Quantifying Environmental Green Index For Fleet Management Model

Transcription

1 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 Quafyg Evromeal ree Idex For Flee Maageme Model Lay Eg TEOH a, Hoo Lg KHOO b a Deparme of Mahemacal ad Acuaral Sceces, Faculy of Egeerg ad Scece, Uvers Tuku Abdul Rahma, 500, Kuala Lumpur, Malaysa; E-mal: eohle@uar.edu.my b Deparme of Cvl Egeerg, Faculy of Egeerg ad Scece, Uvers Tuku Abdul Rahma, 500 Kuala Lumpur, Malaysa; E-mal: khoohl@uar.edu.my Absrac: Worldwde evromeal ssue s worseg owadays ad hece more aeo s ceraly requred. To fulfll he socal resposbly o preserve he evrome, raspor operaors should cocer he ssue of evromeal susaably cosderably. everheless, here s o avalable mehod o how o quafy gree dex ha could provde a proper gudace o he raspor operaors. Therefore, a gree dex model s formulaed o capure flee emsso, fuel effcecy ad ose. The proposed model s able o quafy he 'gree level' of flee respose o sochasc demad. A llusrave case sudy s preseed o exame he applcably of he framework. The fdgs show ha emsso, fuel effcecy ad ose could affec he 'gree dex' of flee a varyg degrees, depedg o boh eral ad exeral facors. I s acpaed ha hs sudy may reveal some beefcal sghs for he raspor operaors o operae evromeally ad profably. Keywords: Emsso, Fuel Effcecy, ose, ree Idex, Evromeal Susaably. ITRODUCTIO owadays, global evromeal ssue becomes oe of he challeges for he raspor operaors o susa such a complcaed rasporao sysem. As repored Ieraoal Cvl Avao Orgazao (ICAO) (200), avao secor accous for abou 2% of oal global carbo doxde ( CO 2 ) emsso, whch s approxmaely % of he CO 2 emsso from all rasporao sources. I erms of greehouse gases (Hs), rasporao secor s foud o geerae % of he global Hs. Udeably, here are que a lo of crcal cosequeces due o he exsece of subsaal polluas he ar. The repored cosequeces cludes ar polluo, clmae chage mpacs, healh effecs, lad-use ad ecosysem mbalace (Jac, 999; Wllams e al., 2002; Frasse e al., 2004; Jarup, 2005, Bruecker ad rv, 2008; Pras e al., 20). Correspodgly, may allevao approaches, amely clmae chage mgao sraeges, advaces alerave fuel, echologcal mproveme ad maageme of hazardous maerals have bee carred ou by he releva pares he rasporao secor (Trasporao Research Board, 202) lesseg he polluas geeraed from he raspor acves. Besdes, varous sadard rules ad polces had bee mplemeed o moor emssos. For sace, he mplemeao of emsso radg scheme (ETS) had bee eforced reducg emsso (Albers e al., 2009; Rohegaer, 200; Saley e al., 20; Vesperma ad Wald, 20). Apparely, greaer cocer ad creasg effors of respecve rasporao secors o preserve he evrome hghlgh he global awareess ad aeos owards evromeal susaably. I such a case, raspor operaors defely play a val role o fulfll her socal resposbly preservg he evrome. From he facal aspec, some raspor operaors were also sufferg subsaal

2 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 facal losses emg excessve polluas o he ar. The arles are charged 000 for peales producg excessve ose (Boeg, 20) whle he vehcle ha does o mee he emssos sadards, he daly charge s 00 for larger vas ad mbuses ad 200 for lorres, buses, coaches ad oher heavy vehcles (Traspor for Lodo, 202). Accordg o ICAO (2008), s approxmaed ha fuel cosumpo accoued for 0% of oal arle operag expeses. Ths hghlghs he crucal mpacs of he evromeal ssues o he operaoal prof of he raspor operaors. Therefore, he effecs of hese elemes should be capured accordgly for he raspor operaors o oly o operae evromeally bu also ecoomcally. 2. LITERATURE REVIEW May pas sudes had bee coduced o look o he ssues of evromeal susaably. eerally, he exsg sudes could be caegorzed 2 major felds,.e. avao secor ad o-avao secor. 2. Evromeal Issues Avao Secor For he avao secor, here are major cocers, amely arcraf emsso, fuel effcecy ad arcraf ose. Recogzg he mpacs of arcraf emsso, Wllams e al. (2002) showed ha alude resrcos o arcraf could be a effecve meas reducg clmae chage effec. Myosh ad Masa (2009) proposed a carbo calculao prooype o moor arcraf emsso whle Yamaguch (200) dscussed he voluary CO 2 emssos reduco scheme by employg ecoomerc aalyss. Wh he am o foser he ulzao of evromeally fredly ege echology, he effec of arle emsso charges ad local emsso charges were aalyzed by Bruecker ad Zhag (200) ad Scheelhaase (200), respecvely. vo ad Reveld (200) speced he evromeal cosequeces upo he choce of arcraf sze ad servce frequecy. They revealed ha a large arcraf would be requred for shor-haul operao o reduce he evromeal mpac. I addo o he use of alerave fuels, demad shf ad carbo prcg, Sgourds e al. (20) revealed ha echologcal ad operaoal effcecy mprovemes are sgfca o decrease he sde effecs o he evrome. Besdes, Jac (999) hghlghed ha larger arcraf would decrease average level of ose ad fuel cosumpo whle Morrell (2009) showed ha he ulzao of larger arcraf s effecve o oly reducg emsso bu also mprovg fuel effcecy. kolers e al. (20) esmaed fuel cosumpo ad emssos durg ax operaos. Ther resuls show ha dlg ad axg saes a cosa speed or brakg were foud o be wo larges sources of fuel bur ad emssos. Besdes, Jac (200) showed ha ose ad ar polluo quoas have sgfcaly affeced he arpor ad arle s performace. Lu (2009) measured he socal coss of arcraf ose ad ege emsso o se up evromeal charges. Specfcally, rv (2009) dscussed arcraf oseabaeme ad mgao sraeges whle Hsu ad L (2005), Ljese (200) ad Breche ad Pcard (202) evaluaed arpor ose charge polces ad he correspodg arle ework adjusme respose. From he sudes as meoed above, could be deduced ha a effce arle's sraegy (cludg flee plag) plays a mpora role susag he evrome. As such, he arles eed o pla properly f hey were o cocer he evrome. Alhough hese sudes had covered evromeal mpacs of he arcraf emsso, fuel effcecy ad arcraf ose a cera exe, mos sudes focused o sgle eleme (emsso, fuel

