IDENTIFICATION OF TRANSPORTATION IMPROVEMENT PROJECTS IN PHNOM PENH CONSIDERING TRAFFIC CONGESTION LEVEL

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 IDENTIFICATION OF TRANSPORTATION IMPROVEMENT PROJECTS IN PHNOM PENH CONSIDERING TRAFFIC CONGESTION LEVEL Sambath NETH Graduate Student Department of Archtecture and Cvl Eng. Toyohash Unversty of Technology 1-1 Tempaku, Toyohash, Ach, 441-8580 Japan Fax:+81-532-44-6566 E-mal: nethsambath@hotmal.com Iv LIM Doctoral Student Department of Envronment and Lfe Eng. Toyohash Unversty of Technology 1-1 Tempaku, Toyohash, Ach, 441-8580 Japan Fax: +81-532-44-6831 E-mal: l987653@acserv.tutrp.tut.ac.p Yasuhro HIROBATA Professor Department of Archtecture and Cvl Eng. Toyohash Unversty of Technology 1-1 Tempaku, Toyohash, Ach, 441-8580 Japan Fax:+81-532-44-6831 E-mal: hrobata@acserv.tutrp.tut.ac.p Abstract: Ths paper ams to dentfy the transportaton mprovement proects by extendng the soluton on traffc congeston proposed by JICA study team, n November 2000, n whch the network mprovement was focused. In ths study, the polcy of urban plannng s ntroduced to be ncorporated wth network mprovement to successfully elmnate the traffc congeston on road network n Phnom Penh. The extensons nclude ncorporaton of urban plannng polcy, network mprovement and reformulaton of the four step models by usng dfferent data set. Three dfferent scenaros, Wth and Wthout network mprovement and Wth both network mprovement and traffc volume reducton, are set up and compared to fnd out the approprate measure to reduce traffc congeston. Ths study shows that a comprehensve approach, that provdes commuters wth an ntegrated transport system for relevng traffc congeston, should nclude proportonal strateges to ncrease the capacty of transport system and to decrease traffc volume partcularly at the man entrances to urban area. Key Words: traffc congeston, traffc assgnment, transportaton mprovement proect 1. INTRODUCTION The ncrease of traffc congeston s the less desrable results of Phnom Penh s contnued populaton growth wthout a correspondng expanson of ts transport system. The prevous study by JICA experts shows that some urban routes have been reached the flow capactes or slghtly beyond the capactes. It means that the urban communty has not been successful at lowerng, or even mantanng traffc congeston levels. Hgh level of traffc congeston has caused the reducton of economc actvtes and the augmentaton of transport costs, whch strongly affect the metropoltan economy. Moreover, traffc congeston has a sgnfcant mpact on the communtes lvablty. It hnders an ablty to attract resdents and busnesses; and degrades the local lves qualty. Wthout control, ths 1265

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 congeston also has been cted as a cause of urban sprawl because of resdent s relocaton to outlyng areas for the sake of less congested communtes. Another effect by hgh level of traffc congeston s to dmnsh ar qualty. Conversely, any technque that reduces traffc congeston by mprovng traffc flow can result n mproved ar qualty. Urban Sprawl Nosy and Ar Polluton Excess Travel Demand. Populaton Growth. No Improvement Of Transport System Fgure 1: Problem Encountered Traffc Conges ton Shpment Cost Increase In ths sense, the purpose of ths research s to dentfy the most congested key roads n Phnom Penh and to make a gudelne for transportaton mprovement proect. Ths wll dentfy whch area needs more roads surface or new road constructon and whch exstng lnk needs to be enlarged ts capacty or the mprovement of ts flow capacty. Ths study wll also dentfy the causes of traffc congeston and make a set of recommendatons for a comprehensve approach to release local traffc congeston. 2. STUDY AREA 2.1 Locaton of the Study Area Camboda s located n south-east Asa. It shares the nternatonal boundary wth Thaland, Laos and Vetnam at the followng part of North-West, North and East ~ South-East. The study area s Phnom Penh, the captal of Camboda, and the three partal dstrcts of Kandal provnce, whch s located n southern of Phnom Penh. Actually, ths cty s located n the core of Kandal provnce. 2.2 Populaton of the Study Area The populaton data are avalable only for years of 1986, 1993, 1995, 1996, 1998 and 1999. Among these data, only the one n 1998 s precse due to the populaton census was undertaken n that year. These data are provded by the Mnstry of Plannng. Based on ths trend, JICA study team made the populaton proecton for the Muncpalty of Phnom Penh, and then added the populaton of a part of Kandal Provnce whch s ncluded n the study area. Accordng to the populaton control polcy n Urban Area, the populaton 184,000 people out of 343,000 of present populaton-trend ncrease need to be nduced from Urban Area to Suburban Area by the year of 2015. Then the populaton growth rate, n the suburban area, s sharply hgh. These rates are ranged from 5.06% n 2005 to 3.68% n 2015. To respond to the hgh populaton ncrease n the suburban area, sound urbanzaton must be acheved wth the proper support of the transport system. 1266

