Over 1.25 lakh old vehicles registered in Gautam Buddh Nagar will be taken off the roads in compliance with a National Green Tribunal order on phasing out diesel and petrol vehicles older than 10 and 15 years, respectively, from the national capital region. The district transport department has started a campaign to phase out such vehicles and begun contacting their owners from October 1 following an Uttar Pradesh government order, officials said.