Mathematical Digest Short Summaries of Articles about Mathematics in the Popular Press "Mathematicians find path less traveled," by Philip Ball. Nature Science Update, 14 January 2003. Science writer Ball gives a preview of the Grand Canyon River Trip Simulator (GCRTSim) that mathematician Catherine Roberts (College of the Holy Cross) presented at the Joint Mathematics Meetings in Baltimore in January 2003. The computer model that Roberts has developed could help park managers control recreation on the Colorado, as the modelusing logged itineraries of 487 expeditions made along the 447km river section over 18 monthspredicts how rafters will move around the river using various forms of transport. "Similar agentbased models are already used to predict traffic flow in cities. The GCRTSim shows their potential for capturing more subtle aspects of human behavior," the article says.  Annette Emerson
