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Sustainable Stainless Steel Transit Station Design

By Catherine Houska

Abstract:

Keywords:

Attractive, sustainable transit buildings are an important part of an efficient modern infrastructure. In addition to beingattractive, properly specified stainless steels are durable, require minimal maintenance and provide long-term safety, securityand traffic control. These factors and its inherent sustainability have made stainless steel an important design material for newtransit buildings around the world. This review of stainless steel applications, benefits and specification will provide designerswith the confidence to use it into designs capable of providing 50 or more years of service.

Stainless steel, train station, airport, subway station, sustainability, finish selection, glass curtain wall, roofing, structuraldesign, fire resistance, corrosion resistance, recycled content, heat absorption reduction, roof runoff.

1. IntroductionTransit facilities such as train stations, airports and subwaystations are a vital part of a modern infrastructure. Theirefficient, uninterrupted service provides substantialeconomic and environmental benefits. While there arenumerous attractive historic transit facilities around theworld, most of the older structures were intended to simplybe functional, low-maintenance and low-cost. Expandingcities and the desire to reduce highway congestion and fossilfuel use have encouraged governments around the world toreplace, update and expand transit systems.

Several factors are influencing the design of new structures.First, the utilitarian, dim, often claustrophobic structures of

the past are being replaced with attractive, spacious, oftenairy buildings. These modern facilities are intended toencourage mass transit use and serve as city gateways towelcome visitors while increasing system capacity andefficiency. Second, with the growing interest in sustainabledesign, governments are increasingly requiring 50 or even100-year service life with minimal material replacement.Consequently, more thorough material comparisons arebeing made for exterior and interior applications whichfrequently include corrosion, scratch, impact and vandalismresistance; maintenance requirements; service life;recycled content; release of volatile organic compounds(VOCs) into the indoor environment; recapture or reuse ofmaterials after service; and energy and water consumption.

Suvarnabhumi Airport in Bangkok Type 316 supports for the glass curtain wall and Type 304 interior detailsPhotos courtesy of Rainer Viertböck

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In addition, public safety issues like floor slip resistance,security, fire and high wind resistance, seismicperformance, long term railing and barrier integrity, andaccess for the elderly and disabled have becomeincreasingly important. When these analyses are done,stainless steel consistently garners high marks, particularlyin structures designed for thirty or more years of service.

Although stainless steel is a relatively new constructionmaterial and only became available to designers in the mid-1920's, it has had a tremendous impact on internationaldesign. There are many high-profile structures wherestainless steel has already provided up to 80 years ofservice without deterioration in appearance or metalreplacement. When properly selected, fabricated, andmaintained, stainless steel should last the life of the

2. The History

structure, even if that life extends over centuries. This makesstainless steel an attractive, cost-effective, environmentallyfriendly choice for sustainable transportation buildingdesigns.

Designers began using stainless steel in train and subwaystations and vehicles shortly after its introduction into themarket. (The first all-stainless passenger train beganoperation in 1934.) By the 1960's and 1970's, stainless steelentrance doors, turnstiles, security gates, ticket booths andother components were common in rail and subwaystations. In the 1950's, passenger air travel expandedsignificantly and stainless steel was selected for the newterminal applications. For example, in 1956, stainless steelwas used for the parabolic roof on New York's JFKInternational Airport's new international arrivals building (theformer Terminal 4). (Figure 1)

Several internationally recognized transit buildings havehelped to significantly increase stainless steel's use duringthe past 16 years. The completion of London's WaterlooInternational Railway Station in 1994 created a sparklingcontemporary new entrance to the city for the internationalEurostar trains. Nicholas Grimshaw Partnership madeextensive use of stainless steel because of the desire for lowmaintenance and 125-year service life. Type 316 stainlesssteel was used for the highly visible station roof and itsstructural components, wear and corrosion resistant treadplate flooring, ticket and information booths, turnstiles, andsecurity barriers. (Figure 2)

2.1 Early TransitApplications

2.2 The Last 16 Years

The designers of London's Waterloo Train Station used Type 316 stainless steel for roof structural supports and panels, slip resistantflooring and stair treads, ticket booths exteriors, railings and other items.

