Valid.
According to Hualu.com, the Wuhan Road and Bridge Center’s lawyer’s letter to demand payment is legally binding. A lawyer's letter is a legal document that can have the legal effect of interrupting the statute of limitations. The period of statute of limitations is recalculated from the time of interruption and the end of the relevant proceedings. Therefore, if Wuhan Road and Bridge Center issues a lawyer’s letter to demand payment, its purpose may be to remind relevant parties to fulfill their obligations and interrupt the statute of limitations. If the relevant parties still fail to perform their obligations after receiving the lawyer's letter, Wuhan Road and Bridge Center may consider taking other legal means to recover the arrears.