Or, what about a bank? Or a dentist office? Or a new gas station with 12 fuel pumps, a mini-mart and a car wash? And if they do create traffic, how much?
When new commercial or residential developments are planned, most communities have guidelines for determining if a traffic analysis is appropriate. A traffic engineer evaluates the land use and access plan to determine if the development creates traffic flow concerns and if so, what can be done to improve them.
This kind of analysis is performed prior to formal approval of the development as it may result in minor adjustments to driveway locations, turn lanes, or modifications at nearby intersections. These recommendations not only improve accessibility for the development and its future patrons but also reduce the impact to existing traffic in the area.
But how does one predict exactly how much traffic a proposed development generates?
One of the best predictors of future traffic is historical traffic. Traffic engineers review traffic data from past developments to predict traffic associated with proposed developments. This historical data includes the type/size of the development, the average weekday traffic volume, peak hour traffic, entering traffic versus exiting traffic, etc.
For example, we can estimate that a 3,000 square foot fast-food restaurant with a drive thru window, generates approximately 98 trips during its evening peak hour (51 vehicles entering and 47 vehicles exiting). What’s also significant, is that 56% of this traffic is already passing by the site. What this means is that only 44% of the restaurant’s traffic is actually additional traffic to the area. Of course, this percentage varies for each type of development. Whereas a majority of a restaurant’s business is comprised of customers already on the roadway, hardly anyone driving by a dentist office spontaneously decides to stop — however, I can think of one exception, my Uncle Kevin (but I think that’s because he had a coupon).
Traffic analysis considers existing traffic, normal background growth in traffic, and the additional traffic associated with the proposed development. We are all aware of examples where little or no concern regarding traffic was considered. Government agencies are getting more proactive regarding traffic analysis to ensure proposed developments are accessible for their patrons and to mitigate potential impacts to existing traffic in the area — it’s a win-win.
Chet Skwarcan (traffic engineer, author, unique insights) with over 25 years of traffic engineering experience, solving traffic problems everywhere — free assessments available at TrafficEngineering.com/Services.