Chapter 7: Local Road Maintenance Management 205 f. Vegetation Control g. Traffic Service Maintenance • Maintenance of signs, road markers, pavement markings; and • Maintenance of guardrails 3.2. Periodic Maintenance Periodic road maintenance (as discussed in Chapter 4) is usually more extensive work, carried out on a larger scale and at less frequent intervals than routine annual maintenance. The purpose of periodic maintenance is to preserve the quality of the road assets, retard the rate of deterioration and extend the economic life of the road infrastructure. Periodic road maintenance works are usually undertaken at between two (2) and five (5) year intervals depending on the particular facility and may include as appropriate, on a case-by-case basis, some or all of the following activities: a. Pavement Resurfacing • Single and double bituminous seals; • Void Filling seal coats; • Texturing seals; • Slurry Seals; • Other approved special purpose seals; and • Thin overlays (bituminous road-mix or plant mix surface course not exceeding 50mm average depth). b. Concrete Re-blocking c. Seal Widening d. Preventive Works • New works that protect existing roads from sea or river damage; • Drainage installed to drain incipient slip; • Toe weighting of unstable slopes; • Burming and hedging of slopes; • Protection planting project; and • Work to overcome changes in a river’s course or bed level that threatens the roads, bridges or other road related structures, but which is not attributable to one climatic event.