California withdrew requests for federal approval to enforce rules limiting emissions from diesel-powered trains and big rigs on Tuesday, Jan. 14, due to anticipated rejection by the Trump administration. One proposed rule would have banned new diesel-powered semi-trucks from being sold in California starting in 2036, as approved by the California Air Resources Board in 2023.

Another rule aimed to ban locomotive engines older than 23 years by 2030 and promote zero-emissions technology for freight transport, but specifics on future actions remain unclear.

Air Resources Board Chair Liane Randolph expressed disappointment at the withdrawal but acknowledged the need to assess options to curb emissions and improve air quality.