4:00 PM - 4:15 PM
[SVC30-09] Evaluation of vehicle running through performance on ashfalls covered roads
Keywords:Volcanic Disaster, Disaster Mitigation, Disaster Manegement, Ash Fall, Scoria, Road Traffic
As a disaster mitigation measure in the event of a volcanic eruption, maintaining nearby urban lifeline is as important as reducing human suffering. Ash fall is unlikely to directly affect human life, although it could paralyze urban lifeline such as power outages and travel disruptions, including roads, highways, railroads, and airlines. It is critical both for public organizations concerned with disaster prevention who engage in a rescue effort or disaster recovery efforts and for citizens who take refuge or maintain their lives, to keep the operation of vehicles on the roads covered with ashfall. However, there has been little discussions of the vehicle dynamics on ash covered roads, which can help establish standards for regulating roads and highways after ashfall.
We conducted vehicle dynamics testing on the special courses covered with volcanic ash and scoria on an asphalt pavement surface to scientifically evaluate the driving performance of private vehicles on roads covered with ashfall after a volcanic eruption. The production cars used for the tests are nine models with different vehicle classes and body types. The drive systems include front-wheel drive (FWD), rear-wheel drive (RWD), and all-wheel drive (AWD), and the vehicle weight ranges from 880 kg to 1600 kg. Since this test is designed to be driven by ordinary people, we decided not to use any special driving techniques and modifications to the vehicles. The same driver did all vehicle running tests to minimize the reproducibility error. In this presentation, we will discuss the running through performance of private vehicles on the roads covered with ash and scoria.
In the running through tests, the vehicle entered the deposited course from the paved road at a speed of 5 km/h and tried to pass the course while keeping a constant speed. In tests on a straight and flat course with a length of 20 m in which scoria was deposited up to a thickness of 30 cm, all AWD vehicles were able to pass the course. On the other hand, the FWD and RWD vehicles got stuck in most cases. We also conducted vehicle tests on 5% grade uphill courses with a length of 30 m in which ash and scoria was deposited with a thickness of about 10 cm or more. The results were similar to those of the flat course; all AWD vehicles could pass the courses, whereas the FWD and RWD vehicles got stuck in most cases. To verify the effects of tire chains, metallic or non-metallic snow chains were put on the drive wheels of the FWD vehicles and conducted the tests in the same ways. As a result, there was no obvious change in the running distance compared to the case without the tire chains, and the FWD vehicles got stuck again. On the contrary, the running distances tended to be shorter in the uphill course. In the tests, the AWD vehicles could run through in all course conditions regardless of the vehicle class or weight. On the other hand, the FWD and RWD vehicles were more likely to get stuck when the thickness of ash and scoria deposit exceeds about 12 cm.
The vehicle running through performances on roads covered with ash and scoria depends on how the driving force transmitted from the driving wheel tires to the ground without being attenuated. This is mainly dependent on the frictional force between the ash and scoria particles deposited on the road surface. Minimizing the sinking of the drive wheels into the deposited layer on the roads is also a key to improving running through performance. This is because it causes tire rolling resistance and a misalignment between the direction of the driving force vector acting on the drive wheels and the vehicle running direction. These are determined by the interrelationship between (1) vehicle characteristics and (2) road surface conditions. The main vehicle characteristics related to running through performance are drive system, traction control system, vehicle weight, and tire size. In addition, the type of prime mover that generates the driving force, such as engine or electric motor, might also contribute to the performance. On the other hand, the road surface conditions that significantly affect the driving through performances of vehicles include layer thickness, grain size, water content, and road grade, which change with time and place. From these points of view, the installation of tire chains does not seem to be of much use in improving the running through performance of vehicles on ash and scoria deposited roads.
We gratefully acknowledge the support in developing the test courses by the Fuji Sabo Office, Chubu Regional Development Bureau, Ministry of Land, Infrastructure and Transport.
We conducted vehicle dynamics testing on the special courses covered with volcanic ash and scoria on an asphalt pavement surface to scientifically evaluate the driving performance of private vehicles on roads covered with ashfall after a volcanic eruption. The production cars used for the tests are nine models with different vehicle classes and body types. The drive systems include front-wheel drive (FWD), rear-wheel drive (RWD), and all-wheel drive (AWD), and the vehicle weight ranges from 880 kg to 1600 kg. Since this test is designed to be driven by ordinary people, we decided not to use any special driving techniques and modifications to the vehicles. The same driver did all vehicle running tests to minimize the reproducibility error. In this presentation, we will discuss the running through performance of private vehicles on the roads covered with ash and scoria.
In the running through tests, the vehicle entered the deposited course from the paved road at a speed of 5 km/h and tried to pass the course while keeping a constant speed. In tests on a straight and flat course with a length of 20 m in which scoria was deposited up to a thickness of 30 cm, all AWD vehicles were able to pass the course. On the other hand, the FWD and RWD vehicles got stuck in most cases. We also conducted vehicle tests on 5% grade uphill courses with a length of 30 m in which ash and scoria was deposited with a thickness of about 10 cm or more. The results were similar to those of the flat course; all AWD vehicles could pass the courses, whereas the FWD and RWD vehicles got stuck in most cases. To verify the effects of tire chains, metallic or non-metallic snow chains were put on the drive wheels of the FWD vehicles and conducted the tests in the same ways. As a result, there was no obvious change in the running distance compared to the case without the tire chains, and the FWD vehicles got stuck again. On the contrary, the running distances tended to be shorter in the uphill course. In the tests, the AWD vehicles could run through in all course conditions regardless of the vehicle class or weight. On the other hand, the FWD and RWD vehicles were more likely to get stuck when the thickness of ash and scoria deposit exceeds about 12 cm.
The vehicle running through performances on roads covered with ash and scoria depends on how the driving force transmitted from the driving wheel tires to the ground without being attenuated. This is mainly dependent on the frictional force between the ash and scoria particles deposited on the road surface. Minimizing the sinking of the drive wheels into the deposited layer on the roads is also a key to improving running through performance. This is because it causes tire rolling resistance and a misalignment between the direction of the driving force vector acting on the drive wheels and the vehicle running direction. These are determined by the interrelationship between (1) vehicle characteristics and (2) road surface conditions. The main vehicle characteristics related to running through performance are drive system, traction control system, vehicle weight, and tire size. In addition, the type of prime mover that generates the driving force, such as engine or electric motor, might also contribute to the performance. On the other hand, the road surface conditions that significantly affect the driving through performances of vehicles include layer thickness, grain size, water content, and road grade, which change with time and place. From these points of view, the installation of tire chains does not seem to be of much use in improving the running through performance of vehicles on ash and scoria deposited roads.
We gratefully acknowledge the support in developing the test courses by the Fuji Sabo Office, Chubu Regional Development Bureau, Ministry of Land, Infrastructure and Transport.