Video of the French TGV.
Train speeds on the Caltrain corridor will
be 125mph for HSR and 110mph for Caltrain. The graph at right above can be found in this 1996 study. As aerodynamics and technology of design (such as slab track versus ballast track) are improved, the sound levels will only come down, but should remain a significant concern in the design process. Sound walls on elevated or at grade structures will add visible mass. The HSRA tells us these sound walls will only need to be 3-5' high. Other studies suggest they should be higher, similar to the sound walls along Rt 101. A lot has to do with the distance between the sound source and the wall, so for a greater ROW width, higher walls may be required.Japan has a national noise standard for the Shinkansen, limiting the noise it generates to 70 decibels in residential areas and 75 decibels in commercial districts. For comparison, a vacuum cleaner at 10 feet produces 70 dB, and a car passing 10 feet away measures 80 dB. To meet Japan's stringent standards, they use lightweight trains with sleek and sometimes odd-looking noses, design windows, doors and the spaces where cars connect to be as smooth and aerodynamic as possible, cover the wheels, and work to quiet the overhead electrical supply system, a major noise source. The railways also install sound-walls in some locations along the tracks, ranging from roughly 2 to 12 feet high, and they travel at reduced speeds in the densest areas.
2005 Federal Railroad Administration High-Speed Ground Transportation
Noise and Vibration Impact Assessment. Of interest on page 4-9 is that a HSR placed in a deep trench produces roughly 19dB less than an elevated structure without a sound wall.
Posts
