AN ESIMAION OF INER-ZONAL BUS DEMAND ON COLOMBO - KALUARA RANSPOR CORRIR Sama J. Widaapathiraage ad Amal S. Kumarage Departmet of Civil Egieerig, Uiversity of Moratuwa, Sri Laka. ABSRAC- I the past, it has bee the practice to use demad estimatio models widely, i trasport plaig studies. Models are importat because trasportatio plas ad their ivestmet are based o what the model say about future passeger travel. herefore the modal verificatio is required before the applicatio. he trasportatio corridor icludes, Colombo, Dehiwala, Moratuwa, Paadura ad Kalutara travel zoes. A traffic zoe is take as the area of the Divisioal Secretary s Divisio(DSD). his corridor carries a large share of daily bus passegers to the city of Colombo for various travel purposes. It is foud that most of the trips are geerated by the employed populatio ad thereby it is take as the mai socio ecoomic variable. Each year bus traveller demad towards the city of Colombo icreases due to growth of ew employee populatio. his idicated that about 97% of iter zoal bus passeger routes are termiated at Colombo. he bus model was developed to estimate iter-zoal travel across this trasportatio corridor which is required to verify the model accuracy of predictors, sice it was calibrated usig the data from various surveys doe durig year 996 to 998. he paper discusses (a) the preparatio of iter-zoal origi destiatio matrix ad (b) the model verificatio process. It cocluded that the model is performig at a acceptable level of predictive ability whe tested o real demad observatios. BACKGROUND he study cocetrates o the 44 kilometre trasportatio corridor o the Galle Road, from Colombo to Kalutara. his corridor coects five traffic zoes - Colombo, Dehiwala, Moratuwa, Paadura ad Kalutara ad exteds a total area of 26 sq. kms. It is assumed that the traffic zoe is the area of the Divisioal Secretary s Divisio. here are ormal ad itercity bus services that are operated by the cluster bus compaies ad private operators which serve all these zoes. Each zoe has a cetral bus stad that coects several itra-zoal bus routes. hese routes are laid out to operate through the idustrial zoes located i these areas ad facilitate better accessibility to the place of work. herefore, there is a high daily bus passeger demad, betwee Colombo ad Kalutara. I 997, the bus passeger travel i the Colombo Kalutara trasport corridor was estimated at 46,598 bus passegers per day (CMRSP,997). Most of the buses have 42 passeger seats ad have a ewly furished look with accessories to attract passegers such as radio/casettes, comfortable seats, good iterior coditio etc,. As a cosequeces a large umber of passegers are attracted to private buses with respect to the Govermet operated cluster compay buses. It is a fact that four private buses follow each CB bus i this corridor ad that a estimated 420 private buses operate per day. herefore, Kumarage ad Silva,( 2003) suggested that a priority lae for buses is required for this corridor i order to reduce traffic cogestio ad road accidets. I this respect, the bus passeger demad estimatio is a importat aspect i plaig a better trasportatio system i this travel corridor.