3 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 effcecy or ose). I s mpora o oe ha order o assure a evromeally susaable sysem, he focus o sgle eleme s oo resrcve as here s o sgle sraegy ha works perfecly o susa he evrome (Yag e al., 200; Sgourds e al., 20; ealer e al., 202). More mporaly, hese sudes dd o quafy he 'gree level' whch s flueced grealy by arcraf emsso, fuel effcecy ad ose. How hese elemes corbue o he 'gree level' of he arles s o explored explcly. Therefore, he eleme of emsso, fuel effcecy ad ose are cosdered reasoably hs sudy formulag a 'gree dex' model for he raspor operaors o operae evromeally. 2.2 Evromeal Issues o-avao Secor To ease he evromeal ssue oher rasporao secor (o-avao secor), here are some major mgao effors, cludg lad-use maageme, modal shf/ermodal plag, schedulg ad roue opmzao, eergy ad echologcal ehaceme, alerave fuel adopo, polcy mplemeao ad ose-abaeme sraeges, as repored he leraure. Abou he same cocer as could be see he avao secor, may sudes focused o vehcles emsso, fuel effcecy ad ose. I erms of lad-use plag, Pooglou ad Kaaroglou (2005) esmaed vehcle emsso by specg rasporao eracos wh lad-use plag. They hghlghed ha urba egraed model s requred o reduce emsso. For mode shf plag, Seehof e al. (2006) explored he processes leadg o Hs emsso chages ad assess he possble cosequeces he fuure. They showed ha Hs emsso was prmarly flueced by creasg fregh operaos ad modal shf owards heavy rucks. More recely, ealer e al. (202) speced mode shf polces by evaluag he eergy ad H emsso mgao effecveess. For er-modal plag, Paerso e al. (2008) looked o he poeal reduco of CO 2 emsso by esmag he demad for er-modal servces. I erms of opmzao mehod, Ercsso e al. (2006) produced roue choce wh he lowes fuel cosumpo sead of he shores me or dsace. They showed ha he proposed avgao sysem s able o geerae he bes roue erms of fuel ecoomy. To solve bus schedulg problem, L ad Head (2009) evaluaed emsso reduco wh alerave eergy sources. They poed ou ha he mplemeao of upper boud o emsso s effecve reducg emsso. To spec eergy ad echologcal mproveme, Yedla ad Shresha (200) examed he mpac of quaave (cos, eergy savg poeal, emsso reduco poeal) ad qualave (echology avalably/adapably, mplemeao barrers) crera selecg alerave rasporao opos for evromeally susaable raspor sysem. They showed ha he cluso of qualave crera explas he falure of may alerave raspor opos. Skppo e al. (202) compared he mpacs of echologcal mproveme ad behavorally-based abaeme approaches by cosderg cumulave emsso budges. They showed ha echologcal developmes ad behavoral chage polces eed o be appled deeply. For alerave fuel adopo, Merlo e al. (2004) evaluaed he assessme of vehcles wh alerave ypes of fuels ad dffere ypes of drve ra. Johso e al. (202) speced he mpacs of bodesel bledg o fregh emsso. Ther resuls show ha he chages emsso due o bodesel are smaller ha ege ad corol echologes. Eglmez ad Taar (202) proposed realsc polcy opos o decrease emsso. They showed ha he egraed approach of polcy-makg (by egrag fuel effcecy, publc rasporao ad elecrc vehcle usage) has a crucal mpac o he success of polcy mplemeao. Wh he am o reduce ose polluo, Kg e al. (20) quafed he effec of he

