The phrase "crowded hallway" means there are a lot of people in a narrow space, like a school hallway, making it difficult to move around easily. Full definition
How I Handled... Keeping Control in Crowded Hallways and Lunchrooms Maintaining control as students congregate and socialize in crowded areas can present a problem; solving the problem offers schools an opportunity to involve the larger community — including parents — and to improve perceptions of what goes on in those schools. (educationworld.com)
All - terrain wheels help floaters navigate the cart over different surfaces and through crowded hallways. (educationworld.com)
It could also mean avoiding crowded hallways and noisy lunchrooms. (verywellfamily.com)