ngers. Infrastructure effects of air travel substitution Like telecommuting, videoconferencing and audioconferencing have long been promoted as substituting for a proportion of long and short distance business trips. Early forecasts suggested that a significant proportion of business travel could be replaced, but these early predictions have proved to be overly optimistic. Rather than replacing travel, it is now accepted that videoconferencing complements travel patterns. In other words, while some business air travel is replaced, increased efficiency and productivity gains from communications technology translates into extra air travel, thus offsetting some or all replaced business air travel. 81 A recent study concludes that videoconferencing has only limited effects on business air travel with substitution rates of 2.5 to 3.5%. 82 In a study on teleconferencing suggested that in the longer term, teleconferencing could displace up to 15% of business travel. 83 An FAA-sponsored study by Apogee Research suggests minimum and maximum substitution of 3% and 11% while INFRASTRUCTURE TO 2030: TELECOM, LAND TRANSPORT, WATER AND ELECTRICITY - ISBN 92-64-02398-4 © OECD 2006 2. TELECOMS INFRASTRUCTURE TO 2030 an Arthur D. Little analysis for Boston's Logan International airport proposes diversion ranging between 13% and 23%. Taking all these studies into account, Transport Canada proposes a substitution rate of 6%. Perhaps use of desktop videoconferencing (with Internet webcams) from home, office or anywhere (with mobile video) could enhance the penetration. The same effect would tend to cap airport infrastructure expansion; under the pressures of oil prices, congestion and possibly pollution, the larger NICs could well use audio and video teleconferencing to substitute for business air travel both now and increasingly up to 2030, with the same proportion - perhaps 10% of business travel - being replaced by some form of conferencing. Secondary effects resulting from travel substitution Whatever the extent of the substitut