4 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 bus gae o ose levels. Ther resuls show ha he mpac o ose levels s mmal. Calvo e al. (202) evaluaed he ose emsso produced by a vehcle real drvg codos ad defed he oses drvg behavors. The resuls show ha eher drver experece or sex has ay apprecable mpac o ose geeraed, ad ege ype has lle effec. Freas e al. (202) assessed raffc ose based o key facors, amely payme ype, raffc speed ad raffc desy. The fdgs show ha hgher car speeds ad hgh raffc deses always lead o greaer aoyace. Besdes, cobblesoes were foud o be he mos aoyg pavemes whle ope asphal rubber paveme mposes less aoyace ha dese asphal. From he leraure, s observable ha he ssue of evromeal susaably could be eased from varous aspecs. everheless, hese sudes jus focused o a specfc mgao sraegy acklg evromeal mpacs. As meoed earler, he oly cosderao o sgle facor s oo resrcve. How he flueal eleme (eg. emsso, fuel ad ose) affecg he overall 'gree level' s o cosdered hese sudes ad hus he raspor operaors would o kow her overall evromeal performace. Therefore, a proper 'gree dex' model s deed ecessary o quafy evromeal mpacs explcly, parcularly o acheve a w-w suao bewee he evrome ad raspor operaors. 2. Evaluae Evromeal Impacs Tll o dae, here s very lmed sudes quafed evromeal mpacs of rasporao felds. To assess he evromeal mpacs for a hghway roue ad pavg projec, Bocl ad Mello (2006) preseed a decso suppor mehod ad her resuls show ha he parkhghway s he mos promsg alerave gvg he bes ecologcal, ecoomc ad socal performace. Ross e al. (2009, 202a, 202b) examed hree-dmesoal cocep of susaably o erpre he prefereces of he decso makers ad also o defy he mos mpora characerscs of alerave rasporao polces. The lmao of hese sudes s ha hey prmarly focused o rasporao aleraves aalyss for whch here s o exac quafcao approach ha could be used o evaluae he gree level of he evrome. I oher felds (o rasporao sysem), Slver (2000) evaluaed he effecs of ffsh marculure o coasal zoe waer qualy by adopg fuzzy logc approach. Four fuzzy ses (l, moderae, severe ad exreme mpacs) were defed for whch he correspodg paral membershps have bee combed o produce a sgle comprehesve score as a overall measure of evromeal qualy. More recely, Valee e al. (20) caegorzed old mg ses ad descrbed her evromeal mpac (low, medum ad hgh). They showed ha he use of fuzzy logc o oba he evromeal mpac dex allowed he egrao of quaave ad qualave compoes. Some oher releva sudes employg fuzzy logc o evaluae evromeal mpacs could also be see Phlls ad Adraasaholaa (200) ad Adraasaholaa e al. (2004). Alhough above-meoed sudes clamed ha boh quaave ad qualave elemes could be capured, he resula oupus were oly a approxmao (o exac soluo). The precso of he resuls s quesoable. As such, a proper approach whch ca produce precse soluos s ceraly ecessary. Furhermore, hese sudes jus focused o a specfc evaluao a prese. They dd o reveal he comparso bewee curre perod ad pas performace. Whou hs compoe, he mproveme saus of a curre operag perod could o be defed (uless furher aalyss s carred ou). Therefore, hs sudy proposes a framework ha s able o quafy exac evromeal performace by coducg a drec evaluave comparso bewee curre operag perod ad s prevous performace. Wh hs eleme place, exac performace of each operag perod hroughou he plag horzo ca be evaluaed accuraely. Addoally, hs sudy s able o

5 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 capure sochasc eleme. The flucuao of demad level should be corporaed as would affec he acves of he operaors ad hece he evromeal performace measures wll vary. However, oe of he exsg sudes address hs aspec quafyg he evromeal performace. To fll hs gap, hs sudy develops a gree dex model ha allows he raspor operaors o quafy he 'gree level' hroughou he plag horzo respose o he evromeal performace ad also demad flucuao of each operag perod. By capurg flee emsso, fuel effcecy ad ose, a gree dcaor owards he operag performace of he raspor operaors ca be defed clearly. A llusrave case sudy s demosraed o exame he feasbly of he proposed mehodology. The fdgs show ha he proposed mehodology s vable, corbug o he maageral pracces of he raspor operaors. I s acpaed ha hs sudy may reveal some formave hghlghs o he raspor operaors order o provde a beer servce profably ad evromeally whch would beef he ravelers ad commuy reur. Ths paper s orgazed as follows. Seco brefly dscusses he cocers ad mpacs of he evromeal susaably. Seco 2 addresses relaed leraure revew o evromeal ssues. Seco explas he formulao of gree dex model. Seco 4 exames he feasbly of he proposed mehodology by preseg a llusrave case sudy wh a comprehesve dscusso o he compuaoal resuls. Seco 5 hghlghs he corbuos of he proposed mehodology as well as he maageral mplcaos. Seco 6 cocludes he sudy ad suggess he prospec research he fuure.. METHODOLOY. omeclaure For he operag perod as follows:,2,..., T, he oaos used for ypes of flee a age y are lsed Parameers T D m A S EX FEI EX m ER UB C LF T AP Plag horzo Demad level Saus of flee (: ew flee, 2: agg flee) Toal operaed flee Agg arcraf o be sold Excessve emsso Fuel effcecy dex Excessve ose Emsso rae Parameer of evromeal susaably Upper boud of oal emsso Cumulave ose level Load facor Threshold of ose Average fuel prce

6 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 X I y Quay of ew flee o be purchased or leased Ial quay of flee Fucos m F D, A Fuco of servce frequecy erms of D ad m TM D, A Fuco of raveled mleage erms of D ad A m FC D, A Fuco of fuel cosumpo erms of D ad A Decso varables E ree level of emsso F ree level of fuel effcecy ree level of ose FI ree dex.2 Formulao of ree Idex I order o capure he evromeal susaably, here are umerous facors (.e. facors) o be cosdered. Ths seco formulaes a gree dex (FI) as a gree dcaor for he raspor operaor o operae evromeally respose o he gree levels of releva evromeal facors. The proposed model of gree dex s show Fgure. I could be see ha each evromeal facor wll bascally geerae dffere gree level whch wll he produce he gree dex as a overall gree dcaor. A Facor ree level, Facor 2 ree level 2, 2 ree dex (FI) Facor ree level, Fgure. The model of gree dex (FI) I s mpora o oe ha he gree dex of flee may vary across he level of sochasc demad. Ths could be jusfed by he quay of flee operao whch would geerae gree levels dfferely. I respose o demad flucuao, he proposed framework s able o quafy correspodg gree dex o mee probable scearos of demad. Praccally, here are scearos of demad o be cosdered: whe here s o chage of

