• Federal regulations help to keep diesel engine noise down.diesel image by Andrey Kiselev from Fotolia.com
  
  People associate diesel engines with the passing of a loud truck or the noisy hum of a huge generator. However, federal regulations are growing more stringent when it comes to the noise produced by these diesel engines. For the benefit of drivers, pedestrians and those who work with diesel engines, several federal requirements pertain to diesel engine noise.
  
  

Truck Regulations

• According to International Trucks, diesel engines in large and small trucks are becoming increasingly quieter, almost within the range of regular gasoline engines. Federal law decrees that truck engine noise at high idle be below 90 decibels. Due to high pressure fuel systems that even out combustion noise, Grundman states that diesel engines in trucks are now regularly in the range of 70 decibels.
  
  

Train Regulations

• Diesel engines in trains are also required to be below a certain decibel range, but the regulations are more for the benefit of the employees that work on them. The Occupational Safety and Health Administration or OSHA maintains rules that keep employees from being exposed to too much noise in the workplace. The maximum amount of noise OSHA deems acceptable in the workplace is 85 decibels. The Federal Railroad Administration amended existing rules on workplace noise in 2006 to reduce workplace noise to below 85 decibels for the safety of employees.
  
  

Diesel Generator Regulations

• Generators that run on diesel fuel are also regulated for the sake of employees and for people nearby. Pollution Engineering states that decibel levels can fluctuate throughout the day and depending on the area, whether it be urban, suburban or heavy industry. In heavy industrial areas, 72 decibels is the peak for daytime operation, falling to 62 decibels for nighttime operation. The levels in quiet neighborhoods is much lower, with a peak during the day of 52 decibels and a night limit of 42 decibels. To comply with these numbers, organizations and companies that run these generators must first measure the noise produced from their engines to ensure that the machine noise combined with ambient noise at the property line does not exceed the legal decibel limit.