Impact of lot and sublot sizes on smoothness specifications using road data in the USA

Abstract

The construction quality of a lot is often measured by collecting and testing a few samples. The statistics of an acceptance quality characteristic of the lot determined based on the samples are used to make an inference on the overall construction quality. The quality measure most commonly used to quantify the quality is per cent within limits (PWL). The PWL value of a lot depends on the samples’ statistical parameters obtained within sublots. This paper evaluates the effects of lot and sublot sizes on estimation of PWL. The results show that, as the sublot size increases, the variability in measured International Roughness Index (IRI) values decreases and the PWL value increases if the mean IRI obtained for all of the sublot sizes is lower than the upper specification limit irrespective of the lot size. Pay factors for smaller lot sizes represent more rational justification of payment based on the true quality.