Fairfax County’s January 2025 SSPA: Take Action to Increase or Modify the Density of Your Development

If your redevelopment goals include increasing density, converting old land uses, or changing the mix of uses in Fairfax County, Wells + Associates is uniquely qualified to help during the upcoming Site-Specific Plan Amendment (SSPA) Process. We can accurately estimate vehicle trips for existing and proposed conditions that account for changes in density or program mix.  

Our ability to forecast trip reductions based on firsthand experience implementing TDM strategies in Fairfax County has enabled us to make more accurate trip reduction forecasts that not only help justify the most density possible, but also ensure the development functions optimally from a mobility perspective.

Our seminal white paper, Don’t Underestimate Your Property: Forecasting Trips and Managing Density Over the Long Term in Fairfax County, Virginia, provides detailed research into how to achieve increased density. 

As our research and experience demonstrates, our team understands how to analyze projects and obtain and leverage data we have captured to help justify a lower vehicle trip generation while increasing their density. 

Several components within an SSPA nomination may require consideration of transportation issues, including the Vulnerability Index, the Illustrative Concept Plan, and Study Acknowledgements. We review these in more detail below.

“The amount of trip reduction expected for new developments in Fairfax County averaged 29%; Fairfax County projected that at non-Tysons locations around 5-10% of trip reduction would come from TDM programming and around 20% would occur naturally as the area urbanized.”
– W+A White Paper on why traffic congestion concerns should not be an impediment to the approval of higher density

An Overview of Fairfax County’s 2025 Site-Specific Plan Amendment Process

Fairfax County has announced that they will accept nominations from property owners as part of their upcoming Site-Specific Plan Amendment Process beginning in January 2025.  

The County’s Comprehensive Plan is required by state law to be used as a guide to decision-making about the natural and built environment by the county’s Board of Supervisors. The Comprehensive Plan is evaluated biannually in order to review site-specific proposals. Under this SSPA Process, nominations will be accepted from January 13 to February 13, 2025.  

Following the Nomination Phase, a Screening Phase will run until approximately May 2025, with an Evaluation Phase after that.

Our firm’s research, based on long-term data from our portfolio of Fairfax County TDM residential and office properties, makes it clear that overestimating trip generation can have deleterious effects on a neighborhood because trip generation is so closely linked to the amount of square footage that a property is allowed. Mike Workosky, transportation planner and President of Wells + Associates, explains, “More than any other feature of a development, vehicle trip generation estimates determine density limits and impacts.”

Transportation Components of SSPA Nominations

A variety of information is required in SSPA nomination submissions, including topics that relate to transportation issues, such as:  

Vulnerability Index Map:

The Vulnerability Index shows how areas in the county are performing relative to other areas of the county based on a range of topics, including transportation (e.g., percent of households with no vehicles available). This information is used to understand the socioeconomic characteristics in the area near the nomination. 

Illustrative Concept Plan:

This section includes information on streets, walkways, parking areas, site access points, and the arrangement of on-site open space, parks, or recreation areas.  

Study Acknowledgements:

If the nomination is added to the Work Program, it is required to provide transportation studies. In these cases, we have been able to apply our research to help demonstrate that with TDM, a mix of land uses, and proximity to transit, nominators can apply for additional density if the primary concern with density is traffic congestion.

If you want to know more about how we help our partners navigate the transportation components of the SSPA process, please contact us and we can talk through the unique needs of your project.

You can view an infographic of the 2025 Fairfax County SSPA Process here.

Contact our Fairfax County SSPA Transportation Team

---