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 Burma South-East Asa Map Tawan Camboda Map Laos Thaland Vetnam Phlppnes Camboda 600 0 600 1200 Klometers B N W E S PHNOM PENH, CAPITAL OF CAMBODIA Phnom Penh Road Network Urban Road Network N N W E W E S S 3 0 3 6 Klometers Road Lne Zone Boundary 4 0 4 8 Klometers Road Lne Phnom Penh Boundary Zone Boundary 2.3 Road Network Revew Fgure 2: Locaton of Study Area Road network s a basc nfrastructure to support a transport system. Wthout an approprate road system, many modes of transport ncludng buses, passenger cars, trucks and motorcycles can not be operated properly. Consequently, a road system s role n a transport 1267

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 master plan s very sgnfcant. Feld surveys were carred out to nvestgate the present road condtons n the Study Area. Usng the data collected durng the feld survey, a consderable porton of road nventory was updated and supplemented wth data of suburban areas. Present road condton a. Pavement Condton of Urban Street Compared to the developed condton of the urban road network, pavement condton of the urban roads n Phnom Penh s very poor. Fgure 3 shows the percentages of each class of surface condton of the arteral streets. About two-thrds are classfed as far or good, whle the rest (32 %) s bad or very bad. Fgure 4 shows the surface condton of the collector streets. Contrary to the case of the arteral streets, the total of good and far remans only 41 percent, whle bad and very bad occupy the rest, 59 percent. Fgure 5 shows the pavement condton of the local streets. It s clearly seen that the percentage of very bad s very hgh compared wth those n arteral streets and collector streets. Very Bad 25% Good 19% Bad 7% Far 49% Fgure 3: Pavement Condton of Arteral Streets Very bad 28% Good 4% Far 37% Good: Structurally ntact wth smooth surface Far: Structurally ntact but rough surface; may need repar n near future Bad: Many cracks wth some pot holes; need careful drve to avod pot holes Very Bad: Many pot holes; substantal decrease n travel speed Bad 31% Fgure 4: Pavement Condton of Collector Streets 1268

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 Good 4% Far 15% Bad 7% Very bad 74% Fgure 5: Pavement Condton of Local Streets n Central Dstrcts Because of the very poor condton of pavement on the local streets, drvers prefer to use the arteral streets, and traffc concentrates on these roads. Table 1 and Fgure 6 show the comparson of the pavement condtons, surveyed on a random bass, of the four Central Dstrcts (Daun Penh, Pramp Makara, Chamkar Mon, Toul Kork). There s a substantal dfference n pavement condtons among the Dstrcts. Pavement condtons n Chamkar Mon and Toul Kork are very poor. Table 1: Pavement Condtons of Local Streets n Central Dstrcts No Name of Dstrct Good Far Bad Very bad Total (Km) (Km) (Km) (Km) (Km) 1 Daun Penh 3.53 8.88 2.75 4.20 19.35 2 Chamkar Mon 0.10 2.40 1.50 32.50 36.50 3 Pramp Makara 0.50 3.85 2.40 6.85 13.60 4 Toul Kork - 0.25 0.50 29.90 30.65 Total 4.13 15.38 7.15 73.45 100.10 Percentage 4% 15% 7% 73% 100% Source: The Study on the Transport Master Plan of the Phnom Penh Metropoltan Area, Fnal Report 100% 80% 60% 40% 22% 46% 14% 50% 18% 89% 98% 20% 0% 28% 18% 4% 4% 7% 1% 0% 0% Daun Penh 7 Makara Chamkar Mon Toul Kok Good Far Bad Very bad 2% Fgure 6: Pavement Condtons of Local Streets n Central Dstrcts 1269

