SCIENCE CHINA Technological Sciences RESEARCH PAPER March 2011 Vol.54 No.3: 625 629 doi: 10.1007/s11431-010-4256-1 Vehicle survival paerns in China HAO Han 12 WANG HeWu 12* OUYANG MingGao 12 & CHENG Fei 1 1 Sae Key Laboraory of Auomoive Safey and Energy Tsinghua Universiy Beijing 100084 China; 2 China Auomoive Energy Research Cener (CAERC) Tsinghua Universiy Beijing 100084 China Received July 1 2010; acceped December 10 2010; published online January 27 2011 The vehicle survival paern describes he process ha he survival raio of vehicles decreases wih he growh of vehicle age. Vehicle average life span and vehicle scrappage inensiy are he key feaures of vehicle survival paerns and are imporan for he projecion of China s vehicle scrappage and ownership. In his sudy we modeled he vehicle survival paerns of nine classificaions of vehicles in China by employing he Weibull disribuion and obained he vehicle survival raio funcions. I is esimaed ha he average life spans of privae passenger vehicles governmen and business vehicles non-operaing buses heavy duy medium duy and ligh duy rucks are 14.5 13.1 11.5 12.8 10.1 and 8 years respecively. The scrappage inensiies of hese vehicles are similar. Average life spans of axis ransi buses and non-ransi operaing buses are 5 9 and 5.5 years wih he paern of mandaory scrappage. Vehicle scrappages in China are mainly regulaed by he upper limis of vehicle disances raveled specified by he compulsory scrappage sandards. vehicle survival paern average life span scrappage inensiy Ciaion: Hao H Wang H W Ouyang M G e al. Vehicle survival paerns in China. Sci China Tech Sci 2011 54: 625629 doi: 10.1007/s11431-010-4256-1 1 Inroducion *Corresponding auhor (email: wanghw@singhua.edu.cn ) Since he 1990s China s vehicle annual producion and sales have experienced rapid growh. In 2009 hey reached 13.79 and 13.64 million respecively [1]. The increase of vehicle producion and sales were followed by he increase of vehicle scrappage. To regulae vehicle scrappage China implemened he compulsory scrappage sandards in 1986 and revised he sandards in 1997. The compulsory scrappage sandards specify he upper limis of service imes and disances raveled for differen classificaions of vehicles. The vehicle survival paern describes he process ha he survival raio of vehicles decreases wih he growh of vehicle age. Vehicle average life span and vehicle scrappage inensiy are he key feaures of vehicle survival paern and are imporan for he projecion of China s vehicle scrappage and ownership. The vehicle survival paern is affeced by many facors including he compulsory scrappage sandards designed lifeime and service condiion. Numerous sudies have been conduced on vehicle survival paerns in wesern counries since he 1950s when hose counries began o face an increasing number of vehicle scrappages [2 5]. Sudies on China s vehicle scrappage paerns were carried ou afer 2000. Yang e al. used he age disribuion and populaion of Beijing s ligh duy passenger vehicles in 1995 and he number of vehicles scrapped beween 1997 and 2002 and employed Weibull disribuion o esimae he vehicle survival paern of Beijing s ligh duy passenger vehicles [6]. The mehodology of his sudy is based on he invesigaion of vehicle age disribuion and is appropriae o be used in local area sudy. Argonne Naional Laboraory esimaed China s vehicle scrappage paerns by making adjusmens o foregone paerns according o he 1997 compulsory scrappage sandards and projeced fuure rends of he paerns [7]. This mehodology has low requiremen Science China Press and Springer-Verlag Berlin Heidelberg 2011 ech.scichina.com www.springerlink.com
626 Hao H e al. Sci China Tech Sci March (2011) Vol.54 No.3 on daa and is appropriae o be used when scrappage daa are no complee. In his sudy we employed Weibull disribuion o model China s vehicle survival paerns and regressed he key coefficiens of he model based on available daa. 2 Modeling of vehicle scrappage paerns 2.1 Vehicle survival raio and scrappage rae funcion Weibull disribuion was named afer Waloddi Weibull who described i in deail in 1951. I is widely used in he field of reliabiliy engineering. The failure laws of many elecronic and mechanical producs are in accordance wih he Weibull disribuion [8]. In his sudy we employed Weibull disribuion o model China s vehicle survival paerns. Vehicle scrappage rae is defined as he absolue value of he derivaive of vehicle survival raio wih respec o vehicle age. The funcions of vehicle survival raio and vehicle scrappage rae are described as k SP () SR () exp (1) RP Tim u k 1 kim im k () exp kim T T where SR im () is he survival raio of vehicles (ype m regisered in year i) a he vehicle age of ; SP im () is he number of no-scrapped vehicles (ype m regisered in year i) a he vehicle age of ; RP im is he oal number of vehicles of ype m regisered in year i; T im and k im are he characerisic parameers; v im () is he scrappage rae of vehicles (ype m regisered in year i) a he vehicle age of. Figure 1 is he schemaic diagram of vehicle survival raio and scrappage rae modeled by Weibull disribuion (T im =10 k im =4). The curve of vehicle survival paern can be divided ino hree phases. 