Traffic Information Estimation Methods Based on Cellular Network Data

Transcription

1 TOPCO 崇 越 論 文 大 賞 論 文 題 目 ( 以 中 文 繕 寫 論 文 者 請 用 中 文 題 目 英 文 繕 寫 者 請 用 英 文 ): Traffc Informaton Estmaton Mthods Basd on Cuar Ntwork Data 報 名 編 號 : AI002

2 基 於 蜂 巢 網 路 資 料 之 交 通 資 訊 估 計 方 法 摘 要 近 年 來 隨 著 經 濟 的 快 速 發 展 及 科 技 的 進 步 智 慧 型 運 輸 系 統 (Intgnt Transportaton Systm ITS) 透 過 先 進 科 技 的 協 助 獲 得 了 有 效 的 改 善 其 中 運 用 基 於 細 胞 流 動 車 輛 資 料 (Cuar Foatng Vhc Data CFVD) 的 方 式 來 產 生 交 通 資 訊 將 可 以 比 傳 統 的 方 式 有 更 好 的 成 本 效 益 本 研 究 提 出 三 種 車 速 估 計 方 法 ( 包 含 有 交 遞 基 礎 (Handovr (HO)-asd) 方 法 指 紋 定 位 演 算 法 基 礎 (Fngrprnt Postonng Agorthm (FPA)-asd) 方 法 蜂 巢 探 針 基 礎 (C Pro (CP)-asd) 方 法 ) 來 分 析 蜂 巢 網 路 訊 號 並 且 提 出 數 個 分 析 模 型 估 計 蜂 巢 網 路 訊 號 ( 如 : 接 收 訊 號 強 度 (Rcvd Sgna Strngth Indcaton RSSI) 通 話 到 達 (Ca Arrva CA) 交 遞 (HO) 一 般 性 位 置 更 新 (Norma Locaton pdat NL) 週 期 性 位 置 更 新 (Prodc Locaton pdat PL)) 和 交 通 資 訊 ( 如 : 交 通 流 量 交 通 密 度 車 速 ) 之 間 的 關 聯 來 取 得 交 通 資 訊 在 實 驗 中 本 研 究 根 據 高 速 公 路 上 車 輛 偵 測 器 (Vhc Dtctor VD) 的 資 料 來 比 較 真 實 的 交 通 資 訊 和 估 計 的 交 通 資 訊 由 實 驗 結 果 顯 示 本 研 究 提 出 之 蜂 巢 探 針 基 礎 方 法 的 車 速 估 計 正 確 率 可 以 達 到 97.48% 其 正 確 率 比 交 遞 基 礎 方 法 和 指 紋 定 位 演 算 法 基 礎 方 法 高 因 此 蜂 巢 探 針 基 礎 方 法 將 可 以 分 析 基 於 細 胞 流 動 車 輛 資 料 來 提 供 即 時 且 可 靠 的 車 速 資 訊 予 以 用 路 人 參 考 關 鍵 字 : 智 慧 型 運 輸 系 統 蜂 巢 網 路 交 通 流 量 估 計 交 通 密 度 估 計 車 速 估 計 Traffc Informaton Estmaton Mthods Basd on Cuar Ntwork Data Astract Informaton and communcaton tchnoogs hav mprovd th quaty of Intgnt Transportaton Systms (ITS). By stmatng from Cuar Foatng Vhc Data (CFVD) s mor cost-ffctv and asr to acqur than tradtona ways. Ths study proposs thr vhc spd stmaton mthods whch ncud Handovr (HO)-asd mthod Fngrprnt Postonng Agorthm (FPA)-asd mthod and C Pro (CP)-asd mthod to anayz th cuar ntwork sgnangs. Morovr som anaytca mods ar proposd to vauat th raton of cuar ntwork sgnangs (.g. rcvd sgna strngth ndcaton ca arrva HO norma ocaton updat and prodc ocaton updat) and traffc nformaton (.g. traffc fow traffc dnsty and vhc spd). In xprmnts ths study compars th ra traffc nformaton of Vhc Dtctor (VD) wth th stmatd traffc nformaton y th proposd mthods. Th xprmnt rsuts show that th accuracy of vhc spd stmaton y CP-asd mthod whch s 97.48% s hghr than HO-asd mthod and FPA-asd mthod. Thrfor th CP-asd mthod can usd to stmat vhc spd from CFVD for ITS. Kyword: Intgnt Transportaton Systm Cuar Ntwork Traffc Fow Estmaton Traffc Dnsty Estmaton Vhc Spd Estmaton

3 . Introducton In rcnt yars th rs of conomc growth and tchnoogy advanc has d to dmand th Intgnt Transportaton Systm (ITS) for traffc srvc. How to construct ra-tm traffc nformaton systms of ITS s mor and mor mportant. Ra-tm traffc nformaton such as avrag vhc spd trav tm traffc fow and traffc congston can rfrncd y road usrs and th mnstry of transportaton to mprov th v of srvc for roadways. Thrfor many xstng rsarch artcs hav n don to mprov traffc nformaton srvc. Th rcnt rsarch artcs ndcat that th mthods of coctng ra-tm traffc nformaton can dvdd nto thr ways: Vhc Dtctor (VD) Goa Poston Systm (GPS)-asd pro car rportng and Cuar Foatng Vhc Data (CFVD). Traffc nformaton has tradtonay n gathrd y puc agncs (Dpartmnts of Transportaton) va statonary VDs nstad n th roadways. Tradtonay th VDs ar dpoyd on major roadways to dtct th avrag vhc spd and traffc fow. Howvr t s qut costy to nsta and mantan such dvcs. Atrnatvy traffc nformaton can coctd from travng vhcs quppd wth GPS rcvrs and wrss communcaton capaty as pros on th road ntwork. Howvr th pntraton rat of GPS-asd pro cars nds to hgh nough to nfr mor accurat ra-tm traffc nformaton. Th thrd knd of mthods CFVD whch cocts and dtcts th ra-tm traffc nformaton y trackng th ocaton of Mo Statons (MSs) through cuar ntwork sgnang (.g. Norma Locaton pdat (NL) Prodc Locaton pdat (PL) Ca Arrva (CA) and Handovr (HO)) s mor and mor popuar for ITS. For xamp ITIS Hodngs whch s a adng Europan traffc nformaton company appd th patntd CFVD tchnoogy for masurng and forcastng ra-tm traffc nformaton asd on anonymousy sampng th postons of MSs (Loggh & Marvot 2007). Thrfor FVD s cost-ffctv mmdat and asy to mantan. As th numr of pop ownng c phons has ncrasd usng MS as a pro for otanng traffc nformaton s fas. To mantan th quaty of srvc cuar ntworks hav rgorous managmnt procsss to kp track of th movmnt of MSs. Th contro sgna vnts ar trggrd through moty managmnt from cuar ntworks such as Locaton pdat (L). By groupd cs Locaton Aras (LAs) can dfnd to dscr hgh v ocatons nformaton of MSs. Whn a MS movs from on LA to anothr a NL vnt s trggrd to nform cuar ntwork th MS s atst LA nformaton through a spcfc c. Th mssag contnt conssts of MS ID (.. Intrnatona Mo Suscrr Idntty (IMSI)) LA dntfr (LAI) C Idntty (CI) tmstamp and th updat rason. For nstanc Cacrs t a. us ocaton updat vnts as a vrtua traffc countr to montor th passag through two LAs for phons so as to masurng traffc fow (Cacrs t a. 2007; Cacrs t a. 2008). Morovr som studs anayzd th raton twn th amount of cuar cas and traffc dnsty. A study dvopd y INRETS dtctd th chang of ca voum and ratd t to th occurrnc of ncdnts (Ygnac 200). Ratt t a. rportd that th amount of phon cas s cosy nkd to vhcuar dnsty y anayzng th ra data thy coctd (Ratt t a. 2006). Howvr th xact stmaton of traffc dnsty and from c phon pro data has not n nvstgatd. For vhc spd stmaton Ln t a. proposd a Fngrprnt Postonng Agorthm (FPA) to anayz th ocaton and vhc spd of MS wth masurmnt rports (Ln t a. 20; Chn t a. 202a; Chn t a. 202). Gundgard and Karsson anayzd th vhc spd stmaton accuracs accordng to handovr ocatons (Gundgard & Karsson 2009). Wh ths approachs provd hghr ocaton dtrmnaton accuracy ach masurmnt rports shoud anayzd wth hghr powr consumpton.

