InfraRed Integrated Systems has develope what it calls its Intelligent Queue Management (IQM) system.  It is targeted toward commercial businesses attempting to reduce and better allocate human resources without further degrading the customer experience. IQM uses infrared sensors that measure and track numbers and behaviours of customers, and predictive algorithms to work out how many checkouts will be required in 15 and 30 minutes time to meet customer demand. It even sends alerts to managers so they can proactively manage staffing levels in real-time to ensure optimal levels of customer service. The company claims that IQM will ultimately lead to shorter queues. Read more here.

Then again, if you were using lean concepts, you would simply kick the manager out of their office to go to the checkout area, see the queues with their own eyes, and actually interact with them.