1) In he preliminary sage vehicle survival raio is close o 1 and vehicle scrappage rae is quie low implying ha few vehicles are scrapped during he firs several years afer regisraion. 2) In he mass scrappage sage vehicle survival raio decreases quickly and vehicle scrappage rae is quie high implying ha quaniies of vehicles are inensively scrapped in his sage. 3) In he final sage boh vehicle survival raio and vehicle scrappage rae are approaching 0 implying ha mos regisered vehicles have been scrapped. The vehicle survival paern presened in Figure 1 agrees well wih he acual siuaion of vehicle scrappage. Leing =T im and subsiuing ino eq. (1) we obain SR im (T im )=1/e. I means ha when vehicle age reaches T im he vehicle survival raio reaches 1/e abou 36.8%. We define his raio as he characerisic raio and define T im as he vehicle average life span. (2) Figure 1 Schemaic diagram of vehicle survival raio and scrappage rae funcions. In his sudy we define ST im as he ime needed for vehicle survival raio o decrease from 90% o 10% as described by 1/ k 1/ k STim T (2.3 0.11 ). (3) The derivaive of ST im wih respec o k im is negaive implying ha ST im decreases when k im increases. The bigger k im he more inensive he vehicle scrappage. 2.2 Influencing facors of he model 2.2.1 The compulsory scrappage sandards The vehicle survival paern is affeced by many facors including he compulsory scrappage sandards designed lifeime and service condiion. The compulsory scrappage sandards specify he upper limis of service imes and disances raveled for differen classificaions of vehicles and have decisive impac on vehicle survival paerns. China announced he firs compulsory scrappage sandards in 1986 [9]. The sandards were revised in 1997 wih a more deailed classificaion of vehicles and scrappage limiaions [10]. The sandards were revised wih minor changes in 1998 and 2000 [11 12]. In 2006 China adoped he exposure draf of he new scrappage sandards [13]. The aleraions of he sandards lead o he changes of vehicle survival paerns. 2.2.2 Vehicle classificaion In his sudy we caegorized vehicles by hree dimensions of vehicle ype purpose and erriory of use as presened in Figure 2. The survival paerns of privae passenger vehicles governmen and business vehicles and non-operaing buses were obained based on firs-hand vehicle scrappage daa. The survival paerns of rucks were obained based on saisical daa of vehicle regisraion and populaion. The survival paerns of axis ransi buses and non-ransi operaing buses were obained based on he survey daa of annual disances raveled of hese vehicles and he upper limis of disances raveled specified by he compulsory scrappage sandards.
Hao H e al. Sci China Tech Sci March (2011) Vol.54 No.3 627 Figure 2 Vehicle classificaion in his sudy. 3 Parameer regression 3.1 Privae passenger vehicles governmen and business vehicles and non-operaing buses In China s saisical sandard of vehicle regisraion and populaion privae passenger vehicles governmen and business vehicles and non-operaing buses can no be separaed from he oal. In his sudy we esimaed he survival paerns of hese vehicles based on firs-hand vehicle scrappage daa. A oal number of 7024 scrappage records were colleced from Beijing Lianhe Vehicle Scrappage Company including 2765 samples of privae passenger vehicles 1472 samples of governmen and business vehicles 1088 samples of non-operaing buses and 1699 scrappage records of oher classificaions of vehicles. The scrappage records include he informaion of vehicle ype purpose of usage regisraion dae scrappage dae and owner of he vehicle. The scrappage daes are beween June 2006 and April 2010. Vehicles in oher areas of China are required o mee he same compulsory scrappage sandards implying ha samples from Beijing can largely represen he overall siuaion of China. Figure 3 presens he obained vehicle scrappage daa from Beijing Lianhe Vehicle Scrappage Company. The scrappage daes of mos records are afer 1997 implying ha hese scrappage were mosly deermined by he 1997 compulsory scrappage sandards. Therefore i is assumed ha he survival paern model parameers regressed by hese samples are consan. T jm and k jm are reduced o T m and k m. The parameers are regressed based on eq. (1) and he resuls are lised in Table 1. Figure 3 Vehicle scrappage daa from Beijing Lianhe Vehicle Scrappage Company. Table 1 Regressed coefficiens of he vehicle survival paerns in China Vehicle classificaion T m k m Remarks Privae passenger vehicles 14.46 4.79 Governmen and business buses 13.11 5.33 Non-operaing vehicles 11.53 5.08 Heavy duy rucks 12.8 5.58 Medium duy rucks 10.09 5.58 Ligh duy rucks 8.02 5.58 Taxis 5 Transi buses 9 Non-ransi operaing buses 5.5 The sample daa represen he effec of he 1997 compulsory scrappage sandards. The sample daa mainly represen he effec of he 1997 compulsory scrappage sandards. T m was esimaed based on he 1997 compulsory scrappage sandards.
