This report, released by the University of Minnesota’s Center for Transportation Studies, explores using a ramp metering algorithm based on density measurements, rather than flows, on Minnesota’s freeways. This algorithm is based on recent research that indicates “the critical value of density at which capacity observed is less sensitive and more stable than the value of capacity.” This next generation ramp metering algorithm is currently being tested on a microscopic simulation of a real 12-mile freeway section with 17 ramps.