Jacobs Engineering Group’s intended purchase of CH2M, announced on Aug. 2, has apparently cost the latter its $57-million construction-management contract for the Massachusetts Bay Transportation Authority’s Green Line extension. The prospective parent is teamed with contractors Walsh, Granite and Barletta as one of three bidders for the 4.7-mile, $1.3-billion construction contract. MBTA determined that a potential conflict of interest required ending CH2M’s contract, awarded in May. The agency, which now is negotiating with runner-up HAKS for the CM contract, says the change will not affect the overall schedule, which calls for construction to begin in early 2018.