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 b. LOS by Travel Speed Table 2 shows the average travel speeds over the entre sectons of maor roads n Phnom Penh. As can be seen n the table, average travel speeds of the maor arteral roads are stll wthn the lowest acceptable range (LOS D). However, Hghway Capacty Manual defnes that LOS D s the stuaton where small ncrease n flow may cause substantal ncrease n delay and hence decrease n (arteral) speed. Therefore, even a small ncrease n traffc volume on these roads wll lead to severe traffc congeston. In addton, travel speeds of those sectons wth LOS C are close to that of LOS D. Based on these facts, t can be sad that the traffc condton on the urban arteral roads s approachng an unacceptable level. Travel speeds on Charles de Gaulle, Inner Rng Road (St. 271) and Shanouk/Jawharal Nehru Blvd are lower than those of other maor arteral roads. Suspected reasons for these lower travel speeds are as follows: Radal Roads Rng Roads Charles de Gaulle: Traffc congeston at three roundabout ntersectons on the route and very bad pavement condton. Inner Rng Road: Very bad pavement condton Shanouk/Jawaharal Nehru: Severe traffc congeston Table 2: Travel Speed and Level of Servce on Arteral Streets Street Name Drecton AM Peak Hr. Noon PM Peak Hr. Average km/hr LOS km/hr LOS km/hr LOS km/hr LOS France / N-bound 21.3 C 28.2 C 24.8 C 26.3 C Norodom S-bound 22.3 C 29.0 C 20.7 D 25.4 C Monvong N-bound 19.9 D 26.2 C 20.6 D 23.3 C S-bound 22.4 C 26.3 C 20.7 D 23.8 C Charles de NE-bound 14.1 D 20.4 C 16.4 D 17.4 D Gaulle / Monreth SW-bound 18.9 D 17.5 D 17.2 D 18.0 D Confederato E-bound 27.6 C 39.1 B 26.7 C 31.9 B n de la Russe W-bound 27.8 C 37.2 B 25.8 C 32.0 B Inner Rng S/E-bound 18.7 D 21.9 C 20.4 D 20.5 C Road W/N-bound 18.7 D 21.1 C 19.4 D 20.1 C Km Il Sung S/E/Nbound / Mao Tse 20.6 D 29.8 C 21.9 C 24.9 C Toung / S/W/Nbound Ssowath 21.5 C 27.4 C 20.0 D 24.3 C Jawaharal S/E-bound 14.6 D 24.2 C 18.3 D 21.0 C Nehru / Shanouk W/N-bound 18.5 D 24.0 C 16.6 D 20.6 C Source: The Study on the Transport Master Plan of the Phnom Penh Metropoltan Area, Fnal Report c. LOS by V/C Rato The rato of traffc volume, V, to the capacty of the road, C, s also commonly used as an ndex for LOS for unform road segments. Table 4 shows the LOS of the sectons of Urban Arteral Roads n Phnom Penh based on the V/C ratos (VCR). In the calculaton of ths table, the assumptons shown n Table 3 were adopted. 1270

