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COSMOGRAIL is a long-term photometric monitoring of gravitationally lensedQSOs aimed at implementing Refsdal's time-delay method to measure cosmologicalparameters, in particular H0. Given long and well sampled light curves ofstrongly lensed QSOs, time-delay measurements require numerical techniqueswhose quality must be assessed. To this end, and also in view of futuremonitoring programs or surveys such as the LSST, a blind signal processingcompetition named Time Delay Challenge 1 (TDC1) was held in 2014. The aim ofthe present paper, which is based on the simulated light curves from the TDC1,is double. First, we test the performance of the time-delay measurementtechniques currently used in COSMOGRAIL. Second, we analyse the quantity andquality of the harvest of time delays obtained from the TDC1 simulations. Toachieve these goals, we first discover time delays through a careful inspectionof the light curves via a dedicated visual interface. Our measurementalgorithms can then be applied to the data in an automated way. We show thatour techniques have no significant biases, and yield adequate uncertaintyestimates resulting in reduced chi2 values between 0.5 and 1.0. We provideestimates for the number and precision of time-delay measurements that can beexpected from future time-delay monitoring campaigns as a function of thephotometric signal-to-noise ratio and of the true time delay. We make our blindmeasurements on the TDC1 data publicly available

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses XV. Assessing the achievability and precision of time-delay measurements