Taiwan, R.O.C.; PH (886-2) ; FAX (886-2) ; (886-4) ; FAX (886-4) ;

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1 Using On-Road Data to Correct Underestimations of Fuel Consumptions of Motorcycles from Laboratory Tests P. C. WEN 1, H. Y. CHEN 2, C. W. CHUANG 3, and Y. W. YANG 4 1 International Division, Chung-Hua Institution for Economic Research, Taipei, Taiwan, R.O.C.; PH (886-2) ; FAX (886-2) ; pam@cier.edu.tw 2 International Division, Chung-Hua Institution for Economic Research, Taipei, Taiwan, R.O.C.; PH (886-2) ; FAX (886-2) ; shinyi@cier.edu.tw; corresponding author 3 Automotive Research & Testing Center, Changhua, Taiwan, R.O.C.; PH (886-4) ; FAX (886-4) ; wei@artc.org.tw 4 Institute of Transportation, Ministry of Transportation and Communications, R.O.C.; PH (886-2) ; FAX (886-2) ; yyw@iot.gov.tw ABSTRACT There is not much literature on fuel economy performance of motorcycle in the real world. The mainstream official statistics report fuel efficiencies for each motorcycle model out of laboratory approval tests. However, our tests reveal that fuel efficiencies of urban arterials are 55~6% to the lab-test harmonic means, regardless age deterioration. Alternatively, with the on-board measurement system OBS-584 developed by ARTC suitable for motorcycles, it enables on-road data available for motorcycles. We found that average fuel consumptions by speeds show positive correlations to speeds, no matter of laboratory approval tests, urban or rural on-road tests. Moreover, similar correlation patterns of younger and older motorcycles suggest that the statistic regressions are probably a shared form among models or across ages. Further investigations into data directly collected from motorcycles in the real world might shed light on new approaches to better quantifying fuel consumptions of motorcycles driving on the road. INTRODUCTION AND LITERATURE REVIEWS In Asian urban areas, motorcycle is the most common private vehicle which is growing rapidly with economic prosperity. Motorcycle is often considered as an efficient mode with less fuel consumption; therefore the characteristics of fuel consumption of motorcycle in real world have not been seriously studied yet. There is not much literature on factors affecting fuel economy performance of motorcycle in real world. It leaves a major piece of fuel saving puzzles unknown in rapidly emerging Asian metropolitans. The mainstream official statistics report fuel efficiency of each motorcycle model out of laboratory standard testing procedure. For example, Bureau of Energy (BoE), Ministry of Economic Affairs, publishes Guidebook of Fuel Efficiency of Vehicles on the Market every year as the most detailed information regarding fuel efficiency among vehicles. The laboratory approval tests required by BoE follow 27-1

2 similar procedures as the U.S. Environmental Protection Agency (U.S. EPA) generates yearly information for its Buyer's Guide to Fuel Efficient Cars and Trucks. It is well known that the various driving patterns, ie. Driving Cycles in the required procedures of DoE or U.S. EPA, result in different fuel consumptions. Therefore, voluminous studies focus on forming typical driving cycles with local driving speed profiles in order to have laboratory tests closer to local realities. Chen, et al., (23) and Tsia, et al., (25) tried to sample driving cycles of motorcycle driving in actual urban and rural environment and develop representative driving cycles for laboratory tests. Zamboni, Carraro and Capobianco, (211) investigated instantaneous speeds of motorcycles in various road classes to identify speed profiles most representing two-wheelers on the chassis dynamometer to improve the standard driving cycles. While it could be up to 2% of measurement deviations between the dynamometer of laboratory and real world driving conditions for a specific driving cycle (Chung-hua Institution for Economic Research, 29). It is clear that in the laboratories it is not possible to replicate conditions of traffic flow and road configurations which are significantly affects fuel consumptions. Even local driving cycles could not promise fuel consumptions out of laboratory tests are able to represent that of the real world. Alternatively, owing to improvements of on-board measurement device, to have data directly from vehicles running on the road had been available since the last decades. It opens up a window toward estimations of fuel consumptions with data from the real world. Yet it is limited to heavy- and light- duty vehicles (Afotey, et al., 213; Liu, et al., 21; Tong, et al., 2; Vojtisek-Lom and Allsop, 21). Available commercialized systems mostly are designed for testing on light/heavy duty vehicles, namely as (1) Horiba OBS-2 Series of Horiba Ltd., Japan; (2) AVL M.O.V.E On-Board Testing/ Gravimetric Filter Module of AVL, Austria; (3) AXionRS+NH3 of GLOBAL MRV, Inc., USA; and (4) SEMTECH-DS/ECOSTAR of Sensors Inc., USA. (Wen, et al., 213). The on board measurement devices with credibility and reliability are not available for motorcycles regarding the size limitations and low weight capability of motorcycles. This study takes advantages of the newly developed on-board measurement device specially designed for motorcycles to collect second-by-second data from motorcycles travelling on roads. With data from the real world, we analyze and test statistics significance then develop a set of parameters to correct underestimates from the results of laboratory. EXPERIMENT DESIGN 1. On-board Measurement System: OBS-584 The on-board measurement system is crucial to this study. It has to be much more compact and lighter than available commercialized systems to be mounted onto motorcycles and consistently operating during road driving conditions. To have the desired on-board system for motorcycle on-road test, the research and development team of the Automobile Research and Testing Center (ARTC) have been devoted in 3 years to realize the compact model we use onto the test motorcycles. The system we use for motorcycle tests is named as OBS-584 which is the third generation prototype (see Figure 1). It is capable to record the synchronized 27-2