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 Table 3: Basc Assumpton for Evaluatng LOS Basc Capacty n PCE 2,500 PCE/hour/lane PCE Converson Factor Motorcycle: 0.33 Cyclo/bcycle: 0.33 Car, Van: 1 Heavy vehcle: 2.5 Basc Capacty n PME 7,575 PME/hour/lane PME Converson Factor Motorcycle: 1 Cyclo/bcycle: 1 Car, Van: 3.03 Heavy vehcle: 7.58 Table 4: Road Sectons wth VCR Larger than 0.8 Name of Road Secton (From To) VCR LOS Tep Phan (a) Mornng Peak Hour Mao Tse Toung J. Nerhu 1.08 E F IRR Mao Tse Toung 1.16 E F Mao Tse Toung IRR 1.29 E F Shanouk St 163 Monvong 1.05 E F Monreth St 163 0.90 E St 163 Monreth 1.25 E F Mao Tse Toung St 163 Monvong 1.22 E F Monvong Tep Phan Shnouk 0.82 E Shonouk Tep Phan 0.91 E Confederaton de la Russe Tchecoslovaque J. Nerhu 0.86 E J. Nerhu Tchecoslovaque 0.86 E Km Il Song St 608 Conf. De la Russe 0.80 E (b) Evenng Peak Hour Name of Road Secton (From To) v/c LOS Tep Phan IRR Mao Tse Toung 1.36 E F Mao Tse Toung IRR 1.18 E F Shanouk St 163 Monvong 1.07 E F Sothearos Norodom 0.85 E Mao Tse Toung Monreth St 163 1.06 E F St 163 Monreth 0.83 E Conf. De Russe Tchecoslovaque J. Nerhu 0.94 E Source: The Study on the Transport Master Plan of the Phnom Penh Metropoltan Area, Fnal Report VT Data (Multple Mode) 3. METHODOLOGY The analyses conducted n ths study are based on the assumpton that the sngle transportaton mode of motorcycle s loaded to the traffc because the motorcycle s a domnant mode n the study area, about 80% of total mode share. OD Table (Sngle Mode) Enlargement Factor Fgure 7: Formaton of Trp Dstrbuton Table Mode Converted Factors for Each Indvdual Indvdual Drver Expanson Factors (Zone, Age & Sex) Soco-economc & Performance Attrbutes (SE & T) 1271

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 Therefore, the other trp modes are needed to be converted to the passenger motorcycle equvalent. And the second assumpton s that the bgger traffc flow represents the hgher level of probable traffc congeston. 3.1 Data Arrangement To expand the sample to a whole populaton, an expanson factor s needed. Ths factor s formulated from three varables of the socoeconomc attrbute namely resdence zone s number, sex and age of the ndvduals. Then, the expanson factor s combned wth mode equvalent factor to create a sngle factor by multplyng. The latest factor s used n the enlargement process. Soco-economc & Performance Attrbutes (SE & T) Traffc Congeston Level Fgure 8: Model Structure and Estmaton Process Present Trp Pattern Generaton & attracton Models Dstrbuton Model Mode Choce Model (skpped) Traffc Assgnment Lnk Flows 3.2 Descrpton of Trp Generaton and Attracton Models Smple regresson and multple lnear regresson models, that have one or several explanatory varables of the soco-economc framework component, have been formulated to represent the present condton of the trp generaton and attracton from/to each traffc zone. Trp generatons are formulated by aggregate models as shown n equaton (1) through (6): For Home purpose: The soco-economc attrbute used n trp generaton for home purpose are some knd of actvtes that create the trp to return home. These actvtes belong to some knd of obs such as Government ob, student and so on. In ths study, only two attrbutes of soco-economc framework are Government ob and Student whch have a best relatonshp for the model. G = β E + β E a (1) hom e gvmnt gvmnt stdnt stdnt + home For Work purpose: For ths purpose only one attrbute, Populaton, that provdes good relatonshp to the model. G = α P + a (2) work pop work For Busness purpose: A good relatonshp for ths model can obtan from the attrbute of Household and dummy varable of Urban status of the zone. G = α H + γu + a (3) bsns hhold d bsns For School purpose: The attrbutes that have a good relatonshp for ths model are the same two varables appled n busness purpose. G = α H + γu + a (4) schl hhold d schl 1272