Photo courtesy Nickel Institute(Figure 2)

The stainless steel parabolic roof on the JFK InternationalArrivals Building (former Terminal 4, 1956).

Photo courtesy Overly Manufacturing Co.(Figure 1)

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In 1997 , Rona ld ReaganWashington National Airport B/Cterminal was completed. LikeWaterloo Station, it was designedto be a long lasting showplaceentrance to a capital city. Type 304stainless steel was used forroofing, entrance canopies anddoors, ticket counters, columncovers, curved stainless steelstaircases, retail store entrances,planters, food service areas andtables, signage, informationbooths, elevators, securitybarriers and baggage carousels.(Figure 3, 3a) Like WaterlooStation, durable embossedstainless steel surface finisheswere used extensively inside thebuilding to limit scratching andimpact damage.

The dull rolled-on stainless steelfinish that was developed to meetthis project's stringent lowreflectivity roof requirements hassubsequently been used on avariety of large airport and trainstation roofs around the world.Kowloon Train Station in HongKong (1998) was developed aspart of a master plan to link the cityto its new airport using a high-speed rail corridor and toencourage development of theWest Kowloon reclamation. Thestation has 1.1 million m (11.8million ft ) of mixed-use space andis many visitors first glimpse ofHong Kong. Attractive durablematerials were selected including

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a dull Type 316 roof that will withstand the corrosive coastalclimate and the high winds associated with typhoons. Type304 was selected for a range of interior applications such asescalators and column covers. (Figure 4)

Recent new sustainable airport, train station and subwaydesigns have made extensive use of stainless steel. Therehas been a substantial increase in the use of stainless steelin traditional applications like ticket desks, turnstiles, columncovers, and security barriers. In addition, several importanttrends have emerged. Small stainless steel tension rods orcable systems are increasingly being used to support largeexterior and smaller interior glass curtain walls. Thesestainless steel supported curtain walls are particularlypopular for larger airport terminals because their lowvisibility creates light airy structures where the structuralcomponents are attractive and do not obstruct the view.There has also been a significant increase in the use ofstainless steel structural supports for glass canopies and forroofing.

Type 304 with a custom dull finish was used for the Bermuda style roof onRonald Reagan Washington National Airport. It was also used for interior

ticket counters, elevators, signage and other applications.Photo courtesy Overly Manufacturing Co.,

(Figure 3a)

The high profile Type 316 stainless steel roof on Hong Kong's Kowloon Station is many visitors first introduction to the city.Photo courtesy TFP Farrells

(Figure 4)

Roof of Ronald Reagan Airport

Photo courtesyOverly Manufacturing Co.,

(Figure 3)

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3. RecentAirport Projects

3.1Aeropuerta de Barajas, SpainWhen it was completed in 2004, Madrid's Aeropuerta deBarajas had the largest glass curtain walls of any airportterminal in the world. Richard Rogers Partnership andEstudio Lamela designed the terminal to be the gateway toSpain with bright open interior spaces. The high strengthduplex stainless steel 2205 rods and connection systemhelp to significantly minimize the size and visibility of theglass structural support system. Type 316 stainless fittingswere also used in the design. Since the stainless steelstructural supports do not have to be painted, long-termmaintenance is minimized and the fine structural details aremore visible and become a decorative design element(Figures 5, 5a). These spectacular glass walls fill theterminal with natural light creating a light airy appearance.

3.2 Dallas/Ft. Worth InternationalAirport, USA

3.3 SuvarnabhumiAirport, Thailand

The Dallas/Ft. Worth International Airport's new Terminal D(2005) used zero-VOC emitting stainless steel wall panelsand other interior components to meet the US green buildingrating system (LEED) indoor air quality standards. And itsstriking dull rolled stainless steel roof meets current solarreflective index (SRI) requirements. New York's newJamaica Station (2006), which provides a new train and bushub for the city's suburbs, has a Type 316 roof with a dullrolled finish to meet 100-year service life requirements in acoastal location as well as many traditional durable stainlesssteel applications. (1)

Bangkok's new Suvarnabhumi Airport terminal wascompleted in 2006 and it is enclosed in glass curtain wallsthat rank among the largest in the world. It was designed tobe a low-energy-need building using state-of-the-arttechnology. One of the most spectacular aspects of thisMurphy/Jahn designed building are its glass curtain walls,which are supported by Type 316 cast spiders and tensionrods that were cold worked to increase their strength(Figure 6) along with galvanized steel cables. Type 316 wasselected because of its improved resistance to chloridestress corrosion cracking. The terminal is in a corrosivecoastal environment and this structural application hassustained high loads.

