(2) Whereas of the measures to support these structural improvement arrangements with the aim of avoiding aggravation of existing overcapacity or the emergence of further overcapacity, the "old-for-new" rule has proved indispensable to balanced operation of the inland waterway market; whereas this rule also remains an essential instrument for intervention in the event of a serious disturbance on the same market, as defined in Article 1 of Directive 96/75/EC(5); whereas steps should be taken to prevent the benefits from the scrapping schemes conducted since 1990 being wiped out by new capacity coming into service as soon as the abovementioned rule ends; whereas it is therefore encessary to retain the "old-for-new" rule for a limited period of not ...[+++]more than four years while gradually reducing the ratios to zero to safeguard the transition and end the Community market intervention stage; whereas it is also important to maintain the "old-for-new" instrument for regulating the capacity of the Community fleets beyond these four years, but as a standby mechanism set at zero which could be reactivated only in the event of serious market disturbance of the kind referred to in Article 7 of Directive 96/75/EC;