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 For Shoppng purpose: Government ob has a better relatonshp n ths model. G = β E + a shop gvmnt gvmnt shop (5) For Other purpose: Travelng for other purpose has an unspecfc trp pattern but only one varable can best descrbe ths knd of trp, the number of Households n that zone. G oth =α hhold H + aoth (6) Where, G home : Trp generaton n zone ; P : Populaton n zone ; H : Number of Households n zone ; E gvmnt : Work base government employments n zone ; E stdnt : School base students n zone ; U d : Urban dummy for zone ; α pop, αh hold, β gvmnt, β stdent, γ : Parameters; a home, a work, a bsns, a schl, a shop, a oth : Specfc adustments. Trp attractons are formulated by aggregate models as shown n equaton (7) through (12): For Home purpose: The soco-economc attrbute used n trp attracton for home purpose s the one that relates to the trp whose destnaton s home. Ths attrbute can be the accessblty that can attract trps to the zone. In ths model, the number of Household s preferred. A = α H + γu b (7) hom e hhold d + home For Work purpose: For ths purpose, there are two varables that provde good relatonshp to the model. A = β E + γu + b work gvmnt gvmnt d work (8) For Busness purpose: A good relatonshp for ths model can obtan from the attrbute of Market obs and dummy varable of Market status of the zone. A = β E + γm + b (9) bsns mrket mrket d bsns For School purpose: The attrbutes that have a good relatonshp for ths model are the number of Government obs and the number of Students n that zone. A = β E + β E + b (10) schl gvmnt gvmnt stdnt stdnt schl For Shoppng purpose: Market ob and dummy varable of Market status gve a better relatonshp n ths model. A = β E + γm + b shop mrket mrket d shop (11) For Other purpose: Travelng for other purpose has an unspecfc trp pattern, there are two varables can best descrbe ths knd of trp, the number of Government obs and dummy varable of Market status n that zone. 1273

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 A = β E + γm + b (12) oth gvmnt gvmnt d oth Where, A : Trp attracton to zone; H : Number of Households n zone ; E gvmnt : Work base government employments n zone ; E mrket : Work base market employments n zone ; E stdn t : School base students n zone ; U d : Urban dummy for zone ; M d : Market dummy for zone ; α hhold, β gvmnt, β mrket, β stdent, γ : Parameters; b home, bwork, b bsns, b schl, b shop b oth : Specfc adustments. Each above model needs to be added the constant term to ensure the equalty between the actual value and the value derved from the model. Ths constant term can be called the specfc adustment for each purpose model. The above trp generaton and trp attracton models are used for each purpose trps. It comes out wth more varety of attrbuted varables. Therefore, trp generaton and attracton models are specfed for each purpose analyses. 3.3 Descrpton of Trp Dstrbuton Model The voorhees gravty model s used for the dstrbuton step for both nter zonal and ntra zonal trps (eq (13)). The orgn of trps from each zone s assumed to be orgnated from the nearest ntersecton of the center of the zone (zone centrod). Traffc resstance s appled to the dstance between zone centrods and the summaton of the ratos between the attracted trps n zone and the power functon of the corresponded dstance. The dstance, d corresponded to T, s assumed to be equal to half of the mnmum of d (half of the nearest dstance). λ A d Where T : Trp between zone and zone ; T = G (13) λ G : Trp generated n zone ; A d 3.4 Traffc Assgnment Ths step uses a statc user equlbrum assgnment model. The lnk performance functon s the BPR formula whch suggested by the Bureau of Publc Road as shown n equaton (14). α Q Where T ' c : Congested lnk travel tme [mn]; Tc = T0 1 + K x (14) T 0 : Free-flow lnk travel tme [mn]; C Q : Daly Traffc volume [veh]; Note: the unt of [veh] s [PME]. 3.5 Defnton of Traffc Congeston A : Trp attracted to zone ; d : Dstance between zone centrod [km]. λ : Parameter. C : Lnk capacty [veh/day]; K x =0.15, α=4 ; As shown n the prevous chapter, the frst step n the process of estmaton of traffc congeston s cost s to defne the travel demand on the road network. Some authors have dentfed the traffc congeston by observng the level of servce of the road network and some others have dentfed by checkng the rato of traffc volume to the road capacty (V/C). The second method s chosen for consderng n ths study. Therefore, the defnton of traffc 1274

