"A", coupled with "B" will be considered singular or plural?

Question

Rising urbanization, coupled with fast growing infrastructure projects is projected to fuel the demand for construction aggregates in the U.S. market

Should it be "is projected" or "are projected"

Answer 1

There is a comma missing in your sentence.

Rising urbanization, coupled with fast growing infrastructure projects [comma] is projected to fuel the demand for construction aggregates in the U.S. market.

Now your question is answered I guess. The subject of the verb conjugated is only the noun phrase "rising urbanization".

Answer 2

Should it be "is projected" or "are projected"

I was wrong. Please see below.

"are projected" because 'projects' is plural.

Another way to think about it is that the sentence references two distinct trends--rising urbanization and fast-growing infrastructure projects.

Even though these two economic forces are 'coupled' they have not become a single unit like a married couple, which is singular.

The image that comes to mind is that of two boxcars coupled together, being pulled by a locomotive. The two boxcars are 'coupled', but they are not 'a couple' (a single unit), therefore one would use plural verbs to refer to the boxcars.

"The boxcars are very old", not "The boxcars is very old."