As a part of the certification process, as set forth in §85.1406, a certifier may request that the Agency approve an alternative test procedure, other than the heavy-duty engine Federal test procedure, to show compliance with the 25 percent reduction in particulate matter emissions as noted in §85.1403(b)(2)(i). The alternative test may be a chassis-based test, but the alternative test shall be representative of in-use urban bus operation. The requestor shall supply relevant technical support to substantiate its claim of representativeness. Upon an acceptable showing that an alternative test is representative of in-use urban bus operation, the Agency shall determine whether to set such alternative test procedures through rulemaking. The provisions of the certification process apply to such a request for alternative procedures.