7 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 demad level (for subseque operag perods) as well as whe here s a creme or a drop of demad. Cocsely, he proposed framework s able o quafy he gree dex of flee accordgly for all possble chages of demad level. Ths s ceraly crucal for he raspor operaors o susa evromeally whle meeg demad flucuaos. For llusrao purpose, flueal facors amely flee emsso, fuel effcecy ad flee ose are cosdered. The followg seco formulaes gree dex as a gree dcaor for he raspor operaors o operae evromeally. Subsequely, he gree levels of flee emsso, fuel effcecy ad ose are quafed accordgly..2. Quafy gree dex (FI) As meoed earler, here are major facors, amely flee emsso, fuel effcecy ad ose o be cosdered order o capure he evromeal susaably. By capurg he gree levels of hese elemes, he proposed model quafyg he gree dex of flee s demosraed Fgure 2 whle he correspodg scalg of gree dex s show Fgure. The dex scalg Fgure shows ha he dex value of (.e. FI ), whch acs as he base value, mples ha here s o mproveme for he curre operag perod comparg o prevous operag perod. The value of gree dex whch s greaer ha (.e. FI ) dcaes ha curre operag perod ouperforms prevous perod. Coversely, he value of gree level whch s less ha (.e. FI ) sgfes ha prevous operag perod performs beer ha curre operag perod. I oher words, a hgher dex sgfes he acheveme of a hgher gree level. I such a case, he elemes of he gree level of flee emsso ( E ), fuel effcecy ( F ) ad flee ose ( ) wh he value less ha refers o a usasfacory codo for a curre operag perod whle he value more ha shows a mproveme curre operag perod. eerally, he fuco of gree dex, FI s defed as follows. ree dex, FI I, () for whch I deoes he al quay of flee o be suppled by he raspor operaors order o mee ravelers demad. By cosderg evromeal facors, Equao () s able o quafy he resula gree dex of flee whle meeg sochasc demad (by havg I operao). By akg o cosderao he elemes of emsso, fuel effcecy ad ose,.e. whe, he gree dex of flee ca be expressed as follows: E F ree dex, FI I (2) where he compuao of he gree levels of E, F ad are dscussed he followg E F seco. As addressed earler, he eleme of FI I serves as a base value,.e. here s o mproveme erms of he gree levels of flee emsso, fuel effcecy ad ose of a curre operag perod. FI I sgfes ha here s a promsg mproveme erms of he gree levels of flee. Operaoally, hs ca be acheved by mprovg E, F ad for he gree level of emsso, fuel effcecy ad ose, respecvely (oe ha he dex scalg as llusraed Fgure also apples o he gree levels of emsso, fuel effcecy ad ose).

8 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 Excessve emsso ree level of emsso, E Fuel cosumpo ree level of fuel effcecy, F ree dex of flee, FI Excessve ose ree level of ose, Fgure 2. The quafcao model of gree dex Usasfacory (FI <) Base Value (FI=) Sasfacory (FI >) Fgure. The scalg of gree dex.2.2 Quafy he gree level of flee emsso For he gree level of flee emsso, oal emsso emed from flee acves cludg excessve emsso of each operag perod s cosdered accordgly. These elemes are mpora o be capured order o esure ha he operaos of he raspor operaors adhere o he compla regulaos whle playg her roles susag he evrome. For sace, he arles have o esure ha her operaos mee he sadard lm of arcraf ege emsso as deermed by ICAO (Ieraoal Cvl Avao Orgazao, 2008). I order o deerme he gree level of flee emsso for a parcular operag perod, he excessve emsso ca be compued as follows (by cosderg he dfferece of oal emsso ad he compla upper lm of emsso): m m EX LF ERF D, A UB,, 2,..., T,, 2,...,, m, 2 () I s mpora o oe ha he eleme of excessve emsso s posve,.e. EX 0 f he oal emsso s greaer ha he upper boud of emsso. Coversely, EX 0 mples ha he oal emsso of a parcular operag year s uder corol (o reachg he upper boud of emsso) whle EX 0 sgfes ha he oal amou of emsso s up o he allowable upper boud ad hece here s o excessve emsso. I such a case, EX 0 s desrable whle EX 0 s udesrable for he raspor operaors because some emsso peales or charges wll be mposed o he raspor operaors for emg (excessve) subsaal emsso.

