Policy sensitivity analysis of Karachi commuters

Transcription

1 Policy sesitivity aalysis of Karachi commuters A. Q. Memo 1 & K. Sao 2 1 Departmet of Civil Egieerig, NED Uiversity of Egieerig ad Techology, Karachi, Pakista 2 Departmet of Civil ad Evirometal Egieerig, Nagoaka Techical Uiversity, Nagoaka, Japa Abstract The commuters chage their behavior after the itroductio of the ew mode of trasport. A icremetal logit model was used i order to measure the chage i behavior of commuters after the itroductio of ew proposed trasport mode of a magetic trai., Motorcycle, Para Trasit, ad Coach were existig modes while magetic trai was cosidered to be a future mode. Both direct ad cross elasticity were calculated for existig ad future coditios of Karachi city. For RP data models, it was revealed that total travel time variable had higher direct elasticity of (-1.017) for bus, however the total time of coach had higher ifluece o the cross elasticity of bus while total cost divided by family icome variable had higher effect o the cross elasticity of car, motorcycle ad Para Trasit. It was also observed that for SP data models the total travel time variable had a higher direct elasticity of (-0.506) for the magetic trai, however the total time of coach, motorcycle ad bus had a higher ifluece o the cross elasticity of the magetic trai ad the total cost divided by family icome variable had a higher effect o the cross elasticity of Para Trasit. Policy sesitivity i terms of a decrease i total travel time ad total cost was aalyzed for both already developed discrete models based o RP ad SP data. It was proposed to ehace the bus system for RP ad the magetic trai system for the SP data model. After evaluatig various policies for preset ad future situatio, it was recommeded to reduce the 10 percet total travel time of both the bus ad magetic trai which will icrease the modal share of bus to 46 percet ad the bus riders will icrease by 12.5 percet ad that of magetic trai to 42.2 percet ad its riders will icrease by 5.4 percet. Keywords: icremetal logit model, direct elasticity, cross elasticity, policy sesitivity aalysis, Rp data, Sp data.

2 366 Urba Trasport X 1 Itroductio The city of Karachi is situated at the extreme wester ed of Idus Delta. It lies at a logitude of 67-degrees east ad a latitude of 25-degree orth. It cosists of 16 tows havig a total area of 3520 sq. km while the urba area is 1800 sq. km. Karachi is the largest ad the most populous city of Pakista. It is amog the worlds largest ad fastest growig cities ad raks withi the top 22 coutries i terms of total populatio. Karachi s estimated populatio is about 13 millio ad it will icrease to about 22 millio by year About 33 percet of all motorized vehicles of the coutry throg its roads ad expressways. Public trasportatio i Karachi presetly cosists of paratrasits, buses ad coaches, The bus system is the most importat mode of public trasport i Karachi ad accouts for approximately more tha half (2.68 millio) of the 5.26 millio weekday perso trips as estimated i I a previous study carried out by Karachi Trasport Corporatio (KTC), the modal share of buses, miibuses, motorcycles, cars ad cycle/walk was 40, 17, 20, 11 ad 12 percet respectively. The road etwork of Karachi cosists of about 7400 km of roads with aroud 250 major itersectios. As the city has expaded very rapidly durig the last three decades, ad cotiues to do so both i populatio ad area, the motorizatio of roads has take place at almost double the rate of this expasio due to o-availability of effective meas of moder public trasport. The existig coditio of most of the city roads is also ot very good due to which the vehicular traffic frequetly has to slow dow to crawlig speed causig uecessary delays ad icoveiece to the users i additio to ecoomic losses ad evirometal problems. I this paper the results of the direct ad cross elasticity aalyses for the existig ad future modes of travel for the Karachi commuters were aalyzed ad the policy sesitivity aalysis performed by usig a icremetal logit model to determie a feasible policy for the city of Karachi. The utility fuctios developed by Memo, 2003 were used to obtai the values of direct ad cross elasticities. These utilities fuctios were developed for the existig ad future traffic coditios of Karachi. For the existig situatio, Motorcycle, Para trasit, Coach ad es were cosidered to be the available modes for commuters while for future modes a ew mode of magetic trai was added to the choice set of commuters. To develop these utility fuctios revealed preferece data ad stated preferece data sets were used, ad to obtai the coefficiets of the utility fuctios HIELOW software was used. 1.1 Utility fuctio for RP data set U = (TC/F.I) (T.T) (No. of s) (Icome) U Mc = (TC/F.I) (T.T) (No. of Motorcycles) U P.T = (TC/F.I) (T.T) (age) (sex) (H.H)