3 second-by-second data of instantaneous speeds, emissions and engine working conditions from the motorcycle, locations, humidity and temperature of the environment. The major component of the OBS-584 is the analyzer of MEXA 584L of Horiba Ltd., Japan. Together with the gas flow meter, it is capable to provide instantaneous emissions data with reliability (IOT 212). Moreover, OBS-584 is equipped with an engine sensor, humidity and temperature meter, the moving speed sensor onto the front wheel, and the global positioning system (GPS). Figure 1. OBS-584 Installed onto One of Test Motorcycles 2. Test Routes According to statistics released by the Ministry of Transportation and Communication (MOTC) in 211, Taiwan has become the home of the highest motorcycle density in the world, with motorcycles per square kilometer. The number of in-use motorcycles is more than 15 million in year 212, resulting in more than 2 motorcycles per household in average. Except for Taipei, it is heavily depends on motorcycles as being with the most convenient and cost-effective one among modes of private transportation to serve diversified urban travel demand. Take Taichung metropolitan as an example, where is central to Taiwan with population over than 1 million in downtown and 3.5 million in metropolitan area, it is estimated that 5% or more trips is made by motorcycles for all trip purposes (MOTC 21). Given this backdrop, two typical roads in Taichung metropolitan area are selected to represent urban and rural arterials. As shown on Figure 2, the representative urban arterial is located in the very central downtown of Taichung city. On the urban arterial, street blocks are quite short and traffic flow is highly mixed with scooters, cars and buses. While a major road in the west outer area of the metropolitan is taken as the representative rural arterial. It is quite obvious from the map that blocks of the rural arterial are much longer than the urban arterial. The directions of traffic movement on the rural arterial are divided by raised crossing islands; and mixture of motorcycles from light/heavy duty vehicles is managed by pavement markings. 27-3

4 Figure 2. The Test Routes in Taichung Metropolitan, Taiwan 3. Test Motorcycles We choose one 2.7-year KYMCO 125 c.c. and one 8.9-year SYM 125 c.c. to be our test models. The configurations of test motorcycles are listed on Table 1. The two models are the most dominant in the past 11 years as strong as 3~45% of the yearly new motorcycles fleet in Taiwan (see Figure 3). It accounts for 1.3 and 1.1 million for KYMCO and SYM respectively, out of 7.6 million of total sales during year 22 to 212. According to the most updated MOTC survey (MOTC 212), the average age of in-use motorcycle fleet of Taiwan is 1 years old. Therefore we believe the KYMCO 125 c.c. and the SYM 125 c.c. are well representatives of in-use motorcycles in Taiwan. We also expect the trends of fuel consumptions we found here are highly possible to be transferred to nearby Asian areas; for the reason that the powertrain technologies on both test motorcycles are similar to those popular types sold in Asian countries. Table 1. Characteristics of Test Motorcycles. KYMCO SYM Engine Type Single Cylinder, 4 Stroke Single Cylinder, 4 Stroke Dry Weight Amount (kg) Displacement (cc) Max. Horsepower (ps/rpm) 9.6/7,5 1/8,5 Max. Torque (kg-m/rpm).98/6,5 1./6,5 Transmission System CVT CVT fuel supply system Fuel Injection Carburetor Bore*Stroke (mm) ψ ψ Fuel Capacity (L) Homologation(R.O.C.) Phase 5 Phase 4 Age (year) Travelled Distance (km) 9,815 31,

5 Accumulated market share of yearly sales 6% 5% 4% 3% 2% 1% % KYMCO SYM Other brands Figure 3. The Market Share of 125 c.c. Between Year 22 to 212, Taiwan 4. Data Collections We collected data from test motorcycles with OBS-584 identically to each road type. Each motorcycle is paired with one specific team member for on-road tests to avoid driver s deviation. Test drivers are subject to follow the traffic flow in morning and evening rush hours in non-raining weekdays. On-road tests were conducted during May to July 212 and 213. The data collected counts for more than 1.2 million seconds for each road types for both models, with driving distance among 7~16 km. To compare with results out of laboratories, fuel efficiency approval tests in laboratory of two test motorcycles are executed by ARTC which is an authorized laboratory for DoE fuel economy approval tests. Tests in laboratory strictly follow the required procedures and specifications according to the model year of the test motorcycle. It is repeated three times to get sufficient data for statistics analysis. RESULTS AND DISCUSSIONS The published fuel efficiencies and counterparts of our tests are listed on Table 2. Fuel efficiencies of lab approval tests of two test motorcycles, executing before road tests, are 8~96% to the published numbers shown on the BoE yearly books. The older SYM performs 5~6 % lower than the younger KYMCO. It confirms that age deterioration leads to lower fuel efficiencies as well that the older the more noteworthy of deterioration. Furthermore, for each test motorcycle, deterioration rations of urban cycles are significantly lower than of cruise at 5 kph. It might imply that urban cycles with accelerations and decelerations retain more deterioration effects than that of cruise at 5 kph. Results from the urban arterial road tests of KYMCO and SYM show only 53% and 46% of the published harmonic means respectively. It indicates that the fuel efficiency of daily commuting on urban arterials will be roughly as half as people learn from the BoE yearly books; and the older SYM performs 7% lower than the younger KYMCO. Regarding accelerations and decelerations arise more often on urban arterials in the real world than of urban cycles of the approval tests, it echoes the previously mentioned statement that driving cycles with more accelerations and decelerations might retain more deterioration effects. year 27-5

