The road authority on the one hand and the promoters on the other hand may from time to time enter into and carry into effect, and from time to time, alter, renew, or vary, contracts, agreements, or arrangements with respect to the paving and keeping in repair of the whole or any portion of the roadway of any road on which the promoters shall lay any tramway, and the proportion to be paid by either of them of the expense of such paving and keeping in repair.