In the event of the refusal or neglect of such street railway companies to pave, repave or repair, when so directed by the mayor and the city council, upon the grading, paving or repaving of any street upon which their track is laid, the mayor and council shall have power to pave, repave or repair the same; and the cost of such paving, repaving or repairing may be collected by levy and sale of any real or personal property of said street railway company, the same as special taxes are collected. Special taxes for paying the cost of such paving, repaving, macadamizing or repairing of any street railway may be levied upon the track, including the ties, iron, roadbed and right-of-way, side tracks and appurtenances, including buildings and real estate belonging to such company or person, and used for the purpose of such street railway business, all as one property, or upon such part of such tracks, appurtenances, and property as may be within the district paved, repaved, macadamized or repaired, or any part thereof, and shall be a lien upon the property of such company in its entirety and as one property from the time of the levy until satisfied. The lien so created shall attach in like manner and with like effect to all property of such company or companies after acquired which shall be used in the operation of such railway. No mortgage, conveyance, pledge, transfer or encumbrance of any such property of any such company shall be made or suffered, except subject to the actual or prospective lien of such special taxes, whether actually levied or not. Such special taxes when levied shall constitute a lien upon the property of such railway in its entirety and as one property prior and superior to all other liens or encumbrances, except liens for taxes or for other special assessments. The treasurer shall have the power and authority to seize any personal property belonging to any such person or company for the satisfaction of any such special taxes when delinquent, and to sell the same upon the same advertisement and in the same manner as constables are now authorized to sell personal property upon execution at law, but failure to do so shall in nowise affect or impair the lien of the tax or any proceeding allowed by law for the enforcement thereof. The railroad track or any other property upon which such special taxes shall be levied, or so much thereof as may be necessary, may be sold for the payment of such special taxes in the same manner and with the same effect as real estate may be sold upon which such special taxes may be levied. It shall also be competent for any such city to bring civil action against any party owning or operating any such street railway and liable to pay said taxes, to recover the amount thereof, or any part thereof delinquent and unpaid, in any court having jurisdiction of the amount, and obtain judgment and have execution therefor, and no property, real or personal, shall be exempt from any such execution; Provided, real estate shall not be levied upon by execution, except by execution out of the district court, on a judgment therein or transcript of a judgment filed therein, as provided by law. No property seized by the treasurer, as hereinbefore provided, or upon any such execution, shall be taken from the officer holding the same upon any order of replevin. No defense shall be allowed in any such civil action, except such as goes to the groundwork, equity and justice of the tax, and the burden of proof shall rest upon the party assailing the tax. In case part of such special assessment shall be shown to be invalid, unjust or inequitable, judgment shall be rendered for such amount as is just and equitable, and costs shall follow the judgment. It shall be competent for the mayor and council, upon the written application of any company, association, corporation or person owning any such street railway, to provide that such special tax shall become delinquent and payable in installments, as in case of taxes levied upon abutting real estate as hereinbefore provided, but such application shall be taken and deemed a waiver of any and all objections to such taxes and to the validity thereof. Such application shall be made at or before the final levy of such taxes. The provisions of this section in regard to the levy, collection, and enforcement of special taxes to pay the cost of paving, repaving, macadamizing or repairing of any such street railways shall apply to all such special taxes.