6 Table 2. Fuel Efficiencies. Fuel Efficiency (km/l) to test of model year KYMCO to published harmonic mean to lab-test harmonic mean Fuel Efficiency (km/l) to test of model year SYM to published harmonic mean to lab-test harmonic mean Published Urban cycle Approval test Cruise at 5 kph (model year) Harmonic Mean Urban cycle % % Lab approval Cruise at 5 kph % % test (test year) Harmonic Mean % % On-Road test Urban arterial % 6% % 55% Rural arterial % 1% % 16% Note: numbers shown on approval test (model year) are from BoE(model year). Based on results of our tests, the on-road fuel efficiencies of urban arterial is 6% and 55% to the lab-test harmonic means for KYMCO and SYM respectively. It leads to potential parameters to correct underestimations of fuel consumption from approval tests in laboratory; though more tests are necessary to confirm to confirm correction parameters with credibility and reliability. Following Wen, et al., (213), we calculate average fuel consumptions for each speed of all tests then plug the results onto Figure 4. It shows positive correlations of averaged fuel consumptions to speeds, no matter in laboratory approval test, urban or rural on-road test. Those similar correlation patterns of average fuel consumptions to speeds among tests or across models suggest that fitted regressions with statistically significance are highly possible, as demonstrated on Wen, et al., (213). Therefore, it is promising to investigate data collected from the real world to approach quantified estimations of fuel consumptions of motorcycle driving on the real world. CONCLUSIONS With the on-board measurement system OBS-584 developed by ARTC suitable for motorcycles, it enables on-road data available for motorcycles. Following Wen, et al., (213), we calculated average fuel consumptions by speeds and found that average fuel consumptions by speeds show strong positive correlations to speeds, no matter of laboratory approval tests, urban or rural on-road tests. Moreover, similar correlation patterns of younger KYMCO and older SYM suggest that the statistic regressions proposed by Wen, et al., (213) are probably a shared form among models or across ages. Further investigations into data directly collected from motorcycle in the real world might shed light on new approaches to better quantifying fuel consumptions of motorcycles driving on the road. While back to the mainstream official statistics of laboratory approval tests, the on-road fuel efficiencies of urban arterials are 6% and 55% to the lab-test harmonic means for KYMCO and SYM respectively, regardless age deterioration. It raises potential parameters to correct underestimations of fuel consumptions from approval tests in laboratory; though more tests are necessary to confirm correction parameters with credibility and reliability. 27-6

7 Urban cycle of lab approval test Urban on-road Rural on-road KYMCO SYM KYMCO: Urban cycle SYM: Urban cycle KYMCO:Urban on-road SYM:Urban on-road KYMCO:Rural on-road SYM:Rural on-road Figure 4. Fuel Consumptions by Speeds. ACKNOWLEDGMENT The Institution of Transportation, Ministry of Transportation and Communications, is acknowledged for providing funding for the series research of fuel consumptions of vehicles on road with a special focus on motorcycles in year 212 and 213. REFERENCES Afotey, B., Sattler, M., Mattingly, S. and Chen, V. (213). "Statistical Model for Estimating Carbon Dioxide Emissions from a Light-Duty Gasoline Vehicle," Journal of Environmental Protection, Vol. 4 No. 8A1, 213, pp doi: 1236/jep A12. Bureau of Energy (213). Guidebook of Fuel Efficiency of Vehicles on the Market. Ministry of Economic Affairs, R.O.C. ( e=5&menu_id=133, accessed 213/9/12). (in Chinese) Chen, K.S, Wang, W.C., Chen, H.M., Lin, C.F., Hsu, H.C., Kao, J.H., and Hu, M.T. (23). Motorcycle emissions and fuel consumption in urban and rural driving conditions. Science of The Total Environment, 312(1 3), Chung-hua Institution for Economic Research (29). A Study on the Relation Analysis between Energy Consumption, Emissions and Transportation Planning, Report for the Institution of Transportation. (in Chinese) IOT (212). The Series Studies of On-Board Measured Fuel Consumptions and Green House Gas Emissions from Vehicle Tailpipes: The Motorcycle with Displacement less than 15 c.c. Institution of Transportation, Ministry of Transportation and Communications, R.O.C. (In Chinese). 27-7

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