4 In ths papr ths study proposs som anaytc mods to stmat traffc fow asd on th amount of NLs and HO and to stmat traffc dnsty asd on th amount of PLs and CAs. Thn ths study proposs th C Pro (CP)-asd mthod whch consdrs th stmatd traffc fow and th stmatd traffc dnsty asd on cuar ntwork data to stmat vhc spd. Furthrmor ths study anayzs and compars two vhc spd stmaton mthods whch ncud: () HO-asd mthod and (2) CP-asd mthod. Ths papr xamns th proposd approach y smuaton and th xprmnta rsuts show that th proposd mod s fas. Th rmandr of th papr s organzd as foows. In Scton 2 ths study proposs th vhc spd nformaton stmaton mods from CFVD. Ths study aso provds a numrca anayss of th proposd mod and ustrats th xprmnt rsuts and anayss n Scton 3. Fnay ths study concuds th papr n Scton Traffc Informaton Estmaton Ths study tracks and anayzs th ocaton of mo usrs sgnang through ntrfacs of GSM GPRS and MTS ntworks. Frsty ths study montors th ntwork ntrfacs (.g. A and IuCS) and dsgns an ITS to rtrv th ntwork sgnang (.g. CAs and NLs) and stmat th ra-tm traffc condton nformaton as shown n Fgur. Ths study proposs som anaytc mod asd on CFVD and anayzs two vhc spd stmaton mthods whch ncud () HO-asd mthod and (2) CP-asd mthod. Fgur.. Th archtctur of ntgnt transportaton systm 2. Handovr-Basd Mthod Ths scton rfy dscrs how spd rports can gnratd from two conscutv handovr vnts. Thn ths study prsnts an anaytc mod to stmat spd rport rat from HO-asd mthod. 2.. Spd Estmaton from Handovr Evnts In a cuar ntwork such as GSM or MTS vry c s dntfd y a unqu C Goa

5 Idntfcaton (CGI). Th BS roadcasts ts CGI prodcay. Whn a MS attachs to th mo ntwork t camps on a BS and stors th BS s CGI. Th MS maks or accpts a ca through th campd-on BS. Whn th MS movs from a c to anothr durng a ca th on-gong ca s handd ovr to th nw BS. For xamp an MS (Fgur 2 (a)) movng aong a road maks or rcvs a phon ca through th BS of C at tm t 0. Whn th MS ntrs C 2 at t t xcuts th handovr procdur to swtch th voc conncton from C to C 2. Fgur. 2. Th c swtchng of a movng MS on a hghway Th spd of th MS can stmatd y utzng th nformaton provdd y th standard handovr procdur dscrd aov. Whn th MS camps on or s handd ovr to a BS t otans th BS s CGI. Thrfor from th two conscutv handovr vnts dpctd n Fgur 2 ths study otans handovr par (C C 2 ) for th frst handovr at tm t and (C 2 C 3 ) for th scond handovr at tm t 2. If ths study can map handovr par (C C 2 ) to ocaton L and handovr par (C 2 C 3 ) to ocaton L 2 thn d ( L L2 ) ths study can comput th spd of th MS as u n th prod [t t 2 ] whr d( L L2 ) dnots t t th dstanc twn L and L 2. In gnra a handovr occurs n a sma ara whch s rfrrd to as a handovr ara n th oundary ara ovrappd y th two cs (s Fgur 2 ()). In practc th handovr ocatons on a roadway can masurd y an MS havng an on-gong ca on a movng vhc quppd wth a GPS rcvr. As th vhc movs aong th roadway and th MS s handd ovr from on c to anothr snc th tm s rcordd whn a handovr occurs th handovr ocaton can otand from th GPS rcvr. Snc th handovr twn C and C + do not occur at an xact ocaton ut n a sma ara ths study can conduct a numr of poston masurmnts and us th avrag as th poston of L. Th covrag ara of a handovr ara may too arg such that thr s unaccpta dscrpancy twn th CFVD spds otand from th handovr ara and th actua vhc spds. In ths cas ths handovr ara cannot usd for CFVD spd stmaton. In gnra th two handovr vnts usd for CFVD spd stmaton nd not conscutv; any two handovr vnts of an MS can usd. Two far-apart handovr vnts can usd to otan vhc spd rports wth hghr accuracy snc th ffct of handovr ocaton naccuracy s ssnd y th argr dstanc twn th two handovrs An Anaytc Mod for Spd Rport Rat Ths scton proposs an anaytc mod to nvstgat how oftn spd rports can gnratd from CFVD undr stady traffc condtons.. how oftn two conscutv handovrs occur. In addton to th traffc fow and spd thr othr factors affct th rat of th vhc spd rports

6 gnratd from two conscutv handovr ocatons. Frst th shortr th dstanc twn th two handovr ocatons th mor oftn spd rports can gnratd caus t taks ss tm to trav through. Scond a ongr ca s mor ky to prform conscutv handovrs and gnrat spd rports. Thrd th mor cas occurrng n th movng vhcs th mor spd rports can gnratd. Our anaytc mod maks th foowng assumptons. Thr s an MS on ach movng vhc. Th ca arrvas ncudng ca orgnatons and ca trmnatons to th MS form a Posson procss wth rat. Th ca hodng tm s xponntay dstrutd wth man / (Chn t a. 203a). Fgur 3 dpcts th tmng dagram of a spd rport gnratd y two conscutv handovrs. An MS on a movng vhc ntats or rcvs a ca at tm t 0 and ts dstanc to th nxt handovr ocaton L s x. Th MS prforms a handovr at L at tm t and th nxt handovr at L 2 at tm t 2 for th ca nds at tm t 3. It s car that tm ntrva (t 0 t 3 ) s th ca hodng tm whos ngth can dtrmnd y ts dstruton. Gvn th ocaton whr th ca ntats and th handovr ocatons tm t 2 can dtrmnd y th spd of th vhc dnotd y. Ths study has t 2 x d( L L2 ) t0 () Gvn th traffc fow and vhc spd masurd y a VD th traffc dnsty.. th numr of vhcs pr unt dstanc on th roadway s. Snc th ca arrva rat to ach vhc s th ca arrva rat pr unt dstanc on th roadway s. As dpctd n Fgur 3 a spd rport s gnratd y a passng vhc f a ca gns for L (.. x > 0) and th ca nds aftr L 2 (.. t 2 < t 3 ). Lt r h dnot th spd rport rat that can otand as foows (Chang t a. 203). x d ( L L2 ) Fgur. 3. Th tmng dagram of a spd rport gnratd r h x0 xd ( L L2 ) t t dtdx (2) d( L L2 ) Thr may mor than on cuar oprator. Snc ach oprator can ony otan th CFVD of ts own ony a fracton of th traffc fow contruts to th spd rports of th oprator. In ths cas th traffc (3)

