March 30


Guest Post by Vernon Swing, PE, Traffic Engineering Manager at Spack Consulting.

As traffic engineers, we are constantly balancing the mobility goals of the surrounding road network with the access requirements of the land use. For instance, all you need to know when considering convenience store land use is the name – convenience. Customers generally choose to visit these sites because of the ease and speed with which they can get in, get their product, and head to their destination. On the flip side, agencies are routinely looking at mobility and how they can help motorists move uninterrupted and safely through the system. Often this means reducing access to eliminate conflict points.

Many public agencies have adopted access spacing guidelines to provide guidance for road designers and site developers. These are a good starting point when applied to developing areas where decisions regarding land use and site design are still fluid. However, the goals of these groups are often conflicted when road designers are retrofitting access management plans into fully developed areas where site access has been in place for years. To prevent these situations from becoming standoffs that can only be settled in the courts, requires designers to actively communicate with land owners, and approach the situation with a willingness to address the site owners’ concerns.

In the case of older convenience store sites, their desired access locations often do not conform with access guidelines. At Spack Consulting we have assisted the development of over 200 convenience stores nationally and have helped to resolve access modification issues as they impact our clients. One example from my career that fits with the Spack Consulting philosophy is the Holiday Station store in West St. Paul, at the intersection of South Robert Street and Marie Avenue East. The City of West St. Paul and MnDOT had plans to provide streetscaping on Robert Street and with the project implement access management to reduce the number of access locations by installing a landscaped median down the center of the road. These are all generally good improvements with an eye toward better safety for all users. However, the impact to the Holiday site was to reduce access on Robert Street from full movement access to right-in/right-out only.

We were asked to assess the impacts to the store and to explore solutions. On the face of it, this seems to be a simple question of how many visitors come to the site from a particular direction or leave the site in a particular direction in the before versus after condition, and whether these patrons can still access the site via alternative access points. But this question gets more complicated when considering if the reduction in access results in changes to on-site circulation.

We identified the following on-site circulation items that need to be examined when access to convenience stores is modified:

  1. Pedestrian /vehicular conflicts – At convenience/gas stations there is a lot of pedestrian/vehicle interaction as customers frequently gas up then walk into the store to buy products. The Robert Street site is a very busy store and is also a very tight site. The planned changes to the site access did not increase the potential for pedestrian/vehicular conflicts.
  2. Vehicle to vehicle conflicts – Convenience/gas stations have access located so vehicles can easily get to fuel pump and to the store entrance. Often these sites have car washes which are removed from the typical access traffic flow to allow for queuing and unencumbered exiting from the wash. This site was very tight with existing conflicts at the wash exit, but the modification in access did not effect this.
  3. Fuel Delivery directions – The delivery of fuel to gas station sites is typically established to allow the fueling vehicles to visit several sites on a delivery trip often originating from a refinery then the freeway system, to the local arterial, etc. In this case, the deliveries arrived from I-494, then Northbound on South Robert Street, and a left turn into the site. The installation of medians associated with the streetscape project, would eliminate this option. This was a problem as an auto-turn analysis showed there was no other access suitable for truck turns.
  4. Fuel Tank locations – For safety reasons, Holiday Station stores do not allow backing of loaded fuel trucks on site, and require the loading of fuel tanks from the passenger side of the vehicle. In this case, the fuel tanks were located on the north side of the site and could only be accessed via a left turn in. The reduction in access is incompatible with this safety requirement and would be fatal to the business.

We worked with the roadway designer to develop a solution that did not reduce the integrity of the planned streetscape project but that would allow the business to continue in this location. Our suggested solution to develop a surmountable curb section to allow trucks to access the site at the driveway nearest the underground tanks was adopted by the agencies.

Mobility versus access is always a tricky balance and many factors need to be considered from the point of view of both the agency and the proposed or existing land use. Be sure to bring in a respected traffic engineer early in the process to help consider all the issues and work to achieve that proper balance for the good of all parties.

  • So at the end of the day, the convenience store / gas station was granted 4 curb cuts? Seems like the agency caved?

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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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