The glass curtain walls on Aeropuerta de Barajas are supportedby high strength duplex 2205 and Type 316 stainless steel.

below shows details)Photos courtesy: FOLCRÁ, Spain

(Figure 5). (Figure 5a

Suvarnabhumi Airport in Bangkok Type 316 supports for theglass curtain wall and Type 304 interior details.

Photos courtesy of Rainer Viertböck(Figure 6)

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The result was a light airy, lowma in tenance s t ruc tu re .Richard Green, who consultedon the curtain wall, indicatedthat “cost analysis showed thatthe ability to use unpaintedType 316 made it lessexpensive than a coatedcarbon steel design”. Like theother airports mentioned, theuse of stainless steel forinterior applications was alsoquite extensive. In addition to

ticket and security desks, baggage handling and othercommon applications, Type 304 stainless steel was used forcable railings, stainless steel stairs and other attractivedurable details. (Figures 6a & 6b)

The new Colonel H. Weir Cook Terminal at IndianapolisInternational Airport opened in November 2008. Like MIA,Type 304 stainless steel was used extensively within thenew 111,000 m (1.2 million ft ) building. A variety of durablefinishes were applied to the stainless steel to provide long-term scratch and impact resistance and durability. Thisincluded non-directional and patterned mechanical finishes.

3.4 Indianapolis InternationalAirport, USA

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Stainless steel provided tremendous design flexibility,because there is such a wide range of finishes that canresist scratching and impact damage.Applications includedticket counters, baggage handling, elevators, signage,planters, seating and other applications (Figures 7, 7a).

Suvarnabhumi Airport Ticketing Counter in Bangkok below gives detail of stair case)Photos courtesy Carl D'Silva

(Figure 6a). (Figure 6b

The new Colonel H. Weir Cook Terminal at Indianapolis InternationalAirport used Type 304 stainless steel extensively in its interior.

Photo courtesy of Forms + Surfaces(Figure 7)

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3.5Ancona-FalconaraAirport, Italy

3.6 Raleigh –Durham InternationalAirport

The Ancona-Falconara Airport in the Marches region ofItaly's Adriatic coast just added two new terminals in 2008.Like Madrid's new terminal, the large exterior glass wallshave minimal visible support. In addition, the interior wallsare also glass. The structural supports for the interior andexterior glass walls are made from Type 316 rods, cable andother components. Type 316 was also used for the signage,door and window frames, and the bar grating sunscreens forthe windows.

Stainless steel's use in recent and current airport projectshas not been limited to interior applications and the supportsfor glass curtain walls. Like the recent US airport terminals atthe Dallas/Ft. Worth, Detroit, and Washington DC airports,the roofs for Phase 1 of Raleigh-Durham InternationalAirport's new Terminal 2 (opened October 2008) are Type304 with a special dull rolled finish, which has a very low levelof reflectivity so that it will not blind pilots. Stainless steelroofing provides reliable longevity and remains attractive.Paint coatings will eventually fade, peel and have to bereplaced. Furthermore, they may deteriorate more quickly ifthere is enough exposure to jet fuels.

Type 304 stainless steel was chosen because these airportsare inland and not exposed to coastal or deicing salt. Thesame finish will be used on Phase 2 of the Raleigh-Durhamterminal, which will open in 2011. It has also been selectedfor the new Sacramento California airport, which is underconstruction.

New airports of all sizes are using stainless steel for veryvisible applications. Several small US airports in resortcommunities have recently invested in new terminals. Sincethese airports primarily serve the private jets of wealthyindividuals and corporations, stainless steel was selectedfor exterior walls panels, roofing, entrance canopies andother details because it gives them a high-end appearance.One example is the new Southwest Oregon RegionalAirport. It is close to one of the most highly rated golf coursesin the world. There are some commercial flights but itprimarily serves private jets filled with golfers. It opened inJuly 2008. The exterior is covered natural 2B finish and blue-green electrochemically colored tiles. Type 316 was chosendue to its coastal location.