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 congeston n ths study s the level that s observed by the rato of traffc volume, (V), to the road capacty, (C). The levels of traffc congeston are dvded nto four levels n sequences such as normal flow, congested flow, moderate congested flow and severe congested flow status. These levels are descrbed below and summarzed n table 5. a. Normal Flow or the Status of No Congeston The status of normal flow or no congeston s the status n whch the traffc can smoothly flow. In ths case, the V/C rato s less than 0.8 whch s the status of free flow as stated n Khsty and Lall (2003). b. Congested Flow Status The congested flow status s the status n whch the traffc flow s reached close to the road capacty and started to be dsrupted by the ncrease of the traffc tself. In ths case, the V/C rato s lad between 0.8 and 1.2 whch s the startng pont of congeston. c. Moderate Congested Flow Status Moderate congested status s the status n whch the traffc s more and more ncrease far above the road capacty. In ths case, the V/C rato s ranked between 1.2 and 1.5. Ths level of congeston can temporary stuck the traffc and the road s temporary become a parkng lot. d. Severe Congested Flow Status The severe congested flow status s the status n whch the traffc s ncreased to a hgh pont that reached a very tght status of traffc flow. In ths case, the V/C rato s hgher than 1.5 whch s the level that the temporary congeston s stretched for longer tme. If ths status occurs so often and the congeston tme s stretched to a long tme, the road network s deterorated. Ths problem may harm the local envronment and cost too much for the socety to spend on tme lost, more fuel consumpton and envronment dluted. Table 5: Summarzed of traffc congeston levels No. Congeston Level Indcator (V/C rato) 1 Normal Flow V/C < 0.8 2 Congested Flow 0.8 V/C < 1.2 3 Moderate Congested Flow 1.2 V/C < 1.5 4 Severe Congested Flow 1.5 V/C The Ro ad In formaton Program (May 2002) descrbed that the steps needed to releve traffc congeston are the effcent strateges n whch the transport network s mproved proportonally to the reducton of traffc volume at the road lnks wth hgh probable traffc congeston. 4. RESULTS OF MODELS ESTIMATION 4.1 Estmaton of Trp Generaton and Attracton Models The relaton between trps generaton, attracton, wth the explanatory varables s poor as shown n Table 6 because of the small sample sze whch appears to be bas. 1275

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 Table 6: Result of Trp Generaton and Attracton Models Purpose & No. M odel Varables Coeffcent Standard t Value Corr. of Zones Error Coef. For Home Gen. GVMNT 2.38 0.59 4.02 0.55 STDNT 0.42 0.23 1.80 (54 Zones) A ttr. HHOLD 0.17 0.69 0.24 0.45 U BN -D 10,561.47 2,985.84 3.54 For W ork Gen. PPLTN 0.34 0.13 2.65 0.34 A ttr. GVMNT 2.89 0.72 4.04 0.59 (56 Zones) U BN -D 7,347.36 3,102.20 2.37 For Busness Gen. HHOLD 0.46 0.28 1.65 0.39 U BN -D 1,888.44 1,149.54 1.64 (28 Zones) A ttr. M R K ET 0.18 0.10 1.79 0.52 M K T-D 1,209.73 587.80 2.06 For School Gen. HHOLD 0.38 0.21 1.84 0.28 U BN -D 774.67 893.69 0.87 (44 Zones) A ttr. GVMNT 2.11 0.50 4.25 0.57 STDNT 0.16 0.20 0.78 For Shoppng Gen. GVMNT 0.33 0.11 2.97 0.50 (29 Zones) A ttr. M R K ET 0.05 0.07 0.65 0.45 M K T-D 1,113.47 466.84 2.39 For Other Gen. HHOLD 0.25 0.10 2.49 0.43 A ttr. GVMNT 0.08 0.08 1.09 0.26 (29 Zones) MKT-D 309.28 289.82 1.07 4.2 Estmaton of Trp Dstrbuton Dstrbuton model shows that there s a good relaton between dstrbuted trp T and the dstance d. Table 7: Result of Trp Dstrbuton Model Dstrbuton model type: Voorhees gravty Parameter λ 0.0879 Number of zones: 54 Correlaton coef. 2 r 0.6525 4.3 Traffc Assgnment In ths study, the flow on each lnk s estmated through the four steps models of travel demand forecastng. Each model s developed by usng the STRADA program. These models are used to predct the future lnk flow wth and wthout network mprovement. Then, another predcton s made wth the pattern of both network mprovement and traffc volume reducton. These patterns are compared to seek out the approprate one. The three scenaros dscussed to predct the future lnk flow are: - Wthout Network Improvement do-nothng - Wth Network Improvement (Improve Pavement & Connect Mssng Lnks ) - Wth both Network Improvement and Traffc Volume Reducton (For traffc volume reducton, 50% of Congested-Source of Urban Inbound Trp s Dverted to suburb) 1276