7 fow n Eq. (3) nds to mutpd y th markt shar prcntag. Not that our anayss assums constant traffc fow and constant vhc spd. In raty oth traffc fow and spd may vary wth rspct to tm and ocaton. Eq. (2) can gnrazd f th functon of traffc fow wth rspct to ocaton s known. In ths cas t (x) dnot th traffc fow at th ocaton whr th dstanc to L s x. Ths study can otan r h x0 ( x) xd ( L L2 ) t t dtdx d ( L L2 ) * (4) whr *(/) s th Lapac transform of th traffc fow wth rspct to ocaton. 2.2 C Pro-Basd Mthod Ths study proposs som anaytc mods to stmat traffc fow asd on th amount of NLs and HO and to stmat traffc dnsty asd on th amount of PLs and CAs. Thn th C Pro (CP) mthod s proposd to consdr th stmatd traffc fow and th stmatd traffc dnsty asd on cuar ntwork data for vhc spd stmaton Traffc Fow Estmaton Ths study consdrs th amount of NLs (q n ) and th amount of HOs (h ) to stmat traffc fow ( ) on th road sgmnt covrd y C Traffc Fow Estmaton y sng NL vnts Fgur 4 ustrats th spac dagram for vhc movmnt and NL on th road. Hr ths study supposs that thr s a road covrd y two LAs whch ar dvdd nto a st of cs and a communcatng MS (Fgur 4 (a)) n car on th road. Th dta stps ar as foows. Fgur. 4. Th spac dagram for vhc movmnt and NL on th road Stp : Th MS rcvd contnuousy LAI from Bas Staton Contror (BSC) and Rado Ntwork

8 Contror (RNC) (Fgur 4 ()) n GSM and MTS for assstng th ntwork n a potnta ocaton updat dcson rspctvy. Stp 2: Whn th car movs from LA to LA 2 th NL procdur s xcutd. Th MS snds th command mssag to BSC or RNC. Smutanousy ths study rcords th mssag whch contans th ocaton of NL L and NL tm t. In Tawan th Mnstry of Transportaton & Communcatons (MOTC) rportd that th avrag numr of prsons pr car n hghway was 3.3 n 20; morovr th Chunghwa Tcom had a markt shar of 33% (MOTC 20). Thrfor ths study assums that th ach vhc carrs n avrag a MS pr oprator. Whn on car s passng through th ocaton of NL th NL vnt s aways trggrd. Thrfor ths study can gt that th amount of NLs (q n ) s qua to traffc fow ( ) Traffc Fow Estmaton y sng HO vnts Whn a communcatng MS n th car movs from th covrag ara of sourc c to th covrag ara of th targt c th chann sourc c provd w rasd and th targt c w provd a chann to th MS f th targt c has a fr chann. Th procss s cad handovr. Thr s a road covrd y a st of cs and a communcatng MS n car on th road. Fgur 5 ustrats th tmng dagram for handovr th spcfc C. Th MS n car prforms th ca st-up at tm t 0 (n Fgur 5) and gos nto th handovr zon of covrag of th C - and C at t (n Fgur 5) and th BSC or RNC w ordr th C to aocat a fr chann to th MS. In th momnt f th C has a fr chann th conncton twn th MS and th C w connctd succssfuy. Th amount of HOs (h ) s addd on up. Fgur. 5. Th tmng dagram for handovr vnts In ths papr ths study assums that th ca hodng tm (t) s xponntay dstrutd wth th man /(Chn t a. 203a) to gnrat th handovr vnt. Bcaus th dstanc of th c covrag s and th spd of th car s th tm whch th MS hodng th ca s t. Th vara x s th tm dffrnc travd from th frst Ca Arrva ocaton to ntrng th spcfc c. Th trav tm / s th tm dffrnc twn t and t 2 whch th car n th C. Ths approach consdrs th ca hodng tm (t) shoud argr than x. Th vara s th traffc fow. Th amount of Handovr (h ) on th road sgmnt covrd y C can xprssd as Formua (5). Th stmatd traffc fow (q h ) can cacuatd as Formua (6). t h Pr t x dx dtdx x x (5) 0 0 t x

9 q h (6) h Traffc Dnsty Estmaton For traffc dnsty stmaton ths study consdrs th amount of CAs (a ) and th amount of Prodc Locaton pdats (PLs)(p ) to stmat traffc dnsty (K ) on th road sgmnt covrd y C Traffc Dnsty Estmaton y sng CA vnts Fgur 6 dpcts th tmng dagram for vhc movmnt and CA on th road. Whn a MS n th car movng aong th road prforms th frst ca st-up (at tm t 0 ) and ntrs C covrag (at tm t ). Morovr th MS prforms th scond ca st-up at tm t 2 for avng C covrag (at tm t 3 ). Fgur. 6. Th tmng dagram for vhc movmnt and CA on th road Ths study proposs a nov mod to vauat th raton of th amount of CAs (r ) and traffc dnsty (k ). Ths approach taks communcaton havor traffc condton and th dstanc of th spcfc c covrag nto consdraton whn stmatng th traffc dnsty. Th assumptons adoptd n th mod ar summarzd ow. Th ca arrvas to/from on MS pr car aong th road can vauatd. Th ca arrva rat to a c s whch can masurd y th mo oprator. Th ca ntr-arrva tm s xponntay dstrutd wth th man / (Chn t a. 203a). Th ra traffc fow ra vhc spd and ra traffc dnsty K aong th road can coctd from th VD data on th road sgmnt covrd y C. Th traffc dnsty can stmatd as K = / (May 990). Th mag x s th tm dffrnc travd from th frst ca arrva ocaton to ntrng C. Th mag s th dstanc of road sgmnt covrd y C. Th output masur s a whch s th amount of CA on th road sgmnt covrd y C. Ths approach consdrs th tm of CA ntrng th c and avng th c of an MS to stmat th amount of CAs (a ). Th amount of CAs on th road sgmnt can xprssd as Formua (7). Ths study assums that th stmatd traffc fow (q ) s qua to th ra traffc fow ( ). Thrfor th stmatd traffc dnsty (k a ) can stmatd y usng Formua (8)(Chn t a. 203a).

