Capacity of TWSC Intersection with Multilane Approaches

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1 Avalable onlne a roceda Socal and Behavoral Scences 16 (2011) h Inernaonal Syposu on Hghway apacy and Qualy of Servce Sochol Sweden June 28 July apacy of TWS Inersecon wh Mullane Approaches Hayuan L a* Zong Tan a and We Deng b a Unversy of Nevada Reno Reno Nevada U.S. b Souheas Unversy Nanjng R. hna Absrac Ths paper presens an proved odel for assessng capaces of vehcular oveens a Two-Way Sop-onrolled (TWS) nersecons. The heorecal odel was derved based on he conflc echnque for esang capaces of vehcular oveens a ullane TWS nersecons under non-sauraed raffc condons. The odel paraeers were calbraed by referencng he relaed research of feld observaons. The effecveness and relably of he proposed odel were verfed by coparng wh he ehodology of Hghway apacy Manual 2000 (HM2000) and VISSIM sulaon wh varous lane confguraons and raffc deands. In coparson wh he gap accepance odel recoended n HM2000 he proposed odel can splfy he process of esang capaces of TWS nersecons and exend o be appled o any ullane TWS nersecons ublshed by Elsever Ld. Open access under BY-N-ND lcense. Keywords: Two-Way Sop-onrolled (TWS) Inersecon; apacy; onflc Technque; Mullane 1. Inroducon As one of he coon nersecon conrol ypes Two-Way Sop-onrolled (TWS) nersecons are exensvely ulzed n he Uned Saes. TWS nersecons have proven o be an effcen and econocal raffc conrol ype copared wh sgnal conrol and oher conrols under ceran condons (Harders 1968). Alhough a sgnfcan aoun of effor has been devoed o assessng capaces of TWS nersecons s sll dffcul o accuraely evaluae capaces of ullane TWS nersecons by curren research. Gap accepance ehodology as a classcal represenave of radonal ehods s prevalenly used o esae capaces of TWS nersecons (Harders 1968; Segloch 1973; Grossann 1991). The TWS odels ncorporaed n Hghway apacy Manual 2000 (HM2000) s also based on he gap accepance heory. Brlon and Wu (2001) presened a heorecal ehod for solvng capaces of TWS nersecons n ers of he raffc conflc echnque. Brlon and Thorsen (2005) provded a odfed ehod o deerne capaces of TWS nersecons n lgh of Wu s ehodology. Hayuan (2008) explored capacy odels for esang capaces of unsgnalzed nersecons under xed raffc condons based on he conflc echnque. Bu he relaed odel paraeers were calbraed by coparng he copued capaces wh hose of radonal ehods snce s nearly possble o drecly calbrae he paraeers hrough feld observaons whch negavely pacs on he effecveness of capacy esaon. The purpose of hs paper s o enhance an earler sudy (Hayuan 2008) for assessng capaces of TWS nersecons wh ullane approaches by he conflc echnque under non-sauraed * Hayuan L. Tel.: E-al address: hayuanl2008@hoal.co ublshed by Elsever Ld. Open access under BY-N-ND lcense. do: /j.sbspro

2 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) raffc condons. 2. rory relaonshp of raffc oveens Accordng o he raffc code n he Uned Saes he prory ran of vehcular oveens a TWS nersecons s shown n Table 1. Table 1 The prory ran of vehcular oveens a TWS nersecons Ran rory Vehcular oveens 1 Absolue prory Major-sree hrough and rgh-urn vehcles 2 Yeldng o vehcles of he frs ran Major-sree lef-urn vehcles and norsree rgh-urn vehcles 3 Yeldng o vehcles of he frs and second rans Mnor-sree hrough vehcles 4 The lowes prory Mnor-sree lef-urn vehcles 3. onflc echnque Snce he prory relaonshps aong vehcular oveens are dfferen a TWS nersecons vehcles of dfferen oveens have o pass hrough correspondng conflc areas unoccuped by hgher prory oveens. As a resul a conflc group (a deparure sequence) s fored n he sae conflc area. Vehcles of a parcular oveen can pass hrough he conflc area as long as s no occuped by hgher prory conflc vehcles. I s assued ha every vehcle of oveen occupes he conflc area for on average of o seconds. All oveens crossng he sae conflc area can use seconds all ogeher n an hour. If all vehcular oveens are under non-sauraed raffc condons and he volue of oveen Q s nown he probably of oveen occupyng he conflc area can be calculaed as follows (Brlon Wu 2001). Q o o = (1) s he probably ha he conflc area s occuped by oveen ; o Q s he volue of oveen n vph; and o s he average e of a vehcle occupyng he conflc area n oveen n sec. The probably ha he conflc area s unoccuped by vehcles of oveen s gven as follows. u = 1 o (2) s he probably ha he conflc area s unoccuped by vehcles of oveen. u For a wang vehcle he conflc area s also occuped f vehcles of hgher prory oveens are approachng he conflc area. The probably ha he conflc area s unoccuped by he approachng vehcles of hgher prory oveens can be esaed as follows (Brlon Thorsen 2005). b Q b = e (3) b s he probably ha he conflc area s unoccuped by vehcles of hgher prory oveens n advance of her arrvals; and s he average e of an approachng vehcle occupyng he conflc area n advance of s arrval n sec. b

