In his first month, as Mr. Lhota crafted an emergency plan to fix the subway, he largely upheld that promise. Calendar records show that he worked an average of 38.2 hours per week at the M.T.A. and 31.3 hours elsewhere, not including unscheduled work at home.

By winter, Mr. Lhota had hired a new management team, and he scaled back his work at the authority. In March, he worked 22.1 hours per week at the M.T.A. and 32.5 hours on other obligations, records show.

Mr. Lhota said his calendar was an incomplete record of his M.T.A. work and that he often sacrificed family time and other interests. “I haven’t played a game of golf since I became chairman,” he said.

Records indicate that Mr. Lhota’s private work has occasionally interfered with his M.T.A. responsibilities. Mr. Lhota has a 7:30 a.m. daily conference call with the officials who report directly to him, but his calendars show that he has had another commitment during that call 29 of the last 50 times it has been held. Mr. Lhota also has met with M.T.A. officials at N.Y.U. Langone on at least two occasions.

When a crisis has struck, Mr. Lhota has sometimes been elsewhere. Last July, he was at N.Y.U. Langone when a track fire at a subway station in Harlem injured nine people; last December he was at a meeting at Madison Square Garden when snow snarled service; and last week, he was driving to a Greater New York Hospital Association meeting when a major storm forced the suspension of Metro-North trains.

Mr. Lhota also angered the City Council when he missed a hearing and left another early. “I think if he wants to ask us for funding, he should be here and ask himself,” Jumaane D. Williams, a Council member, said at an August hearing.

Transit activists have questioned Mr. Lhota’s independence from the governor and complained that he does not have time for them. Nick Sifuentes of the Tri-State Transportation Campaign provided emails showing requests for meetings that he said were ignored. “Lhota is totally the ghost in the machine,” Mr. Sifuentes said.