10 x x x x K a a a a dx d dx x x t t t a m whr m whr Pr Pr (7) a K q a q k m whr - - (8) Traffc Dnsty Estmaton y sng PL vnts Whn consdrng th proaty of a PL vnt n a spcfc c ths study has to tak th foowng two scnaros: () thr s no ca twn two conscutv PL vnts and (2) thr ar svra cas twn two conscutv PL vnts. Fnay ths study consdrs and sum up th two scnaros aout th proaty of PL vnt n a spcfc c for traffc dnsty stmaton Scnaro (): No Ca twn Two Conscutv PL Evnts Th spac dagram s ustratd n Fgur 7 and th tmng dagram s ustratd n Fgur 8 for scnaro (). Thr s on car wthn a MS whch movs aong th road. Th frst PL vnt s trggrd at tm t 0 and thn th car ntrs th c at tm t. Th scond PL vnt s trggrd at tm t 2 and thn th car avs th c at tm t 3. Fgur. 7. Th scnaro dagram for vhc movmnt and PL vnts on th road whn thr s no ca twn two conscutv PL vnts

11 Fgur. 8. Th tmng dagram for vhc movmnt and PL vnts on th road whn thr s no ca twn two conscutv PL vnts Th assumptons and paramtrs n th mod ar dfnd ow. Thr s ony on road rsdng n th c. (hr): Th cyc tm of th PL. x (hr): Th tm dffrnc twn th frst PL vnt and ntrng th c. Ths study assum th tm functon f(x) s a unform dstruton functon as f(x) = /. (km): Th ngth of road sgmnt covrd y a c. (km/hr): Th avrag spd of a car crossng a c. In ths scnaro th proaty of PL trggrd n th c s as Formua (9). Pr( Scnaro ) Pr x x f ( x) dx x dx (9) Scnaro (2): Svra Cas twn Two Conscutv PL Evnts Th spac dagram s ustratd n Fgur 9 and th tmng dagram s ustratd n Fgur 0 for scnaro (2). Thr s on car wthn a MS whch movs aong th road. Th frst PL vnt s trggrd at tm t 0. Thr s a ca arrvd at tm t and thn th car ntrs th c at tm t 2. Th scond PL vnt s trggrd at tm t 3 and thn th car avs th c at tm t 4. Aftr that a scond ca arrvs at tm t 5. Fgur. 9. Th scnaro dagram for vhc movmnt and PL vnts on th road whn thr ar svra cas twn two conscutv PL vnts

12 Fgur. 0. Th tm dagram for vhc movmnt and PL vnts on th road whn thr ar svra cas twn two conscutv PL vnts Th assumptons and paramtrs n th mod ar dfnd ow. Th ca arrvas to/from on MS pr on car aong th road can vauatd. Th ca arrva rat s (ca/hr). Th ca ntr-arrva tm s xponntay dstrutd wth th man /. Th ca ntr-arrva tm functon g s an xponnta dstruton functon as g (Chang t a. 203a). y (hr): Th tm dffrnc from frst ca arrva to ntrng c. Th tm functon h(y) s an unform dstruton functon so h(y) = /(2). In ths scnaro th proaty of PL trggrd n th c s as Formua (0). Pr( Scnaro 2) Pr y Pr Pr y 2 g d h( y) dy (0) y d Summary Ths study uss th Formua () to consdr and sum up th two scnaros aout th proaty of PL vnts n a spcfc c for traffc dnsty stmaton. Pr(PL) Pr Pr(Snaro) Pr Pr(Snaro 2) Formua () s th proaty of PL vnt trggrd n a spcfc c of on car. To fnd th proats of PL vnts trggrd n a spcfc c of a cars ths study has to mutpy Formua () ()

13 wth th traffc fow (car/hr). Th amount of PL vnts (p ) (vnt/hr) on th road sgmnt covrd y C can xprssd as formua (2) whch shows th raton twn th amount of PL vnts and th actua traffc dnsty K (car/hr). Thrfor ths study can us Formua (3) to nfr th stmatd traffc dnsty k p (car/hr). K p PL ) Pr( (2) p k p 2 3 (3) Vhc Spd Estmaton In ths papr th vhc spd s stmatd y th stmatd traffc fow y usng NL vnts (q n ) th stmatd traffc fow y usng HO vnts (q h ) th stmatd traffc dnsty y usng CA vnts (k a ) and th stmatd traffc dnsty y usng PL vnts (k p ). Basd on Sctons 2.2. and th stmatd vhc spds can xprssd as Formuas (4) (5) (6) or (7). - - n a n na q a k q u (4) - - a h ha h a k q u (5) n p n np p q k q u 2 3 (6) p h hp p h k q u 2 3 (7) Howvr th amounts of NLs and CAs ar usuay argr than th amounts of HOs and PLs. Thrfor th stmatd traffc nformaton wth owr randomnss can otand from NLs and CAs. Furthrmor ths study uss machn arnng mthod and consdrs th NL-asd mthod (Cacrs t a. 2007) and HO-asd mthod to propos a vhc spd stmaton agorthm whch s cad CP-asd agorthm (shown n Fgur ). In accordanc wth Scton th amount of CAs s ratd wth traffc dnsty whch mans th amount of CAs s th rcproca of vhc spd. Morovr ths study uss rgrsson mod and hstory data to anayz th paramtrs n Formua (8)(Chn t a. 202c) from vhc spd and th amount of CAs. Thr ar W cycs n hstory data and th vhc spd u and th

14 amount of CAs a ar rcordd n th -th road sgmnt n th -th cyc for vhc spd stmaton. Thn th NL-asd vhc spd th HO-asd vhc spd and th stmatd vhc spd from rgrsson mod ar consdrd and anayzd y CP-asd agorthm to stmat CP-asd vhc spd. u a whr W W a W W and 2 u a W W 2 W W a a u W a W u (8) Fgur.. Th consdrd factors n CP-asd mthod Fgur 2 shows th CP-asd agorthm to anayz th NL-asd spd HO-asd spd and th stmatd vhc spd from rgrsson mod for vhc spd stmaton. In accordanc wth th xprmnt rsuts n prvous studs NL-asd mthod can provd hgh vhc spd stmaton accuracy whn th traffc stat s fr fow (Cacrs t a. 2007). Thrfor th NL-asd spd s adoptd whn th NL-asd spd s fastr than th thrshod of fr fow spd ( f ). Howvr NL-asd mthod cannot mmdaty stmat th vhc spd of th short road sgmnt. Thrfor th HO-asd spd and th stmatd vhc spd from rgrsson mod n accordanc wth th amount of CAs ar consdrd n ths papr. Th HO-asd spd rport s not aways avaa n accordanc wth th ca hodng tm so t shoud chckd n ach cyc. Morovr th HO-asd mthod can provd hgh vhc spd stmaton accuracy whn th traffc stat s congston or fr fow. Thrfor HO-asd spd s adoptd whn t s fastr than th thrshod of hgh spd ( h ) or s sowr than th thrshod of ow spd ( ); othrws th stmatd vhc spd from rgrsson mod n accordanc wth th amount of CAs s adoptd. 3. Exprmnt Rsuts and Anayss In ths scton th thr proposd mthods ncudng HO-asd mthod FPA-asd mthod and CP-asd mthod ar vauatd and compard. 3. Handovr-Basd Mthod Ths scton uss th HO-asd mthod to stmat vhc spd and gvs th anayss of spd rport rats.

15 CFVD NL-asd Spd > f Ys NL-asd Spd No Is HO-asd Spd Exstng? No Estmatd Spd from Rgrsson Mod Ys No HO-asd Spd < HO-asd Spd > h Ys HO-asd Spd > f No Ys HO-asd Spd f Fgur. 2. CP-asd agorthm 3.. Th Error Rato of Vhc Spd Estmaton Th am of th xprmnts s to anayz th accuracs of ocaton dtrmnaton and spd stmaton. Th xprmnts ar carrd out on a 30 km ong hghway sgmnt n th Hghway No. n Tawan shown as Fgur 3. Th sgmnt s drvn 0 tms wth an MS dvc wth a GPS rcvr. Sgnang data and gographca coordnats ar coocatd from a MS smutanousy. In xprmnts thr ar 0 dffrnt HO ocatons dtctd on th Hghway No. n Tawan. Fgur. 3. Th xprmnt nvronmnt n Hghway No. n Tawan For spd stmaton ths study cocts two conscutv HO ocatons and uss th quaton n Scton 2.. to cacuat th stmatd spd (u). In xprmnts ths study cocts th actua spd () nformaton otand from GPS rcvr and anayzs th rror rato (R h ) of spd stmaton y Eq. (9). u R h mn 00% (9) Ta shows th xprmnt rsuts of spd stmaton y HO-asd mthod. HO-asd mthod can osrvd that th avrag rror rato of spd stmaton s aout 7.30% and th dstanc twn HOs s aout.72 km. Th rsuts show som HO pars ar qut good to sctd for spd stmaton Th Anayss of Spd Rport Rat Ths scton provds th nvstgaton on rar rport ssu and uss th fd tra data to vauat th spd rport rat. Fnay computr smuaton for car accdnt scnaros s gvn and dscussd.

