2014 Issue

38 One of the most discussed bridge moves was the Sam White Bridge, part of the I-15 Corridor Expansion (I-15 CORE) project in Utah County. The 24th bridge move for UDOT, this bridge is 345 feet long and almost 77 feet wide, making it the longest two-span bridge ever to be moved in the western hemisphere. The bridge weighed almost two thousand tons. It was moved on a cold night in March 2011, to the delight of 1,000 spectators, and was in place by the following morning, only six hours later. Automated Signal Performance Measures In 2011, UDOT leaders challenged the UDOT Traffic Management Division to reach “world class” status in the operations and main- tenance of traffic signals. The intent of this move was to meet the increased traffic demand by improving efficiency rather than adding more capacity (additional lanes). For over 15 years, UDOT has found that advanced traffic operations can accommodate some of the traffic growth inherent in Utah’s expanding population. Adding ca- pacity is usually not possible, due to fiscal and physical constraints. UDOT owns and operates about 1500 traffic signals statewide, mostly on interstate interchanges andmajor arterial highways. Most of these are connected to the UDOT TrafficOperations Center over a broad, and ever expanding, fiber optic network. Several hundred other signals are owned and operated bymunicipalities throughout Utah, andmany of these are also connected to the UDOT network. A single central software system operates all of these connected signals, regardless of which government entity owns them. This makes Utah unique in the country; in no other state or major met- ropolitan area are all connected signals on a single central system. The TrafficManagement teamdetermined that one key element of improving traffic signal operations would be tomove froma reactive mode to a proactivemode through real-timemonitoring of system health and operations. They teamed with a nationally recognized signals expert, Professor Darcy Bullock, of Purdue University, to implement some innovative performance measurements in Utah that he had developed for the Indiana DOT. This pioneering effort gathers real-time, high-resolution data from individual traffic signal controllers and radar sensors and analyzes the data to assess how well the signal timing schemes are moving traffic smoothly down corridors. The “PurdueCoordinationDiagrams” indicate howmany cars arrive at a signal during the green phase or the red phase, and how effectively the timing schemes accommodate turning vehicles and pedestrians. Traffic engineers use this data to modify and improve signal performance, and optimize performance during various times of the day and week and special weather conditions. This is now done much more often, more quickly, and more effec- tively than was possible without this stream of data. UDOT has implemented these new performancemeasures at over 750 intersections in the state. Timing schemes have been updated on over 50 intersections. Problems with vehicle detectors have been identified and repaired at over 100 intersections in 2013. UDOT leads the nation in the deployment of this innovative performance measure approach, and continues to expand their system. Sam White Bridge before being moved into position TRANSPORTATION INNOVATION | continued from page 37 Purdue Coordination Diagram for an intersection on Foothill Drive in Salt Lake City Approach Volume Diagram for an Intersection on Foothill Drive in Salt Lake City