Miami International Airport (MIA) is currently one of theworld's largest airports and has the highest traffic flow of anyairport in the world. It is a major gateway between North andSouth America. MIA is near completion of a major multi-phased expansion and renovation program that began in1997 and will be completed in 2010. The expansion of theNorth and South Terminals and concourses will add 250,838m (2.7 million ft ) to the facility. In addition, there have beensignificant renovations to the pre-existing terminal andconcourse facilities, passenger parking garages additions,and a major expansion of cargo handling facilities.

3.7 Southwest Oregon RegionalAirport, USA

3.8 Miami InternationalAirport, USA

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The new Colonel H. Weir Cook Terminal at Indianapolis InternationalAirport used Type 304 stainless steel extensively in its interior.

Photo courtesy of Forms + Surfaces(Figure 7b)

Ticketing counter at Miami International's AirportPhoto courtesy of Forms + Surfaces

(Figure 8)

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Stainless steel has been used extensively forinterior and exterior applications throughout MIAbecause of its durability, impact and scratchresistance and the range of available finishoptions and patterns. Type 304 with embossed,bead blasted, non-directional scratch patterns, orNo. 4 polished finishes was used extensively forinterior applications such as signage, phonebanks, display cabinets, column covers, elevatorcabs, planters, recycling receptacles andwainscoting. Figures 8 & 8a. Some of theseapplications in the new South Terminal andrenovated sections of the North and CentralTerminals are given elsewhere in this article.

Type 316 was used for the exterior applications atMIA because of the airport's corrosive southernFlorida location. Even inland locations in Floridahave at least some coastal salt (chloride)exposure. Embossed and polished finishes havebeen used for parking garage wall panels andelevators, terminal entrance doors and columncovers, and a sculpture. Despite the additionalyears of service, the stainless steel installedduring the early and late project phases has asimilar attractive appearance becauseappropriate grades and finishes were used forthis demanding high traffic environment.

Columns clad in Type 304 stainless steel with bead blasted finishat Miami International

Photo courtesy of Forms + Surfaces(Figure 8a)

4.0 Train and Subway Stations

The Koperkhairane railway station at New Bombay used 10,000 square meters of painted Type 304 stainless for roofingPhoto courtesy Salem Steel Plant (SAIL)

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4.2 Britomart Train Station,AucklandThe Britomart Train Station in Auckland is the largestinfrastructure project ever undertaken by a local authority inNew Zealand. Completed in 2003, it used Type 316 for boththe sheltered interior and exterior applications because ofits close proximity to the coast. The ceiling, walls and

column covers in the station's interior are covered withwoven Type 316. (Figure 10) Custom embossed andpolished covers were used on the forced ventilation pillarsaround the tracks and for decorative columns and otherapplications in the station. There was also selective use ofelectrochemically colored stainless steel. The exterior plazahas Type 316 ringed skylights, bus shelters and ventilationstacks.

In Europe, new train and subway lines in Paris, London andBrussels have made extensive use of stainless steelbecause of its durability, corrosion and fire resistance anddesign flexibility. London's Vauxhall Cross Bus Station(completed in 2004), which is the second busiest in London,was designed to provide a link between the bus, rail, andsubway lines; make public transit system access easier forcyclists; and help to revitalize the area. Type 316 with acoined linen finish was used for the sections of the curvingroof and wall panels that are readily visible to pedestrians toprovide a homogenous appearance. Photovoltaic solar cellpanels placed on the roof reduce the station's energyrequirements by 30%. (Figure 11)

The stainless steels most commonly used in architectureare Types 304/304L, 316/316L, and to a lesser extent 2205but many other grades have been used. Stainless steelsprovide much higher corrosion resistance than othercommon architectural metals, particularly when there ispollution and chloride salt exposure (primarily deicing and

