Painting a Straight Line
I’ve seen start and finish lines that were pretty sloppy, and it doesn’t have to be. The problem is that the line-painter has a badly-calibrated eyeball. Mine isn’t so hot.
I had a chalk line left over from a construction job, and found it to be very handy for painting start and finish lines. You give the thing a shake, to agitate the chalk within, then draw the string out of the case until it is long enough to span the road. This is a two-person job. You lower the ends to the roadway, keeping the line tight. When it’s all the way down you give it a pluck, the line snaps, and a nice chalk line is on the road, ready to be painted.
No need to buy a chalk line. You can do just as well with any old piece of string. Put it down, stretch it tight, and paint. Then throw away the nasty, painty string. Hint: Have your helper pick it up.