by Oshkosh - it is now the leading maker of fire trucks in the US with a market share of about one third in North America.


Mr Michal says Pierce's strategy of working with customers is two-pronged.


First, the company tailors each vehicle, from the artwork on its grille to the water-pumping technology. "The customer has an option list for specifications," he says. "The result is that no two vehicles are exactly the same."


While that makes Pierce vehicles among the most expensive on the market, it also wins fierce brand loyalty among purchasers.


Customers are paying about $30,000 more than it would for a vehicle from a rival, but a customer will only need for a fire truck to be replaced about every 20-25 years there are other considerations, such as dependability and the unique features the company offers.


Oshkosh is so confident that its customers will stick with the Pierce brand that in April - while the US industrial sector appeared to be mired in recession - it increased the price of its vehicles, citing rising steel costs.


Charlie Szews, Oshkosh's president and chief operating officer, says the tailoring strategy has been honed over decades.


"We operate in relationship markets. These products last up to 50 years - there are still Pierce fire trucks from the 1950s that operate in the field. We have to think long-term."


The second part of Pierce's strategy involves using contacts with customers to aid redesign and spur innovation.


Before undertaking a fundamental redesign of its basic fire truck model two years ago, Pierce surveyed its customers to get ideas for improvements.


Then the company invited more than 100 firefighters to visit the factory to give them more detailed feedback. It put them in groups and asked them to design their ideal fire truck from scratch.


The company fed ideas from this exercise into the redesign: it removed a pillar from the windscreen and changed the location of wing mirrors to improve visibility; made door handles bigger so they were easier to use for firefighters wearing gloves; and installed side airbags for extra protection.


Oshkosh also used the opportunity to measure firemen - and found out they were, on average, taller and broader than federal guidelines on cab heights and seat widths had led them to expect.


As a result, the company widened the standard seats in their trucks.During a standard sales process, too, the company has a lot of time to get to know its customers.


Customers who buy a fire truck infrequently - such as volunteer departments serving rural areas - typically have three meetings with the company over the course of the six months leading up to a sale.


Up to 10,000 visitors a year come through the factory to inspect and collect their vehicles, and Pierce uses the opportunity to collect feedback.


"We line them up with a series of lunches and dinners while they're here so we can hear their ideas," says Mr Michal.


"At every meal we have a staff member from a different department go out with them to chat informally.


Then the employees document what's been said and send it on to the engineering department or the marketing department."


Bob Bohn, Oshkosh's chairman and chief executive, says the ability to listen to customers in such an informal setting is an invaluable part of the production process.


"It gives them a chance to really tell us what they like and what they don't like," he says.


It is only through taking advice on its products from their users that Pierce has been able to claim a progressively larger slice of the fire truck sector, the company says.


"These markets only grow at about 1-3 per cent a year," says Mr Szews.


"We need to think differently in order to increase our market share."


Source: Financial Times – “Truck maker heeds firemen's call” By Hal Weitzman Published: May 13 2008

The Collapse of the Kansas City Hyatt Walkway

Management responsibility is ultimately not delegable.


On July 17, 1981, nearly one year after its completion, the Hyatt Regency Hotel in Kansas City, Missouri filled its lobby with guests participating in and watching the evening “tea dance.”


Suspended above the lobby were concrete walkways designed to connect both sides of the 2nd, 3rd, and 4th floors.


Shortly into the dance, two of the walkways, packed with spectators, collapsed onto the crowded atrium floor below.


The event was triggered by a failure in the connection between a supporting rod and the box beam of the fourth floor walkway.


The disaster killed 114 people and injured approximately 200 more, which at the time was the deadliest structural collapse in U.S. history.


***


The owner of the project was Crown Center Redevelopment, but primary responsibility for the overall design and construction of the hotel rested on the shoulders of PBNDML Architects as the project manager.


The project was divided into three aspects: design team, construction team, and a safety inspection team.


