Plaintiff waived its claims against the City for extra and additional work allegedly performed by failing to comply strictly with the notice and documentation provisions in Articles 27 and 28 of the parties' contract. These provisions required the contractor to notify the Commissioner promptly, in writing, that the work directed to be done was extra work and request a final determination from the Commissioner, and also required contemporaneous written detailed documentation of the alleged extra or disputed work performed ( Huff Enters. v Triborough Bridge Tunnel Auth., 191 A.D.2d 314, lv denied 82 N.Y.2d 655; Smith Elec. Contrs. v City of New York, 181 A.D.2d 542).
Plaintiff is not entitled to recover its actual costs of rock excavation on the grounds that the actual quantities removed exceeded the Engineer's estimate. The exculpatory clauses in the parties' contract, intended to insulate the City from liability, expressly warned prospective bidders that the Engineer's estimates of unit items of work to be performed were merely an approximation and that the contractor could make no claim for damages when the actual work required under the contract varied from the Engineer's estimate ( Kalisch-Jarcho, Inc. v City of New York, 58 N.Y.2d 377; Conduit Found. Corp. v State of New York, 52 N.Y.2d 1064; Buckley Co. v City of New York, 121 A.D.2d 933).
Concur — Sullivan, J.P., Rosenberger, Wallach, Ross and Asch, JJ.