2012 Issue

44 Guiding motorists through the DDI Being the first DDI in Utah, special attention was provided to ensure that drivers would be able to correctly navigate through the interchange. Overhead guide signs are provided to notify drivers in advance about appropriate lane usewhen approaching the interchange. An extensivemedia campaign was also undertaken to help familiarize driv- ers with the new design. In addition to overhead signs, additional signs and pavement markings were in- cluded to clearly define lanes and paths. Large through-arrows were placed at the crossover intersections to emphasize where turning movements are prohibited. Also, dashed lines with short spacing between dashes were used to indicate to motorists that they are in a dedicated lane requiring a turn ahead. These dashes have been used to direct arterial traffic through the interchange to the respective on-ramps, reducing last minute weave movements. Access Management Proper spacing of driveways and accesses when approaching an interchange or other major intersection improves safety and reduces delays. Access management has proven to be an important aspect of maintaining efficient operations at the Pioneer Crossing DDI. Several changes were made to driveways near the inter- change, including converting a right-in/ right-out driveway to right-in only. Two full movement driveways were combined into a single access and another full movement driveway was converted into right-in/right- out only. Similar types of changes were made at the Timpanogos Highway DDI. These access management techniques reduce the number of conflict points, thus improving safety and increasing capacity. Pioneer Crossing DDI Now and Into the Future While savings in construction costs and as- sociated impacts are important, ultimately the determining factor for a successful de- sign is the quality of operation provided to INTERCHANGE | continued from page 43 Figure 3: Signal phasing favoring off-ramps. 3 Figure 2: Signal phasing favoring the cross-street. 3 Figure 4: Conflicting NB and SB through movements. 3