Maintaining California’s highways and freeways will be costly in the coming years. Caltrans estimates it will need $80 billion over the next ten years. It warns of a $60 billion shortfall under current funding. A plan issued Friday plan warns that the state highway system will deteriorate and necessitate much more expensive remedies in the future. Excise taxes on gasoline and diesel fuel are the primary revenue source for Caltrans, funding the maintenance and operation of the state highway system as well as the administration of the department. These revenues are declining as a result of reduced fuel consumption due to more energy-efficient vehicles and increased alternative fuel use.