You certainly won't find Tim Bowen's article on the word heavy and its collocates heavy going.
The adjective heavy can go with certain types of weather to indicate there is an excessive amount of it, for example, heavy snow, heavy rain, heavy showers, heavy downpours.
Traffic can also be heavy in the same sense, as can one’s workload, as in ‘A lot of students find it difficult to cope with the heavy workload on this course’.
Heavy can also be used to indicate that something involves a lot of people, things or money, for example, heavy casualties or heavy losses, as in ‘The heavy losses made by the company this year could lead to many redundancies’.
Certain activities can also be described as heavy, meaning that an excessive amount is involved, e.g. heavy drinking, heavy smoking, heavy fighting (for example, ‘There has been heavy fighting around the airport’) but, although it is possible to be a heavy drinker or a heavy smoker, it is not possible to describe a fighter as heavy.
If something is described as heavy going, it is difficult to achieve or understand, as in ‘I tried reading his latest novel but I found it heavy going’.
If you make heavy weather of something, you make it more difficult than it really is, as in 'France are through to the next round after making heavy weather of beating Luxembourg'.
Some medical problems can also be described as heavy, notably heavy bleeding and a heavy cold.
Finally, if something takes a heavy toll on something, it affects the situation very badly, as in 'The armed conflict is taking a heavy toll on health services around the country’.