FAQs About Drive Time Trade Areas in Retail Site Selection

Posted by Sam Lowder on Jul 30, 2019 9:30:00 AM

FAQs About Drive TimesIn early 2019, SiteSeer made major updates to our flagship software, SiteSeer Professional, including the installation of the latest version of Freeway, a third-party plugin by partner Applied Spatial Technology. Freeway provides the calculations behind the drive-time trade area boundaries you see in SiteSeer.

Our support team has heard your questions! Here are answers to some frequently asked questions:

What is drive time?

Drive time is a measure of travel, typically in minutes driven by car or bicycle, or walked.  A drive-time boundary, or isochrone, determines the travel time from a location (your site) to points in all directions. So, if you chose a drive time of 10 minutes by car from your site, SiteSeer will simulate travel outward along all roads until it reaches 10 minutes.  By connecting all the points along the roadway that are 10 minutes away from the site, a drive-time boundary or trade area can be created. 

Are drive-time trade areas better than mile radius “rings”?

Drive times are often used in place of mile rings, or radii around a site. Most users believe that drive time is a more accurate measure of a trade area because it accounts for how consumers actually travel.

In areas with barriers to travel, including water bodies or stretches of freeways without exits, the drive time can be much more accurate. Drive times also take longer to create compared to radii, so they can be less practical if you are completing an analysis with millions of drive-time calculations. Radii also allow apples-to-apples comparisons from one area to another. Population within three miles in one area will be directly comparable to population within three miles in another area.  It can be more difficult to make those same comparisons with drive time.

How are drive times calculated?

Although the actual methodology used by the companies that produce drive-time software is proprietary, generally it works like this:

  • Each road segment has certain attributes such as typical travel speed.
  • The software will travel outward from your location (site) in every direction, using the travel speed to determine how much time has elapsed.
  • For example, if your site is on a freeway and the typical travel speed is 60 mph, one should be able to travel five miles down that road in five minutes. If traveling in the opposite direction requires taking city streets with travel speeds between 20-35 mph, then the travel distance in that direction will be more like 2-3 miles. 

What is the difference between light and heavy traffic, or traveling by bicycle or walking?

For most users, choosing the defaults for drive-time trade areas will give them the most accurate drive-time boundaries. SiteSeer has spent countless hours running scenarios to find the options that work best in most situations. However, there are times when you may feel that the drive time calculations aren’t appropriate for your area.  Perhaps your retail site or other site is heavily traveled by walk traffic or plagued by excessive traffic. In these cases, you can override the defaults. Choosing “light” traffic will result in more optimistic travel conditions – perhaps what you’d encounter at 3:00 am if you hit all green lights. “Heavy” traffic will be more typical of travel speeds during the busier times of day such as rush hour. Bicycle and walk times are calculated using typical urban bike and walk speeds following the street network. 

My models use the metric 5-minute drive-time. What travel speeds were used?

Unless indicated otherwise, SiteSeer uses the moderate or typical automobile travel speeds for its model variables. If a model required a walk or bicycle travel time, the name of the metric will indicate that it is using walk or bicycle travel time.

Why don’t I have the ability to change the options for my drive-time trade areas?

Users have the display or hide drive-time options in SiteSeer. If you do not see these options, please contact SiteSeer support to make this change. 

My trade areas look different. Is the new drive time engine working right?

Although we believe that the new drive time engine is more accurate than its predecessor, your new trade areas will not match your old trade areas. There are several causes of these changes. 

  1. The road network is always changing.
  2. Travel volume is always changing. One road that moved at 50 mph in 2017 might only move at 35 mph in 2019 due to congestion.
  3. The travel-time algorithm has changed. In our opinion, the old drive engine was overly optimistic and its default was for light traffic.  This default was later changed to moderate, but long-time users may have older trade areas with these large “light” traffic trade areas. 

With the new drive-time calculations, my trade areas have lost population. Is this right?

As discussed above, there are several reasons why your trade area boundary calculated using the latest drive-time engine is different than a trade area created using the old drive-time engine.

Methodologies evolve over time. Your latest vehicle is probably safer and more efficient than your old one. Your camera on your smartphone is likely better than an older phone you had.  New technology will always reveal flaws with older technology. 

We believe that for most users, the new calculations are more accurate (and thus, better for your methodology when choosing a retail site), but we recognize the challenge in having to explain why your trade areas have changed. You always have the ability in SiteSeer to change trade areas. If your new trade areas are too small, make traffic lighter. Or perhaps using the trade area editor to make edits to the trade area or manually create your own. 

My models have drive-time calculations.  Do I need a model update?

Your model has a metric called Bachelor’s Degrees within 10 minutes. Your trade areas are now smaller and you assume that hurts your forecasts. It’s a legitimate concern. The truth is, all models are outdated to some degree from the moment they are created. The data behind your models is being updated continuously. The up-to-date data that makes your site selection modeling more accurate can also make it less accurate.

With machine learning/AI and analog site selection modeling, these changes are handled very well. For more static approaches, such as scorecards and regression, regular updates are more important. However, for most users, the answer is to continue to update your models as scheduled. If you wish to update sooner due to the drive-time change, we are happy to discuss options with you.

Have other questions?

Please visit the SiteSeer help menu to watch our video tutorials, including Using Trade Areas in SiteSeer.  Or contact our support team today for all your SiteSeer questions: 866-524-2804.

Topics: Retail Trade Area, Site Selection Software, Analyzing Retail Sites