April 8


Trip/Parking Generation Rates for an Urban Grocery Store

By Mike Spack

April 8, 2011

Traffic Study Grocery Store Trip Generation Grocery Store Parking Generation Grocery Store

LundsParking I'm preparing a traffic study for the proposed 25,700 square foot Lunds grocery/liquor/pharmacy store at Hennepin/12th in downtown Minneapolis.  We would typically use the Institute of Transportation Engineers' reports (industry standard data sets) to help us forecast the amount of parking needed at the site as well as the amount of traffic that will be generated. 

Based on discussions with the city, we think the standard data sets may overestimate the traffic/parking needs of the downtown grocery store since the existing data sets are largely based on suburban locations.  Lunds has another urban grocery store on the edge of downtown Minneapolis on Central Avenue.  Here is the data table from a p.m. peak hour study of that existing urban grocery store (Download Parking-Trip Generation at Central Lunds).

We found slightly lower peak hour trip generation rates and significantly lower peak period parking rates compared to the Institute of Transportation Engineers' reports.  This makes sense at an urban grocery store.  They still have a good volume of customers, but those customers are making a quick stop in for a few items and then getting out as fast as possible.  At more suburban grocery store locations, we'd expect patrons to buy more and stay longer.  Suburban grocery stores aren't as well set up for convenience stops.

  • What kind of rate of growth is the area finding? How long before the suburban area grows large enough to be considered urban? And should these thoughts be weighed?

  • ITE uses a generic 36% pass-by rate for supermarkets. Did you determine a pass-by rate for the urban store you surveyed? We are trying to determine pass-by rates associated with CBD (mixed-use area) grocery stores. We already have discounted trip generation rates for grocery stores in CBD’s (approximately 40% less compared to ITE trip gen).

  • You state that the ITE trip generation rates are approx. 40% higher than what you have applied in grocery stores in CBDs. Is that 40% total or are you considering the 36% pass-by reduction as part of the 40%?

    What have you used to justify the lower rate? This study references a rate of 9.31 trips, whereas ITE has a rate of 9.48. Not a big difference.

    I would have expected the walking, biking and transit trips (mode split) would also be more for this CBD site. Any counts or observation re: mode split at Lunds in MN.

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    Mike Spack

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