9 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 eerally, he gree level of emsso, E ca be compued drecly by comparg he operag performace of a curre operag perod wh prevous operag perod,.e. by geg he dfferece of excessve emsso of he operag perod ad, whch s possble o be zero or o-zero (.e. posve or egave). Ths reflecs he real suao of he possble excessve emsso from he raspor acves. Accordgly, he gree level of flee emsso ca be expressed as follows: EX, EX 0 EX -, EX EX 0 E - (4) 0, EX 0, EX 0 2, EX 0, EX 0 where EX EX EX -. Comparavely, whe wo successve perod produce dffere excessve emsso (.e. EX, 0, EX, 0, EX 0, EX 0 or EX - EX - - EX 0, EX - 0 ), he correspodg gree level ca be compued accordgly by evaluag he rao of he dfferece of excessve emsso (of boh perod) ad excessve emsso of prevous perod. By dog hs, he mproveme saus of curre operag perod could be defed. If he curre operag perod has a beer performace ha s prevous perod, he resula gree dex s E oherwse E whch meas ha prevous operag perod performs beer. EX EX - 0 sgfes ha curre operag perod does o produce excessve emsso,.e. has he same level wh s prevous perod. Sce boh perod do o show ay mproveme ( reducg emsso), he resula gree level remas as. For EX - 0, EX 0, he resula gree level s 0 owg o a cred (.e. dex) of - whch s gve o curre operag perod because performs wors ha s prevous perod. O he oher had, EX - 0, EX 0 mples ha curre operag perod performs beer ha s prevous perod. Therefore, he resula gree level s foud o double he base value (.e. 2) due o he fac ha a cred (.e. dex) of s gve o curre operag perod for s beer performace. Ths leads o a oal dex of 2 (.e. he sum wh he base value of )..2. Quafy he gree level of fuel effcecy I s acpaed ha flee s more fuel-effce f ulzes less fuel servcg he operag eworks. Less fuel cosumpo for a parcular flee (e.g. ew flee) s beefcal o he raspor operaors o ravel furher. Therefore, oal raveled mleage ad oal fuel cosumpo are cosdered quafyg he gree level of fuel effcecy. Ths hghlghs ha from he maageme ad operaoal perspecves, he raspor operaors should cosder her flee plag wsely, especally geg ew flee (va acquso or leasg) order o assure fuel effcecy whle meeg sochasc demad operaoally. Mahemacally, he fuel effcecy dex, FEI ca be expressed as follows: m TM FEI,, 2,..., T,, 2,...,, m, 2 (5) m FC eerally, he gree level of fuel effcecy ca be compued by comparg he operag performace of a curre operag perod wh prevous operag perod,.e. based o he fuel effcecy dex of operag perods ad. By dog hs, he gree level of fuel effcecy, ca be defed as follows: F

10 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 FEI FEI,, 2 T F -,..., (6) As meoed earler, gree level of sgfes ha here s o mproveme of curre operag perod comparg o s prevous perod. I s acpaed ha F f prevous operag perod ouperforms curre operag perod (whe FEI 0, FEI 0 ). - Coversely, he suao of FEI 0, FEI 0 would resul he value of F whch s - greaer ha (.e. F ) due o he fac ha he fuel effcecy dex of curre operag perod s hgher ha s prevous perod. For FEI FEI -, could be see ha F for he same performace of wo successve perod..2.4 Quafy he gree level of flee ose I order o quafy he gree level of flee ose, oal ose emed (cludg excessve ose s here s ay) durg he flee operaos of each operag perod s cosdered order o esure ha he operaos of he raspor operaors adhere o he compla regulaos. By akg o accou he dfferece of cumulave ose level of flee ad permed ose hreshold, excessve ose level ca be evaluaed as follows: EX C F T F,, 2,..., T,, 2,..., (7) Operaoally, cumulave ose level of flee ca be compued based o he oal servce frequecy of flee of a parcular operag perod. Ths hghlghs ha he servce frequecy of flee ad he correspodg cumulave level eeds o be plaed ad corolled wsely due o he grea mpacs o he commuy as well as he raspor operaors. I such a case, how o esure ha he oal cumulave ose level does o exceed he hreshold of flee eeds o be capured. For sace, some arpors se a parcular hreshold of arcraf ose for whch he arles exceed he hreshold have o pay ose charges as a pealy. For Equao (7), he eleme of excessve ose level whch s posve (.e. EX 0 ) shows ha he cumulave ose level s more ha he permed hreshold. Ths s a udesrable suao for he raspor operaors as hey eed o pay more for excessve ose level. O he oher had, EX 0 mples ha he cumulave ose level of a parcular operag perod s lesser ha he allowable lm (uder corol) whle EX 0 sgfes ha he cumulave ose s equvale o he allowable lm (.e. o excessve ose). Smlar o he cocep quafyg he gree level of flee emsso (as descrbed seco.2.2), he gree level of ose ca be compued by comparg he operag performace of a curre operag perod wh s prevous perod,.e. based o he excessve ose of operag perods ad. Smlarly, he gree level of ose, for wo cosecuve operag perod could be defed as follows: EX, EX 0 EX, EX EX 0 (8) 0, EX 0, EX 0 2, EX 0, EX 0 where EX EX EX. Bascally, whe wo cosecuve perods produce excessve ose dfferely, he correspodg gree level ca be compued by evaluag he rao of he dfferece of excessve ose (of boh perod) ad excessve ose of prevous perod. If he

