SECTION 1. There is hereby established a special commission to investigate and report on retirement benefits provided to employees of the Massachusetts Bay Transportation Authority consisting of the following members:  the secretary of transportation, or a designee; the treasurer, or a designee; the executive director of the Public Employee Retirement Administration Commission, or a designee; the secretary of administration and finance, or a designee; and the president of Massachusetts AFL-CIO, or a designee.  The executive director of the MBTA Retirement Fund shall serve on the commission ex officio as a non-voting member.  The report shall analyze the feasibility of providing retirement benefits to future employees of the Authority solely and exclusively under chapter 32 of the General Laws as opposed to any other statutory or contractual plan or system under which current Authority employees are eligible to receive retirement benefits, and shall examine and report on, without limitation:  (i) all retirement benefits currently received by retirees of the Authority and retirement benefits for which current employees of the Authority are eligible; (ii) relevant  contractual provisions and applicable federal and state laws and the legal effects thereof; (iii) transition costs and implementation and logistical considerations;  (iv) the relative impact on pension benefits; and (v) the advisability of so providing retirement benefits to future employees of the Authority pursuant to chapter 32 of the General Laws, and if so, a proposed effective date;  provided, that any recommendations contained in the report shall have considered the need for the continued sustainability of the statutory and contractual retirement benefits provided for existing employees of the Authority.  Not later than January 1, 2020, the commission shall file the report with the the house and senate committees on ways and means, the house and senate chairs of the joint committee on transportation, and the clerks of the house of representatives and senate.