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 N ormal Flow Congested Flow Moderate Congested Flow Severe Congested Flow Fgure 8. Congeston n Urban Base Year of 2000 Normal Flow Congested Flow Moderate Congested Flow Severe Congested Flow Fgure 9. Hgh Congeston 2015 Wth Do-Nothng Pattern Normal Flow Congested Flow Moderate Congested Flow Severe Congested Flow Fgure 11: Low Congeston 2015 Wth Network Improvement Normal Flow Congested Flow Moderate Congested Flow Severe Congested Flow Fgure 12: No Congeston 2015 Network Improvement &Traffc Volume Reducton Table 8: Congeston levels a t the man entrances to urban and the average level n Phnom Penh wth do-nothng pattern 2000 2005 2010 2015 NR1 Entrance 2.11 2.38 2.56 2.56 NR3 Entrance 2.07 2.36 2.58 2.78 NR4 Entrance 1.97 2.31 2.55 2.77 NR5 Entrance 2.72 3.17 3.46 3.56 Avrg n P.P 0.28 0.32 0.36 0.38 In the second scenaro, wth network mprovement, traffc congeston s stll remaned on some road segments especally at the entrances to urban area but ts level s sgnfcantly reduced to a low one. Ths shows that the mprovement proect s nadequate for the soluton on traffc congeston. Of course, expanson of the mprovement proects, such as more constructons of new roads, can completely elmnate these congestons. More constructons of outer rng roads can escape some trps from enterng the urban area. Ths may reduce some trps from urban entrances but the problem s that the communty have a constran budget for 1277

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 every proects. Moreover, the constructon of outer rng roads can reduce only the trps on the urban entrances, not the urban roads. Then the congeston stll reman n the urban area where there s no ablty to construct more roads. Table 9: Congeston levels at the man entrances to urban and the average level n Phnom Penh wth network mprovement pattern 2000 2005 2010 2015 NR1 Entrance 2.11 2.38 1.92 1.52 NR3 Entrance 2.07 1.63 1.60 1.44 NR4 Entrance 1.97 1.94 1.77 1.71 NR5 Entrance 2.72 2.16 2.00 1.96 Avrg n P.P 0.28 0.30 0.34 0.33 Cascetta (2001) descrbed that the demand for travelng cannot be reduced but travel pattern can be changed f ts purposes or reasons of travelng are clearly dentfed. In ths sense, the am to reduced traffc flow from the hgh congested lnks s to alter the destnaton of some congested-source trps. Thus, the soluton to support the mprovement proect s to reduce the traffc volume to a sutable level that matches the road capactes. Ths scenaro ams to reduce the traffc volume on the roads that support hgh traffc flow especally at the man entrances to urban area. Table 10: Congeston Levels at the man entrances to urban and the average level n Phnom Penh wth network mprovement and trp reducton pattern 2000 2005 2010 2015 NR1 Entrance 2.11 0.37 0.31 0.28 NR3 Entrance 2.07 0.07 0.08 0.07 NR4 Entrance 1.97 0.11 0.11 0.11 NR5 Entrance 2.72 0.22 0.24 0.23 Avrg n P.P 0.28 0.06 0.06 0.06 Table 11: Total Trp Length n 10 6 Vehcle-klometer 2000 2005 2010 2015 Remarks Do-Nothng 7.41 8.55 8.83 9.35 Hgh Congeston Network Improvement 8.38 8.21 8.65 Low Congeston NI and Trp Reducton 5.91 6.42 6.62 No Congest on Table 12: Average Speed n km/h 2000 2005 2010 2015 Remarks Do-Nothng 25.7 25.5 25.3 25.2 Hgh Congeston Network Improvement 27.0 31.1 32.1 Low Congeston NI and Trp Reducton 28.2 32.5 33.4 N o Congeston 5. CONCLUSIONS Through the above dscusson, t can be concluded that the source of traffc congeston s not only the bg volume of travel demand but also the condton of transport faclty and traffc pattern especally the concentraton of trps n a small area such an urban of Phnom Penh. And the effcent strategy to remove ths concentraton s to dvert the destnaton of congestedsource trps. As shown above, the effcent and effectve technque to dvert those trps s to provde a corresponded number of obs to the suburb to alter the trp attrbute of ths area. 1278

