Each transit agency must establish and implement a Safety Management System under this part. A transit agency Safety Management System must be appropriately scaled to the size, scope and complexity of the transit agency and include the following elements:

(a) Safety Management Policy as described in § 673.23;

(b) Safety Risk Management as described in § 673.25;

(c) Safety Assurance as described in § 673.27; and

(d) Safety Promotion as described in § 673.29.