16 Ta.. Th rror rato of spd stmaton y HO-asd mthod Mpost (km) HO par Th dstanc twn HOs (m) Error Rato (0 02) % (02 03) % (03 04) % (04 05) % (05 06) % (06 07) % (07 08) % (08 09) % (09 0) % (0 ) % ( 2) % (2 3) % (3 4) % (4 5) % (5 6) % (6 7) % (7 8) % Avrag % Invstgaton on Rar Rport Issu Fgur 4 dpcts th fow-spd data rcordd y a VD ocatd at 4.5 km on th north-ound Numr Hghway n Tawan durng hours n th days of a month. Each dot rprsnts th avrag traffc fow and vhc spd dtctd y th VD n a 5-mn. ntrva. As shown n Fgur 4 th rcordd data dspay a typca fow-vocty curv n an arch shap. Th ft foot of th arch rprsnts traffc congstons whr th traffc fow s modrat and th spd s ow. Th rght foot of th arch rprsnts fr fow (.. ght traffc) whr th fow s ow and th spd s hgh. Th top of th arch rprsnts th maxmum capacty of th road.. th saturatd traffc fow. Th curv ndcats that th traffc s saturatd whn th fow s around 5000 cars pr hour; at that fow th vhc spd s around 60 km/hr Traffc Fow (cars/hr) Vhc's avrag spd (km/hr) Fgur. 4. Th fow-vocty curv rcordd y a VD on No. Hghway Tawan

17 For ach VD rcord.. a data par of traffc fow and spd dspayd n Fgur 4 ths study can stmat th spd rport rat from CFVD usng Eq. (3). In our anayss ths study assums that th ca arrva rat = 0.5 cas/hr and th avrag ca hodng tm / = mn. Th assumptons ar asd on th statstcs of ra fd tra data dscrd atr n ths papr. Th markt shar prcntag of th mo oprator undr study s assumd to 38%.. 38% of th vhcs carryng MSs that can masurd n th cuar ntwork. Th rmanng 62% of th vhcs do not contrut to spd rport masurmnt ut w contrut to th road traffc. Th dstanc twn two handovr ocatons s.5 km whch s a typca ngth of a c damtr. Fgur 5 dpcts that th rats of CFVD spd rports that can gnratd from th ra traffc rcordd y th VD. Th rport rat vrsus spd curv aso dspays an arch shap ut ttd to th rght. Ths mans that th spd rports from CFVD ar rar oth at traffc congstons and at vry ght traffc. As ths study can s from th curv th ack of spd rports s mor svr durng traffc congstons; th xpctd rport rat can as ow as 0.04 pr hour. Ths mans whn th traffc s svry congstd thr s vrtuay no spd rport at a. Th maxmum rport rat s aout 4.4 rports pr hour whch occurs whn th vhc spd s around 90 km/hr.. whn th traffc s nary a fr fow far from saturatd ut th traffc s not ght (th fow s around 3000 pr hour as ndcatd n Fgur 4). Th CFVD spd rport rat mprovs whn th ca hodng tm ncrass. Fgur 6 dpcts th ffcts of ca hodng tm on th spd rport rat. Thr dffrnt avrag ca hodng tms hav n usd /= 2 and 3 mn. Th c damtr s.5 km and 38% of th vhcs carryng MSs that can masurd n th cuar ntwork. Th anaytc rsuts n Fgur 6 ndcat that th spd rport rat mprovs sgnfcanty as th ca hodng tm ncrass. Whn th traffc s svry congstd and th avrag ca hodng tm s 3 mn. mor than 6 spd rports pr hour can otand from CFVD.. n avrag a spd rport vry 0-mn. ntrva whch s satsfactory for TIS appcatons. Th maxmum rport rats ar around 5 6 and 29 for ca hodng tms mn. 2 mn. and 3 mn. rspctvy. Ths ndcats that th rport rat ncrass at a fastr rat than th ca hodng tm ncrass. Howvr th avrag ca hodng tm s aout mn. on th cuar ntworks n Tawan. Ths suggsts that CFVD woud not gnrat spd rports on a svry congstd hghway. Ths study vs that th ack of CFVD spd rports durng congston woud mor svr on surfac strts caus oth th traffc fow and spd ar owr. Spd rport rat (/hr) = 0.5 cas/hr / = mn.5 d =.5 km Vhc's avrag spd (km/hr) Spd rport rat (/hr) Vhc's avrag spd (km/hr) /m /= = mn mn /m /= = 2 2 mn mn /m /= = 3 mn 3 mn = 0.5 cas/hr d =.5 km Fgur. 5. Th spd rport rat of CFVD Fgur. 6. Th ffcts of ca hodng tm on th spd rport rats of CFVD Th Fd Tra Data In gnra th ca arrva rats and th ca hodng tms for th cas orgnatd or trmnatd n movng vhcs may chang whn vhc spds chang. For xamp n a hghway congston pop may start cang and hnc th numr of orgnatng cas ncrass. On th othr hand durng congston

18 th tm takn to trav th sam dstanc twn two handovrs s ongr. As a rsut ra fd tra data nd to anayzd frst for fuy nvstgatng th spd rport rat durng traffc congston. Th contro sgnangs of Chunghwa Tcom s MTS ntwork on a 0-km sgmnt of Numr 3 Hghway Tawan wr coctd for a prod of two wks. Th coctd contro sgnangs ncud NL CA CC and HO. Snc th hghway sgmnt crosss a ocaton ara MSs on th vhcs passng th road sgmnt woud prform two NLs on whn ntrng th sgmnt and th othr whn avng. Th tm ntrva twn th two NLs was usd to dtrmn f th MSs wr on th vhcs travng on th hghway; f an MS s tm ntrva matchs th vhc spd otand y th hghway VDs wthn 25% rror margn th MS s assumd to on th hghway. Th ca arrva rats (CAR) th ca hodng tms (CHT) of th MSs movng on th hghway as w as th vhc spd otand y th VDs wr rcordd. Snc ths study s ntrstd n th ffcts of vhc spd on CHT and CAR for ach 0 km/hr rackt of th vhc spds th avrag CHTs and CARs wr computd. Fgur 7 dpcts th ffcts of vhc spd on CHT and CAR. Th rsuts ndcat that oth CHT and CAR ncras as vhc spd drops ow 50 km/hr.. pop mak or rcv mor and ongr phon cas durng traffc congstons on th hghway. Th CHT ncrass from aout 60 sconds durng fr fow traffc to aout 80 sconds durng traffc congstons. Smary th CAR ncras from 0.43 pr hour to 0.52 pr hour. Ths may partay avat th ffcts of fw CFVD spd rports durng traffc congston. CHT CAR Ca Hodng Tm (sc.) Traffc Spd (km/hr) Ca Arrva Rat (cas/hr) Fgur. 7. Th ffcts of vhc spd on th CHT and CAR From th rsuts dpctd n Fgur 7 ths study has th CHT and CAR for ach vhc spd rackt. Whs study can pug th CHTs CARs and vhc spds nto Equaton (3) to otan th anaytc spd rport rats and compar th anaytc rsuts wth th fd tra data. Two sctd handovr aras ar usd n our anayss; thy ar sctd caus th aras ar ratvy sma and mor accurat CFVD spds can otand. Th dstanc twn th two sctd handovr aras s.7 km. Du to th soft-handovr dsgn of MTS ony 75% of th passng MSs wth on-gong voc communcatons prform th frst handovr and 88% th scond handovr. Thrfor th rport rat otand from our anaytc mod must mutpd y 0.66 (= 0.75*0.88).. ony th cas that prform oth handovrs gnrat spd rports. Fgur 8 pots th CFVD spd rport rats from th anaytc mod and from th fd tra data aganst vhc spds. Ths study osrvs that th anaytc rsuts match th fd tra data n most cass xcpt that th anaytc mod undrstmats th rport rat y 60% whn th vhc spd s ony 30 km/hr. Ths phnomnon s du to th fact that th ca hodng tms ar not xponntay dstrutd and mor phon cas ast ong nough to prform two conscutv handovrs. Howvr oth th anaytc rsuts and th fd tra data ndcat that thr s no CFVD spd rport whn th vhc spd s n th 5 km/hr rackt