3 666 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) Vehcles of oveen can only ener he conflc area f boh of he above condons are e sulaneously. The probably ha boh condons are e s gven as follows. u = ( 1 o ) b = u (4) b u s he probably ha he conflc area s unoccuped by vehcles of prory oveen. The axu capacy of oveen s he axu hroughpu of vehcles ha can pass hrough he conflc area whou beng affeced by vehcles of oher conflc oveens. ax = (5) o ax s he axu capacy of vehcles crossng he conflc area for oveen n vph. Accordng o Brlon and Thorsen (2005) he acual capacy of oveen under non-sauraed raffc condons can be obaned as follows. = (6) a ax ux x D s he acual capacy of vehcles crossng he conflc area n oveen n vph; a D s he se of prory oveens conflcng wh oveen ; and s he probably ha he conflc area s unoccuped by vehcles of oveen x conflcng wh oveen. ux Vehcles can proceed o cross an nersecon only f all relaed conflc areas are unoccuped by oher prory conflc vehcles. If all vehcular oveens n he deparure sequences are n non-sauraed raffc condons he probably ha all conflc areas are free of oher oveens of hgher prory s he produc of probables of each conflc area unoccuped. Accordng o Brlon and Thorsen (2005) he acual capacy of oveen can be esaed as follows. = (7) a ax u Dc s he probably ha he conflc area s unoccuped by prory oveens conflcng wh oveen ; u D c s he se of conflc areas ha oveen needs o pass hrough. 4. apaces of 421 TWS nersecons A 421 TWS nersecon refers o a 4-leg nersecon wh wo-way wo-lane ajor approaches and wo-way one-lane nor approaches. When non-oorzed road users are no consdered a 421 TWS nersecon ay conan up o 14 vehcular oveens n he lane confguraon as shown n Fgure 1. All hese conflc cases can be arranged no 13 conflc areas whch nvolve hree ypes of enry cenral and ex conflc cases based on he conflc echnque (Brlon Wu 2001). Vehcles a a TWS nersecon have o pass hrough several conflc areas o cross he nersecon. In nonsauraed raffc condons vehcles of oveen can ener he nersecon only when all relaed conflc areas are free of oher prory conflc oveens. In such a case capaces of vehcular oveens can be esaed as follows. If ax2 ax2 ax2 = (8) a1 ax1 u E2 u 8 u F9 a2 = a2 + a2 = ax2 u E1 + ax2 u E3 (9) = = hen a2 = ax2 ( u E1 + u E3) (10)

