Engineers are challenging Kiwirail's reasons for removing electric trains from the Main Trunk Line. Last week RNZ revealed Labour was refusing to enact a pre-election promise to keep electric engines running up and down the North Island. Kiwirail said it has received no new directive and replacing the aging electric locomotives with diesel engines makes economic sense. Roger Blakeley is a former Secretary for the Environment and an engineer. He tells Guyon Espiner he disagrees.