I have a segment of a marathon to measure and would like some input regarding the best approach considering complexity of course setup, runner safety and distance integrity. The parameters given to me by the organizer are as follows: runners will be restricted and instructed to run in the left lane against traffic from approximately the 4.5 mile point to the finish. Cones would be placed along the centerline of the roadway in right turns to prevent runners from crossing to the opposite shoulder of the road. The segment I question most is from about mile 17 to 23. It is a rural area with a lot of curves and intersections with no distinct centerline to follow. It will take a truck load of cones and a lot of course marshals to keep runners to the measured route, if it is anything other than the SPR. Also there are typically about 600 finishers for the marathon distance so by mile 17; runners will be pretty spread out. Roads are open to traffic.
I have three options; measure the SPR shoulder to shoulder, measure the SPR using only the left lane or restrict runners to 3 or 4 feet of the left shoulder. Any thoughts?