DNL Calculator

The Day/Night Noise Level Calculator is an electronic assessment tool that calculates the Day/Night Noise Level (DNL) from roadway and railway traffic. For more information on using the DNL calculator, view the Day/Night Noise Level Calculator Electronic Assessment Tool Overview.


  • To display the Road and/or Rail DNL calculator(s), click on the "Add Road Source" and/or "Add Rail Source" button(s) below.
  • All Road and Rail input values must be positive non-decimal numbers.
  • All Road and/or Rail DNL value(s) must be calculated separately before calculating the Site DNL.
  • All checkboxes that apply must be checked for vehicles and trains in the tables' headers.
  • Note #1: Tooltips, containing field specific information, have been added in this tool and may be accessed by hovering over all the respective data fields (site identification, roadway and railway assessment, DNL calculation results, roadway and railway input variables) with the mouse.
  • Note #2: DNL Calculator assumes roadway data is always entered.

DNL Calculator

Airport Noise Level
Loud Impulse Sounds?
Combined DNL for all
Road and Rail sources
Combined DNL including Airport
Site DNL with Loud Impulse Sound


Mitigation Options

If your site DNL is in Excess of 65 decibels, your options are:

  • No Action Alternative: Cancel the project at this location
  • Other Reasonable Alternatives: Choose an alternate site
  • Mitigation