11 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 curre operag perod performs beer ha s prevous perod, he resula gree dex s. Oherwse, mples ha prevous operag perod has a beer performace. EX EX 0 sgfes ha curre ad prevous operag perods do o produce excessve ose,.e. hey have o mproveme reducg ose level ad hece he resula gree level remas as. For he cases of EX 0, X 0 ad EX 0, EX 0, he resula gree levels are 0 ad 2, respecvely owg o a cred (.e. dex) of - ad are gve respecvely o curre operag perod. 4. A ILLUSTRATIVE CASE STUDY I order o exame he applcably of he proposed model, hs seco carres ou a case sudy focusg o he arle dusry wh he am o quafy he gree levels of arcraf emsso, fuel effcecy ad arcraf ose. The case sudy demosraes how hese facors (.e. arcraf emsso, fuel effcecy ad arcraf ose) cosue o he gree dex as a gree dcaor for he arles o operae evromeally. 4. Daa Descrpo I hs case sudy, 2 ypes of arcraf.e. A ad A0-00 are cosdered for a se of OD pars. Oly 2 ypes of arcraf are cosdered as may of he low-cos carrers operae her busess wh few varees of arcraf ypes (O Coell ad Wllam, 2005). I addo, a plag horzo of 5 years s also jusfed as accordg o Malaysa Arles (200) ad ArAsa Berhad (200), he acquso of ew arcraf, average, requres a perod of 5 years o be delvered compleely. Table shows he emsso rae of arcraf, by cosderg major polluas.e. roge oxdes ( O x ), hydrocarbos (HC) ad carbo mooxde (CO) whch are emed durg he ladg ad ake-off (LTO) sage (Ieraoal Cvl Avao Orgazao, 20a). Table. Arcraf emsso durg LTO sage Arcraf Amou of Ox HC CO (kg/arcraf) A A A bechmark problem s creaed o es he applcably of he proposed mehodology quafyg he gree levels of emsso, fuel effcecy ad ose as well as he correspodg gree dex for each operag perod. Mos of he values for he pu daa are obaed from he publshed repors (ArAsa Berhad, 200; Malaysa Arles, 200; Arbus, 200; ICAO, 20b). These values are show as follows: By assumpo: 2 A, al quay of arcraf o be years old s I I Parameer of evromeal susaably, 96.5% By assumpo (based o real daa): A, al quay of arcraf s Load facor of arcraf, LF 77% I 2 I 50 4

12 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 7 Upper boud of emsso, UB 20,000 oes 2x0 kg 2 Cumulave arcraf ose, C EPdB ad C EPdB Threshold of ose, T 265 EPdB Average fuel prce, AP $89 per barrel For ypes of arcraf, he fuco of he umber of flghs s F A 9.776x0 A 7.8x0 [R 0.97] (9) The fuco of he raveled mleage s 2 TM 2,066F 2,875,8 [R 0.8] (0) For ypes of arcraf, he fuco of fuel expeses s FE 7.46F 8.x0 F 98,572 [R 0.88] () From he operaoal aspec, load facor s a measure of he amou of ulzao of he oal avalable capacy of arcraf. I average, load facor of 77% as saed above sgfes ha he occupacy of he operag arcraf s up o 77% hroughou he plag horzo. To allevae flee emsso, upper boud of emsso refers o compla lm of emsso ha ca be emed by he arcraf operao. As meoed earler, he arles have o esure ha her emssos are uder he regulaed lms as deermed by ICAO (Ieraoal Cvl Avao Orgazao, 2008). If he oal emsso exceeds he allowable lm, he arles wll be fed wh emsso pealy. Smlar rules apply corollg ose polluo for whch he hreshold of ose refers o maxmum level of ose ha ca be geeraed from he arcraf acves. Comparavely, he cumulave ose level refers o he accumulaed ose level from he arcraf operaos, hrough hree major sages,.e. laeral, flyover ad approach. Based o he daa as repored by Malaysa Arles (200) ad ArAsa Berhad (200), Equaos (9)-() are obaed by coducg polyomal regresso aalyss. The regresso aalyss shows ha Equaos (9)-() are fed well as o-lear fucos erms of oal operaed arcraf, A. Equao (9) dcaes ha he umber of flghs s affeced by oal operaed arcraf (whch could be gaed from he arcraf acquso ad leasg). Equao (0) deoes ha a flgh fles 2,066 klomeres average. Equao () shows ha oal fuel expeses deped o he umber of flghs, whch are operaed durg he plag horzo. Ths mples ha he fuel expeses assocae wh he oal operaed arcraf, A whch s very much depedg o he flee maageme decso. By cosderg he rao of fuel expeses ad average fuel prce, oal fuel cosumpo could be obaed. I order o compue he emsso rae of ew arcraf, parameer of evromeal susaably,.e. s eeded. I s acpaed ha ew arcraf ems less emsso comparg o agg arcraf ad hece s assumable ha 96.5%. The mulplcao of ad he emsso rae of agg arcraf would gve he emsso rae of ew arcraf. I erms of he varao of demad for he bechmark problem, specfc scearos are cosdered order o capure demad flucuao hroughou he plag horzo. These scearos are ouled as follows: Scearo (S): here s o chage of demad level,.e. 0 Scearo 2 (S2): here s a creme of demad level,.e. D 0 Scearo (S): here s a fall of demad level,.e. D 0 for whch D D D. 4.2 Sesvy Aalyss D