4.3 European Stations

5. Stainless Steel Specification

4.1 Singapore Expo Center MRT StationSingapore Expo Center's MRT Station (opened in 2001) wasdesigned by noted architect Sir Norman Foster as part of theChangi Airport train line extension. It provides improvedaccess to the Expo Center. It was designed to handle thehigh loads associated with events at the venue. Durablecorrosion resistant materials were selected because of thecoastal salt exposure and anticipated high traffic volumes.The spaceship inspired shapes of the domes have titaniumroofs and the sheltered canopies, wall panels, and glasssupport system are Type 316 stainless steel. (Figure 9)

The spaceship inspired shapes of the domes on the Singapore ExpoCenter's MRT Station have titanium roofs and the sheltered areasand glass support system are Type 316 stainless steel.

Photo courtesy: Nickel Institute(Figure 9)

The interior of the new Britomart Train Station in AucklandNew Zealand used woven Type 316 of the ceiling and column

covers. Custom embossed and polished covers were usedon the forced ventilation pillars around the tracks.

Photo courtesy: Nickel Institute, Catherine Houska photographer(Figure 10)

Vauxhall Cross Station, LondonPhoto credit: Thomas Pauly, Euro Inox

(Figure 11)

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coastal salt). In architectural applications, structural orperforation failure is generally only a concern in severeenvironments when an inappropriate stainless steel hasbeen selected. Aesthetic deterioration from surfacecorrosion (rust colored staining) can be avoided withappropriate stainless steel grade and finish selection. Thereare numerous articles and industry association brochures toassist with stainless steel selection. (2)

Types 304/304L and 316/316L are the most commonly usedstainless steels for architectural applications. They provideidentical strength levels and are easily formed and weldedinto virtually any architectural product. Both can be cold-worked to higher strength levels.

Type 304 is generally appropriate for climate controlledindoor and mild outdoor applications with low levels of urbanpollution. If there will besome ch lor ide sa l texposure or higherpollution levels, Type 304should be specified witha smooth finish andregular cleaning and thepossib i l i ty of somes t a i n i n g b e t w e e ncleanings should beexpected.

Because Type 316contains molybdenum inaddition to equivalentamounts of chromiumand nickel to Type 304, iti s m o r e c o r r o s i o nresistant. It is usuallysuggested for exposureto low to moderatelycorrosive coastal anddeicing chloride saltsa n d / o r m o d e r a t eindustrial or higher urbanpollution levels. It doesnot provide sufficientcorrosion resistance forapplications with highsurface chloride salta c c u m u l a t i o n s o rexposure the salt-waterspray or splashing unlessa smooth f in ish isspecified and there will be regular cleaning.

Duplex stainless steels like 2205 are significantly strongerthan non-cold worked Types 304 and 316 and commonstructural carbon steels. Some, like 2205, can providesignificant improvements in corrosion resistance comparedwith even Type 316. Their high strength and corrosionresistance allows designers to reduce structural sectionsize, use the fine details of the bare metal supports as asculptural design feature, and avoid the on-goingmaintenance of coating reapplication.

5.1Austenitic Stainless Steels

5.2 Duplex Stainless Steels

5.3 Identifying Coastal Locations

5.4 StructuralApplications

6.1 Sheltered Locations

Coastal locations are typically defined as those within 8 to 16km (5 to 10 miles) of a large salt water body (e.g. ocean,harbor, or salt lake). On islands, like Japan and Great Britain,and in areas with strong coastal storm patterns (US GulfCoast), coastal salts have been documented much furtherinland. In addition, coastal salts can also be found muchfurther inland on large peninsulas and in coastal areas withstrong storm and weather patterns. For example, the entireUS state of Florida is exposed to coastal salts. (3) Morecorrosion resistant stainless steels are typically used insaltwater spray and immersion applications and may beneeded for sheltered locations that are not rain-washed.

Cold worked Types 304 and 316, 2205 and other stainlesssteels are increasingly being used for low profile glasscurtain walls, lightweight canopies, and other structures. For

example, spectacular glasscurtain walls supported bystainless steel were used tocreate striking exterior wallsfor Aeropuerta de Barajas( M a d r i d , 2 0 0 4 ) a n dSuva rnabhumi A i rpo r t(Bangkok, 2006), which rankamong the largest in theworld. Smaller Type 316 andglass subway entranceswere used for New YorkCity's new Bowling GreenStation and are shown inpublished plans for the city'snew 2 Avenue line (underconstruction).