3 Urba Trasport X 367 U Coach = (TC/F.I) (T.T) (Icome) (H.H) U = (T.T) (TC/F.I) (H.H) 1.2 Utility fuctio for SP data set U = (TC/F.I) (T.T) (No. of s) (Icome) (Sex) U Mc = (TC/F.I) (T.T) (No. of Motorcycles) (Sex) U P.T = (TC/F.I) (T.T)-1.823(Sex) (age) (H.H) U Coach = (TC/F.I) (T.T) (Icome) (H.H) U = (T.T) (TC/F.I) (age) (H.H) U M.T = (TC/F.I) (T.T) (Icome) (age) (H.H) (No. of trasfers) A multiomial logit model was used to predict the modal choice probabilities for each commuter. The equatio used was Ui e P ( i) = (1) U j e jεc P (i) = Probability of choosig mode i U i = Utility fuctio for mode i U j e = Summatio of the utility fuctio for all available modes jεc The sample eumeratio method was used for aggregatio. The predicted share of the sample choosig alterative i is used as a estimate for W(i) Ns 1 W () i = P i X (2) N s = 1 N s is the umber of idividuals i the sample. The aggregatio results for the RP data set revealed that the modal share was 41 percet for, 25.4 percet for coach, 18.3 percet for motorcycle, 12.3 percet for car ad 2.3 percet for Para trasits. However for the future coditio, the SP data set was used which showed that the ew mode of magetic trai will be the domiatig mode with 39.5 percet share; where as there will be 25.3 percet for bus, 12.8 percet for motorcycle, 10.3 percet for coach, 8.1 percet by car ad 3.85 percet for Para trasits. After obtaiig the modal share results ad lookig at the preset traffic coditios of Karachi city,

4 368 Urba Trasport X it was experimeted to icrease the level of service of bus ad magetic trai for existig ad future coditios. The level of service was icreased by decreasig the variables of total travel cost ad total travel time of both the modes. 2 Methodology for selectig best policy 2.1 Elasticity aalysis Elasticity was used to determie the percetage chage i the respose variable with respect to a oe percet chage i a explaatory variable. I the applicatio of trasportatio plaig, to kow the aggregate elasticity is cosidered more importat tha to kow the disaggregate elasticity. Direct elasticity was calculated by usig equatios (3) ad (4). X ik Direct Elasticity = [ β ik Pi ( 1 Pi )] = ik X i( Pi ) P β 1 (3) i X jk Cross Elasticity = [ β jk Pi Pj ] = β jk X jk Pj P (4) i Table 1 illustrated the results for the existig coditio (RP data). The direct elasticity for bus had a higher egative ifluece o the probability of bus which shows that a oe percet decrease i the value of travel time will cause a 1.07 percet icrease i the probability of bus choice. However the cross elasticity of bus choice revealed that the total time of coach, ad the total cost divided by family icome whe family icome is held costat for car, motorcycle ad paratrasit had a higher ifluece o the probability of bus choice as these values icreased. Table 1: Attributes elasticity for existig data (RP data). Variables Motorcycle Paratrasit Coach (Direct) Total time TC/FI Table 2 shows that the total travel time had a higher direct elasticity for magetic trai, which idicates its higher ifluece o the probability of magetic trai choice. This meas that a oe percet decrease i the value of travel time will cause a 0.50 percet icrease i the probability of magetic trai choice. However the cross elasticity of magetic trai choice revealed that the total time of car, motorcycle ad bus had a higher ifluece o the icrease probability of magetic trai. Moreover the total travel cost divided by family

5 Urba Trasport X 369 icome whe family icome is held costat for paratrasit ad coach has also the same effect o the icrease probability of magetic trai choice as these values icreased. Table 2: Attributes elasticity for future data (SP data). Variables Motor cycle Para trasit Coach M. trai (Direct) Total time TC/FI Selectig suitable policy for RP data From the elasticity aalysis, it was observed that total travel time ad total cost divided by family icome had a higher ifluece o the selectio of the mode. Icremetal logit was used to predict chages i behavior of the Karachi commuters, with the existig choice probabilities of the alteratives ad chages (proposed) i variables. The revised choice probability resultig from a chage i utilities is give by P (i) = P jεc ( i) e V i P ( j) e V j (5) where V i = the chage i utility for alterative i For the RP data set selectio of the most effective policy was suggested, which ca cause the diversio effect o shiftig the rider ship from other modes to bus. For this purpose the icremetal MNL model was used. 3.1 Reducig the total travel time of bus There are several measures which ca reduce the total travel time of bus such as icreasig the frequecy, itroducig a express bus service ad providig bus laes o the mai routes. The results of the policy sesitivity aalysis are show i table 3. It revealed that as the total travel time of bus decreases by every 5.0 percet, the modal share of bus icreases by 5.5 percet. I additio it is also observed that Para trasit users are less iclied to shift to bus, as a very small share of commuters will trasfer from that mode. However the major share will shift from coach. The reaso for this may be that coach usually takes much more time tha other modes. The results also reveal that for RP data the percetage shift from coach to bus has the highest proportio of about 78 percet.