19 .. th traffc s svry jammd. Ra Data Anaytc Rsuts 3 Spd Rport Rat (/hr) Traffc Spd (km/hr) Fgur. 8. Th ffcts of vhc spd on th CFVD spd rport rat 3.2 C Pro-Basd Mthod For CP-asd mthod ths study provds a numrca anayss of th proposd mods to dscuss th ffct on ra vhc spd and vhc spd stmaton accuracy n Scton Morovr th trac-drvn xprmnts ar dsgnd to smuat th traffc and communcatons nvronmnts for traffc nformaton stmatons n Scton Numrca Anayss Th numrca anayss of traffc dnsty stmaton asd on th amounts of CAs and PLs s gvn and dscussd n ths scton Numrca Anayss of Traffc Informaton Estmaton from Ca Arrvas Ths study frst apps th ra spd data otand from th spcfc VD on a hghway n Tawan to Formua (7) and drv th stmatd amount of cas. Ths study uss th amount of cas to compar th stmatd traffc dnsty wth ra traffc dnsty to show th corraton twn thm. Thn ths study compars th stmatd vhc spd wth ra vhc spd. Fnay ths study dscusss th proposd mod y usng dffrnt vaus for ca arrva rat Estmatd Vhc spd Drvd y Ra Data from VD Fgur 9 shows th ra traffc nformaton whch ncuds traffc dnsty and vhc spd from spcfc VD at 42 km mpost on hghway n Tawan durng Fruary For th amount of ca arrvas ths study adopts th foowng paramtrs: =.0 km and = ca/hr accordng to th statstca rsuts coctd y Chunghwa Tcom n Tawan. Fgur 9 shows th stmatd traffc dnsty drvd from Formuas (7) and (8) usng th ra traffc data from VD ogs as nputs. Th rsuts show that th avrag asout dffrnc twn th ra traffc dnsty and stmatd traffc dnsty s 0.63%. Ths study osrvs that th ra traffc dnsty and stmatd traffc dnsty ar qut smar. That s ths study can rtrv th stmatd traffc dnsty (k ) on th road sgmnt covrd y th spcfc c from cuar ntworks to stmat th ra-tm traffc dnsty of th road sgmnt. For vhc spd stmaton ths study adopts th stmatd traffc fow and stmatd traffc dnsty from th rsuts n Fgur 20. Thn ths study uss Formuas (8) and (4) to stmat vhc spd y usng

20 VD ogs. Th rsuts show th avrag asout dffrnc twn th ra vhc spd and stmatd vhc spd s 0.63% n Fgur 2. Fgur. 9. Th ra traffc nformaton (vhc spd and traffc dnsty) from VD Fgur. 20. Th stmatd traffc dnsty n th spcfc c y usng VD ogs Traffc Spd Estmaton Accuracy (%) 00% 99% 98% 97% 96% 95% = 3600 car/hr = ca/hr = km 94% Ra Traffc Spd (km/hr) Fgur. 2. Th ra vhc spd and th stmatd vhc spd Fgur. 22. Th corraton of ra vhc spd and vhc spd stmaton accuracy Effct on Ra Vhc spd and Vhc spd Estmaton Accuracy In ths scton ths study consdrs th ra vhc spd ( ) and stmatd vhc spd (u ) to u cacuat th vhc spd stmaton accuracy whch s dfnd as. In ths papr ths study uss = ca/hr accordng to th actua statstca rsuts coctd y Chunghwa Tcom n Tawan. To show th corraton twn vhc spd stmaton accuracy and ra vhc spd ( )ths study adopts th foowng paramtrs: = 3600 car/hr =.0 km and ca arrva rat = ca/hr. Fgur 22 dpcts that th accuracs of spd stmaton ar hghr than 94.92% whn ra vhc spd ( )rangs from 0 to Numrca Anayss of Traffc Informaton Estmaton from Prodc Locaton pdats In ths scton ths study anayzs th raton twn th amount of PL vnts and traffc dnsty to vauat th fasty of our traffc nformaton stmaton mod. For th purpos of dmonstraton ths study adopts som paramtrs as foowngs to stmat th traffc dnsty and th amount PL vnts: = 5000 car/hr = ca/hr = km and = hr. Fgur 23 shows that th amount of PL vnts (p ) coud rfct th trnd of th actua traffc dnsty (K ) wth dffrnt vhc spds. Whn th vhc spd gts hghr th amount of PL vnts (p ) and traffc dnsty (K ) w rducd. Whn th vhcs ar n

21 hgh-spd stat th amount of PL vnts stmat th traffc dnsty w provdd wth hgh accuracy. In ow-spd and hgh traffc dnsty stat th amount of PL vnts (p ) w hghr aftr th product procss wth 3 2 to corrspond wth th traffc dnsty (K ). Thrfor ths mod can usd to stmat traffc nformaton for ITS to anayz th traffc nformaton. D (car/hr) v (km/hr) Dnsty f = 5000 car/hr = (ca/hr) = (km) c = (hr) PL u (vnt/hr) Fgur. 23. Th raton twn th amount of PL vnts and traffc dnsty wth dffrnt vhc spds Smuaton Rsuts In ths scton ths study dsgns trac-drvn xprmnts to nvstgat th traffc nformaton stmatons from CFVD. Fgur 24 ustrats ths approach that conssts of th vhc movmnt trac gnraton MS communcaton trac gnraton and th comnd trac gnraton of th two havors. Th nputs of trac gnrator ncud th road condtons (.g. th ngth of th road th numr of ans th ocatons of handovr ponts and traffc fow) th vhc movmnt havors (.g. th dsrd spds th car foowng mod and an-changng mod) and MS communcaton havors (.g. norma ocaton updat and ca ntr-arrva tm). Th output s a trac f whch rcords th vhc s ID dsrd spd ts ocatons ts ca arrva tm and ts ca dpartur tm. Ths trac fs ar otand from th traffc smuators as w as ra masurmnts of a hghway n Tawan. In addton thy ar usd to drv th moty managmnt smuator to stmat th ra-tm traffc nformaton whch ncuds spd and traffc dnsty. Fgur. 24. Trac-drvn Smuaton for th traffc nformaton stmatons from cuar-ntwork-asd data Tracs Gnratd from a Traffc Smuator Th vhc movmnt and MS communcaton tracs ar gnratd y a traffc smuaton program VISSIM (Panung Transport Vrkhr AG 2009). Th hghway scnaro whch s charactrzd y th Wdmann psycho-physca car-foowng mod and an changng mod whr th vhc spds rang from 85 km/hr to 20 km/hr and th ngth of a 3-an hghway s 0 km. Fgur 25 shows 0

