Identify exactly what is closed
Do not assume an entire area is unavailable because one road or section is marked closed. Find the precise blocked segment and work out where the normal route becomes unusable.
Preserve as much of the natural route as possible
A good detour often leaves the natural route shortly before the closure and rejoins it shortly afterwards. Huge diversions can be a sign that the closure has been treated as a much larger obstacle than it really is.
Check the detour itself
A detour is not automatically valid just because it avoids the closed road. Check one-way direction, turns, central reservations and whether the roads genuinely connect. A legal-looking bypass can still fail if the first or final connection is impossible.
Compare two alternatives before clicking
If two obvious detours exist, compare them before plotting. Count major turns, consider road continuity and look for restrictions. This takes less time than drawing one option, discovering a problem and clearing half the route.
Practise closures deliberately
Closure questions are ideal for targeted drills because the decision can be isolated. Repeat the same map with different closure positions and explain why your detour is sensible. That builds a general method rather than a memorised answer.
The four-point closure method
A simple way to reason about a closure is to identify four points: where you would normally approach the closed section, where you need to leave the natural route, where you can legally get around the obstruction, and where you can rejoin the original corridor. Plotting becomes much easier once those four points are clear.
This method also stops the common habit of detouring too early. If you leave the natural route several streets before necessary, you create more turns and more opportunities for one-way or junction errors.
Do not let the closure hide other restrictions
Candidates sometimes become so focused on avoiding the red closure marker that they stop reading the rest of the map. The detour still needs to obey all the normal rules. Scan one-way arrows, road continuity and divided carriageways on the bypass just as carefully as you would on any other route.
How to review a closure attempt
If your detour differs from the accepted route, first ask whether it is actually invalid or simply less direct. Then look at where the two routes diverge and what information you missed at that decision point. The useful lesson may be about route efficiency rather than legality.
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