It's correct. It's in the passive voice, which is used when you don't need to show who does the action of the verb.

Active voice: "[The police?] never allow motorists to drive into the business district."

If you don't need to mention the subject, "the police", you can turn the object, "motorists", into the subject, and change the sentence structure. The sentence structure of the passive voice is "subject (which is the object of the active voice) + to be + past participle":
"Motorists are never allowed to drive into the business district."

It's present simple tense.

Don't be tricked! Allowed, by itself, is past tense. Are allowed is present tense (this form of allowed, the past participle, doesn't have a functioning tense).

Look up "passive voice" and you'll see how it works. The tense is defined by "to be".

@Abdullah

@Peachey

Thanks a lot. It was very helpful.