How to use nouns as adjectives?
It is correct. The rule of using adjectival noun in Chinese is the same as in English. You can take any standard noun and use it as an adjectival noun to modify a main noun as long as it make sense.
For example:
交通 (traffic) + 意外 (accident) = 交通意外 (traffic accident)
You don't need to use particles like 的 to link the two nouns

交通意外(traffic accident) is a single noun * with 交通 as the adjectival noun and 意外 as the main noun

交通的意外 (traffic's accident) is a phrase


Important:
Many Chinese nouns are made up of two noun characters that combined into one stand-alone word.
Example:
車 (Car) + 禍 (disaster) = 車禍 (car accident)
Since 車禍 (car accident) is a noun on its own, you cannot break them up and treat them as two individual nouns and write 車的禍 (cars' disaster)