4 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) Fgure 1 Traffc oveens and conflc areas a a 421 TWS nersecon. Noe: E F and denoe conflc areas of vehcular oveens a enres exs and cenral area respecvely. = a 3 = ax3 ue 2 a4 ax4 u E5 u E6 u 1 u 2 u 7 u 11 u F8 = a5 ax5 u E4 u E6 u 2 u 7 u 8 u F1 u F9 a 6 = ax6 ue 4 ue 5 uf 2 a 7 = ax7 ue 8 u 2 uf 3 a 8 = a 8 + a 8 = ue + = = hen a 8 = ax8 ( u E7 + ue 9) If ax8 ax8 ax8 a10 ax10 u E11 a 9 = ax9 ue 8 ax8 7 ax8 ue 9 = ue 12 u 1 u 5 u 7 u 8 uf 2 = a11 ax11 u E10 ue 12 u 1 u 2 u 8 uf 3 uf 7 a 12 = ax12 ue 10 ue 11 uf 8 ue denoes he probably of he enry conflc area unoccuped by oveen ; u denoes he probably of he cenral conflc area unoccuped by oveen ; and uf denoes he probably of he ex conflc area unoccuped by oveen. I should be noed ha here are wo hrough oveens a each ajor-sree approach. The probables of wo hrough oveens on he sae approach occupyng he cenral conflc area are no ndependen of each oher. Applyng he sple produc of boh probables wll lely overesae he oal e of boh hrough oveens occupyng he cenral conflc area. The probably of he cenral conflc area unoccuped by boh hrough oveens should be beween he axu and nu probables. (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) uax j = 1- oj ax ( ) ( Q Q ) j ax Q j Q e j j b j j=2 8 ( 22)

5 668 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) oj ( ) ( Q j + Q j ) bj Q j + Q j j=2 8 (23) un j = 1- e s he axu probably of he cenral conflc area unoccuped by vehcles of oveens j and uaxj j wh he sae drecon; nu probably of he cenral conflc area unoccuped by vehcles of oveens j and j wh unj he sae drecon; average e of a vehcle n oveen j occupyng he cenral conflc area n sec; and oj bj average e of a vehcle n oveen j occupyng he cenral conflc area n advance of s arrval n sec. In addon capaces of vehcular oveens a 421 TWS nersecons wh varous lane confguraons can be deerned based on he basc odels derved above. 5. apaces of 432 TWS nersecons A 432 TWS nersecon refers o a 4-leg nersecon wh wo-way hree-lane ajor approaches and wo-way wo-lane nor approaches. When non-oorzed road users are no consdered a 432 TWS nersecon ay conan up o 18 vehcular oveens n he lane confguraon as shown n Fgure 2. The arrangeen of conflc areas s shown n Fgure 2. Fgure 2 Traffc oveens and conflc areas a a 432 TWS nersecon. Noe: E F and denoe conflc areas of vehcular oveens a enres exs and cenral area respecvely. Under non-sauraon raffc condons capaces of vehcular oveens can be assessed as follows. = = = hen a 2 = a If ax2 ax2 ax2 ax2 a 1 = ax1 ue 2 u 8 = + + = + + a2 a2 a2 a2 ax2 ue 1 ax2 ax2 ue 3 a4 ax4 a5 a5 a5 ax5 ue 4 ( 1 ue ue ) + + ax2 1 3 a 3 = ax3 ue 2 = ue 5 u 1 u 2 u 7 u 11 uf 8 = + = + u 2 u 7 u 8 uf 1 ax5 ue 6 u 2 u 7 u 8 uf 9 (24) (25) (26) (27) (28) (29)

6 If ax5 ax5 ax5 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) = = hen a 5= ax5 u 2 u 7 u 8 ( u E4 u F1 + u E6 u F9) (30) If ax8 ax8 ax8 ax8 = (31) a6 ax6 u E5 u F2 = (32) a7 ax7 u E8 u 2 a 8 = a 8 + a 8 + a 8 = ax8 ue 7 + ax8 + ax8 ue 9 (33) = = = hen a 8 = ax8 ( 1+ u E7 + u E9 ) (34) If ax11 ax11 ax11 (35) a9 = ax9 u E8 = (36) a10 ax10 u E11 u 1 u 5 u 7 u 8 u F2 a 11 = a 11 + a 11 = ax11 ue 10 u 1 u 2 u 8 uf 7 + ax11 ue 12 u 1 u 2 u 8 uf 3 (37) = = hen a 11 = ax11 u 1 u 2 u 8 ( ue 10 uf 7 + ue 12 uf 3) (38) = (39) a12 ax12 u E11 u F8 I should be noed ha here are hree hrough oveens a each ajor approach and wo hrough oveens a each nor approach. The probables of hrough oveens wh he sae drecon occupyng he cenral conflc area are no ndependen of each oher. In addon capaces of vehcular oveens a 432 TWS nersecons wh varous lane confguraons can be obaned based on he basc odels derved above. 6. apaces of Mullane WS Inersecons A general expresson can be derved for deernng capaces of vehcular oveens a ullane TWS nersecons as follows. = = (40) a ax u E u u F ax u Dc E Dc Dc F Dc Wh: ax = o E o E Q u E= 1 Q b o Q u = 1 e Q b of Q uf = 1 e esaed approxaely accordng o he capacy of oveen crossng he enry conflc area n vph; ax D ce denoes he se of vehcular oveens conflcng wh oveen n he enry conflc area; D c denoes he se of vehcular oveens conflcng wh oveen n he cenral conflc area; D cf denoes he se of vehcular oveens conflcng wh oveen n he ex conflc area; oe denoes he average e of vehcles n oveen occupyng he enry conflc area n sec; o denoes he average e of vehcles n oveen occupyng he cenral conflc area n sec; of denoes he average e of vehcles n oveen occupyng he ex conflc area n sec; and

