The writers neglected the importance of practicability. Elsewhere, doubts remained concerning the practicability of the scheme. A pilot plant was erected to demonstrate the practicability of renewed mining. Experts in the field of environment protection have questioned the practicability of the concept. The architecture of MTR stations is less artistic, instead focusing on structural practicability. This is one major technical challenge which limited the practicability of the design. The washability of yarn affects its practicability. Practicability is also determined by regulatory, logistical, and economic considerations.