Generally transit buildingsare expected to provideexcep t iona l l ong - te rmperformance with minimalma in tenance . Th i s i sparticularly true for rail andsubway stations and theirexterior wall, roof andelevated interior areas.Corrosive substances in theenvironment can acceleratet h e d e t e r i o r a t i o n o fconstruction materials andprotective coatings. There isa direct correlation between

a material's corrosion resistance and its longevity and thefollowing factors should be considered during materialsselection. The presence of pollution, particularly industrial,and de-icing and coastal salts can increase building exteriorand sheltered component corrosion rates.

Building areas that are open to the outside air, such assubway and train station entrances, are consideredsheltered and are usually more corrosive than applicationsthat are washed by rain. The guidelines for selectingstainless steel in the previous section can be applied to

nd

6. Design Considerations

Telephone Booth at Miami InternationalPhoto courtesy of Forms + Surfaces

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boldly exposed rain-washed components but shelteredlocations can be more corrosive.

It is common for transit structures to have sheltered areasthat are exposed to outside air. This should be consideredduring the selection of any sheltered material as it can leadto more corrosive conditions than would otherwise beexpected. Higher levels of particulate deposits (e.g. dirt,salts, pollutants) accumulate on surfaces when there is norain or manual washing and, if there is sufficient moisturefrom humid air, corrosion could occur if the material is notsufficiently corrosion resistant or if coatings deteriorate. Amore corrosion resistant stainless steel or somemaintenance washing is suggested for sheltered locationswith chloride salt or corrosive pollution exposure.

Designers also have toconsider whether paint andcoating deterioration onother types of architecturalmetals may be acceleratedb e c a u s e o f l o c a l i z e dconditions. For example, thismight occur on airportexteriors exposed to jetengine fuel fumes and inenvironments with highlevels of wind blown abrasiveparticles (e.g. sand). Fuelexposure is not a concernwith bare stainless steel,which is used for handlingfuels because of its corrosionresistance. Sand storms andsimi lar condi t ions caneventually change surfacetexture but stainless steeldoes not rely on coatings forcorrosion protection and it isquite wear resistant.

Stainless steel is preferredf o r p u b l i c b a t h r o o mpartitions, dispensers, sinksand other items because,unlike painted and plasticsurfaces, it can be quicklyand thoroughly sanitizedusing chemical-free steamcleaning. It is also more ductile and impact resistant thanporcelain or enameled steel. Many transit authoritiesspecify Type 316 bathroom fixtures and partitions becauseit is more resistant to urine than Type 304. In fact theAmerican Public transit Association (APTA) guidelines fortransit buildings specifically recommend Type 316 whereurine exposure is likely. Unfortunately, urine exposure intransit facilities is not always limited to bathrooms.Sometimes less visible areas in subway and train stationsare also exposed. This can cause corrosion of some metalsand odors can be difficult to remove from unsealed poroussurfaces. For this reason, Type 316 is often used for wallpanels, elevator cabs and other applications in these areas.

6.2 Local Conditions

6.3 Urine Exposure

6.4 Iron Particle Exposure

6.5 Fire Resistance

6.6 Cleaning

7.1 Non-Directional & Textured Finishes

When subway and train systems use heavy rail (subway) orcommuter trains that decelerate quickly, iron particles fromtrack abrasion may be pushed into the station in the rushingair. These particles are most likely to be deposited onsurfaces that are rough or porous and they can cause surfacediscoloration. Woven and rough stainless steel surfacefinishes should be avoided under these conditions, butsmooth surfaces generally perform well because the windforces generated by the trains blow particles from thembefore staining can occur.

Finally, stainless steel is preferred for acoustical panels inmany parts of the world because of its superior resistance to

fire and thermal radiation.Aluminum loses its strengthquickly when exposed tor e l a t i v e l y l o w f i r etemperatures and that canlead to acoustical panelcollapse which can thenblock exits. While carbonsteel can meet fire resistancerequirements, it is a highermaintenance material andcan become unattractive anddeteriorate as coatings fail.

