June 20


Preliminary Traffic Assessment

By Mike Spack

June 20, 2017

ITE Trip Generation, preliminary traffic assessment, traffic assessment, traffic corner, Traffic Corner Tuesday, Travel Demand Management Plan

By Mike Spack, PE, PTOE

Every development goes through an approval process prior to being green-lighted for construction. The traffic portion of that process can range from a full-scale traffic study plus a Travel Demand Management Plan to a simple tech memo discussing the amount of traffic that will be generated by the development. Equally important for the developer or the city is to determine any glaring flaws, from a traffic perspective, of the proposed site plan.


Before we get into the specifics of a Preliminary Traffic Assessment, it’s helpful to talk about why we created this assessment process and what it should entail.

A Preliminary Traffic Assessment is a one-page memo that is geared to quickly give a snapshot of traffic data and potential issues related to a proposed development, whether the client is a developer, the site designer or a public agency. The reason we provide a Preliminary Traffic Assessment is to bring any potentially disruptive news to the client up front in the very beginning when issues can be addressed easiest.  After all, if you wait until after you’ve undergone an entire Traffic Impact Study to deliver potentially disruptive news, you may end up with a pretty upset client if they were not prepared to receive that kind of information.

[Free webinar recording: Preliminary Traffic Assessments.]

Components of a Preliminary Traffic Assessment

Here, we’ve provided an example of what our Preliminary Traffic Assessment might look like.

The top of the document contains a header with four critical components:

  • Title of the document
  • Project title or description
  • Location of the project
  • Date of the assessment

The next section should be a very simple and easy to understand evaluation. We include the following information in our evaluation:

  • Access – Are the access locations appropriate, necessary, insufficient, etc.?
  • Geometric changes – Are geometric changes, such as turn lanes, splitter islands, etc., likely necessary?
  • Traffic control – Based on traffic volumes, are traffic control changes likely needed?
  • Multi-modal – Are there multi-modal opportunities (i.e. bus stops nearby, bike lanes, etc.)
  • Traffic study – We give the customer an idea of what they can anticipate as it relates to their traffic study needs.

We then dig a little deeper and create a table that provides information on the existing roadway conditions adjacent to the site. Here we include the following:

  • Street name
  • Designation (city road, county road, state road, etc.)
  • Daily traffic volumes (utilizing historical data)
  • Number of lanes
  • Presence of transit facilities
  • Presence of bike/pedestrian facilities

We then take the concept site plans that we have and, using traffic data that is available to us either from TripGeneration.org or ITE Trip Generation manual, provide preliminary, estimated traffic and parking for the following:

  • Daily
  • M. Peak Hour
  • M. Peak Hour
  • Peak Parking

The next section is an opportunity to identify any potential traffic related issues that we foresee for the site plan. This could include a wide-array of red-flags, and we use a checklist of internal issues that we know to be commonplace in traffic developments.

The final component of our Preliminary Traffic Assessment is a simple disclosure that lets the customer know that this is not an official engineering report, but just the first step in what we hope will be an ongoing conversation.

The Preliminary Traffic Assessment is a free service that we provide to all of our clients. We strongly encourage others in the industry to adopt a similar practice, because we believe that it adds value and establishes trust early in the project.  It is much better for our clients to address traffic issues early instead of at the tail end of the design process when Traffic Impact Studies are typically finished.

Interested in learning more about how we traffic assessments when planning a study? Check out our Traffic Corner Tuesday webinar recording: Preliminary Traffic Assessments.

Also check out our free Traffic Corner Tuesday webinars. Join the Spack Consulting team for 30-mintues as we share interesting traffic engineering case studies and best practices.


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Mike Spack

My mission is to help traffic engineers, transportation planners, and other transportation professionals improve our world.

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