22 handovr ponts and 0 cs dstrutd n 4 ocaton aras on th road from 0 km to 0 km and th covrag of a c s km. Morovr ths study assums that thr ar 0 VDs whch ar ut n th sam ocatons wth handovr ponts. Thos VDs can coct th ra-tm traffc nformaton ncudng vhc spd and traffc dnsty. In ach smuaton run up to 3600 vhcs ar njctd n th road durng smuatd hour whr th dsrd spd of a vhc s unformy randomy sctd twn km/hr. For MS communcaton havors ths study gnrats th random numrs of ca hodng tm and ca ntr-arrva tm for ach MS n car. Th ca hodng tm s xponntay dstrutd wth th man / and th ca ntr-arrva tm s xponntay dstrutd wth th man / (Ln t a. 20a). Fgur. 25. Th dstruton of cs ocaton aras and VDs n smuaton xprmnt Th assumptons usd n th xprmnts ar summarzd ow. Th ra vhc spd km/hr ra traffc dnsty K car/km and ra traffc fow car/hr aong th road can otand from th VD data on th road sgmnt covrd y C. Th stmatd vhc spd u km/hr stmatd traffc dnsty k car/km and stmatd traffc fow q car/hr aong th road can otand from th CFVD data on th road sgmnt covrd y C. Th xpctd vau (/) of ca ntr-arrva tm s hr/ca. Th accuracy of vhc spd stmaton s xprssd as u Traffc Fow Estmaton Accuracy In th proposd approach th ra amounts of NLs and HOs from C ar coctd from CFVD to gnrat q n and q h. Bcaus NL s ony prformd wth MS ntrng nw LA th stmatd traffc fows ar consstnc n th sam LA n th proposd approach. For xamp a of th stmatd traffc fows q n q 2n and q 3n n LA ar 3547 NL vnts. Morovr thr ar 66 HOs (.. th amount of HOs h ) whch man th stmatd traffc fow (q h ) s 3960 car/ht n accordanc wth th MS communcaton havors (.g. th xpctd vau (/) of ca hodng tm s mn/ca) on th road sgmnt covrd y C n LA n xprmnts. Ths study cacuats th accuracs of traffc fow stmaton as q n and q h. As shown n Ta 2 th rsuts of th traffc fow comparsons wth NL and HO ndcat that th amount of NLs s mor suta for traffc fow stmaton than th amount of HOs.

23 Ta. 2. Th comparsons of traffc fow stmaton accuracy LA C K q n h q h q n q h % 88.36% % 84.09% % 96.30% % 92.4% % 76.29% % 76.53% % 94.23% % 84.43% % 9.6% % 96.75% Avrag 98.92% 88.03% Traffc Dnsty Estmaton Accuracy In ths scton th comparsons of traffc dnsty stmaton accuracs asd on th amounts of CAs and PLs ar gvn and dscussd Traffc Dnsty Estmaton Basd on Ca Arrvas In th proposd approach th ra amount of CAs from C s coctd from CFVD to gnrat th stmatd traffc dnsty (k a ). Thr ar 38 cas (.. th stmatd traffc dnsty k a ) whch ar gnratd y MS accordng th MS communcaton havors (.g. th xpctd vau (/) of ca ntr-arrva tm s hr/ca) on th road sgmnt covrd y C n LA n xprmnts. Ths study compars th stmatd traffc dnsty k a wth th ra traffc dnsty K whch s cacuatd as / from VD No.. As shown n Ta 3 th rsuts of th traffc dnsty comparsons wth VD and CFVD ndcat that th avrag traffc dnsty accuracy s 93.92% y CFVD Traffc Dnsty Estmaton Basd on Prodc Locaton pdats In ths scton th ra amount of PLs (p ) from th spcfc C s coctd from cuar ntwork data to gnrat th stmatd traffc dnsty k p y Formuas (2) and (3). Ths study compars th stmatd traffc dnsty k p wth th actua traffc dnsty K and cacuat th traffc dnsty stmaton accuracy K k p K. Th actua traffc fow traffc dnsty and vhc spd wr coctd from spcfc VD at 42 km mpost on Natona Hghway No. n Tawan durng 24 hours on 3 Juy For xamp th traffc nformaton whch ncuds vhc spd traffc dnsty and traffc fow on th road sgmnt covrd y C s dpctd n Fgur 26. Ths study compars th stmatd traffc nformaton wth th ra traffc nformaton from VD. By stmatng smuaton of C th smuaton rsuts of actua and stmatd traffc dnsty ar prsntd n Fgur 27. Thr ar fwr vhcs on th road and wth hgh-spd durng ary mornng hours (.g. 2 a.m.

24 - 7 a.m.). sng Formua (3) to stmat th traffc dnsty k p whch s consstnt wth th actua traffc dnsty K th rsuts wr corrspondng wth th traffc dnsty s ow and th amount of th PL vnts ar aso ss. Comparatvy th traffc dnsty apparancs two hgh paks as an M-shap durng rush hours (.g. 8 a.m. - 9 a.m. and 7 p.m. - 8 p.m.). Ta. 3. Th comparsons of traffc dnsty stmaton accuracy LA C K q k a K k a K % % % % % % % % % % Avrag 93.92% Fow (car/hr) Smuaton Tm (hr) Dnsty (car/km) Spd (km/hr) Fow Spd Actua Dnsty Fgur. 26. Th ra-tm traffc nformaton on th road sgmnt covrd y C Th stmaton mthod prsnts th trnd of traffc dnsty wth th avrag accuracy of on day for ach c s 76.33% y usng th accuracy stmaton s xprssd as K k p K. Ths study aso cocts and anayzs th handovr vnts to stmat traffc dnsty (Chang t a. 203a). Th avrag accuracy of on day for ach c whch s 75.29% s owr than that of proposd mthod Actua Dnsty Estmatd Dnsty y sng HO vnts Estmatd Dnsty y sng PL vnts Dnsty (car/km) Smuaton Tm (hr) Fgur. 27. Th comparson of actua and stmatd traffc dnsty on th road sgmnt covrd y C

25 Vhc Spd Estmaton Accuracy In accordanc wth th rsuts n Sctons and th traffc fow stmaton accuracy s ttr asd on th amount of NLs and th traffc dnsty stmaton accuracy s ttr asd on th amount of CAs. Thrfor ths study uss th stmatd traffc fow q n and stmatd traffc dnsty k a to stmat th vhc spd u na y Formua (4). Th stmatd vhc spd u na can cacuatd as q /k. For xamp th stmatd vhc spd u na s km/hr whn th stmatd traffc fow q n s 3547 car/hr and stmatd traffc dnsty k a s 38 car/km. Thn ths study compars th stmatd vhc spd wth th ra vhc spd from VD No. n xprmnts. As shown n Ta 4 th avrag spd accuracy s 92.92% y CFVD. Ta. 4. Th comparsons of vhc spd stmaton accuracy LA C q k u na Vhc spd Estmaton Accuracy % % % % % % % % % % Avrag 92.92% Ths study aso usd two-tad t-tst to dtrmn sgnfcanc of th dffrnc twn ra vhc spd and stmatd vhc spd u na. Ta 5 shows th t-tst for th popuaton mans of two ndpndnt samps and s st to Comparng th popuaton mans th tst rsuts show that P-Vau s 7.63% and thr s not sgnfcanty dffrnc. Thrfor th nu hypothss (H0: u na ) s accptd. Ta. 5. t-tst for ra vhc spd and stmatd vhc spd u na Man Varancs t-vau 2.00 Crtca Vau 2.26 P-Vau 7.63% For CP-asd mthod ths study adopts som paramtrs as foows to stmat th vhc spd: f = 90 km/hr = 50 km/hr and h = 85 km/hr. Th CFVD from Chunghwa Tcom and th VD data from

