The device, a contraption that a 9-year-old boy helped to develop in the early 1970s, allowed Katz and Jones to measure 26 miles 385 yards along the most direct path that America's best distance runners will follow at the United States Olympic men's marathon trials in New York on Nov. 3. Most of the course -- all but about 1.3 miles -- will be run on the roads of Central Park. -nytimes.com
I hate inaccurate courses! This is not rocket science- you measure a stretch of road and accurately calibrate a bicycle, and off you go.