6 370 Urba Trasport X 3.2 Reducig the total travel cost of bus There are several measures to reduce the total travel cost of bus such as itroducig mothly ad weekly tickets, adjustig fare structure, ad offerig cocessios to frequet users. The results show that as the total travel cost of bus decreases by every 5.0 percet, the modal share of bus will icrease by 1.7 percet. However the major share will shift from coach. The reaso for this may be that coach usually takes much more time tha other modes ad it is used by low-icome groups so total travel cost has a higher ifluece o coach users, especially for low class people, tha ay other modes. The results also reveal that for RP data the mode shifted from coach to bus has the highest proportio of about 78.6 percet. Table 3: Impact o modal split by reducig travel time of bus. % Decr T.T MC P.T Coach (+%) % Shift from other Competitive modes M.C P.T Coach Table 4: Impact o modal split by reducig total travel cost of bus. % dec T.C MC P.T Coach (+% ) % Shift from other Competitive modes M.C P.T Coach Selectig suitable policy for SP data For SP data set attetio was paid to the selectio of the most effective policy, which ca cause the diversio effect o shiftig the rider ship from other modes to magetic trai.

7 Urba Trasport X Reducig the total travel time of the magetic trai There are several measures to reduce the total travel time of the magetic trai rider, such as itroducig a feeder bus service, reducig the headway, providig specific parkig lots for park ad ride (P & R), ad Kiss ad ride (K & R) for magetic trai users ad relocatig the existig bus stops ad routes as close as possible to magetic trai statios. The results of the policy sesitivity aalysis are show i table 5, which illustrates that as the total travel time of the magetic trai decreases by every 5 percet, magetic trai passegers will icrease by 2.5 percet. I additio it is also observed that very few paratrasit users will shift to magetic trai. However the major share will shift from coach ad bus users. The reaso for this may be that coach ad bus usually take much more time tha other modes. The results also revealed that for SP data the mode shifted from bus to magetic trai has the highest proportio of about 35 percet. Table 5: Impact o modal split by reducig total travel time of magetic trai. % Dec i T.T MT MC P.T Coa M.T M.T (+%) % Shift from other Competitive modes MC PT Coa Reducig the total travel cost of the magetic trai There are several measures to reduce the total travel cost of a magetic trai rider such as adjustig the fare structure of magetic trai ad itroducig a feeder bus service for a mothly ticket. The results of the policy sesitivity aalysis are show i table 6 which reveals that as the total travel cost of the magetic trai decreases by every 5.24 percet, magetic trai passegers will icrease by 0.6 percet. I additio it was also observed that car ad paratrasit users were less sesitive about the total cost, as a very small share of commuters will trasfer from these modes. However the major share will shift from motorcycle, coach ad bus users. The reaso for this may be that the low-icome group usually uses coach ad bus ad that this group is more sesitive to cost tha other groups. The results also revealed that for SP data the mode shifted from bus to magetic trai has the highest proportio of about 35 percet.

8 372 Urba Trasport X Table 6: Impact o modal split by reducig travel cost of magetic trai. % Dec T. C MC P.T i Coa MT MT (+) % Shift from other Competitive modes (MT) MC PT Coa Coclusio Policy sesitivity i terms of decrease i total travel time ad total cost was aalyzed for both RP ad SP data models. It was proposed to ehace the bus system for the RP data model ad the magetic trai system for the SP data model. 1. For the RP data model, i terms of gaiig more bus riders the icrease i performace of the bus service, takig measures such as icreasig frequecy, decreasig the waitig time, providig bus laes ad express bus service, should be itroduced to decrease the total travel time of bus. It was also foud that i the case of the improvemet of the bus service, the major share would be divertig from the coach. A selected policy to reduce by 10 percet the total travel time of the bus will icrease the modal share of bus to 46 percet; the bus riders will icrease by 12.3 percet. 2. For the SP data model, i terms of gaiig more riders for the magetic trai service, measures such as itroducig a feeder bus service, reducig the headway, providig specific parkig lots for park ad ride, a kiss ad ride facility ad relocatio of existig bus stops to ear magetic trai statios should be carried out to decrease the total travel time of magetic trai. It was also foud that i the case of the improvemet of the magetic trai service, the major share would be divertig from the bus. A selected policy to reduce the total travel time of magetic trai by 10 percet will icrease the modal share of magetic trai to 42.2 percet; the magetic trai riders will icrease by 5.2 percet. 3. I terms of ecouragig car users to shift their mode to bus for the existig situatio ad to magetic trai for the future situatio, the most effective policy was reducig the total travel time of the bus ad magetic trai.

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