Temporal coordination of services, as a crucial aspect of integration in public transport systems, has always been a big concern for transit planners and schedulers. One of the major issues in the way of coordinating transit services is the lack of a robust measure of effectiveness for assessing the quality of temporal coordination in public transport systems. Even though the network-wide summation of transfer waiting times is commonly used as a measure for this purpose, this index is not always calculable particularly when transferring passengers count is unavailable. This paper aims to present a practical method for quantifying the level of temporal coordination in transit systems, even in the absence of transfers count data. In this paper, first the timetable coordination indices proposed in the literature are evaluated and discussed. Then, a quantitative index is mathematically developed based on the actual waiting time incurred by transferring passengers in transit systems. A numerical example is also presented to examine the applicability of the proposed index. The results of this application revealed this index could be reliably used as a measure of effectiveness for assessing the level of coordination between public transport services, as well as for evaluating the impacts of different timetabling scenarios on transit systems integration.