Stainless steel is easilycleaned with non-acidic,mild, chloride-free householdcleaning products. Theproduct choice depends onwhether there is dirt, food,fingerprints or grease on thesurface. Products l ikedishwashing detergents,degreasers, and evenwindow cleaning productsare regularly used to restorestainless steel surfaces.W h e n s u r f a c e s a r evandalized by the applicationof posters, paint or markerpens, they can be removedwith paint and adhesiveremovers, soft non-metallicbristle brushes, and plasticscrapers. (4)

Two factors must be considered when selecting stainlesssteel finishes for transit facilities. First, smoother surfacefinishes ( Ra 20 micro-inches [Ra 12 microns] or less)accumulate fewer deposits ( salt, dust or pollution), whichcan improve corrosion performance and appearance.Second, the ideal finishes for transit applications hideaccidental scratching, impact damage or both.

Non-directional light or heavy scratch patterns are ideal forapplications like countertops, seating and baggage handling

7. Finish Specification

i.e.i.e.

Flight Information at Miami InternationalPhoto courtesy of Forms + Surfaces

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equipment because they hide surface damage. Deeperscratch patterns are rougher and will accumulate more dirtand corrosive deposits. For that reason, they are moresuitable for interior surfaces or those that will be cleaned.When both impact and scratching damage is a concern(e.g. column covers and wall panels), textured (embossedor coined) or woven stainless steel should be considered.

Textured finishes are usually applied by pressing patternsinto very smooth mill finishes, and, as long as the particularpattern selected is easily cleaned by rain and particulatelevels in the air are not high, they can perform as well asmuch smoother finishes in exterior applications. Wovenstainless can also be used for exterior applications likeparking garages, airport fences, sunscreens and plantsupports. But, woven products should not be used forapplications with coastal or deicing salt exposure unless amore corrosion resistant grade than Type 316 is selected ascrevice corrosion could occur.

In addition to providing long service life and the ability toavoid potentially toxic cleaning chemicals, stainless steellimits negative impacts on the environment in many ways.On average internationals t a i n l e s s s t e e lproduct ion containsabout 60% recycledscrap content, and it isestimated that over 92%of the stainless steelused in buildings andinfrastructure is recycledat the end of service. (5)In countries with a highhistorical use of stainlesssteel , the recycledcontent may be higher,particularly for commonaustenitic grades likeType 304 and 316.Stainless steel is notd o w n - c y c l e d a n drepeated recycling doesn o t d e t e r i o r a t eproperties. Unlike coatedmetals, carpeting, and other common constructionproducts, stainless steel interior panels produce noemissions (VOCs). Stainless steel roofing and wall panelscan also help reduce building cooling requirements andurban heat islands (UHIs).

Testing of exterior wall and roof materials in the UnitedStates has shown that common stainless steel roofing andwall surface finishes retain and transmit less heat into thebuilding than brick, concrete, wood and asphalt. Thisimprovement can be even more substantial when roofs arewell insulated and cavity wall construction is used. Stainlesssteel's low corrosion rate helps panels retain this high levelof performance over time (with occasional cleaning toremove dirt buildup). As is true of other metals, special highreflectivity paints can be applied to further limit heat gain.

8. Sustainable Design Benefits

8.1 Heat Retention

8.2 Roof RunoffNumerous studies around the world have examined runofffrom a wide variety of roof materials ( . asphalt, metal, claytile, concrete). The primary purpose has been to determinewhether the runoff is potentially toxic to humans, plants orwildlife. Stainless steel has lower metal or toxic substancerun-off rates than any other common roof material.Furthermore, the runoff rates for nickel and chromium fromstainless steel were often so low that they were belowdetectable limits and well under typical drinking waterconcentration limits. This makes stainless steel an idealroofing material for environmentally sensitive locations andwhen water will be collected for irrigation and humanconsumption. Additional information on stainless steelsustainability can be found in previous ConstructionSpecifier articles. (6)

