UIJRT | United International Journal for Research & Technology | Volume 01, Issue 11, 2020 | ISSN: 2582-6832 Analysis of Passengers Ride Comfort Based on Smartphone Vibration Measurement for Chengdu Metro Mekonnen, H.T. Southwest Jiaotong University, School of Civil Engineering [email protected] Abstract— Whole-body vibration transmission influences physical quantities that affect ride comfort, and the comfort, performance, and long-term health of the metro measurement of human reactions and consciousness. In passengers. Here in Chengdu, Metro is a major latter cases, it is very challenging to evaluate ride comfort transportation system which is why this study has an quantitatively by in view of all factors, since the feelings objective of, analyzing ride comfort level passengers of each passenger along with various factors that affected based on international standard ISO 2631-1 (1997). ride comfort were dissimilar. Therefore, vibration Transmission of vibration on passengers was measure in accelerations are generally effective in evaluating ride three lines (line 3, 4 and 7) using a smart phone application comfort of railway vehicles. [1] called Digital Metro. The application is used to collected acceleration data from different location of the train and Vibration is complex because it is containing many passengers sitting location and position. According to ISO frequency and effect of whole body vibration exposure 2631-1 (1997), results indicate that, passengers are not causes a complex distribution of oscillatory motion and likely to be uncomfortable during all trip except two forces within the body that led to discomfort sensation and locations that were found to be fairly uncomfortable in health effect [2]. Usually WBV occurs in seated postures line seven and line four routes, which is, the vector sum while people are driving the vehicle or passenger were result were 0.659 m/sec2 and 0.516 m/sec2 respectively on used transportation system [3]. Its appears that locomotive a seat-pan location. It also shows that the vibration engineers and conductors are working in a unique acceleration value is much higher on seat-pan location environment with likely exposure to significant WBV and compered to floor location and vibration transmitted along shocks depending on locomotive design, train speeds, and mainly the vertical direction. Also it can be seen that the operational tasks [4] [5]. WBV gained by human body highest values of the acceleration were found from the z- increased when the duration of vibration exposure and axis, it reaches up to 0.381 m/sec2. total train trips experienced by the subject enlarged [6]. As the speed of the train increases the vibration magnitudes Keywords— Ride comfort; Vibration transmission; whole will also increase. Reducing the train speed can decrease body vibration; Acceleration root mean square; vibration the vibration exposure of the persons in the train but this dose value. will result in an escalation in the travel time. Neither the railway line nor the passengers will like it [7]. I. INTRODUCTION Ride comfort is a dynamic performance characteristic of Trains are becoming an important part of the passenger’s railway vehicle and its affected by a variety of elements in day to day life activities. Information concerning the such as temperature, noise, humidity, smell, and visual response of passengers to a train has become gradually stimuli and vibrational however it’s challenging to important for use in the development of new consider all component simultaneously S [8]. The transportation system. Train offers a safe and fast way of passenger comfort related to vibrations is vital importance transportation. Because of high demand for quality among the variety factors concerned in comfort service, railway companies are forced to meet more evaluation. The quantity that is relevant to the vibration restrictive and severe specifications to meet the demand aspect of ride comfort is the acceleration that uncovered of passengers. Passengers ride comfort using rail vehicles to the passenger throughout the motion of railway vehicle. is determined by the collective effects of vibration, noise, (Abqari et al., n.d.) [9] temperature, humidity, light, seat texture, height of ceiling, view, ventilation, etc. Accordingly, studies on ride According to Griffin & Erdreich [10] when magnitude of comfort can be categorized into the measurement of vibration is increased, there is possibility growing in All rights are reserved by UIJRT.COM. 1 UIJRT | United International Journal for Research & Technology | Volume 01, Issue 11, 2020 | ISSN: 2582-6832 discomfort. In addition, at low frequencies the force that acting on the human body is proportionally with the input of acceleration transmitted to the entire body. Simonyi et al. [12] says the “smartphone-world” is expanding with an relatively speedy pace; in 2012 already about 80% of the world’s population owned some type of an intelligent device according to Go-Gulf web- application