NEW DELHI, July 8: The Delhi transport department has impounded a large number of buses in wake of the Supreme Court's order to convert the school vans and school buses to CNG mode and formally register them as commercial contract carriage passenger vehicles. The department impounded a total 45 vans and six school buses on Monday. The drive began on July 1 and till now 455 buses have been impounded. According to a senior official over 6,000 school van owners had applied for conversion of their petrol-run vans into CNG mode along with other safety measures till June 30. However, 4,500 scored eligibility for plying for schools in the capital. The official said that those who applied till Tuesday will be allowed to commercially ferry commuters and schoolchildren. The official reiterated that a penalty will be imposed on the private vans if norms are flouted as per the provisions of the Motor Vehicle Act. No relaxation will be given to the impounded vehicles. He said that any number of applications cannot bail out the erring drivers and owners who have been putting the lives of small children at risk. As per the Supreme Court guideline, school buses and vans should have speed governors, horizontal grills on windows, fire-extinguisher, first-aid box and fitting trays under the seats for school bags.