Phasing out Polluting Motorcycles in Bangkok: Policy Design by Using Contingent Valuation Surveys

Transcription

1 Publc Dsclosure Authorzed Phasng out Pollutng Motorcycles n Bangkok: Polcy Desgn by Usng Contngent Valuaton Surveys Publc Dsclosure Authorzed Jan Xe Jtendra J. Shah Elsabetta Capannell Hua Wang Publc Dsclosure Authorzed Publc Dsclosure Authorzed World Bank Polcy Research Workng Paper 3402, September 2004 The Polcy Research Workng Paper Seres dssemnates the fndngs of work n progress to encourage the exchange of deas about development ssues. An objectve of the seres s to get the fndngs out quckly, even f the presentatons are less than fully polshed. The papers carry the names of the authors and should be cted accordngly. The fndngs, nterpretatons, and conclusons expressed n ths paper are entrely those of the authors. They do not necessarly represent the vew of the World Bank, ts Executve Drectors, or the countres they represent. Polcy Research Workng Papers are avalable onlne at The authors wsh to express ther thanks to other team members of the Bangkok Motorcycle Upgrade Program and local experts, especally Nagaraja Rao Harshadeep, Noreen Beg, Govanna Dore, Phl Sayeg, Edward Dotson, Patchamuthu Illangovan, Chttrakarn Bunchandranon, Kanchalka Klad-Angkul, Chura Tapvong, Pt Manomaphbul, and Somcha Chanchaona for ther partcpaton n and contrbutons to the motorcycle testng clncs and survey and to Aknor Tomohara for hs research assstance n the CV survey data analyss. Correspondng emal: HWANG1@Worldbank.org.

2 Abstract Ths paper reports a contngent valuaton study for the desgn of economc ncentves to phase out pollutng motorcycles n Bangkok. Lke n many other ctes, the government of Bangkok has been consderng a seres of control measures to dscourage and eventually elmnate the usage of heavly pollutng motorcycles. Two of the possble polcy nstruments under consderaton are charges on those pollutng vehcles whch are operatng n the streets and compensaton to those pollutng vehcles whch would stay off the roads. The polcy research questons then nclude what are the charges mpled or compensaton provded, gven a polcy target, and what are the reactons of motorcycle owners to those charges or compensaton. In order to answer those polcy questons, a stochastc contngent valuaton survey was conducted n Bangkok to queston motorcycle owners on the lkelhood they would keep or gve up rdng ther motorcycles n the streets gven certan charges or compensatons. Results show that among others, about 80% of those motorcycles whch dd not pass the emsson tests would be off the streets f a charge of 1000 baht per year was leved, whle under a one-tme compensaton of 10,000 baht, the number would be about 50%. The average values of maxmum wllngness to pay (WTP) for stayng on the road and mnmum wllngness to accept (WTA) compensaton for stayng off the street are also estmated, and the determnants of WTP and WTA are analyzed. The econometrc analyss shows that, among other factors, household ncome, fuel costs, use of motorcycles and/or publc transt affect the value of WTP and WTA. 2

3 Phasng out Pollutng Motorcycles n Bangkok: Polcy Desgn by Usng Contngent Valuaton Surveys I. Introducton Motorcycle polluton emssons have caused serous envronmental health problems n many urban areas n the developng world. One regulatory approach to solve the problems s to ban all vehcles whch volate emsson standards. Ths, however, can be unnecessarly costly to a developng socety, because the varance of benefts n usng the motorcycles by dfferent users s not taken nto consderaton. Another regulatory approach s the use of economc ncentves charges or compensaton can be desgned and mplemented to phase out, cost-effectvely, the use of pollutng vehcles. The major polcy ssues that a muncpal government s facng n ths area are two-fold: 1) how much the charges or compensaton should be leved or provded, and 2) how the motorcycle users would react to the charges or compensatons. Ths paper presents a case study whch uses the contngent valuaton approach to help desgn charge and compensaton polces for phasng out pollutng vehcles. Bangkok, lke many other bg ctes, has a serous ar polluton problem and the use of motorcycles contrbutes a sgnfcant porton. To mprove the ar qualty, the Government of Bangkok has been consderng to adopt a seres of counter-measures to dscourage and eventually elmnate the usage of heavly pollutng motorcycles. Two economc nstruments under consderaton are to charge or tcket owners of those pollutng vehcles operatng n the streets and to compensate owners of those pollutng vehcles that stay off the roads. Smlar to studes conducted n many other bg ctes, the polcy research questons focus on how much the charges and/or compensatons should be gven a certan vehcle control target. In order to help the Government of Bangkok mprove ts understandng of motorcycle owners possble reacton towards the possble economc ncentves offered and, consequently, to assst the polcy makers better desgn economc nstruments, a stochastc contngent valuaton survey at a motorcycle testng clnc was conducted n Bangkok n 3