26 Tawan Ara Natona Frway Burau ar rcordd durng 200 for tranng and tstng. Ta 6 shows that th avrag accuracy of th CP-asd mthod n ths xprmnt days s 97.48%. 3.3 Comparsons wth th Proposd Mthods Th comparsons of dpoymnt and computaton cost and vhc spd stmaton accuracy ar gvn n ths scton Th Comparson of Dpoymnt and Computaton Cost For computng cost th rportng rats of th FPA-asd mthod (r f ) and th rportng rats of th HO-asd mthod (r h ) wr compard. Th rportng rat mod for th handovr-asd mthod was proposd and anayzd as Eq. (3). Th paramtr D(L L 2 ) s dfnd as th ngth of a road sgmnt twn two conscutv handovr vnts (shown n Fgur 3). Th avrag D(L L 2 ) on th frway n Tawan s aout.5 km. Thrfor th foowng paramtrs wr adoptd to stmat th avrag spd rat: = ca/hr / = 60 sc d = 5 km and D(L L 2 ) =.5 km. Th rportng rats of ths mthods ar shown n Ta 7 and Fgur 28 and th vau r f /r h ndcats th comparson of th rportng rat and computng cost. Th rsuts show th FPA-asd mthod rqurd mor computng cost than th HO-asd mthod. Ta. 6. Th spd stmaton accuracs of th CP-asd mthod Dat Day Vhc Spd Estmaton Accuracy 200/09/03 Frday 98.55% 200/09/04 Saturday 98.40% 200/09/05 Sunday 97.85% 200/09/06 Monday 98.57% 200/09/07 Tusday 98.9% 200/09/08 Wdnsday 98.45% 200// Thursday 98.0% 200//2 Frday 96.64% 200//3 Saturday 96.94% 200//4 Sunday 95.5% 200//24 Wdnsday 98.8% 200//27 Saturday 97.72% 200//28 Sunday 95.7% Avrag 97.48% Furthrmor A-s and Iu ntrfacs ar ndd to montord for FPA-asd mthod (shown n Ta 8). Th numr of ths ntrfacs n Tawan s argr than 0000 and mor montor srvrs ar rqurd. Athough th FPA-asd mthod can provd th owr rror rato of vhc spd stmaton than HO-asd mthod th cost of FPA-asd mthod s too xpnsv. Howvr th numr of A and IuCS ntrfacs n Tawan s smar than 00. Thrfor n th vw of cost HO-asd mthod and CP-asd mthod ar mor suta for ITS.

27 Ta. 7. Th comparson wth FPA-asd mthod and HO-asd mthod FPA-asd Mthod (r f ) HO-Basd Mthod (r h ) r f /r h Rport rat (count/hr) Spd (km/hr) = ca/hr = 3000 car/hr d = 5 km =.5 km Th Proposd Mthod ( rf ) Handovr-Basd Mthod ( rh ) Fgur. 28. Th comparson of FPA-asd mthod and HO-asd mthod Ta. 8. Th comparson wth th proposd mthods HO-asd FPA-asd CP-asd Montord Intrfacs A and IuCS A-s and Iu A and IuCS Th numr of rqurd srvrs < 00 > 0000 < 00 Th rror rato of spd stmaton 7.30% 3.39% 2.52% Th Comparson of Vhc Spd Estmaton Accuracy For vhc spd stmaton ths study anayzs th cuar ntwork sgnangs from Chunghwa Tcom and provds th comparson wth NL-asd mthod (Cacrs t a. 2007) HO-asd mthod and CP-asd mthod. Th am of th xprmnts s to anayz th accuracs of vhcs spd stmaton asd on th dffrnt mthods. Th contro sgnangs of Chunghwa Tcom s MTS ntwork on a 2-km sgmnt of Numr 3 Hghway Tawan wr coctd durng hours of 4 days. Th coctd contro sgnangs ncud NL CA and HO and th traffc nformaton rportng cyc s 5 mn/cyc. Th rsuts of a cas study of 20/0/07 ar showd n Ta 9 and Fgur 29. Th spds asd on NL-asd mthod ar sow

28 twn 8 p.m. (th 26-th cyc) and 20 p.m. (th 240-th cyc) ut a spds of VD twn ths prods ar fastr than 80 km/hr. Thrfor th status of othr road sgmnts may nfunc th NL-asd spd to gnrat th argr spd stmaton rrors. Athough HO-asd mthod can provd good accuracy th numr of avaaty cycs s ony 4 on durng hours on 20/0/07. Morovr th spd stmaton accuracy of th CP-asd mthod s aout 97% and th avaaty rato of ths mthod s 00%. Thrfor th CP-asd mthod s mor suta for ITS. Ta. 9. Th comparson of vhc spd stmaton accuracy NL-asd HO-asd CP-asd Accuracy 93% 89% 97% Avaaty cycs Avaaty rato 00% 9% 00% Spd (km/hr) NL SHO_Sg2 CFVD_sg2 CP VD Sg Tm (cyc/5mn) Fgur. 29. Th comparson of vhc spd stmaton accuracy 4. Concusons and Futur Work Svra studs hav rvwd and anayzd how to otan th traffc nformaton from CFVD. Howvr thy can not provd th nformaton of traffc dsty and traffc congston snc th stat of fr fow s poss wth hgh traffc fow. Thrfor ths study proposs thr vhc spd stmaton mthods whch ncud HO-asd mthod FPA-asd mthod and CP-asd mthod to anayz th cuar ntwork sgnangs. Morovr som anaytca mods ar proposd to vauat th raton of cuar ntwork sgnangs (.g. RSSI CA HO NL and PL) and traffc nformaton (.g. traffc fow traffc dnsty and vhc spd). In xprmnts ths study compars th ra traffc nformaton of VD wth th stmatd traffc nformaton y th proposd mthods. Athough FPA-asd mthod can provd good vhc spd stmaton accuracy t nds to rtrv th cuar ntwork sgnangs va A-s and Iu ntrfacs. Howvr HO-asd mthod and CP-asd mthod nd to rtrv th cuar ntwork sgnangs va A and IuCS ntrfacs whch ar usuay montord n ach tcom company. Thrfor th dpoymnt and computaton cost of FPA-asd mthod s too xpnsv and s not suta for vhc spd stmaton. Morovr th xprmnt rsuts show that th accuracy of vhc spd stmaton y CP-asd mthod whch s 97.48% s hghr than HO-asd mthod and FPA-asd mthod. Thrfor th CP-asd mthod can usd to stmat vhc spd from CFVD for ITS. As dmand for ra-tm traffc nformaton ncrass th nxt goa s to stmat and anayz th traffc congston and transportaton days for ITS wth th proposd mods. Morovr th proposd

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