7 670 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) average e of vehcles n oveen occupyng he conflc area n advance of s arrval n sec. b If here are ore han one vehcular oveens of he sae drecon on he sae approaches he probably of he cenral conflc area unoccuped by vehcular oveens of he sae drecon can be derved based on he relaed research (Wenquan 2003; Hagrng 1998). onsderng several facors such as safey geoerc condons and crossng beween oveens has proven o be reasonable o assue ha he arrval dsrbuon of vehcles obeys M3 dsrbuon a unsgnalzed nersecons (Wenquan 2003). Supposng ha headways of raffc oveens also obey M3 dsrbuon he dsrbuon funcon of he h oveen wh he sae drecon can be nown as follows (Wenquan 2003). λ ( ) a e ( h ) Δ > Δ = (41) 1 Δ Wh a q λ = 1 Δ q h s he headway of he h oveen n sec; λ s he decay consan n he h oveen; a s he proporon of free vehcles n he h oveen; q s he flow rae of he h oveen n vph; and Δ s he nu headway beween wo successve vehcles n plaoon n sec. The nu headway Δ of vehcles n he h oveen us be less han he crcal gaps c of srea. Tha s Δ< c. So he headway of he h oveen can be avalable for vehcles of oveen crossng he conflc area when he headway s larger han Δ. When every headway h n he h oveen s greaer han he gven and s greaer han Δ he jon dsrbuon funcon of vehcle headways on oveens wh he sae drecon s obaned as follows (Hagrng 1998). Wh Then For furher use one can nroduce ( ) h1 h2 h Λ q a = h = e >Δ = 1 Q = 1 λ Λ( Δ) { } (42) Λ=λ = 1 β Λ Q a q = Δ q = q λ = 1 1 q a = (43) Q = 1 λ ( ) 1 2 Λ( Δ) β (44) h h h = e >Δ If here are equal crcal gaps and follow-up es for vehcles of oveen wh he sae drecon he probably of he coon gap aong oveens wh he sae drecon allowng n vehcles of oveen o cross he gap s gven as follows (Hagrng 1998). ( n) = { h c + ( n 1) f} { h c + n f} = 1 = 1