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 Ths study shows that a comprehensve approach, that provdes commuters wth an ntegrated transport system for relevng traffc congeston, should nclude proportonal strateges to ncrease the capacty of transport system and to decrease traffc volume partcularly at the man entrances to urban area of ths cty. In ths stage of study, the causes of traffc congeston were dentfed and a set of recommendaton for a proper soluton was made. Nevertheless, the comparson of three dfferent scenaros was made to fnd the approprate one. Ths comparson should be made not only on the outcome of traffc congeston released but also on the cost beneft analyss of each scenaro. The comparson base on beneft cost analyss can evaluate the proposed proect thus quantfy how much budget s necessary for the proect and how much beneft wll be receved for the communty n term of money and tme savng, less fuel consumpton, less nosy and ar polluton. Thus, to deeply understand the effects of the mplemented proect n each scenaro the cost beneft analyss should be made. REFERENCES Cascetta, E. (2001) Transportaton Systems Engneerng: Theory and Methods. Kluwer Academc Publshers, the Netherlands. Fu wara, A., Zhang, J. and Okamura, T. (January 13, 2004) Influence of Urban Form on Transportaton Energy Consumpton. Socal Capacty Development for Envronmental Management and Internatonal Cooperaton n Developng Countres, Hroshma Japan. Iso moto K. (2000) Traffc Survey Data for the Study of Transport Master Plan of Phnom Penh Metropoltan. Katahra & Engneers Internatonal. JICA, Japan Internatonal Cooperaton Agency. (November 2001) The Study on the Transport Master Plan of the Phnom Penh Metropoltan Area n the Kngdom of Camboda. Fnal Report. Katahra & Engneers Internatonal. Khsty, C.J. and Lall, B.K. (2003) Transportaton Engneerng: An Introducton. Ed.3. Prentce Hall, Pearson Educaton, Inc.: Upper Saddle Rver, New Jersey. Khun S. (2003) GIS Maps of Phnom Penh Metropoltan. Mnstry of Publc Works and Transport, Kngdom of Camboda. Ma rn, E. (2003) Demand Forecast, Congeston Charge and Economc Beneft of an Automated Hghway Network for the Pars Agglomeraton, Transport Polcy Vol.10, 107-120. NIS, Natonal Insttute of Statstcs. (1998) Populaton Census of Camboda. Kngdom of Camboda. NIS, Natonal Insttute of Statstcs. (2003) Statstcal Year Book. Kngdom of Camboda. OrtÚza, J.D. and Wllumsen, L.G. (2001) Modelng Transport. Ed.3. John Wley & Sons, Ltd.: Chchester, Great Brtan. 1279

Proceedngs of the Eastern Asa Socety for Transportaton Studes, Vol. 5, pp. 1265-1280, 2005 Recker, W.W., et al. (2001) Measurng the Impact of Effcent Household Travel Decsons on Potental Travel Tme Savngs and Accessblty Gans. Transportaton Research Part A Vol.35, 339-369. The Road Informaton Program, TRIP-Nonproft Organzaton. (May 2002) The Cost of Traffc Congeston n Colorado, Transportaton Issue The Steps Needed to Releve Traffc Congeston. V egas, J.M. (2001) Makng Urban Road Prcng Acceptable and Effectve. Transport Polcy Vol.8, 289-294. 1280