| The department may alter, widen or change the grade of any |
| state or state aid highway whenever in its judgment the public |
| exigency may require, and may lay out, establish and open a |
| new highway as a state highway, and upon appropriate petition |
| from municipal officers may lay out, establish and open a new |
| highway as a state aid highway. It may discontinue a highway, |
| or a portion thereof, as a state or state aid highway and the |
same shall must be thereafter maintained by the town or county |
| originally liable therefor except as otherwise provided. All |
| costs of the construction, maintenance and repair of state or |
| state aid highways are the responsibility of the department |
| and may not be passed on to a local unit of government except |
| with the agreement of the legislative body of that local unit. |