Online supermarket Peapod is bringing its foodstuffs to Chicago's "L" transit system, with a new ad campaign that allows commuters to do their grocery shopping from directly within the city's train stations. Last week, the company plastered Chicago's State and Lake Station Tunnel with a "virtual grocery store" ad — posters of grocery shelves stocked with popular household items and food products. People travelling through the station can scan an accompanying QR code to download the free PeapodMobile app, which will allow them to scan barcodes listed on the products displayed in the ad. With the app, iPhone and Android users can place orders, manage their shopping lists, and schedule deliveries as they wait for the next train.

This isn't the first time that a grocer has used QR codes to spur a virtual shopping campaign; Homeplus, Tesco's South Korea affiliate, announced an essentially identical program in October. Peapod itself launched a similar initiative back in February, when it placed barcode-laced posters across 15 commuter stations within Philadelphia. That program lasted for 12 weeks, and the company reported a 90 percent reorder rate among customers who scanned its ads. There's no word yet on how long the Chicago pilot program will last, or if it will ever expand to other stations.