he bus demad estimatio model is developed to capture iter zoal travel characteristics based o the data collected durig the period of 996 to 998 by various trasportatio studies ad published by Widaapathiraage ad Kumarage (2003). I that model, the impedace to travel is expressed i a geeralized form, which icludes fare, waitig time, trasfer time ad travel time for the trip. he socio-ecoomic variable of the employmet populatio ad the demographic variable of housig desity are formulated i to the gravitatioal form of the model. It is calibrated to a 5% level of sigificace of the model variable with coefficiet of correlatio 72.% ad show i equatio (). his idicated that these variables have bee the primary determiat of the demad for iter-zoal travel together with a expoetial form of the variable that represets direct travel betwee these zoes. 0.860 0.854* B EiK * e BiK = 0.255* 0.97 2.562 () HDiK * BGC Where B ik = Bus passeger trips betwee i th ad K th zoe per day i both directios. E ik = Product of employmet of i th ad K th zoe. HD ik = Product of the housig desity of i th ad K th zoe, where housig desity is give as housig uits per sq. km. BGC = Geeralized travel cost of bus i Rupees to travel betwee i th ad K th zoe give as, the sum of bus travel cost, waitig time cost ad cost of ivehicle travel time. B = Selected bus travel route betwee i th ad K th zoe is a direct or idirect. he employed populatio determies to a large extet the travel that is geerated ad attracted to that zoe which is mostly related to work ad busiess purposes. he housig desity represets a trasportatio iteractio characteristic ad the variable that represeted to capture existig direct bus service shows, bus passeger demad doubled i these routes i cotrast to idirect travel routes. It may be the high waitig ad trasfer time that are cosidered for the calculatio of geeralized cost of travel for the idirect routes. he predictors of this model idicate that if the product of employee populatio icreases by 0%, the bus passeger iter-zoal travel icreases by 5.8 % ad thereby the growth of primary variables result i icreases of daily bus passeger demad. hese results are estimated based o the data i 998 ad the variables of bus demad model at year 2004 are estimated usig the growth factors. he growth factors are take as 6% of the employed populatio ad 0% of housig desity per year. It also assumes that the bus geeralized cost remaied uchaged. I this approach there is a high percetage of error accumulated i the model predictors. herefore, to maitai the acceptable level of accuracy of the predictors, a verificatio stage of the modellig is required to test the model. OBJECIVES AND MEHOLOGY he aim of this paper is to preset (a) a approach for the formulatio of a origi-destiatio matrix usig partial data of passeger loadig, boardig ad alightig couts ad (b) the result of a model verificatio process for the bus model that was developed for iter-zoal passeger demad estimatio for a chose trasport corridor. Datas et. al.(200), collected bus boardig ad alightig data to improve a bus route capacity. LSC Cosultats Ic, (2003) collected bus boardig ad alightig couts to develop a bus loadig profile of a route. Prethika et.al. (200), collected bus passeger boardigs ad loadigs 2
