Can I say, "Building tunnels" or "new ring roads" can also do?

There are contexts where saying that something "will do" or "won't do" (with the emphasis placed on the word "do"), as a synonym for "will work" or "will be satisfactory", is perfectly appropriate.

I wouldn't say (as a commenter does) that the term is informal, but it is regarded as idiomatic, along with phrases like "make do" (i.e. find a way of performing only within means that are already available) or "it'll have to do" (I.e. you/we will have to be satisfied with what is available or already offered).

"Make do", for example, has been in popular British usage in the past, such as in the post-war policy of "make do and mend", so most people are familiar to some degree with this usage of "do".

"Could do with" is another idiom (meaning that something is desirable, or as an oblique way of saying that something is imperative or necessary) which follows a similar pattern, as is "can't be doing with" (meaning that a person, thing, or eventuality cannot be tolerated).

I would definitely say that the word "do" is not a straightforward substitute for the word "work". You wouldn't say "a ring road can also do" or "could also do".

The idiomatic way of saying this would be "a ring road might do", and if you had to add the word "also", then it wouldn't go between the words "might" and "do" (as in "might also do"), it would go before or after ("also might do", "might do also").