PBNDML subcontracted the structural engineering and primary design responsibilities to G.C.E. International, including the roles of the project engineer and the senior project designer.


On the construction side of the project, the fabrication and erection of the atrium and steel cable construction, including the walkways, was subcontracted to Havens Steel Co.


In addition, Crown Center Redevelopment hired an independent safety inspection team, including an investigating engineer.


Design Changes


In order to implement the primary structural drawings, the fabricator, Havens Steel, would have had to thread the entirety of the steel rods below the 4th floor in order to screw on the nuts to hold the 2nd floor walkway in place.


To simplify the process, Havens altered the design to a two-rod system, where the rods from the 2nd floor would attach separately to the 4th floor beams, and the 4th floor rods would attach to the same beams and connect to the roof.


This change was intended to make fabrication and connection of the steel rods easier and faster. However, this essentially doubled the load on the 4th floor walkway beams, as these beams now supported the 2nd floor walkway as well.


In effect, this design change resulted in a new load path which introduced a compounding shear stress element to the 4th floor walkway box beam.


An investigation by the National Bureau of Standards (NBS) after the incident determined that the proximate cause of the collapse was a failure of the walkway box beam at a support rod connection.


Inadequate Design Verification Process

G.C.E., the structural engineering design contractor, created only a partial design and left the most safety critical design decisions to the fabrication/installation contractor, Havens Steel.

Havens created the design without any documented engineering analysis and submitted it to G.C.E., who approved the design, without any documented engineering analysis either.


NBS investigators were unable to find any significant recorded calculations of safety factors or yield strengths of the walkway connections.


Lack of Accountability and Oversight


All parties involved had a responsibility to identify and recognize the walkway as a safety-critical suspended load, which warranted special consideration and care.


During construction in 1979, the atrium roof had collapsed, prompting G.C.E. to ask Crown Center Redevelopment for an on-site inspection of the entire site.


Three different requests were denied due to the additional costs.


Clear delineation of accountability was absent with shared design responsibilities, numerous contractors and sub-contractors, and overlapping design verification processes.


PBNDML failed to exercise oversight of support contractors.


And the Kansas City Division of Public Works Department failed to provide adequate oversight and evaluation of design documents when it approved of the original design, which NBS investigators said violated the building codes even before the design change.


Poor Communication


G.C.E. management failed to retain safety-critical design information when two key structural engineers, involved in preliminary design activities, left the company.


The senior project designer and project engineer, both of whom had an exceptional knowledge of the design, left G.C.E. midway through the design process.


The switch to the alternate design of the walkway support structure was never fully communicated to the new G.C.E. design engineers, and the downgrade in structural integrity went unnoticed.


***


A grand jury investigation into the collapse found no criminal actions linked to the accident.


Nonetheless, after two years of civil suits involving all parties totaling more than $100 million, G.C.E. International Inc. had its license revoked.


In addition, the two lead structural engineers working for G.C.E. were found guilty of gross negligence, misconduct, and unprofessional conduct in the practice of engineering.


The board of the American Society of Civil Engineers finally placed the accountability for this disaster on the G.C.E. engineers and defined the necessity of determining individual roles in overlapping responsibilities.


It reinforced the need for requirements ownership, requirements clarity, and requirements change control.


Ambiguity associated with overlapping responsibilities, matrixed support relationships, and complex supply chains must be overcome by implementation of rigorous configuration management with formal requirement change boards that include independent engineering and assurance representation.


Finally, it noted that it is important to consider how big projects can and do fail when small details are overlooked.


The collapse was a single system failure within the context of a 750-room hotel project, which one could reasonably assume included innumerable safety-critical design details and decisions.


The sheer magnitude of the undertaking further underscores the need for disciplined design build processes that include appropriate independent reviewers to ensure that every single safety-critical detail is addressed with rigor and care.


The American Society of Civil Engineers concluded by observing that it must be remembered that responsibility is ultimately not delegable.