data i a route to develop a bus operatioal schedule. I this study, boardig ad alightig partial data are collected to develop a matrix. he estimatio of O-D matrix for iter-zoal travel requires two type of data. I the first istace boardig ad alightig couts are required ad secodly, roadside passeger loadig couts are also required. he bus passeger loadig data collected i 2003 are available at the rasportatio Egieerig Divisio of the Civil Egieerig Departmet. he data were collected at strategically selected locatios at the traffic zoes. here are 5 bus routes coectig these zoes as show i able 2. Four roadside loadig observatio locatios are selected such a way that the maximum umber of bus routs ca observed at the observatio poit. he average loadig observatios that are collected accordig to the bus passeger occupacy ad bus size categories are show i able. able. Passeger Occupacy i Buses Bus Size Mea Passeger Load by Level of Loadig 2 3 4 5 6 7 Empty < /2 > /2 Full Full +Capacity Capacity Overflow < 20 Seats 2 3 8 5 8 3 37 20-29 Seats 4 7 8 27 32 39 58 30-39 Seats 5 2 24 32 38 56 67 Over 40 Seats 6 3 3 46 48 69 0 he occupacy survey of bus passegers is somewhat difficult as there are a large umber of stadig passegers at the time of observatio. he estimatios are doe i such a way that the bus size ad the level of loadig is observed as agaist coutig the actual umbers as i able. he bus boardig ad alightig survey were doe by travelig observers o a umber of idividual buses operate i bus routes are give i the able 2. able 2 Iter- Zoal Bus ravel Routes Betwee Colombo ad Kalutara Zoes Colombo Dehiwala Moratuwa Paadura Kalutara Colombo 00,0,54, 55,67,76, 400,400/, Dehiwala 00,0,54, 55,67,76, 400, 400/, Moratuwa 00, 0, 400, 400/, Paadura 00, 400, 400/, Kalutara 400, 400/, 00, 0, 55, 83, 400, 400/, 00, 83, 400, 400/, 00, 0, 400, 400/, 00,0,55, 83 400, 400/,, 00, 400, 400/, 83, 42, 400, 400/, 400, 400/, 00, 400, 400/, 00, 83 400, 400/, 00, 400/, 83, 42,, 400 400, 400/, 400/7, 400, 400/, 400, 400/, 400, 400/, 400, 400/, 400/7, 3
A group of traied eumerators were used for this purpose. wo eumerators were assiged to a bus to collect these data durig peak ad off- peak period of the day. he surveyig period was set at 3 hours o a day startig at 6.00 hours ad edig at 9.00 hours depedig o the data requiremet. I developig a geeral approach to formulate a matrix from partial data such as passeger loadigs, boardigs ad alightigs, it is assumed that there are umber of traffic zoes across which a bus route or corridor operates. he iter-zoal travel demad from origi to destiatio ) at the ed of zoe (-) is illustrated i Figure. ( ( ) 2 B 2 K LD K = B Origi O ZB -2 B LSP ZB - Zoe - ( ) ( ) Zoe Figure. A Bus Route Crossig th Zoes (ravelig from O to D ) Where LD( ) = he total bus passeger loadigs observed at a roadside loadig observatio poit located withi (-) th zoe from origi o to destiatio d. ( ) = he iter-zoal bus passeger demad betwee the (-) th zoe ad th zoe from origi o to destiatio d. 2 B = Bus passeger boardigs i the (-) th zoe from roadside observatio poit(lsp) to the zoal boudary (ZB - ) for the directio of origi o to destiatio d. 2 A = Bus passeger alightigs i the (-) th zoe from roadside loadig observatio poit(lsp) to the zoal boudary (ZB - ) from origi o to destiatio d. 2 K = 2 K = B K + B = he cumulative bus passeger boardigs up to the roadside loadig observatio poit ( LSP). A + A = he cumulative bus passeger alightigs up to the roadside loadig K 2 K = A K A 2 A observatio poit(lsp). Destiatio D he first step is to calculate a differece of cumulative passeger boadigs to cumulative passeger loadigs. It is determied the iter-zoal passeger travel (IP) betwee the (-) th zoe ad the th zoe give i equatio (2) estimates the average umber of bus passegers who would be travelig across the (-) th zoal boudary (ZB - ) whe a bus moves from origi o to destiatio d. 4
