Why is it necessary to maintain a lower grade on interstates than local or state roads? Explain 2-3 sentences

Roads are very important for any of country. These play a part in economy of a country.

Explanation:

The interstates road are important to maintain because transport went from one state to another state on these roads.

There is no much need local or state level road because there is less chances to go heavy vehicles on these roads.

Interstate road are important because the transport work happen by these roads.

Highway and roads both are used to travelled for people, animals, and for the movement of heavy vehicles. The local road are less used by heavy vehicle.

Thus it is necessary to maintain the lower grade on the interstate than the local or state road.

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explanation: