Need a Traffic Letter in the State of Colorado for Your Development? Here’s What You Should Know

Most land development applications in counties throughout Colorado require a traffic impact letter as part of the approval process. Signed and stamped by a Professional Engineer (PE), a traffic letter not only includes an analysis of current and projected traffic volumes but also recommendations on how to mitigate and improve traffic flow. Our Denver traffic engineering team explains what you should know.

Traffic letters are required during the scoping process for a wide variety of real estate developments in Colorado, including:  

• Rezoning permits 
• Planned unit development (PUD) applications 
• Site development plans 
• Special use permits (SUP) – sometimes called “Special use by review” permits 
• Preliminary/final plats for subdivisions 

Depending on the nature of the development, a traffic letter may include analysis and recommendations relating to trip generation, traffic control requirements, signage, and roadway improvements. Traffic letters include a trip generation analysis consisting of background traffic conditions and traffic that is expected to be generated by the new use on the site. Trip generation is calculated using ITE (Institute of Transportation Engineers) trip generation rates in the ITE Trip Generation Manual.  

Traffic letters also include:  

• A determination on the impacts that the additional traffic will have on the surrounding area, 
• An analysis of the surrounding intersection/area to determine how additional trips will affect traffic conditions, 
• Recommendations and a summary of expected traffic impacts, and  
• A letter that explains the impact of the development and traffic impacts.  

Depending on peak hour trip generation and access to local or collector roads, a full traffic impact study may be required. Traffic analysis software is used to further analyze traffic volumes, intersection and roundabout capacity, turn lane requirements, signal warrants and timing, and other issues.  

In most cases, traffic letters can be processed within a week or two. We handle traffic letters for developments in counties across the state. If you need more information, please reach out to us. 

Contact our Colorado Transportation Team

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