8 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) ( c ( n 1) f ) ( c nf ) Λ + Δ Λ + Δ β e = β e s he crcal gap for srea n sec; and c ( c n f ) f ( 1) = e e (45) β Λ + Δ Λ f s he follow-up e for srea n sec. Le T n denoe he nu coon gap aong oveens wh he sae drecon o allow n vehcles of conflc oveen crossng he gap. ( 1) T = + n (46) n c f Because he oal raffc flow rae of vehcular oveens wh he sae drecon s Q vehcles per hour here are Q coon gaps offered n an hour. The oal e used by vehcles of conflc oveen crossng he cenral conflc area can be derved as follows. o n ( ) (47) T = Q T n n= 1 T o s he oal e used by vehcles of conflc oveen crossng he cenral conflc area n sec. Wh regard o oveen he probably of he cenral conflc area unoccuped by vehcles of conflc oveens wh he sae drecon can be approxaely esaed as follows. To uj = uj uj = (48) probably of he cenral conflc area unoccuped by vehcles of oveen j conflcng wh oveen ; uj uj and uj probables of he cenral conflc area unoccuped by vehcles of oveens j and j wh he sae drecon. 7. albraon of odel paraeers There are four odel paraeers ( oe o of b ) ha need o be calbraed based on feld observaons. The average e of vehcles n nor-sree oveen occupyng he enry conflc area oe can be esaed by he average sop e of vehcles on enry plus he ove-up e of he second vehcle afer he deparure of he frs vehcle under he condons ha here are no raffc oveens conflcng wh oveen. Accordng o he sudy by Kye e al. (1999) f he hrough oveen s aen as he base case he sauraon headway s hgher for lef-urn vehcles and lower for rgh-urn vehcles a sop-conrolled approaches. The adjusen facor was proposed o be 0.9 for lef-urn vehcles and 1.36 for rgh-urn vehcles. Sauraon headways for passenger cars and heavy rucs show a sgnfcan dfference. assenger cars have a lower value han heavy rucs. The dfference averages 1.5s or 22 percen. Under he condons ha he subjec vehcle does no face he conflcng vehcles sauraon headways were proposed o be 4.0s/veh for lef-urn oveen 3.7s/veh for hrough oveen 2.8s/veh for rgh-urn oveen 3.2s/pcu for passenger cars and 4.6s/veh for heavy rucs. Accordng o he recoendaons n HM 2000 he deparure headway s proposed o be 3.2s/pcu under he condons ha here are no conflc vehcles on oher approaches. The ove-up e s proposed o be 2.0s. Based on he above referenced values he value of he paraeer oe n nor-sree oveen s proposed o be he deparure headway of 3.2s/pcu plus he ove-up e of 2.0s for he hrough oveen. The adjusen facor s proposed o be 0.9 for lef-urn vehcles and 1.36 for rgh-urn vehcles. onsderng he pac of heavy vehcles on he deparure headway he average deparure headway can be esaed by he odfed deparure headway accordng

9 672 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) o he proporons of passenger cars and heavy vehcles n oveen. Then values of he paraeer oe for he hrough oveen lef-urn oveen and rgh-urn oveen on sde approaches can be esaed as follows. = (49) oet HV ( ) ( ) = (50) o ER HV = (51) oel HV denoes he average e of a vehcle occupyng he enry conflc area n hrough oveen n sec; oet o ER denoes he average e of a vehcle occupyng he enry conflc area n rgh-urn oveen n sec; oel denoes he average e of a vehcle occupyng he enry conflc area n lef-urn oveen n sec; s he proporon of passenger cars n oveen ; and HV s he proporon of heavy vehcles n oveen. The average es of ajor-sree vehcles occupyng he enry conflc area oe and ex conflc area of are proposed o be he sae as he follow-up e of ajor-sree vehcular oveen n HM The average e of nor-sree vehcles occupyng he ex conflc area of s also proposed o be he sae as he follow-up e of nor-sree vehcular oveen n HM Therefore he basc values of he paraeers are proposed o be 2.2s for he ajor-sree vehcular oveen 3.3s for he nor-sree rgh-urn oveen 4.0s for he nor-sree hrough oveen and 3.5s for he nor-sree lef-urn oveen. Slarly values of he paraeers are copued based on he presence of heavy vehcles. = + (52) o E o base o HV HV o F = o base + o HV HV (53) s he base follow-up e n sec; and obase ohv adjusen facor for heavy vehcles (0.9 for one-lane and 1.0 for wo-lane and over wo-lane approaches). The average e of vehcles n oveen occupyng he cenral conflc area o can be esaed as follows. L o = (54) V L he rac lengh of oveen crossng he cenral conflc area beween he enry and he ex n eer; and V he average speed for vehcles n oveen crossng an nersecon n ps. Based on he sudy by Brlon (2005) he average e of vehcles n oveen occupyng conflc areas n advance of her arrvals can be esaed as shown n Table 2. Table 2 The paraeer b of he odel Major Lef-urn Major Through Major Rgh-urn Mnor Lef-urn Mnor Through Mnor Rgh-urn Vehcular oveen b (s)

