The board of the Centre City Development Corp. voted unanimously yesterday to reimburse $501,000 in design work to be done by the North County Transit District for the northern third of the project, which stretches from Broadway to Laurel Street.

To create a quiet zone, safety improvements must be made at each rail crossing. The federal government allowed for quiet zones when it passed new train regulations last year.

Many downtown residents have complained about being disturbed by more frequent horn blasts caused by the updated regulations.