628 Hao H e al. Sci China Tech Sci March (2011) Vol.54 No.3 3.2 Trucks Hisorical saisical daa of ruck regisraion and populaion are available which can be used o regress he parameers of he ruck survival paern models. In his sudy he parameers were regressed using VP RP SR ( j i ) (4) jm im im i j where VP jm is he vehicle populaion of vehicle ype m a he end of year j. Eq. (4) describes he fac ha he vehicle populaion a he end of year j is he sum of survived vehicles regisered in he previous years (including vehicles regisered in year j). In his sudy he parameers of he ruck survival paern models were regressed based on saisical daa of ruck regisraion from 1980 o 2004 and ruck populaion from 2000 o 2004 as lised in Table 2 [7]. The ruck scrappages beween 1980 and 2004 were mosly deermined by he 1986 and 1997 compulsory scrappage sandards. During he period when he 1986 compulsory scrappage sandards were in effec he ruck regisraions were quie low implying ha survival paerns of his period had lile influence on he paerns aferwards. To simplify he models we assumed ha ruck scrappage beween 1980 and 2004 were deermined by he same compulsory scrappage sandards and he parameers of survival paern models were consan. To furher reduce he difficuly of parameer regression we firsly regressed parameer k m using he oal regisraion and populaion of rucks. Then we fixed he obained k m and regressed T m for heavy duy medium duy and ligh duy rucks respecively. The resuls are lised in Table 1. 3.3 Taxis ransi buses and non- ransi operaing buses In China he majoriy of axis ransi buses and non-ransi operaing buses are owned and managed by companies. They are managed in a flee and scrapped mandaorily. The vehicle age of scrappage depends on he service condiions of vehicles and he compulsory scrappage sandards. According o he 1997 compulsory scrappage sandards he upper limis of service imes and disances raveled were 8 a and 500000 km for axis 10 a and 500000 km for ransi buses and 10 a and 600000 km for non-ransi operaing buses. I is invesigaed ha he annul disances raveled are 80000 120000 km for axis 45000 65000 km for ransi buses and 80000 100000 km for non-ransi operaing buses [14 16]. In his sudy we esimaed he annual disances raveled by aking he averages. In his case axis ransi buses and non-ransi operaing buses reach he limied disances raveled specified by he compulsory scrappage sandards a he vehicle ages of 5 9 and 5.5 a which are all lower han he limied service imes respecively. k m is assumed o be infinie o reflec he paern of mandaory scrappage. 4 Resuls and analysis The parameers of vehicle survival paern models were regressed as lised in Table 1. Based on parameers in Table 1 Figure 4 presens he survival raio funcions of all classificaions of vehicles. The followings can be concluded. 1) The average life span of privae passenger vehicles is higher han ha of governmen and business vehicles. This conclusion agrees well wih he acual fac. There are wo reasons for his phenomenon. The firs is ha operaing frequency of governmen and business vehicles is higher han ha of privae passenger vehicles; he second is ha he governmen and business cusomers are less sensiive o he cos of vehicle replacemen and have more moivaion o scrap he old vehicles. 2) Heavier rucks have longer average life span han ligher ones. This phenomenon agrees well wih he foreign sudies. The high cos of displacing heavy duy rucks reduces cusomer s will o scrap he old ones. Besides he upper limis of disances raveled for heavy and medium duy rucks are higher han ha for ligh duy rucks according o he compulsory scrappage sandards. 3) The values of parameer k m for privae passenger vehicles governmen and business vehicles non-operaing buses and rucks are similar implying ha heir scrappage inensiies Table 2 China s new regisraion and populaion of rucks New regisraion (housand) Populaion (million) Heavy duy Medium duy Ligh duy Heavy duy Medium duy Ligh duy 1980 2 93 99 0.4 2.3 3.6 1990 21 196 180 0.6 2.2 3.7 2000 84 157 523 0.8 2.1 4 2001 148 163 511 1 1.9 4.4 2002 248 164 661 1.3 1.8 4.8 2003 258 138 825 0.4 2.3 3.6 2004 371 175 979 0.6 2.2 3.7
