The new I-25 and High Plains Road Interchange seven miles south of Cheyenne showcases the first ever roundabouts on the Wyoming highway system. The growing development southeast of Cheyenne prompted construction of the new interchange, which will relieve traffic at the College Drive Interchange to the north. Built in a standard diamond configuration, the interchange serves the Swan Ranch business park and the planned Southeast Wyoming Welcome Center and new offices for the State Travel and Tourism Division. The east side of I-25 proved too close to the railroad for conventional access, so roundabouts for the intersection of the ramps with High Plains Road solved the right-of-way problem. The Wyoming Department of Transportation awarded the contract to Reiman Corp. with Interstate Highway Construction as the paving contractor. Construction of the intersection included placing approximately 27,500 square yards of 10" thick PCCP.
Scheduled to begin on March 31, 2010, paving prep work was delayed by three storms, including 1.8" of rain in one day followed by a day of 60 MPH winds. The weather cleared on April 14, leaving only one week before the April 21 scheduled paving start. Despite the delay, paving operations began as planned. Although two more storms interfered in May, dumping 7" of snow on the 11th, paving was completed on May 18, as scheduled.
Designed with mountable curb and gutter, the roundabouts also have stamped and stained aprons. Roundabout transitioning to the ramps, bridge, High Plains Road and site work for the future Welcome Center provided for creative input.
Construction and Innovation
Numerous different paving widths within the ramp configuration were required, so monolithic paving of the ramps was achieved by using multiple pavers in line to accommodate different widths. Beginning 2' wide at the ramp bottoms until reaching the 8' width; transitioning to a 6300 Gomaco to pave to 16' wide; changing to a CMI 350 paver to a width of 25', then off the I-25 mainline and continuing up the ramp. By continuously filling in behind, and paving 37' wide in the gore area, each ramp was completed in one paving day. WYDOT survey was instrumental in the success of the paving due to the grade breaks and transitions. Roundabouts were paved with the CMI 350, using expansion baskets to preclude gaps.
The paving contractor's project QC Manager had oversight of all testing administered at the paver, as well as all QA testing at the batch plant to maintain uniformity. The paving contractor hired an independent Certified Laboratory to perform companion QC/QA testing.
Safety for the paving operations is held as the number one priority. In addition to weekly safety "Toolbox" meetings, core level training, MSDS and environmental training were held prior to paving.