Tutor Perini Corp was required to open all seven lanes by 6 a.m. but didn't do so until 7:30 a.m.
That caused a backup that stretched past Suffern. Delays lasted through the morning rush.
Thruway officials said under the contract, two Westchester-bound lanes must be open by 5 a.m. and four lanes by 6 a.m. On the Rockland-bound side, two lanes must be open by 6 a.m. and all three by 7 a.m.
A spokesman for Tutor Perini blamed "changed conditions in the field" for the problem and plans to appeal.
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