The US Federal Railroad Administration (FRA) is proposing new rules on noise produced by trains travelling at over 160 mph (257 km/h). The standards, modelled on European Union regulations, would allow trains to operate at speeds of up to 220 mph (354 km/h) and introduce a special procedure for even higher speeds.
Federal Railroad Administration – FRA, the US federal authority for rail transport, has launched a consultation on an amendment to the regulations concerning noise produced by high-speed trains.
The proposal introduces an alternative standard for trains travelling at speeds greater than 160 mph, equivalent to approximately 257 km/h, and up to 220 mph, approximately 354 km/h. Exceeding this threshold would require special approval.
The current rules date back to the era of diesel locomotives
The current US standards were based on studies carried out before 1976, at a time when the maximum permitted speed for trains was around 177 km/h, and the noise from diesel locomotives was dominated by the engine and exhaust.
Up to around 200 km/h, noise from the propulsion system, wheels and contact with the track remains the main component. Once speeds exceed 257 km/h, aerodynamic noise caused by air flowing over and around the train becomes dominant.
Current regulations mainly address the mechanical noise produced by locomotives and railcars. In the case of a modern high-speed train, factors such as the shape of the nose, pantograph fairing and wheel protection increasingly influence noise levels.
“Updating this regulation will remove a major obstacle faced by companies seeking to operate high-speed trains,” said David Fink, the FRA Administrator.
Standard inspired by European rules
The FRA has adapted the proposal in line with the European technical specification on rolling stock noise, known as the NOI TSI, and the international standard ISO 3095.
Instead of measuring the maximum noise levels produced by the locomotive and railcars separately, the new method analyses the equivalent noise level over the entire duration during which the train passes the measurement point.
The proposed reference level is 96 dB(A) at 257 km/h, measured 7.5 m from the centre of the track.
The permitted value increases with speed, reaching approximately 103 dB(A) at 354 km/h. These figures cannot be directly compared with the current limits, as the distance and measurement method are different.
The FRA maintains that the total exposure of people living near the lines would remain comparable to that permitted under the existing rules. Even if the instantaneous value may be higher, the faster train passes through in a shorter time.
Current rules remain valid up to 257 km/h
The new standard would be optional. Operators could continue to demonstrate compliance with current limits, including at high speeds, if their trains are capable of meeting them.
The existing rules will continue to apply mandatorily to all operations carried out at speeds of up to 257 km/h. The proposal does not remove the obligation for each rail project to assess its environmental impact and to install noise-reduction measures where necessary.
The FRA estimates that the new approach could bring the industry benefits valued at up to approximately 100.5 USD million over the next 30 years, mainly by avoiding costly modifications to trains to comply with standards designed for a different type of rolling stock.
Projects for trains travelling at over 300 km/h
Currently, no commercial service in the US exceeds 257 km/h. The new NextGen Acela multiple units are designed for a maximum speed of 160 mph, but the infrastructure of the North-East Corridor limits the actual speed along most of the route.
This situation will change with future high-speed projects. The system being built in California is designed for speeds of up to 354 km/h, and the first track, electrification and control systems are due to be installed on the Central Valley section.
The private Brightline West project, between Las Vegas and Southern California, is developing electric trains capable of exceeding 320 km/h. Siemens has been selected to supply multiple units known as the American Pioneer 220.
The draft noise regulation is open for comments from the public, operators, manufacturers and other interested parties until 2 October 2026. After reviewing the comments, the FRA may amend the text before adopting a final rule.
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