1) generating a new route from scratch
2) setting controls and measuring shortest distance
I'll take the first two of these. There are undoubtedly several ways to go about it, but I think this is the quickest:
a. Go to "Get Directions" and select walking directions (the pedestrian icon).
b. Select "Show Options" and select "km".
c. Select "Add Destination" until you have enough boxes for all the controls you want to use.
d. Type in the control locations into the boxes. Only rough locations are needed at this stage in form "Village, Nearby town", for example "Hauxton, Cambridge". (You should be able to figure out what names Google Maps is expecting to see here by looking at what appears in the auto-completion dropdown, but Google Maps may later ask you to disambiguate your locations if they are vague.)
e. If you get the controls in the wrong order or need to add extra controls, you can use the green circles to drag them into the right order.
f. Hit "Get Directions".
g. Drag the pushpins on the map to move the control locations into the right places.
h. The total distance is near the top of the left-hand panel, and the stage distances are given at the end of the directions for each stage.
For example, for Terry Dickerson's "End of Hibernation" 200, the rough controls are:
A. Hauxton, Cambridge
B. Silverley, Newmarket
C. Stradishall, Newmarket
D. Onehouse, Stowmarket
E. Finchingfield, Braintree
F. Great Hormead, Buntingford
G. Hauxton, Cambridge
(
See here for the route after this step.)
Looking at the map, we need to adjust control C—it's not at Stradishall village, but a couple of km west along the A143—and control D—it's outside the village on Lower Road.
(
See here for the route after this step.)
Shortest distance between controls: 197 km (how did Terry get away with this?
).
Now to make the path follow the actual route (rather than the shortest route). You can drag the lines directly with the mouse, adding a new waypoint each time you do so. The first stage and last stage need some waypoints to avoid the big roads.
(
See here for the final route.)
200 km exactly.