IP 2 2 2 2 BK AK + B + B A A --------------------(2) K = K = = I estimatig the total passeger demad at the (-) th zoal boudary(zb - ), further adjustmets are required to estimate the umber of boardigs ad alightigs betwee the roadside loadig observatio poit ad the boudary. his ca be give by equatio (3), 2 2 ( B A ) ( ) = + * LD 2 2 2 2 BK AK B B A A + + K = K = ( ) ---------(3) Similarly, equatio (4) is derived to estimate the total iter-zoal passeger demad at the same boudary whe travelig from destiatio zoe d to origi zoe o is give as, 2 2 ( B A ) ( ) = * LD 2 2 2 2 BK AK B B A A + + K = K = ( ) - ----(4) I this estimatio, it was assumed that the roadside loadig observatio poit was situated ahead of the zoal boudary. For this type of arragemet the geeralized form of origi to destiatio travel matrix for the give bus route ca be illustrated as, 2. ( ) ( ). 2 0 2 = 2 2 0 2 23... 0... 2 ( )... 0 ( ) 2 0 2 Where ij is the estimated iter-zoal passegers travel betwee i th zoe ad j th zoe. (i =,2,.,) ad (j =,2,,); 2, 3,. ( ) are the factors that are derived from the bus passeger boardigs ad alightigs couts o the bus route as show below, 5
ij = P ij * m= A j.(5) B m where P ij = the ratio of all passegers who alighted i zoe j to the passegers who boarded from zoe i to travel up to zoe j is expressed as a percetage. I this study, the value for ij was ivestigated based o experiece of the route boardigs ad alightigs patter. A = Bus passeger alightig i the j th zoe. j B m m= = he cumulative bus passeger boardig up to destiatio d. As a example, the above approach is used to estimate the iter zoal travel for bus route umber 0 from Colombo zoe to Moratuwa Zoe. he zoes that cross this sectio are Zoe, as the Colombo DSD, Zoe 2, as the Dehiwala DSD ad Zoe 3, as the Moratuwa DSD. he box is give how this ca be doe. Box Estimatio of Iter-zoal Bus Passeger ravel o Moratuwa- Colombo Bus Route (Route Number 0) I the Moratuwa- Colombo bus route, the roadside passeger loadig observatio poits were located at Maliba Juctio (LSP) ad Bambalapitiya (LSP2). I this example, the observatio poits were situated ahead to the zoal boudary. he observed average daily passeger demads were,34 ad 3,442 for the Moratuwa to Petah directio ad 7,950 ad,304 for the directio of travel from Petah to Moratuwa. he summary of passeger boardigs ad alightigs couts o this route are show i able 3. able 3. Passeger Boardigs ad Alightigs Couts (Bus Route Number 0) Locatio From Moratuwa to Petah Average Average IP passeger passeger Boardigs Alightigs From Petah to Moratuwa Average Average IP passeger passeger Boardigs Alightigs Moratuwa 55 6 39 29 67 0 zoal limit LSP 4 5 02 6 Dehiwala 22 22 39 65 20 42 zoal limit LSP2 0 20 78 42 Colombo zoal limit 36 64 0 25 7 43 6
Calculatio ravel from Moratuwa to Petah. ( 4 5) Moratuwa = *,34 4 + 5 5 6 = 567 Passegers per day. (0 20) Dehiwala = *3,442 ( 0 22 4 55 20 22 5 6) + + + = 8,243 Passegers per day. Assumig the P (Moratuwa to Dehiwala) is 90 %. he we ca estimate, ( 4 + 22) Mortuwa Dehiwala = 0.9* = 0.84 27 Iter zoal travel (Moratuwa-Dehiwala) =043 Passegers per day / (Moratuwa-Colombo) = 4628 Passegers per day ad (Dehiwala-Colombo) =3,65 Passegers per day. Calculatio 2 ravel from Petah to Moratuwa. ( 25 7) *,304 ( 25 + 78 7 42) ( 65 20) ( 65 + 02 + 25 + 78 20 6 7 42) Colombo = + = 3,359 Passegers per day. = + * 7950 = 0,702 Passegers per day. Dehiwala Assumig the P (Colombo to Dehiwala) is 95 %. he we ca estimate, Colombo Dehiwala ( 20 6) + = 0.95* = 0.257 299 ( ij ) (Colombo-Dehiwala) =3,433 Passegers per day / (Dehiwala-Moratuwa) = 776 Passegers per day / (Colombo-Moratuwa) =9,926 passegers per day. he aalysis was carried out for each of the other bus routes ad estimates were thereafter made usig the summatio of all the ij travels as show i equatio (6) relevat to the travel from origi o to destiatio d to obtai the iter-zoal bus demad ( ij ) for that zoal pairs. ij = ij -----------------------------------------------------------------( 6) j= he results are show i colum 3 of able 4 together with the model predictio at year 2004 ad 2006. Widaapathiraage ad Kumarage (2003) metioed that this model could be applied to trasport plaig studies. I order to verify this statemet, the predictios of the model at 7