4 July Motorcycle owners were questoned on the lkelhood they would keep usng ther vehcles under a set of possble charges per year or gve up usng ther vehcles gven a set of one-tme compensaton. Answers were analyzed to draw probablty curves of vehcle use under dfferent charges or compensaton and to estmate the mean value of charges and compensaton for mplementng the polces. The determnants of mean wllngness to pay (WTP) for operatng the vehcles and mean wllngness to accept (WTA) to stay off the road were also modeled and analyzed. Ths paper conssts of fve sectons. Ths frst secton ntroduced the topc. The followng second secton provdes an overvew of ar qualty, motor vehcle use and the control of emssons from motorcycles n Bangkok. Secton 3 llustrates the contngent valuaton survey. Responses to the charges and compensatons are presented n secton 4, and WTP and WTA estmatons are provded n secton 5. Fnally, secton 6 concludes wth polcy dscussons and closng remarks. II. Polcy Context Bangkok s well known for ts traffc congeston and poor ar qualty. The ar has been serously polluted. The cty s maxmum roadsde carbon-monoxde (CO) levels are one and a half tmes the Tha 8-Hour standard. The maxmum roadsde partculate smaller than ten mcrons (PM10) levels are two tmes the Tha 24-hour standard and ts average levels are one and a half tmes the Tha annual average standards. And, the maxmum ambent ozone levels are two tmes the Tha 1-Hour standard. Due to the ncreases n ntrogen oxdes (NOx) and HC emssons from motor vehcles, the level of ozone s stll rsng. Publc health n Bangkok s farly senstve to the effects of ar polluton. It s estmated that, f the annual average concentraton of PM10 could be reduced by 10µg/m3, the resdents of Bangkok would receve a beneft worth bllon Baht (or $US bllon, n 1995 prces) per year (Hagler Bally, 1998). Specfcally, there would be 700 to 2,000 premature deaths and 3,000 to 9,300 new cases of chronc respratory dsease avoded f the mprovement n ar qualty took place. 4

5 Motor vehcles have been heavly used n Bangkok. In 1999, the total number of motor vehcles n the cty was between 2.2 mllon n-use and 4 mllon regstered. Lke many southeast and south Asan ctes, one thrd of the motor vehcle fleet n Bangkok s motorcycles. Natonwde, the percentage of motorcycles n the entre motor vehcle fleet was 60% n Most of the motorcycles s powered by two-stroke engnes, although the sale of four-stroke engne motorcycles has been steadly rsng n recent years. Many people n Bangkok rely on ther motorcycles for transportaton and some of them use ther motorcycles for busness purposes (such as tax servces). Low cost, convenence, and flexblty n drvng motorcycles are major reasons why many Bangkok people rely heavly on rdng motorcycles. The motorcycle fleet s agng however, partally due to the economc slowdown caused by the Asan fnancal crss n The use of motorcycles s a sgnfcant source of ar polluton n Bangkok. It was estmated that motorcycles contrbuted up to 70% of total HC, 30% of total CO, and 18% of PM10 n the ar. It s wdely perceved that the old, two-stroke engne powered motorcycles contrbute sgnfcantly to the emssons, especally HC and PM10, due to factors such as adulteraton and excessve use of lubrcatng ol, poor mantenance, and low acceptance of new technologes avalable. In addton, the use of motorcycles has caused other external soco-economc costs to socety as a whole and has ncreased purchasng and mantenance costs to motorcycle drvers more specfcally. The serous loss of tme and productvty caused by traffc jams are among those negatve externaltes. The Government of Bangkok has been takng actons to reduce the emssons from both new and n-use motorcycles. The government has recognzed the need to reduce whte smoke emssons from two-stroke engne motorcycles as far back as The use of lubrcatng ol wth polybutylene addtve, nstead of mneral ol, became mandatory for two-stroke engne motorcycles n Thaland back then. Accordng to a techncal report by the Petroleum Authorty of Thaland n 1993, two-stroke engnes wth lower ol/fuel ratos had already been ntroduced nto Thaland to further reduce hydrocarbon emssons. The Tha government has adopted progressvely tghter standards for 5

