Monthly Archives: October 2012

SIGNAL HISTORY

The traffic signal systems of today are the result of a stream of innovative technologies starting with a simple light box on a pole.

Salt Lake City Police Officer Lester Wire designed and built a pole mounted box that housed green and red lights.

Utah has approximately 1700 traffic signals owned by city, county and state governments. Sophisticated and efficient, modern signal systems are coordinated and monitored by traffic engineers and centrally controlled by computers. Devices that detect cars can adjust signal timing along traffic corridors to allow for directional traffic flow throughout the day. When needed, traffic engineers can make changes to keep traffic flowing.

Effective signal coordination improves safety, saves fuel, reduces emissions, enhances traffic flow, and decreases travel delay and traffic congestion.

The story of how modern signal systems were developed starts in Utah; the first traffic signal for automobiles was put into service in 1912 in Salt Lake City at the intersection of Main Street and Second South.

Salt Lake City Police Officer Lester Wire saw the need to help move traffic through intersections safely and efficiently.  He designed and built a pole mounted box that housed green and red lights. Wires connected to the trolley system overhead carried electricity. The lights were changed manually by an officer who stood nearby and used his discretion to make the switch.

UDOT has created an exhibit that shows how technology has progressed since the early days of traffic management. A collection of signals and equipment, including a model of Lester Wire’s first traffic light, will be on permanent display at the UDOT Traffic Operations Center. The collection is open to the public.

Signal innovations

Shortly after Wire’s traffic light was put into use, other inventions pushed signal technology forward quickly. Signal development followed electronic and computing trends, and some key transformational changes include:

1927    The invention of the fixed control timer, which made it possible for the first traffic operations center to manage 31 signals in Los Angeles.

1928    The first semi-actuated signal, installed in Detroit, which used a microphone to detect the sound of a car horn and assign right-of-way.

1952    The first actuated signal system which adjusted timing based on traffic demand. Installed in Denver, the system was made possible by analog technology.

1972    The first Advanced Traffic Control system which used microprocessors, fiber optic cable and inductive loops to connect and control timing at 113 intersections in Washington DC.

UDOT Today

UDOT is currently using radar detection to improve safety and optimize traffic signal performance.

Radar is being used to detect cars in the ‘dilemma zone’ – a space prior to entering an intersection where drivers decide to stop or keep going. Software used with the radar equipment is programmed to extend the signal phase to allow cars in the dilemma zone more time to get through the intersection.

UDOT also uses an online tool to improve the way traffic engineers monitor and optimize signal performance. Signal Performance Metrics, originally developed by Indiana Department of Transportation and Purdue University, uses dilemma zone radar detection along with software developed by UDOT in cooperation with Wavetronics and Econolite.

The system locates and counts cars, places a time stamp on every car and then pulls that data into online graphs that can be observed in real time. By observing traffic movement as it occurs, engineers can make immediate changes to optimize traffic flow.

Director John Njord has charged UDOT traffic engineers with creating a world-class traffic signal system. UDOT has taken full advantage of modern innovations and established itself as a leader in modern traffic management.

 


Created with Admarket’s flickrSLiDR.

More about signals

  • Pulse, a trade magazine published by Wavetronics, published a great article on the history of traffic signals.
  • A page on the FHWA website explains the benefits of signal coordination.

SILVER BARREL

Congratulations to UDOT Region One Signal Engineer Carrie Jacobson who received a Silver Barrel Award for heading a team of engineers who kept traffic moving during a major event – the annual Hill Air Force Base Air Show.

The Silver Barrel Award is way to call attention to employees who excel.

The team worked with the Utah Highway Patrol and city officials to plan and carry out ways to help road users get to and depart from HAFB.

Building on experience UDOT signal engineers have gained from managing other events, the Region One Signal Team first offered to help, then met with base officials to identify problems that have occurred in the past. Jacobsen’s team then developed some signal timing plans that gave more green light time where needed. The team paid special attention to places where traffic congestion has occurred in the past.

Approximately 225 thousand people attend the two-day event. Engineers manned stations at the Traffic Operations Center to observe traffic. Signal engineers were posted at critical locations along the route to observe traffic and make adjustments at signal cabinets when traffic backed up.

HAFB officials and the Utah Highway Patrol were grateful for the help and gave Jacobson’s team an award called a Challenge Coin, usually reserved for those in the military, for helping with traffic flow during the event.

WETLAND BANKING

A wetland bank can be a successful and accepted way to mitigate for the loss of wetland habitat areas due to transportation projects.


Created with Admarket’s flickrSLiDR.

The EPA s defines a wetland mitigation bank as a “a wetland, stream, or other aquatic resource area that has been restored, established, enhanced, or (in certain circumstances) preserved for the purpose of providing compensation for unavoidable impacts to aquatic resources…” The Water Resources Development Act of 2007 calls mitigation banking “the preferred mechanism for offsetting unavoidable wetland impacts associated with Corps Civil Works projects.” Wetland banks are regulated by the The U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service with guidance from the Environmental Protection Agency.

EPA rules call for a “no net loss” policy in compensating for wetlands that are impacted by transportation or other projects. An ecological assessment assures that the bank area is functioning as intended. A credit system, representing the value of the compensation, assures that lost wetlands are adequately compensated for. Banks must be monitored and managed on an ongoing basis to make sure performance standards are met.

UDOT has established a wetland a mitigation area, called the Northern Utah County Mitigation Bank, which compensates for  of transportation project impacts in Utah County, including I-15 CORE and Pioneer Crossing. The NUCMB totals 120 acres and is located in Lindon, Utah. This wetland bank will eventually provide 76 mitigation credits — enough capacity to provide mitigation for any UDOT FHWA transportation project throughout the majority of Utah County .

Advantages of UDOT’s mitigation bank

The NUCMB provided a cost-effective way to mitigate wetland impacts in northern Utah County. Having a mitigation bank also accelerated the permitting process, saving taxpayers millions of dollars and years of time. UDOT, along with private sector partners, worked together throughout the process to design, permit and monitor the NUCMB.