ion effect, secondary effects would be felt in terms of reductions in: The built environment in terms of levels of construction of offices (as workplaces) and shops, as well as roads, with knock-on effects in demands for building, materials, finished parts, bulk and fine chemicals and aggregates, construction machinery, and so on. However, there may be expansion in small and home offices (the SOHO sector). The manufacturing sector in terms of vehicles and parts, leading on to reductions in demand for finished goods such as steel and raw materials to make them. The services sector which supports the industries of vehicle manufacture and construction of all kinds, from planning to insurance to roadside services. Hence, direct links to construction, energy consumption and vehicle manufacture characterise substitution for passenger travel with knock-on effects in their supply chain and support services - such as construction machinery hire - and also the tax base, for instance for property taxation. This would lead to a reduction in the supply chain required and its own infrastructure - for instance lower fuels and materials usage would reduce the demand for shipping and ports, reversing the current trends for a global shortage of shipping tonnage. These causal chains of secondary effects are shown in a relevance tree in Figure 2.26. 84 Energy consumption effects of electronic mobility Saving on transport costs with telecommuting includes the energy costs in fuels for: Private road transport - car journeys for regular commuting and for mundane shopping. Aircraft for business trips. INFRASTRUCTURE TO 2030: TELECOM, LAND TRANSPORT, WATER AND ELECTRICITY - ISBN 92-64-02398-4 © OECD 2006 2. TELECOMS INFRASTRUCTURE TO 2030 Figure 2.26. Relevance tree for passenger travel Direct links to construction, energy and vehicle manufacture characterise the passenger travel sector. The major Relevance Tree connections are as follows: Telecommunications substitutes CONSTRUCTION Private Road and car park construction Office and super