6 motorcycle manufacture. Tha Level 5 standards, whch was enacted n 2000, mantan a smoke opacty level requrement of 15% or less, CO level of 3.5 g/km or less, and HC+NOx level of 1.8 g/km or less. Whle motorcycle manufacturers are more lkely able to contnue manufacturng two-strokes engnes under these standards, further tghtenng of the standards (as proposed) wll lead to manufacturers ether swtchng to four strokes or adoptng two-strokes wth catalytc converters. In order to provde an ncentve for the latter, manufacturers ntend to have a program whereby drvers can brng n ther motorcycles for free replacement of catalytc converters. Besdes these measures, an ncentve scheme has been envsoned n order to speed up the removal of hghly pollutng motorcycles from crculaton. The scheme ams at takng off a sgnfcant number of n use pollutng motorcycles by offerng two effectve fnancal ncentves. It s desgned so that all motorcycle drvers are nformed and nvted to brng n ther motorbkes for an emsson test. If the vehcles pass the test, the owners can obtan a free tune-up and lube ol. But f a motorcycle fals the test, the owner s offered a fnancal package: he or she could obtan a rebate for tradng n the old vehcle and purchasng a new one, or take a certan amount of cash for surrenderng ther pollutng motorcycles. The fnancal package proposed ncludes a cash ncentve of 3,000 Baht from nternatonal donors, a dscount of 1,000-3,000 Baht on the new purchase and a waver of 2,500 Baht of nsurance charges from motorcycle manufacturers, and an nterest reducton of 0.5% from fnance companes. In Bangkok, the trade-n value of an old motorcycle s estmated at 7,000 to 20,000 Baht, and the purchase prce of a new motorcycle s 20,000 to 25,000 Baht at the mnmum. Consderng the nterest charges, a motorcycle can cost as much as twce the purchase prce. Ths fnancal package, whch ams to provde ncentves for motorcycle owners to gve up ther pollutng motorcycles or replace them wth new ones, was tested n a plot traden project n In order to better desgn the ncentve scheme, two motorcycle emssons testng clncs were conducted by the Bangkok Metropoltan Admnstraton 6

7 wth the assstance of the World Bank and the motorcycle manufacturers n the summer of Durng the second clnc, a contngent valuaton (CV) survey was conducted n order to better understand the values that those motorcycle owners n Bangkok may put on the vehcles and possble reactons they may take towards dfferent possble fnancal packages. III. The Survey Two three-day clncs were conducted n Bangkok n May and July 2000, respectvely, to test the motorcycle emssons. About 1,500 motorcycles were attracted to the frst clnc and about 2,000 to the second one. Besdes testng the emssons, a soco-economc survey on motorcycle owners was carred out. The survey questons fall n the followng three categores: owners soco-economc profle, ther awareness of ar polluton, and the use and condton of ther motorcycles. In the second clnc, a set of contngent valuaton questons were asked of those owners of motorcycles who faled the fnal emsson (CO, HC and opacty) tests. The stochastc payment card approach developed by Wang (1997) was used to elct lkelhood nformaton regardng the possblty that those owners would keep or gve up usng ther vehcles under certan charges or compensatons. A lst of hypothetcal charges (300, 600, 1000, 1500, 2000 and 3000 baht /year) was presented to 231 owners, who were asked the lkelhood they would keep usng ther motorcycles under these charges. The answers nclude defntely wllng to pay, probably wllng to pay, not sure, probably not wllng to pay, and defntely not wllng to pay. One hundred and nnety-one of those owners whose vehcles ddn t pass the emsson tests receved a lst of lkelhood questons about ther wllngness to gve up runnng ther vehcles under certan compensatons (2000, 4000, 6000, 8000, 10000, baht/year). The answers to these questons of wllngness to accept compensaton nclude defntely not wllng to accept, probably wllng to accept, not sure, probably wllng to accept, and defntely wllng to accept. 7