year 2004 are compared with the iter-zoal travel observatios ad calculated the percetage error with respect to the observatios as show i the colum 5 of able 4. able 4. Compariso of Predicted ad Observed Iter-zoal ravel. Zoe Name 2004 (Verificatio Year) % Error of Model 2006 From Zoe o Zoe Obs.( ij ) Pred. Pred. Pred. Colombo Dehiwala 68,952 49,305 28.49 55,34 Colombo Moratuwa 3,55 27,290 3.4 39,753 Colombo Paadura 7,858 2,543-59.62 2,32 Colombo Kalutara 4,87 6,234-27.98 8,07 Dehiwala Moratuwa 8,68 0,57-7.86 0,6 Dehiwala Paadura 8,047 7,896.88 8,655 Dehiwala Kalutara 2,545 2,783-9.35 4,825 Moratuwa Paadura 35,927 24,34 32.82 27,742 Moratuwa Kalutara 3,675 4,25-4.69 6,204 Paadura Kalutara 9,06 9,42-3.46 0,987 (Where Obser = Actual observatios, Predic = Model predictios). able 4 shows the predictios at year 2004 ad 2006 are radomly varyig with respect to the observatios. his may be the effect of the growth factors that are assumed for the traffic zoes. It idicated that the employed populatio after the base year is ot uiformly distributed across this corridor. he statistical abstracts have show that the housig desity i Kalutara ad Paadura has bee growig sigificatly. As a result the passeger demad towards Kalutara, Paadura traffic zoe shows a sigificat variatio with respect to the actual observatios. However, the predictio of 2006 ca be adjusted i accordig to the error distributio of the year 2004 travels. CONCLUSIONS he mai coclusios that are reached i this study are; A Bus passeger Origi-destiatio travel matrix is estimated successfully usig the partial data such as the passeger loadigs, boardigs ad alightigs of buses that are operated o this travel corridor. he bus model is based o gravitatioal form ad ca capture the iteractio betwee the mai two variables (ie. he effect of oe o the other ). he accuracy of these variables depeds o the accuracy of the model predictios. he model performs at a acceptable level of predictive ability whe tested o real demad observatios. REFERENCES COLOMBO MEROPOLIAN REGIONAL SRUCURAL PLAN,997, rasport Ifrastructure & Service Requiremets for Colombo Metropolita Regio, Fial Report, Urba Developmet Authority, Sri Laka. pp. 2-3. 8
DANAS L, AMANDA A ad J. GALLAGHER, MBA Bus Route 66 Arterial Improvemet Study, Massachusetts Bay rasportatio Authority, Massachusetts, pp. 4-5, 200. KUMARAGE, A.S., ad G.L.D.De SILVA, 2003, Feasibility of a Bus Priority Lae for Galle Road, Aual rasactios of IESL-2003, Vol. -Part B, echical Papers, Istitutio of Egieers, Sri Laka, pp. 23-30. LSC RANSPORAION CONSULANS Ic., he Bus Comprehesive Operatios Aalysis, Merced Couty Associatio of Govermets, Fial Report, Merced, Califoria, pp. 7-8.,2003. PREHIKA L.U., JAYAWICKRAMA M.D.S.P. ad JEEWANANDA H.G., A Aalytical Study of the Operatioal Characteristics of a Suburba Bus Route, Upublished Udergraduate hesis, Departmet of Civil Egieerig, Uiversity of Moratuwa, Sri Laka, pp. 2-25, 200. WIDANAPAHIRANAGE, S.J. ad A.S.KUMARAGE, 2003, Bus ad Rail Demad Model for the Colombo Metropolita Regio, Research for Idustry, Proceedigs of the 9 th Aual Symposium-2003, Egieerig Research Uit, Uiversity of Moratuwa, Sri Laka, pp. 0-. ANNEXURE he List of Iter-zoal Bus ravel Routes Betwee Colombo Kalutara rasport Corridor. Route No. From o Route No. From o 00 Moratuwa Petah 67 Dehiwala otalaga 00 Paadura Petah 76 Karagampitiya Hettiyawatta 0 Moratuwa Petah 83 Paadura Nugegoda 02 Agulaa Kotahea 400 Aluthgama Colombo 42 Moratuwa Paadura 400. Kalutara Colombo 54 Agulaa Kiribathgoda 400.7 Paadura Kalutara 55 Soysapura Hettiyawatta Mathugama Colombo 55 Mt.Laviiya Muttakkuliya 9