10 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) Evaluaon of he proposed odels In order o assess he relably and effecveness of he proposed odel for esang he capaces of ullane TWS nersecons he capaces produced by he proposed odel were copared wh hose obaned by he ehodology n HM 2000 and VISSIM sulaon. Three ypcal confguraons of and 432 TWS nersecons were seleced as exaples o verfy he proposed odel based on assung varous raffc deands of dfferen lanes and approaches. Fgure 3 shows he capacy coparson of nor approaches under he condons of varous raffc deands a 411 TWS nersecons. Fgure 4 reflecs he capacy coparson of nor approaches under he condons of varous raffc deands a 421 TWS nersecons. In Fgures 5 and 6 capacy coparsons of nor approaches are gven under he condons of varous raffc deands a 432 TWS nersecons wh a lef-urn and hrough shared lane and a hrough and rgh-urn shared lane. apacy of nor-sree enrance lane (veh/h/ln) Sulaon Model HM Nuber of dfferen volue scenaros Fgure 3 apacy coparsons of nor approaches a 411 TWS nersecons apacy of nor-sree enrance lane (veh/h/ln) Sulaon Model HM Nuber of dfferen volue scenaros Fgure 4 apacy coparsons of nor approaches a 421 TWS nersecons

11 674 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) apacy of shared lane wh lef-urn and hrough oveens (veh/h/ln) Sulaon Model HM Nuber of dfferen volue scenaros Fgure 5 apacy coparsons of lef-urn and hrough shared lanes on nor approaches of 432 TWS nersecons Nuber of dfferen volue scenaros Fgure 6 apacy coparsons of hrough and rgh-urn shared lanes on nor approaches of 432 TWS nersecons As shown n he fgures here are o soe exen ceran correspondng relaonshps beween he capaces by he proposed odel and VISSIM sulaon. I s obvous ha he capaces calculaed by he proposed odel aches beer wh he sulaon resuls han he resuls by he ehodology n HM2000. The close correspondences beween he resuls of he proposed odels and VISSIM sulaon show prosng resuls regardng he accuracy and relably of he proposed odels when evaluang capaces a ullane TWS nersecons wh varous lane confguraons and raffc deands. 9. onclusons apacy of shared lane wh hrough and rgh-urn oveens (veh/h/ln) Sulaon Model HM The assessen of capacy s crcal o evaluang nersecon level-of-servce and ae operaonal proveen decsons. For TWS nersecons wh ullane approaches odels were derved based on he conflc echnque under non-sauraed raffc condons. In coparson wh VISSIM sulaon and he ehodology n HM 2000 he proposed odel produces prosng resuls and deonsraes he effecveness and

12 Hayuan L e al. / roceda Socal and Behavoral Scences 16 (2011) relably alhough ore coprehensve daa for calbraon and valdaon are desrable. The proposed odel provdes an proved ehod for esang capaces of vehcular oveens a ullane TWS nersecons wh varous lane confguraons and raffc deands. Usng he proposed odel he curren ehods for assessng capaces of TWS nersecons can be sgnfcanly proved and exended. References Brlon W. and Wu N. (2001). apacy a unsgnalzed nersecons derved by conflc echnque. Transporaon Research Record Brlon W. and Thorsen M. (2005). apacy a Inersecons whou Traffc Sgnals. Transporaon Research Record Grossann M. (1991). Updaed alculaon Mehod for Unsgnalzed Inersecons. Forschung Srassenbau und Srassenverehrsechn Bundesnser fuer Verehr Bonn. No.596. Harders J. (1968). The apacy of Unsgnalzed Urban Inersecon. Forschung Srabenbau and Srabenverehrsechn Geran Hef 76. Hagrng O. (1998). A Furher Generalzaon of Tanner s Forula. Transporaon Research ar B Vol.32 No Hayuan L. and We D. (2008). Research on apacy a Urban Inersecons whou Traffc Sgnals. roceedngs of he Frs Inernaonal Syposu on Transporaon and Developen Innovave Bes racces Kye M. and Ls G. (1999). A capacy odel for all-way sop-conrolled nersecons based on srea neracons. Transporaon Research ar A Segloch W. (1973). apacy Evaluaon a Unsgnalzed Inersecons. Srassenbau und Srassenverehrsechn Bundesnser fuer Verehr Bonn. No.154. Transporaon Research Board. (2000). Hghway apacy Manual. 4h ed. Washngon D: Naonal Research ouncl Wenquan L. We W. and Dazh J. (2003). Unsgnalzed Inersecon apacy wh Mxed Vehcle Flows. TRB Naonal Research ouncl. Washngon D..