Study On ECG And Operating Behavior Characteristics Of Long-distance Bus Drivers On Nighttime Freeway

With the rapid construction of the road network and rapid economic growth in China, thecrucial role of road transportation in the national integrated transportation system is moreprominent, driving safe of vehicle became an important factor for restricting the operation anddevelopment of freeway to some extent, especially long-distance bus was the focus forpreventing and managing vicious traffic accidents featured by serious mass injuries and death.In this paper, the physiological changes and operating behavioral parameters of large busdrivers in the process of the actual long driving were obtained from the real-time acquisitionsystem of the physiological indices and steering behaviors of long-distance bus drivers tocarry out the quantitative studies on fatigue conditions of long-distance driving at night andsteering behaviors under the different traffic conditions for large bus drivers.(1) For eight states of the shift mode of “Sunset-Departure and Sunrise-Arrival” for largebus drivers on the freeway, the distribution trend and relevance of various indices at differentstages were analyzed using physiological indicators such as heart rate and heart ratevariability. It was found that heart rate of the driver before and after departing was at thehighest level or a higher stage in the whole trip, average heart rate per hour and growth rateshowed an alternatively “V” and “W” distribution trend with extended driving time, and thelowest point was at rest or before and after the night shift. Quantitative analysis of thedistribution features of relative normal value of heart rate variability index indicated that theheart condition of bus drivers at the whole night was poor. And based on the characteristics ofphysiological changes, the longest time for large-scale long-distance bus drivers was3~3.5hours each time at night as the control index.(2) The throttle pedal stroke, brake pedal stroke, rate of change, speed and accelerationand deceleration were selected as the evaluation indices of the operating behaviors, theevaluation index system of operating behaviors was established according to the maximum,minimum, and average value of various indices,15%,50%and85%percentile change andstandard deviation, the difference between85%and15%percentiles as well as the differencebetween the maximum and mean value. The distribution feature and change trend of variousindices of different drivers were analyzed in different speed ranges and different roadconditions.(3) The impact of continuous deceleration zone on the long slope and special way on two-way deceleration zone on operating behaviors of the large bus drivers was analyzedaccording to the throttle pedal and brake pedal strokes and the rate of change, speed, as wellas acceleration and deceleration speed to find that the facilities had some effect on the speedcontrol of vehicle, but the maximum speed of large bus still continued to increase in thecontinuous downhill section, which means that there were still hidden dangers of speedingand the curve downhill was still a road segment with more steering loads and safety problems.When parking to enter the toll station in the main straight section of the freeway, themaximum speed, average speed, average brake pedal travel, parking distance and averagedeceleration of drivers were analyzed quantitatively. Drivers were expected to acceleratethrough the tunnel, and the maximum speed limit at the tunnel entrance and exit were higherthan the actual highest speed limit in the tunnel; the speed changes and steering behaviors oflarge bus drivers speed passing the freeway tunnel were obtained according to the speeddifference between the entrance and exit, acceleration and deceleration speeds in the tunnel aswell as the speed changes passing through the slope.(4) Using R-type dimensionality reduction cluster, the15%percentile of the speed,standard deviation of the speed, time domain cluster indices such as85%and15%percentiledifference of the throttle pedal stroke, cluster indices such as the throttle pedal stroke andspeed FFT dc frequency spectrum value, cluster indices of the maximum value and15%percentile of the throttle pedal stroke and speed FFT ac frequency spectrum value, integratedcluster indies such as15%percentile of the throttle pedal stroke FFT dc frequency spectrumvalue and ac frequency spectrum value, speed FFT dc frequency spectrum value andmaximum ac frequency spectrum value were proposed for the throttle pedal stroke and speedtime domain index, FFT constant and ac component index. Using Q-type cluster, differentclusters of drivers were divided into different groups and the same cluster of drivers weredivided into the same group to achieve the differential identifying of steering behaviors ofdifferent drivers, as well as steady identifying of steering behaviors of the same driver in freeflow conditions on the freeway.