The board of county commissioners shall erect and maintain on county roads, where not already done, one or more guardrails on each end of a county bridge, viaduct, or culvert more than five feet high. The board also shall protect, by guardrails, all embankments with a rise of more than eight feet in height and with a downward slope of greater than seventy degrees, where the embankments have an immediate connection with a county road.
The expense for a guardrail required under this section shall be paid out of the county bridge fund.