These are the most rapidly developing form of Advanced Transport Telematics (ATT) application. 3s Information from equipped vehicles or traffic sensors is used to provide radio or in-vehicle display messages of delays, or to indicate preferred routes to avoid congestion. Evidence suggests that familiar drivers are more likely to prefer information, and to choose their own routes, while unfamiliar drivers prefer guidance. 5m Several studies have predicted reductions in travel time of around 10 per cent from such systems, when applied in urban areas, together with reductions in accidents. 52 Unfortunately, the only documented field trial of dynamic route guidance, in Berlin, has suggested that the benefits may be much lower than this. 53 Most benefits will, of course, accrue to equipped vehicles in the form of improved accessibility; benefits for other private traffic and for buses may well be very small, thus raising important equity considerations. It has also been suggested that improved information may generate additional travel. There is, however, little evidence to support such claims.