Olketa Bridge—Bae Iumi Hao Sapos Olketa No Stap?
“Praisim bridge wea karim iu kam.”—George Colman, wanfala mek-19 century man bilong England for raetem story.
WANEM taem nao lastaem wea iu akrosim wanfala bridge? Iu ting abaotem tu? Planti million pipol akrosim bridge evriday. Iumi ting small long olketa. Iumi wakabaot, or draev antap long olketa or underneath, and maet iumi no ting abaotem. But waswe sapos olketa no stap?
For planti thousand year, man and animal fit for krosim olketa bigfala spes wea bifor olketa hard for akrosim, olsem wanfala river, deepfala valley, or wanfala bigfala hol, bikos long planti kaen bridge. Hem hard for tingim samfala taon for no garem bridge—Cairo, London, Moscow, New York, Sydney, and planti narawan. Tru nao, olketa bridge garem longfala history.
Olketa Bridge Bilong Bifor
Winim 2,500 year bifor, Queen Nitocris bilong Babylon buildim wanfala bridge for krosim Euphrates River. Why nao olsem? Greek savvyman Herodotus ansa olsem: “Disfala river divaedem [Babylon] long tufala haf. Taem olketa king rul bifor, sapos wanfala man want for akros go long narasaed, hem mas go insaed wanfala boat; wea long mi, luk olsem hem mas hard lelebet.” Nitocris iusim timber, brik wea olketa beikem, and olketa ston, and joinim withim iron and lead for buildim wanfala bridge ovarem disfala nambawan river bilong bifor.
Samfala bridge barava changim gogo bilong history. Taem King Darius the Great bilong Persia startim war bilong hem againstim Scythia, hem laek followim wanfala shortkat from Asia go kasem Europe long land. Datwan meanim hem mas leadim army bilong hem wea garem 600,000 man for akrosim Bosporus Strait. Hem danger for akrosim disfala passage long boat bikos long hevi fog and wata wea ran strong tumas, so Darius taemap olketa boat tugeta go-go hem garem wanfala bridge wea float wea long bilong hem 900 meter. Distaem, iumi no need for work hard tumas olsem Darius duim for akrosim disfala passage. Iu savvy iusim kar and akrosim olketa Bosporus bridge long Istanbul, Turkey, insaed tufala minute.
Sapos iu wanfala Bible student, maet iu tingim wanfala taem wea history hem change bikos no eni bridge stap. Tingim wanem happen taem King Nebuchadnezzar bilong Babylon hem attackim island bilong Tyre. For 13 year hem trae for winim disfala taon, but hem no fit for duim, maet bikos no eni bridge stap midolwan disfala island and mainland. (Ezekiel 29:17-20) Bihaen long three hundred year, olketa winim disfala island taem Alexander the Great buildim wanfala ston bridge from mainland go long island.
Kam kasem first century, ‘evri road lead go long Rome,’ but olketa bilong Rome needim olketa bridge tu for joinim tugeta disfala kantri. Long kleva way olketa engineer bilong Rome iusim olketa ston wea hevi bilong each wan hem eit ton, and olketa buildim olketa arch bridge wea samfala long olketa standap distaem for winim tu thousand year. Olketa buildim tu olketa spesel bridge for karim wata.
Long taem bilong olketa Middle Ages, samfala taem olketa bridge kamap olsem olketa strongfala ples. Long 944 C.E., olketa Saxon buildim wanfala timber bridge wea krosim Thames River long London for stopem olketa bilong Denmark wea want for attack. Bihaen samting olsem three hundred year, olketa changim disfala timber bridge withim Old London Bridge, wea part long history and olketa story.
Taem Queen Elizabeth I start for rul long England, Old London Bridge hem no wanfala strongfala ples nomoa. Olketa building kamap antap long disfala bridge. Olketa stoa stap long main floor. And waswe long olketa floor antap? Olketa richfala bisnisman and samfala member bilong royal famili stap long there. London Bridge kamap important part long living bilong pipol long London. Rent wea olketa kasem for olketa stoa and ples for sleep help for peim olketa samting for fixim disfala bridge, and tu, pipol mas pei for akrosim London Bridge!
Long taem wea olketa long Europe go ahed for buildim olketa bridge from timber and ston, olketa pipol bilong Inca long South America workim from rope. Wanfala bridge wea planti pipol savvy abaotem hem bridge bilong San Luis Rey, wea akrosim Apurímac River long Peru. Olketa Inca tekem olketa string bilong wanfala plant and twistim olketa tugeta for mekem olketa rope wea big olsem body bilong man. Olketa putim olketa rope hia akros long olketa ston post and then pullim akros long river. Bihaen olketa mekem strong tufala end, olketa hangim wanfala timber platform for mekem road. Olketa man for fixim savvy changim olketa rope evri tufala year. Olketa barava buildim gud disfala bridge dastawe hem stap kasem faev hundred year!
Olketa Bridge and Need Bilong Iumi Wea Change
Olketa bridge mas strong long olketa earthquake, strongfala wind, and temperature wea change. Olsem iumi lukim, no longtaem go nomoa olketa engineer iusim timber, brik, or ston for buildim bridge. Taem way for iusim kar start long end bilong mek-19 century, olketa bridge wea stap long datfala taem need for kamap moabeta and moa big for savvy karim olketa samting wea moa hevi.
