By Bryant Ficek, PE, PTOE
Convenience stores are expected to be exactly that – convenient. Take a look at various convenience stores, gas stations, and similar developments and you are likely to see some common themes about their location: highly visible locations, directly adjacent to a very busy road or intersection (often both), and generally multiple ways to drive into the site. After all, making sure customers can quickly and easily get to the front door can be the difference between an average year and a great year for the owner.
Working with various convenience store developments, we work on the balance between making their site convenient while protecting the operations on the public roads. On a couple recent projects, these two factors were out-of-balance requiring more in-depth conversations and a look at various options.
A first case involved access to a right-in/right-out only intersection, just upstream from a busy signalized intersection. The new proposed development wanted to maintain the existing connection while the city wanted to close the access. In our review, we identified the potential risks of traffic using the right-in/right-out and completed a queuing analysis on the road. Based on this review, we recommended allowing right-out movements only and shifting the driveway away from the signalized intersection another 100 feet.
The second case also involved a right-in/right-out only access, only this time it was located on a major highway. Our evaluation of the site revealed that the access could not be closed due to it being to only access to several other residential properties. With the access being open, the new development would likely increase traffic on this limited-access intersection, although the increase would be minimal. In addition, our analysis showed the operations would remain about the same as today. However, the state traffic personnel would have preferred the access closed if possible. For this project, the politics of the situation overruled any traffic information we could provide. Based on standard access management guidelines and the potential risk associated with this access, projecting a similar level of service to today’s operations was not enough reason to maintain the status quo in the state’s eyes. They therefore demanded changes in the site access eliminating their access to the highway through this right-in/right-out only access.
Both cases resulted in changes to the site plans and a shock to the developers who expected their access to be exactly where they wanted it. This represents one of the top five traffic-related mistakes we see regarding convenience-type store developments: Assuming you can put your driveway(s) anywhere you want on the public street under the type of control you want.
You can see the entire list in the September 2015 issue of Convenience Store Decisions in their article titled Dealing with Real Estate (page 98). We provided this list to them based on our experience working with convenience stores and other similar development. You can view our Kwik Trip case study on the Spack Consulting website. The bottom line is to be sure and bring in a respected traffic engineer early in the process to help avoid these mistakes and make sure your project balances convenience with overall traffic operations in the area.
I think #4 on that list, if you included all traffic studies (not just convenience stores) would quickly rise toward the top. Often times the science/data/number-crunching kicks off the discussion. I can only count a handful of times when the final decision was based solely on the analysis. Inevitably some form of politics and preference make it into the final recommendation.
But isn’t that what we are supposed to love about engineering? The politicians, public, client, and even our own project managers place a boatload of constraints on the problem we are looking to solve. Then we ‘engineer’ a solution which balances all the constraints with what the analysis is actually saying. Maybe I’m the crazy one, but that is what keeps me in this field. The variables we can’t control are often times the most ‘fun’ and challenging to address.
Thanks for the comment. My old boss/mentor would always say that Traffic Engineering is a mix of art and science. As I continue moving through my career, I find those words to echo true more often than not.
And I agree with you that this aspect makes projects more interesting as well. Developing creative solutions and working hard to successfully navigating the review/approval process makes our field an enjoyable one.
One of the most interesting developments in traffic engineering was the introduction of the Highway Safety Manual five years ago. Like the Highway Capacity Manual does for flow rates and delays, it uses numeric analysis methods to predict the safety performance of a street or highway based on geometry and traffic volumes.
As a county permit engineer, I’d welcome access submissions that included a safety analysis along with the usual capacity analysis. From a developer point of view, this might help allay fear, uncertainty and doubt regarding the safety effects of their project.
Hi Zed – Thank you for the comment about the Highway Safety Manual. I agree it is a very important resource for us. The gray area for me related to safety analyses being done within a Traffic Impact Study is responsibility. Should a development be denied if there’s an existing safety problem or should the developer be on the hook for correcting the existing safety problem? One could argue that is a role of government. Mike