8 The basc statstcs of the survey s presented n Table 1. The statstcs shows that the owners of those pollutng motorcycles are mostly male at an average age of 33 years old. Two thrds of them are marred and, on average, they have two kds. Most of them drve motorcycles for busness. One sxth of them ndcated that ther households suffered from respratory symptoms and qute a number of them admtted that ther households actually pad for the medcal treatments of ar polluton symptoms. The survey also shows that these drvers are hghly aware of ar polluton problems and actually consder motorcycles a contrbutor. Contradctorly, however, two thrds of these drvers thought ther own motorcycles, whch had faled the fnal test, were n good condton. Three quarters of drvers never servced ther motorcycles. IV. Response to Charges and Compensatons The responses to the charges and compensatons are presented n Table 2 and Table 3. Under a charge of 300 baht per year, about 48% of those pollutng motors would defntely be operatng n the streets. When the charge ncreases to 600 baht per year, the responses ndcate that only about 8% would defntely reman operatng n the streets, and about 46% would defntely stay off the streets. When charges ncrease to 1000 and 1500 baht per year, responses then ndcate that 79% and 90% of pollutng vehcles, respectvely, would defntely be off the streets. If a compensaton polcy s adopted, there would be a 72% chance of pollutng motors defntely on the streets and only 7% defntely off the streets wth a total compensaton of 2000 Baht per vehcle. To brng about a reducton of 50% of pollutng motors off the street, the necessary compensaton may have to be as hgh as baht per vehcle. Fgures 1 and 2 present percentages of pollutng vehcles on or off the streets under dfferent charges or compensaton. V. WTP and WTA 8

9 In order to have a better understandng of motorsts behavors under dfferent charge and compensaton polces and a better desgn of the two potental fnancal nstruments, an n-depth analyss s conducted on the values of the maxmum wllngness to pay for keepng the operatons of the vehcles and of the mnmum wllngness to accept for compensatons to gve up the operatons. In the followng, Wang s stochastc valuaton approach (Wang, 1997) s employed to estmate the mean values of WTP and WTA. Econometrc analyses are also conducted to examne the determnants of the WTP and the WTA. The Model In the CV surveys, the probabltes of each ndvdual s agreements to the charges or the compensatons were obtaned wth the stochastc payment cards. Specfcally, those motorcycle drvers whose vehcles faled the fnal emssons test were questoned on the lkelhood they would be wllng to pay for rdng ther motorcycles at a range of suggested charges/prces (300, 600, 1000, 1500, 2000, and 3000 Baht) per year. If the motorcycle owners dd not want to pay the suggested mnmum charge, ther mnmum values were asked. The lkelhood answers whch respondents may select for the suggested prces are: defntely yes, probably yes, not sure, probably not, and defntely not. To enable to estmate a respondent s cumulatve dstrbuton functon, a probablty s assgned to each lkelhood category;.e., 99.9% to defntely yes, 75% to probably yes, 50% to not sure, 25% to probably not, and 0.05% to defntely not. For example, f a person responded defntely yes to 300 Baht, not sure to payng 600 Baht and defntely not to 1,000 Baht, the probabltes of 99.9%, 50%, and 0.05% would be assgned to the three prces, respectvely. The reason that 99.9% and 0.05%, rather than 100% and 0% are adopted n the analyses s because 100% and 0% would ntroduce nfntes wth lkelhood functons. The procedure of estmatng WTP values s modeled as follows. Let X j be the jth prce offered to a respondent, where j = {1,2,3,4,5,6 }, and X be the set of the sx charges or 9

10 prces X = {300,600,1000,1500,2000,3000}. A drver would agree to pay the prce as far as the prce s lower than her/hs wllngness to pay (WTP): P Yes) = Pr( WTP > X ) = 1 F ( X ), j ( j j where F s a cumulatve dstrbuton functon. Under a normalty assumpton ( Φ ), t can be rewrtten as P j µ X j = 1 Φ( ) or σ X j 1 = µ + σ Φ (1 P ). j The mean µ and standard error σ of respondent s valuaton dstrbuton are estmated by regressng X on Φ 1 (1 P ) acceptng the prces., where P s the respondent s lkelhood vector of The value of WTA can be estmated by usng a smlar approach. The prce (or compensaton) values at whch motorcycle drvers were asked for ther WTA are 2000, 4000, 6000, 8000, 10000, Baht. Let Y j be the jth compensaton or prce offered to a respondent, where j = {1,2,3,4,5,6 }, and Y be the set of the sx prces Y = {2000,4000,6000,8000,10000,12000}. A drver would not agree to accept the prce f the prce s lower than her/hs wllngness to accept (WTA): P j ( j j No) = Pr( WTA > Y ) = 1 F ( Y ), where F s a cumulatve dstrbuton functon. Under a normalty assumpton, t can be rewrtten as 10