Taem olketa workim steam train diswan tu changim way for buildim and planim olketa bridge. Planti taem hem moabeta for train akrosim olketa waed river or deep valley. Waswe, olketa savvy buildim bridge for krosim datfala spes and supportim hevi bilong planti moa train wea bae iusim? Olketa cast iron bridge help for lelebet taem. Wanfala main bridge long start bilong mek-19 century, wea engineer from Scotland Thomas Telford hem planim, hem nao suspension bridge wea stap antap long Menai Strait long North Wales, wea olketa finis for buildim long 1826. Long bilong hem 176 meter and olketa go ahed for iusim distaem! But cast iron savvy brek kwiktaem, and planti taem olketa bridge savvy fall daon. Go-go, long olketa last year bilong 1800, olketa start for iusim steel. Olketa savvy iusim diswan for buildim olketa bridge wea moa long, and moa sef.
Olketa Different Kaen Bridge
Sevenfala main plan bilong bridge nao stap. (Lukim box antap.) Bae iumi story lelebet abaotem tufala.
Olketa cantilever bridge garem tufala maeti tower long each saed bilong river. Olketa beam stap long each tower, lelebet olsem wanfala diving board hem pas strong long swimming pool. For mekem bridge strong, olketa beam hia join long midol withim truss.
Sapos river savvy ran strong or bottom bilong river hem barava soft, olketa laek iusim cantilever bridge bikos hem no needim bigfala post for go insaed midol bilong river. Bikos hem strong, olketa cantilever bridge barava gud for karim hevi samting olsem olketa train.
Maet iu lukim wanfala acrobat wakabaot akros long wanfala taet rope. Waswe, iu savvy long really way hem wakabaot akros long wanfala bridge—wanfala suspension bridge? Samfala suspension bridge klosap semsem olsem wanfala taet rope. Maet hem garem rope wea stap long tufala end wea basket hang from. Passenger hem sidaon insaed basket and muvim hemseleva for gogo daon then hem kasem narasaed. Pipol raonem world iusim olketa simple rope bridge evritaem.
Hem tru, maet iu no ting for draevem wanfala trak akros long bridge wea olketa workim from rope. Bihaen olketa workim olketa iron-link chain and steel-wire rope, hem easy for buildim olketa suspension bridge wea savvy karim olketa hevi load. Olketa suspension bridge distaem savvy garem long wea kasem 1,200 meter or winim. Suspension bridge maet garem tufala steel post, wea each wan supportim wanfala tower. Olketa steel rope, wea garem planti thousand wire, olketa taemap strong long olketa tower and long road long daon. Olketa steel rope hia nao main samting wea supportim hevi bilong traffic and road. Sapos olketa buildim gud, suspension bridge nao wanfala long olketa barava sef bridge long world.
Bifor, maet iu ting nating long olketa bridge. But, next taem iu wakabaot akros long wanfala bridge, askim iuseleva: ‘Wanem nao mi savvy abaotem disfala bridge? Wanem taem nao olketa buildim?’ Lukluk gud long hem. Waswe, hem wanfala cantilever, suspension, or different kaen bridge? Why nao olketa choosim diskaen design?
Then, taem iu wakabaot akros, luk go daon and askim iuseleva, ‘Bae mi hao sapos hem no stap?’
[Box/Piksa long page 14]
OLKETA BRIDGE PLAN
1. GIRDER BRIDGE planti taem stap long olketa bigroad. Olketa girder stap antap olketa bigfala post or faondeson. Long bilong bridge hia savvy kasem 300 meter.
2. TRUSS BRIDGE kasem support from olketa truss wea shape olsem triangle. Olketa bridge hia, planti taem for olketa train, savvy akrosim deep valley, olketa river, and narafala samting.
3. Long olketa ARCH BRIDGE each sekson garem wanfala arch. Diswan hem wanfala barava old kaen bridge. Olketa bilong Rome buildim diskaen bridge for karim wata and iusim wanfala keystone for joinim arch. Planti stap yet distaem.
4. CABLE-STAYED BRIDGE luk semsem olsem olketa suspension bridge but olketa steel rope nao go stret long olketa tower.
5. BRIDGE WEA MUV savvy liftap or swing go raon mekem olketa ship savvy go pas. Gudfala example nao Tower Bridge long London.
6. CANTILEVER BRIDGE iumi storyim insaed disfala article.
7. SUSPENSION BRIDGE iumi storyim insaed disfala article.—World Book Encyclopedia, 1994.
[Chart long page 13]
SAMFALA IMPORTANT BRIDGE
SUSPENSION
Storebaelt Denmark 1,624 m
Brooklyn U.S.A. 486 m
Golden Gate U.S.A. 1,280 m
Jiangyin Yangtze China 1,385 m
CANTILEVER
Forth (tufala span) Scotland 521 m each
Quebec Canada 549 m
Mississippi River U.S.A. 480 m
STEEL ARCH
Sydney Harbour Australia 500 m
Birchenough Zimbabwe 329 m
CABLE-STAYED
Pont de Normandie France 856 m
Skarnsundet Norway 530 m
[Piksa long page 12]
Girder bridge bilong distaem wea stap antap long oldfala arch bridge long Almería, Spain
[Piksa long page 15]
Brooklyn Bridge, New York, U.S.A. (suspension)
[Piksa long page 15]
Tower Bridge, London, England (wea muv)
[Piksa long page 15]
Sydney Harbour Bridge, Australia (arch)
[Piksa long page 15]
Seto Ohashi, Japan (cable-stayed)