and development website (2012). Smartphone-world, therefore, is a huge market and facilitates practical measurements and data collection based on the built-in sensors on a range of scales. The built-in sensors, which currently can be observed in most smartphones include among others GPS sensors and accelerometers. used smartphones equipped with built-in accelerometers for recognizing easily daily activities of subjects. [13] [14] Fig. 1 Sitting position Griffin & Erdreich, 1991 [10] This study analysis passengers comfort through the B. Test Route general evaluation of Whole body vibration for For the purpose of this study, three randomly selected passengers, based on ISO 2631-1-1997 focusing on routes were used to measure and evaluate the whole body through calculating the root mean square value for the vibration. The measurement was conducted during non- three orthogonal directions and the vector sum as well as peak hours. vibration dose value. First route that is used for whole body vibration II. MATERIALS AND METHODS measurement was metro line 7. This metro line was open A. Whole Body Vibration Measurements for public service in December 6/2017. It is the first There are now accepted international standards for circular metro line running across the central areas of evaluation of human exposure to vehicle vibrations. Chengdu, it is also the longest among all metro station ISO2631-1 (1997) standard defines measurement have been opened containing 31 stations it stretches 38.6 methods for measuring periodic, random and transient kilometers circularly between the second and the third vibration affecting the human body as a whole. And it also ring roads. The measuring time for the first route test took defines measurement methods and provides health risk about 20 minute and the total stations covered on this rout prediction in case of the multiple shocks. These standards was 11 station. summarize factors that determine separately or in combination the degree to which a vibration exposure will The second route used for whole body measurement was be acceptable for humans. [2] Chengdu metro line 3. This metro line stretching in the WBV that absorbed by human body will improved when southwest-northeast direction is a trunk line of the the magnitude of vibration exposure experienced by local subway system. It passes the core area of the city's passenger is increased. Moreover, generally vibration CBD (Central Business District) and mainly serves the factors from train cause by indelicate track passed via Shuangliu, Wuhou, Jinjiang, Chenghua, Jinniu and Xindu train, train operation fashion and speed of the train [11]. Districts. The whole line will connect the Shuangliu West High-speed Railway Station and Xindu East Railway Vibration measurements were done according to the Station. The operating route, which is the phase one of measuring procedure outlined in ISO 2631-1 (1997). Chengdu metro line 3, passes 17 stations for a distance of Acceleration levels were measured on the passenger seat 12 miles (20 kilometers). It runs between Taipingyuan and and on the floor beneath the seat, in three perpendicular Military General Hospital with the cost of CNY2-4. The directions (x - longitudinal, y - transverse, z – vertical, (see phase two and three of line 3 are expected to serve the Fig. 1). public in early 2019. All rights are reserved by UIJRT.COM. 2 UIJRT | United International Journal for Research & Technology | Volume 01, Issue 11, 2020 | ISSN: 2582-6832 The measuring time for the second route and the total collect the vibration data from seat-pan and floor for a stations covered for the measurement of whole body seated passenger. The smartphones were fixed on the seat- vibration was about 17 minute and 9 station respectively. pan and floor of the passenger’s seat in each of selected Extending in the east-west direction, Chengdu metro line carriages. Three students were willing to participate in the 4 was the third route used for whole body vibration test. It measuring process and they were also being part of is the third metro in the city following line 1 and line 2. It passengers. Adhesive tape was used at the back of the covers a distance of 40 km (25 mi) and passes 30 smartphone to firmly fix the smartphone on the floor for stations, linking Wannianchang and Intangible Cultural feet location and on the surface of the seat to avoid any Heritage Park. Passengers can easily transfer to metro line unnecessary movement that could occur during the travel. 1, line 2 and line 3, respectively at stations of Luomashi, Chengdu University of TCM & Provincial People's Hospital and 2nd People's Hospital. Chengdu subway line 4 passes West Railway Station, Luomashi Commercial Zone, and several attractions such as Wide and Narrow Alley, Cultural Park, Sichuan Museum and Intangible Cultural Heritage Park. The measuring time for the third route and the total stations covered for the measurement of whole body vibration was about 15 minute and 8 station respectively. C.