13 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 I order o vesgae he mpac of chages of he pus o he compuaoal resuls, 4 addoal cases wh varaos o some of he modelg parameers used he bechmark problem are ouled as follows: Cases A ad B have he load facor of 65% ad 85%, respecvely Cases C ad D have he ose hreshold of 250EPdB ad 285EPdB, respecvely. 4. Resuls ad Dscusso 4.. Resuls for bechmark problem eerally, he resuls of bechmark problem show ha he gree dex vares grealy accordace o demad flucuao ad he quay of arcraf. The resuls of operag perod are llusraed Table 2 (for he brevy, he resuls for oher operag perod are o show hs paper). As show Table 2, here are 27 possble demad combaos,.e. scearos of dema d 27 for he operag perod. For sace, scearo SS2S mples ha operag perod has o chage erms of demad level, operag perod 2 have a crease of demad whle operag perod has a drop demad. I erms of dffere demad level, he fdgs show ha he gree levels of scearo S (wh a fall of demad) ed o be hgher ha scearo S2 (wh a creme of demad), leadg o a hgher gree dex for scearo S comparg o scearo S2 hroughou he plag horzo. Ths happes maly due o he creme of demad level of scearo S2 whch volves more arcraf operaos, whch show a hgher edecy o em more polluas. As such, could be see ha he gree dex assocaes closely wh he level of demad for whch he gree dex s foud o be versely proporoal o he demad level. I oher words, a hgher level of demad resuls a lower gree dex. I erms of he quay of arcraf hroughou he plag horzo, could be see ha more arcraf a he begg of a parcular operag perod eds o produce a lower gree levels of emsso, fuel effcecy ad ose,.e. he gree level eds o be hgher wh a lower oal arcraf operao. Ths could be explaed by he arcraf acves whch would produce more emsso ad ose wh a hgher servce frequecy. Scearo S2 (wh creme of ravel demad) has a hgher servce frequecy ha scearo S (wh a fall of ravel demad) ad hece scearo S2 produces a lower gree dex compared o scearo S. Thus, could be deduced ha he gree dex s also versely proporoal o he quay of arcraf operao (prmarly due o he servce frequecy). From Table 2, s eresg o see ha he fdgs of scearo S s reasoably smlar wh he resuls of scearo S as he oal arcraf operao for scearo S (wh o chage erms of demad level) s he same as he oal arcraf for scearo S. Alhough scearo S has a lower level of demad comparg o he scearo S, he arle would o make mmedae decso o sell some arcraf due o he fac he sales of agg arcraf fac requres sellg me durao o look for prospecve buyer advace. As such, he quay of arcraf as ouled for scearos S ad S (as show Table 2) remas he same. Ths fdg hghlghs ha he gree dex assocaes closely wh he flee plag of he arles, especally o mee demad flucuao. For he arles, hs s crucal f hey were cocer o he evrome. As dsplayed Table 2, some of he gree levels of he emsso, fuel effcecy ad ose are greaer ha whle some are smaller ha. As meoed earler, he value of gree level ha s greaer ha dcaes a mproveme whle he value less ha mples usasfacory performace for whch he arcraf operaos of a parcular operag perod s

14 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 foud o em more polluas (produce more emsso or ose) ad operae less fuel-effce arcraf. For sace, he gree dex of he scearo SSS s egave (.e ) maly due o he gree level of fuel effcecy whch s oposve (-.49). Ths sgfes ha erms of he gree level of fuel effcecy, operag perod 2 ouperforms operag perod. I oher words, operag perod 2 s more fuel-effce, whch s approxmaely 4 mes more effce ha operag perod. I overall, he gree dex of operag perod s udesrable (as s a egave umber) alhough he gree levels of emsso ad ose are oegave. Ths reveals ha he resula gree dex (could be a egave dex) for a parcular operag perod s relavely depedg o he egrave elemes of emsso, fuel effcecy ad ose. For he arles o susa evromeally, hs hghlgh s mpora as here s o sgle eleme ha could perfecly guaraee a desred gree level. Table 2. The resuls of operag perod for he bechmark problem Ref EX EX o. Scearo 2 (YY2Y) I I X X S S 6 ( 0 ) ( 0 ) FEI E F FI SSS SSS SSS SS2S SS2S SS2S SSS SSS SSS S2SS S2SS S2SS S2S2S S2S2S S2S2S S2SS S2SS S2SS SSS SSS SSS SS2S SS2S SS2S SSS SSS SSS Average Resuls for sesvy aalyss For he resuls of sesvy aalyss (as show Tables -4), case A wh load facor 65% s foud o em less emsso comparg o he bechmark problem ad case B wh load facor 77% ad 85%, respecvely. Ths could be jusfed by he oal wegh of arcraf (clusve ravelers ad baggage) whch would affec he amou of emsso drecly. I oher words,

15 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 whe he load facor creases (.e. oal wegh of arcraf creases), here s more emsso ad hece he gree level of emsso decreases accordgly. The resuls of cases A ad B ( Table ) dsplay ha he gree level eds o be hgher for a lower load facor,.e. case A produces he hghes gree level, followed by he bechmark problem ad case B. However, for he operag perods 2-4, he gree level of emsso of case A s he lowes alhough produces less emsso. Ths happes prmarly owg o he comparso of he emsso amou of curre operag perod wh prevous operag perod, whch reflecs a beer mproveme for case B ad bechmark problem. Operag perod Operag perod 2 Operag perod Operag perod 4 Operag perod 5 Table. The resuls of he sesvy aalyss for dffere load facors 5 EX ( 0 ) EX ( 0 ) FEI Bechmark problem Case A Case B Bechmark problem Case A Case B Bechmark problem Case A Case B Bechmark problem Case A Case B Bechmark problem Case A Case B E F FI From he resuls of cases C ad D (as show Table 4), s observable ha he varao of he hreshold of ose could affec he gree level of ose a varyg degrees. Whe he hreshold of ose creases, s less lkely for he arles o exceed he allowable ose level as he arles have a greaer corol o moor her cumulave ose level. The resuls Table 4 show ha case D (wh 285 EPdB) does o have excessve ose whle he excessve ose of case C (wh 250 EPdB) s greaer ha he bechmark problem (wh 265 EPdB). Ths could be explaed as case C has he lowes allowable lm (followed by he bechmark problem ad case D) ad hece s mos lkely for case C o exceed he permed hreshold. Besdes, s also eresg o see ha he bechmark problem, cases C ad D geeraes same gree dex alhough respecve scearos produces dffere amou of excessve ose. Ths s possble due o he comparso of he excessve ose of a parcular operag perod wh prevous operag perod for whch he respecve scearo geerae smlar mproveme. Therefore, he gree dexes for all scearos (as show Table 4) demosrae same values. Ths hghlghs ha srge complace rules (or hresholds) are effecve reducg excessve ose of he arcraf alhough he resula gree dex may dsplay same umercal value across compla hresholds. I s mpora o oe ha he resula gree dex s relavely depedg o 2 major facors,.e. eral ad exeral facors. Ieral facor refers o he compoe ha s drecly relaed o he operaos, for sace he quay of arcraf for a parcular operag perod ad s load facor. O he oher had, he exeral facor refers o he aspec cludg compla face ha s o uder he corol of he arles, for sace he hreshold ose level a he arpor ad also he demad flucuao uder uceray. Therefore, a proper

