| Revision as of 14:01, 18 August 2015 edit168.235.197.216 (talk)No edit summary← Previous edit | Revision as of 01:36, 3 October 2015 edit undoBryce Carmony (talk | contribs)2,039 edits physics in this sense is plural not singular. The individual physics at work not the concept of physicsTags: Mobile edit Mobile app editNext edit → | ||
| Line 1: | Line 1: | ||
| {{Refimprove|date=October 2012}} | {{Refimprove|date=October 2012}} | ||
| '''Tunnel boom''' is a phenomenon of radiation of impulsive sound from the exit of a ] by high-speed trains. The perception of this sound by humans is similar to that of a ] from supersonic aircraft. However, the physics of tunnel boom |
'''Tunnel boom''' is a phenomenon of radiation of impulsive sound from the exit of a ] by high-speed trains. The perception of this sound by humans is similar to that of a ] from supersonic aircraft. However, the physics of tunnel boom are different. In particular, unlike sonic boom, it has no relation to train speeds exceeding the velocity of sound in air (this is not possible even for the fastest high-speed trains currently in operation). The effect occurs because a train moving at high speed compresses and displaces a great deal of air; normally this air diffuses in all directions. However, when the train enters a tunnel, a high pressure shock wave with a very large pressure gradient is created, which travels down the tunnel and arrives at the opposite exit some time before the train. When this shock wave reaches the tunnel exit, it generates a loud sound propagating in all directions from the tunnel, thus creating a boom. | ||
| Tunnel boom can disturb residents near the mouth of the tunnel, and it is exacerbated in mountain valleys where the sound can echo. Reducing these disturbances is a significant challenge for high-speed lines such as Japan's ] and the French ]. Methods of reducing the phenomenon include making the train's profile highly ] and widening the tunnel entrance.{{cn|date=October 2012}} | Tunnel boom can disturb residents near the mouth of the tunnel, and it is exacerbated in mountain valleys where the sound can echo. Reducing these disturbances is a significant challenge for high-speed lines such as Japan's ] and the French ]. Methods of reducing the phenomenon include making the train's profile highly ] and widening the tunnel entrance.{{cn|date=October 2012}} | ||
Revision as of 01:36, 3 October 2015
 | This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Tunnel boom" – news · newspapers · books · scholar · JSTOR (October 2012) (Learn how and when to remove this message) |
Tunnel boom is a phenomenon of radiation of impulsive sound from the exit of a tunnel by high-speed trains. The perception of this sound by humans is similar to that of a sonic boom from supersonic aircraft. However, the physics of tunnel boom are different. In particular, unlike sonic boom, it has no relation to train speeds exceeding the velocity of sound in air (this is not possible even for the fastest high-speed trains currently in operation). The effect occurs because a train moving at high speed compresses and displaces a great deal of air; normally this air diffuses in all directions. However, when the train enters a tunnel, a high pressure shock wave with a very large pressure gradient is created, which travels down the tunnel and arrives at the opposite exit some time before the train. When this shock wave reaches the tunnel exit, it generates a loud sound propagating in all directions from the tunnel, thus creating a boom.
Tunnel boom can disturb residents near the mouth of the tunnel, and it is exacerbated in mountain valleys where the sound can echo. Reducing these disturbances is a significant challenge for high-speed lines such as Japan's Shinkansen and the French TGV. Methods of reducing the phenomenon include making the train's profile highly aerodynamic and widening the tunnel entrance.
Tunnel boom has become a principal limitation to increased train speeds in Japan where the mountainous terrain requires frequent tunnels. Japan has created a law limiting noise to 70 dB in residential areas, which applies to many tunnel exit zones.
References
- "新幹線鉄道騒音に係る環境基準について（昭和50年環境庁告示） The Environmental Regulation of Shinkansen Noise Pollutions (1975, Environmental Agency) (Japanese)". Env.go.jp. Retrieved 1 October 2012.
 | This rail-transport related article is a stub. You can help Misplaced Pages by expanding it. |
 | This engineering-related article is a stub. You can help Misplaced Pages by expanding it. |