11 P Y j j µ Y j = 1 Φ( ) or σ 1 = µ + σ Φ (1 P ). j The mean µ and standard error σ of respondent s valuaton dstrbuton are estmated by regressng Y on Φ 1 (1 P ) acceptng the compensaton., where P s the respondent s lkelhood vector of not The Values The means and varances of WTP and WTA are estmated for all respondents by usng the models presented n the last secton. The mean WTP of pollutng motorcycle owners for rdng ther motorcycles s 580 Baht per year, wth the mnmum value of 194 and the maxmum of 2060 Baht. The sample standard devaton s 320 Baht and the mean of the estmated standard error s 180 Baht. The frequency dstrbuton and cumulatve dstrbuton of WTP are shown n Fgures 3. Fgure 3 llustrates that 80% of pollutng motorcycle owners are wllng to pay 320 Baht per year to keep rdng ther pollutng motorcycles. At the prce of 720 Baht per year, there s only 20% of the owners would be more lkely to pay for usng ther motorcycles. In other words, f the government charges an annual fee of 720 Baht on those who rde pollutng motorcycles, 80% of the drvers may dspose of ther motorcycles. A charge of 460 Baht per year could make 50% of the drvers gve up rdng ther motorcycles. The estmaton shows that the mean of WTA s 6,650 Baht n total, or about 1,500 Baht per year over a span of 4.5 years n whch an average owner expects to keep hs or her motorcycle n the future. The range of estmated ndvdual WTA values s from 1,180 to 12,820 Baht. The standard devaton s 2,780 and the mean of the estmated standard error s 1,

12 The dstrbuton plotted on Fgure 4 ndcates that 20% of motorcycle owners were wllng to accept a one-tme compensaton of 4,000 Baht for gvng up ther motorcycles. The fgure further shows that about 80% are wllng to gve up ther motorcycles at the compensaton of 9,000Baht. In the trade-n plot project, there were 43 pollutng motorcycle owners who actually traded n ther motorcycles, gven the fnancal ncentve package of a 3,000 Baht of cash rebate and other ncentves descrbed n last secton. Ths number composes 13% of the 331 drvers whose motorcycles faled the emsson test. It s evdent that the results from a real test are pretty close to the results from the WTA study. The Determnants Table 4 presents the determnants of the motorcycle owners wllngness to pay (WTP) for charges so that they can use ther vehcles and ther wllngness to accept (WTA) compensaton for gvng up the use of ther vehcles. Household ncome s negatvely correlated wth the WTP and WTA, ndcatng that the rcher the motorcycle owner, the easer t s for them to gve up the use of pollutng vehcles (wth smaller charges or compensaton). Fuel costs are also negatvely correlated wth the WTP and WTA, whch mples that the hgher the fuel prce, the easer t s for motorsts to gve up the use of ther pollutng vehcles. For those motorsts who take publc transt often or very often, a lesser charge s ncentve enough for them to gve up the use of ther motors, but a hgher compensaton would be needed f a compensaton polcy apples. A hgher compensaton would be necessary for a motorst who drves more frequently each day. A retred person would be wllng to pay more for keepng the use of ther vehcles. VI. Polcy Implcatons and Concludng Remarks 12

13 The CV survey results are nstructve and provde a base for draftng ncentve nstruments, ether charges or compensatons, to phase out pollutng motorcycles n Bangkok. The study shows that a charge of 460 Baht per year could make 50% of the drvers whose motorcycles fal emsson test gve up rdng ther motorcycles. If the charge was rased to 1,000 Baht, 80% of them would dspose of ther motorcycles. If a compensaton s provded, 20% of motorcycle owners would be wllng to gve up ther motorcycles at a one-tme compensaton of 4,000 Baht. The estmate s very close to the actual result of a plot project n whch 13% of pollutng motorcycles drvers accepted an offer of 3,000 Baht of cash plus other ncentves towards purchasng new motorcycles. The study further shows that about 80% would gve up ther motorcycles f the compensaton ncreases to 9,000Baht. The actual transacton of a drver s determned by a number of factors. Household ncome s a key factor drvng down both the WTP and the WTA. In other words, the rcher the motorcycle owners, the easer t s for them to gve up the use of pollutng vehcles gven smaller charges or compensaton. Therefore, the economc growth and the resultng ncrease n drvers household ncome can eventually be the drvng force of phasng out pollutng motorcycles. Fuel costs are also negatvely related to the WTP and the WTA, and therefore, an ncrease n fuel prce can motvate the drvers to gve up the use of ther motorcycles. Those who also use publc transt often appear to be more easly lkely to gve up rdng ther motorcycles, whch ndcates the mportance of developng publc transt systems n elmnatng pollutng motorcycles. The study llustrates that CV surveys can be a useful tool for polcy makers to analyze the behavors of motorcycle drvers n desgnng a fnancal ncentve scheme, ether a charge or a compensaton, to help phase out pollutng motorcycles. The study results can also help ntroduce a combnaton of carrot and stck,.e., the use of charges and compensaton together, as an ncentve nstrument to effectvely elmnate pollutng motorcycles. 13

