People living along the line have the most voice when the train passes by. On the same road, change sleepers, and you can hear different. It is not surprising that wooden sleeper track can be 3-5 decibels lower than cement sleeper in engineering.
It's three or five decibels less than listening. But the noise is logarithmic, and the human ear is particularly sensitive to low-frequency roaring, and the actual listening feeling is better than the number. Near the old line of the residential area, a truck passed by at midnight, and the window on the side of the wooden sleeper shakes a little less, and the shallow people rarely wake up once. Small numbers make great difference in the days.
Why can wood be quieter? Root in one layer elasticity.
When the wheel hits the rail, the impact will be transmitted to the subgrade along the rail. At this level of sleeper, the wooden sleeper is made of pine, the fiber itself has toughness, the stress will slightly yield, the impact will be swallowed and then sent down. The cement sleeper is hard, and the impact basically rubs the ballast and subgrade hard and vibrates in one step.
The section swallowed by wooden sleepers, transmitted to the ground is a little noise, and transmitted to the adjacent residents' ears is a little rumble.
The cement pillow is hard to touch, which also causes a trouble. The vibration is directly poured into the ballast, and the crushed stone is repeatedly vibrated, easy to be broken into powder, and the subgrade is also loosened. The impact of wooden sleeper shall be removed, the ballast bed shall be less affected, and the line itself shall be more stable. So the wooden sleeper is quiet, not only for the ear, but also for the maintenance.
When carrying wooden sleepers, some people often think it is not good to be soft, and they have to be carried by hard people. The materials selected for the line are not harder than others. Walking close to the place where people sleep, quiet itself is a hard indicator. The new trunk line can avoid residential areas and go on ballastless tracks. However, there are buildings on both sides of old tracks and freight tracks in the city, which cannot be removed and cannot be bypassed. Therefore, the elasticity of wooden sleepers is just needed.
Pine wood can handle this because of its natural moderate modulus of elasticity. Too hard to absorb impact and too soft to hold the train. Pine wood is stuck in the middle, and its service life is increased by oil immersion corrosion prevention, so it can be dried on the residential area line year after year. It absorbs the impact of wheels and then rebounds slowly. The rails and fasteners are less damaged and the accessories are more durable.
Of course wood isn't for nothing. It shall be maintained regularly, and its service life is shorter than that of cement sleeper, and it shall be replaced when it reaches the service life. In noise-sensitive areas, existing lines near residential areas, hospitals and schools, the general ledger can be calculated. Wooden sleepers are quite enough. The old line of many cities is still covered with wooden sleepers, and ears are one of the reasons.
It doesn't mean that the wooden sleeper is pressed with one end of the cement sleeper. For the trunk line with large traffic volume, it is necessary to carry decades of heavy load. The service life of cement sleeper is long, the replacement is less and it is more economical. Wooden sleepers shall be fixed on certain types of lines, close to people, with many curves, and shall be changed at any time. Quiet is just one of the most frequently spoken of by residents.
Sleeper selection depends on working condition, not on which one is stronger. The line passes through the bottom of the window, and quiet is the hard way. Wooden sleepers against this flexibility have not been replaced on residential routes.
The anti-corrosion sleepers made by Qingdao Tiehan are mainly pine wood and subject to oil immersion treatment. They are quite on the lines near many residential areas.
