There are various factors that determine the “Goldilocks Zone,” but they’re all driven by traffic.
By Bryant Ficek
All you really need to know about convenience store land use is in the name: convenience.
Customers generally choose to visit these retail sites because of the ease and speed with which they can get in, get their product and continue onward to their destination. Selecting the optimal location for a convenience store with just the right amount of convenient access and traffic volume can be challenging. That where the “Goldilocks Zone” comes in.
Surrounding traffic volumes can impact a store’s success. So, what is the Goldilocks Zone, or the number of vehicles, for convenience store developments? In terms of traffic, research suggests the optimal convenience store location is adjacent to roads with between 5,000 and 15,000 vehicles per day. This is based on the expected pass-by traffic and the ability to obtain access to that public road. Here’s an overview of how to evaluate a site’s traffic suitability using pass-by traffic and direct access.
PASS-BY TRAFFIC
Studies regarding the traffic generated by convenience stores suggest most of the site’s trips will come from the adjacent roadway. In traffic engineering lingo, this is referred to as ‘pass-by’ trips and defined as traffic already traveling on the road for a different purpose (like the standard commute from a home to the workplace) that will include a stop at the new store in the future. The importance of this term is that the success of a site will be partially determined by the amount of nearby traffic and how much of that traffic stops at a new store.
To translate this into traffic volumes, consider a typical convenience store with gas pumps (building size of roughly 4,500-5,000 square feet). The average daily traffic for this typical site would be expected to be about 2,000 cars entering and 2,000 cars exiting.
Traffic studies show half or more of these expected trips will come from pass-by traffic on the adjacent road or roads, translating into about 1,000 or more cars. The remaining 1,000 vehicles would be considered ‘new’ (more traffic jargon) to the surrounding roads.
New traffic is defined here as representing a driver specifically going to the development (not associated with a commute or other purposed trip) or diverting from another nearby major road not immediately around the site.
To convert this expected pass-by traffic into the total traffic on an adjacent road requires thinking about individual drivers. How many can reasonably be expected to stop at a new development?
Obviously not all or even most drivers on a road will stop at one individual store. At the high end, we think a reasonable expectation is assuming one out of every five drivers already on the road will become a pass-by trip. Therefore, continuing the calculation, the adjacent road must have an average daily traffic volume of at least 5,000 to support the expected pass-by trips at the new convenience store. Our minimum threshold of adjacent street traffic is thus established to optimize the chances for pass-by traffic and for the store’s success.
DIRECT ACCESS
To establish maximum threshold of adjacent street traffic, our experience leads us to consider the ability to obtain direct site access to a road.
Public agencies (particularly counties and states) are focused on safety and mobility, which is related to access. New site access to public roads goes against both of these metrics. More access results in more conflicts and a greater chance of crashes. In other words, the road becomes less safe.
Mobility is optimized with limited and controlled access, the extreme example being the Interstate system, which has highly controlled interchange locations. Obviously, direct access to a road is the most convenient option for a new store. Access management, where the public agency controls and limits access, can therefore go against the success of a site.
In general, public agencies apply access management principles to higher order roads like highways and arterials. The traffic volume on a road is often indicative of its status, meaning highways and arterials usually have larger volumes and vice versa. The higher volumes and status mean a public agency obtains a greater safety benefit and improves mobility for a large number of drivers by limiting direct property access.
Access that could be allowed and justified on a road with 5,000 vehicles per day gets tougher when that daily volume increases two- or three-fold. Based on our work, at approximately 15,000 vehicles per day, even a limited direct access right-in/right-out or entrance only can be tough for many public agencies to approve. Thus, the maximum threshold of adjacent street traffic is established to optimize the potential for direct access and for the store’s future success.
IN THE ZONE
As discussed above, we have established our Goldilocks Zone for a successful new convenience store as between 5,000 and 15,000 vehicles per day on the adjacent road. These roads provide enough volume to maximize the pass-by trips, but not enough that the safety of the road is compromised with direct access.
There are exceptions to every rule and we obviously want every trip to and from a site to be safe. Many successful stores are located in small towns without high volume roads.
Similarly, stores can be successful with less than ideal access that may require a driver to turn down a side street before reaching the development.
But for site planning regarding surrounding traffic, your chance of success increases if you are located along a road in that sweet spot. Ideally, on a corner of two roads that are each in that range.
Accounting for adjacent traffic volumes and site access is just one aspect of how using a respected traffic engineer can help identify desirable sites. Other roadway characteristics that may be of impact include the traffic control type, multi-modal options (transit, bikes, pedestrians), and the geometry of the surrounding transportation network.
When brought in early in the planning process, the traffic engineer can also consider site circulation and other issues to help make the new store as convenient—and successful—as possible.
Bryant Ficek is the vice president of Spack Consulting, an engineering services company, which is part of the Spack Enterprise family of companies. He is responsible for the firm’s traffic engineering and transportation projects. His experience includes managing and working on more than 1,000 traffic impact studies, including those for convenience stores.