Hao H e al. Sci China Tech Sci March (2011) Vol.54 No.3 629 he projecion of China s vehicle scrappage and ownership. Suppored by he Naional High Technology Research and Developmen Program of China ( 863 Projec) (Gran No. 2008AA11A157). Figure 4 Vehicle survival raio funcions of all classificaions in China. are similar. 4) The average life spans of axis ransi buses and non-ransi operaing buses are quie low and hese vehicles are mandaorily scrapped. 5) The survival raios of all classificaions of vehicles are approaching 0 before hey reach he limied service ime specified by he compulsory scrappage sandards implying ha vehicle scrappage in China are mainly regulaed by he upper limis of vehicle disances raveled specified by he compulsory scrappage sandards. 5 Conclusive remarks In his sudy we modeled he vehicle survival paerns in China by nine vehicle classificaions and obained he survival raio funcions of vehicle age. I can be concluded ha among passenger vehicles he average life span of privae passenger vehicles is higher han ha of governmen and business vehicles. Heavier rucks have longer average life span han ligher ones. The average life spans of axis ransi buses and non-ransi operaing buses are quie low and hese vehicles are mandaorily scrapped. Vehicle scrappage in China are mainly regulaed by he upper limis of vehicle disances raveled specified by he compulsory scrappage sandards. The resuls obained by his sudy are valuable for 1 China Auomoive Technology & Research Cener. China Auomoive Indusry Yearbook 2010. Beijing: China Auomoive Indusry Yearbook Press 2010 2 Walker F V. Deerminans of auo scrappage. Rev Econ Sais 1968 50(4): 503 506 3 Parks R W. Deerminans of scrapping raes for poswar vinage auomobiles. Economerica 1977 45(5): 1099 1115 4 Greenspan A Cohen D. Moor vehicle socks scrappage and sales. Rev Econ Sais 1999 81(3): 369 383 5 Chen C Niemeier D. A mass poin vehicle scrappage model. Transp Res PT B-Mehod 2005 39(5): 401 415 6 Yang F Yu L Song G H e al. Survival probabiliy-based dynamic vehicle age disribuion model. China Safey Sci J 2005 15(6): 24 27 7 Huo H Wang M Johnson L e al. Projecion of Chinese moor vehicle growh oil demand and CO 2 emissions hrough 2050. Transp Res Rec 2007 2038: 69 77 8 Pinder III J E Wiener J G Smih M H. The Weibull disribuion: A new mehod of summarizing survivorship daa. Ecology 1978 59(1): 175 179 9 Naional Economy Commisssion. Regulaions on Acceleraing he Scrappage of Old Vehicles. Beijing: Naional Economy Commisssion 1986 10 Office of Naional Vehicle Scrappage Leading Group. Vehicle Scrappage Sandards. Beijing: Office of Naional Vehicle Scrappage Leading Group 1997 11 Office of Naional Vehicle Scrappage Leading Group. Announcemen on Adjusing he Scrappage Sandards for Ligh Duy Trucks. Beijing: Office of Naional Vehicle Scrappage Leading Group 1998 12 Office of Naional Vehicle Scrappage Leading Group. Announcemen on Adjusing Some Clauses of he Scrappage Sandards. Beijing: Office of Naional Vehicle Scrappage Leading Group 2000 13 Naional Developmen and Reform Commission. Compulsory Scrappage Sandards for Moor Vehicles (exposure draf). Beijing: Naional Developmen and Reform Commission 2006 14 China Academy of Transporaion Science. Curren saus and projecion of China s moor vehicle populaion and annual disance raveled. In: 2010 Conference on he China Susainable Energy Program of Energy Foundaion. Beijing: Energy Foundaion 2010 15 China Auomoive Technology & Research Cener. Invesigaion of disance raveled of passenger vehicles in some ciies. In: 2010 Conference on he China Susainable Energy Program of Energy Foundaion. Beijing: Energy Foundaion 2010 16 Vehicle Emission Conrol Cener. Progress on invesigaion of China s moor vehicle annual disance raveled. In: 2010 Conference on he China Susainable Energy Program of Energy Foundaion. Beijing: Energy Foundaion 2010