16 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 framework by corporag boh eral ad exeral facors s ecessary for he arles order o assure a effecve mproveme respose o he evromeal susaably. Operag perod Operag perod 2 Operag perod Operag perod 4 Operag perod 5 Table 4. The resuls of he sesvy aalyss for dffere hresholds of ose 5 EX ( 0 ) EX ( 0 ) FEI Bechmark problem Case C Case D Bechmark problem Case C Case D Bechmark problem Case C Case D Bechmark problem Case C Case D Bechmark problem Case C Case D E F FI 5. IMPLICATIOS FOR MAAERIAL AD OPERATIOAL PRACTICES A proper framework quafyg gree dex s ecessary for he raspor operaors o operae profably ad evromeally uder uceray. I fac, he proposed framework ca be appled ay oher dusry whch has a cocer o he evrome. Praccally, he proposed framework (whch ca be subsequely corporaed o ay releva maageral/operaoal sraegy, e.g. a well-developed flee maageme model for flee plag) s playg a val role from major perspecves amely socal, supply ad demad as well as susaably as addressed below: From he aspec of socal: o reduce he polluas preservg he evrome o geerae greeer flee, leadg o a healher commuy From he aspec of supply ad demad: o maage flee plag sraegcally a evromeal fredly maer o mee sochasc demad ecoomcally ad evromeally o mprove operaos sysem (for performace ehaceme) From he aspec of susaably: o assure profable operaos ( reducg emsso coss ad fuel cosumpo) o assure he beefs of sakeholders profably ad evromeally o promoe he good ame by creasg he saus of he raspor operaors For he raspor operaors, he aspecs as addressed above ca be acheved sasfacorly by praccg a well-balaced operag sysem (.e. by corporag evromeal cocers maageral ad operaoal sysem). Theorecally or praccally, could be deduced ha

17 Proceedgs of he Easer Asa Socey for Trasporao Sudes, Vol.9, 20 gree dex as a evromeal dcaor s exremely sgfca for he raspor operaors o assure ha he operag ework s operaed a evromeal fredly fasho, whch s beefcal o he raspor operaors (from hree aspecs as meoed above). Ths shows ha here s a srog lkage bewee he proposed framework ad he maageral/operaoal pracces. However, here s a heorecal/praccal gap ha eeds o be ackled wsely. Alhough could o be deed ha he evromeal cocers may o be he umos prory for he raspor operaors due o he ma cocer o he operaoal prof, s mpora o oe ha fac he evromeal coss (as pars of he operag expeses) would affec he opmal prof a varyg degrees, especally for log-erm flee plag. As such, a balace bewee he evrome ad he prof of he arles should be maaed. Oly by capurg boh prores (.e. evromeal susaably ad operaoal prof) cocurrely, a w-w suao ca be acheved. Besdes, as revealed by he leraure (Yag e al., 200; Sgourds e al., 20; ealer e al., 202), here s o perfec sgle sraegy due o he fac ha he operaoal ad maageral decso s decsvely depedg o may ercorrelaed facors, e.g. he maageme polcy of he raspor operaors, sadard compla rules as well as he flee ad resources avalably. Therefore, he proposed framework may be alered ecessarly o work ou a desred operag sysem, parcularly o move oe more sep furher from curre foopr (performace). 6. COCLUSIOS Ths sudy proposed a ovel framework o quafy 'gree dex' by specfcally focusg o he elemes of flee emsso, fuel effcecy ad flee ose. The proposed sudy reflecs he acual suao of he rasporao dusry respose o he challeges of he evromeal susaably ad demad flucuao. The proposed framework s able o evaluae possble gree dex for varyg demad. The resuls of he llusrave case sudy demosraed ha he proposed framework s sesve o he modelg parameers as well as sochasc demad. Specfcally, gree dex was foud o be dsproporoally wh he sochasc demad, quay of flee operao as well as s load facor. Besdes, he resula gree dex was sgfcaly affeced by some exeral facors, cludg he compla lms of ose ad emsso. Ceraly, hese aspecs are mpora for he raspor operaors makg maageral decso evromeally, especally flee plag. everheless, here are some shorcomgs o be mproved. Ths sudy maly focused o hree evromeal facors, whch are praccal ye he modelg may seems o be smplsc a cera exe. A more comprehesve model may be developed capurg more flueal facors. I order o susa ecoomcally, he operaoal prof of he raspor operaors should be cosdered. For fuure research, a opmzao model wll be developed o capure boh objecves (prof ad gree dex) order o work ou a opmal gree flee maageme model. Besdes, he demad of ravelers s flucuag ad ucera due o varous uceraes, such as global ecoomc codos ad aural dsaser. Therefore, he level of sochasc demad caused by hese uceraes should be capured ad corporaed he flee maageme model. Ths wll be lef for fuure research. ACKOWLEDEMET The auhors would lke o hak Msry of Hgher Educao (MOHE) Malaysa for he facal suppors uder he research gra FRS (FRS//202/TK08/UTAR/0/).

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