14 Last but not the least, any ncentve nstruments, whether a charge or a compensaton, wll not be effectve unless regulatons on emssons have already been n place and been actually enforced. Ths requres an adequate framework of regulatory and economc polcy nstruments, ncludng vehcle regstraton, emsson standards, montorng and supervson through pre-sales testng, and after-sales nspecton and mantenance, etc. 14

15 References Acutt, M. and P. Mason, 1998, Envronmental valuaton, economc polcy and sustanablty, MA: Edward Elgar, pp Mantymaa, E., 1999, Wllngness to pay, wllngness to accept: A CVM feld study of envronmental commodtes, n M. O Connor and C. Spash eds., Vaulaton and Envronment, pp Petroleum Authorty of Thaland, 1993, Motorcycles n Thaland, A Techncal Report by the Research and Development Center. Wang, Hua, 1997, Contngent valuaton of envronmental resources: A stochastc perspectve, Unversty of North Carolna, Chapel Hll, NC, USA. Wang, Hua, and Dale Whttngton, 2000, Wllngness to pay for ar qualty mprovements n Sofa, Bulgara, The World Bank Polcy Research Workng Paper

16 Table 1. Statstcs of the Respondents Varable name Obs. Mean Std Medan Mn Max Age # of household members # of household members workng Personal ncome Household gross ncome Years ownng MC Drvng dstance (Km/day) Max WTP for Inspecton and mantenance Spendng on mantenance per month Spendng on fuel per week Years to keep MC MC prce Table 2: Lkelhood to stay on road under dfferent charges Charges (Baht/year) Defntely on 48.4% 8.4% 2.7% 1.3% 0.9% 0.9% Probably on 19.1% 8.4% 2.2% 1.8% 0.4% 0.0% Not-Sure 22.2% 26.7% 8.0% 4.4% 1.3% 0.4% Probably off 1.3% 10.7% 8.4% 2.2% 3.1% 0.4% Defntely off 8.9% 45.8% 78.7% 89.8% 94.2% 98.2% 16

17 Table 3: Lkelhood to stay on road under dfferent compensatons Compensatons (Baht/year) Defntely on 72.3% 60.1% 48.9% 39.4% 25.5% Probably on 5.9% 5.3% 2.1% 2.1% 1.1% Not-sure 13.3% 14.9% 14.9% 9.0% 6.4% Probably off 1.6% 8.5% 11.7% 14.9% 16.0% Defntely off 6.9% 11.2% 22.3% 34.6% 51.1% Table 4. Major Determnants of WTP and WTA Dependent Varables: Independent Varables: Explanaton Sample mean (std) Hhncome Household Income (Baht/Month) (11428) Puboft 1=Use publc transportaton often or very often; 0=otherwse Fuelcost Fuel cost (Baht/week) (305.6) Kmday Dstance drvng 67.1 (km/day) (45.0) Retred 1=the person s retred;0=otherwse WTP Model Mean WTP Coeffcents (t-value) (-1.18) ** (-2.04) (-1.59) ** (2.33) WTA Model Mean WTA Coeffcents (t-value) (-1.94)** (1.72)* (-1.55) 14.4 (2.28)** Const Constant term of the model 665.1*** (13.62) *** (10.91) R-squared Obs

18 Fgure 1. Pollutng Motorcycles under Charges % 120.0% 100.0% 80.0% 60.0% 40.0% 20.0% 0.0% 89.8% 94.2% 98.2% 78.7% 48.4% 45.8% 8.9% 8.4% 2.7% 1.3% 0.9% 0.9% Charges per motorcycle per year n Baht Defntely on Road Defntely off Road Fgure 2. Pollutng Motorcycles under Compensatons % 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% 72.3% 60.1% 62.2% 48.9% 51.1% 39.4% 34.6% 22.3% 25.5% 21.8% 6.9% 11.2% Compensatons per motorcycle per year n Baht Defntely on Road Defntely off Road 18

19 Fgure 3. Dstrbuton of WTP Percentage % Frequency % Cumulatve 20 0 [ ] [ ] [ ] [ ] [ ] WTP Ranges Fgure 4. Dstrbuton of WTA Percentage % Frequency % Cumulatve 20 0 [ ] [ ] [ ] [ ] [ ] [ ] WTA Ranges 19