Work continues on a fiber optic cable project along Interstate-17 south of Flagstaff this week. Construction will take place from 6 a.m. to 7 p.m. through Thursday and 6 a.m. to noon on Friday. During construction, northbound I-17 will be narrowed to one lane in two-mile increments from the McGuireville rest area to Rock Park Road. The speed limit in the area will be reduced to 55 miles-per-hour. The project is expected to continue through the middle of the year and will proceed along I-17 in segments of several miles per week.