Be prepared for delays on I-25. Construction is beginning Monday on the new North Express Lanes between Johnstown and Fort Collins, near Colo. 402. The work should last through 2020. Crews are going to begin by constructing temporary roads on the southbound side of the highway, so most of the work should be done off the interstate. But CDOT says there will be some nighttime lane and ramp closures. Colo. 402 will be shut down between the I-25 ramps next summer.