Stainless steel is one of the most sustainable materialsavailable for transit building construction because itprovides long service life, can reduce energy requirements,does not require the use of hazardous cleaning chemicalsand minimizes maintenance requirements. The use ofstainless steel in transit buildings has increased

substantially in thepast 15 years withincreased interest ins u s t a i n a b l econstruction but ita l s o p r o v i d e sinteresting aestheticdesign alternativessuch as low profileglass curtain wall.P e r f o r m a n c e i sdependant on these lec t i on o f anappropriate stainlesssteel and finish forthe application andliterature and adviceshould be obtainedfrom producers andt h e i n d u s t r yassociations. (7)

The author would like to thank the Nickel Institute, theInternational Molybdenum Association, Euro Inox,Murphy/Jahn Architects, Richard Green, Forms & Surfaces,Next Door, and Overly Manufacturing Company for theirassistance in the preparation of this article.

Catherine Houska is senior development manager at TMRConsulting. She is an internationally recognizedarchitectural metals consultant specializing in stainlesssteel and finish selection, specification, restoration, andfailure analysis and the author of over 100 publications. Shewas a member of the American Public Transit Association(APTA) committee that developed the current NorthAmerican guidelines for transit station design, specificationand maintenance. Houska can be reached via email at

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e.g

9. Conclusions

Acknowledgement

Author

chouska@tmr-inc.com

Passport control area at Suvarnabhumi Airport in BangkokPhotos courtesy Carl D’Silva

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Resources

Notes

Additional free information on stainless steel selection andits use in architectural applications is accessible through theNickel Institute and International Molybdenum Associationwebsites and offices.

1) “Wrapped in Stainless Steel, Sustainable curtainwalls and roofing”, Catherine Houska,

August 2008, pgs. 48-62.

2) Additional information on stainless steel selectionand design can be found in “Designing on theWaterfront”, Catherine Houska,

, November 2007, pgs. 54-66; “Pushingthe Design Envelope with Structural StainlessSteel”, Catherine Houska and Kirk Wilson,

, April 2007, pgs. 28-42;“Architectural Metal Corrosion; The de-icing saltthreat” Catherine Houska,

December 2006, pgs. 104-112; “Metalsfor Corrosion Resistance: Part II”, CatherineHouska, November2000; “Guidelines for Corrosion Prevention”, NickelInstitute, Pub. 11 024; and “Which Stainless SteelShould Be Specified For Exterior Applications”,International MolybdenumAssociation (IMOA).

TheConstruction Specifier,

The ConstructionSpecifier

TheConstruction Specifier

The ConstructionSpecifier,

The Construction Specifier,

3) Mapped historical data is available on the USNational Atmospheric Deposition Program (NADP)website http://nadp.sws.uiuc.edu/isopleths/

4) Information on cleaning stainless steel can befound on the IMOA website (http://www.imoa.info)and in the Nickel Institute brochure (11 014)Guidelines For Maintenance and Cleaning

5) International Stainless Steel Forum (ISSF) websitehttp://www.worldstainless.org/

6) “Comparing the Sustainability of ArchitecturalMetals”, Catherine Houska and Dr. Steven Young,

, July 2006, pgs. 80 – 90.and “Wrapped in Stainless Steel, Sustainablecurtain walls and roofing”, Catherine Houska,

August 2008, pgs. 48-62.

7) There are stainless steel industry associationsaround the world. Some of the most useful sourcesfor free technical literature and case studies are theNickel Institute http://www.nickelinstitute.org,In te rna t iona l Mo lybdenum Assoc ia t ionhttp://www.imoa.info, Specialty Steel Industry ofNorth America http://www.ssina.com, and EuroInox http://www.euro-inox.org/.

The Construction Specifier

TheConstruction Specifier,

Reprinted byfrom Construction Specifier Magazine, February 2010

Website:

Indian Stainless Steel Development Association

For guidelines on material selection, fabrication and surface finishing, contact :

Indian Stainless Steel Development AssociationL-22/4, Ground Floor, DLF Phase-II, Gurgaon 122 002, Haryana.

Tel : 91-124 4375 501, 502 & 503, Fax : 91-124 4375 509Email: issdastainless@gmail.com, nissda@gmail.com

www.stainlessindia.org