The high-speed data access provided by HFC networks has been a great success story. In many systems and municipalities, the penetration within the first year exceeded all expectations. Moreover, the early adopters were Internet and computer networking savvy and generated high traffic in both downstream and upstream directions of the HFC access network. The same high capacity utilization was experienced in the interconnects between CMTSs, proxy server locations and regional data centers (RDCs). This paper analyzes capacity utilization of several major components of the high-speed data access in HFC networks: · access side of CMTSs (downstream and upstream channels), · network side of CMTSs, · interconnects between CMTS locations and proxy server locations, · RDC LANs, and · interconnects to global Internet. This analysis accounts for the number of customers served and for the user behavior. The purpose of this exercise is to develop simple tools for initial network design and capacity engineering for different levels of penetration and for different behavior of the users. The data for this analysis has been collected over a period of several months. This data by itself is interesting and representative of diurnal and weekly traffic patterns, and can be used for capacity engineering in networks shared by different user categories: residential and business.