The green tribunal had on November 26, 2016, banned 10-year-old diesel vehicles, including tractors on Delhi-NCR roads to reduce pollution, which was challenged in the Supreme Court, but it was dismissed.
Security at the railway station has beefed up in light of protest, officials said.
The Thursday protest was led by the national spokesperson of BKU, Rakesh Tikait, who said, the agitation will continue till their demands are not met.
The union also demanded the ban on government vehicles including train engines which are older than 10 years and gheraoed a fisheries department jeep and a fire brigade vehicle too.
(With inputs from agencies.)