o the years 2005, 2015 and 2025. 2. Transmission and distribution only. 3. Only OECD countries, Russia, China, India and Brazil are considered here. In addition to highlighting the importance of telecoms and water infrastructure investment requirements, the table gives some idea of the relative weight of infrastructure spending within the economy. Annual investment in the five sectors taken together is likely to account on average for about 2.5% of world GDP. If electricity generation and other energy-related infrastructure investments (oil, gas, coal) are included, the share rises to around 3.5%. An equally rough calculation suggests that for the period through to 2030, total cumulative infrastructure requirements in the above sectors amount to about USD 53 trillion. Adding in electricity generation would lift the figure to around USD 65 trillion, and other energy-related infrastructure investments to about USD 71 trillion. Clearly, the figure would rise further if one were to include other infrastructures not covered by this project, e.g. ports, airports, storage facilities. Over the time scale considered here, it can be seen that investment in land transport and telecommunications is likely to decline, whereas that in electricity and water looks set to remain steady or increase slightly. The expected fall in telecoms infrastructure spending results not only from the assumed progress in technology but also from the main focus of the analysis on telephony. Contrasting challenges in OECD countries and non-OECD countries OECD countries already have much of their infrastructure stock in place. Nonetheless, over the next two or three decades they will require very significant amounts of investment in all the sectors covered here. These requirements stem to an important degree from the need to replace and maintain existing networks. INFRASTRUCTURE TO 2030: TELECOM, LAND TRANSPORT, WATER AND ELECTRICITY - ISBN 92-64-02398-4 - © OECD 2006 1. A CROSS-SECTORAL PERSPECTIVE ON THE DEVELOPMENT OF GLOBAL INFRASTRUCTURES TO 2