Dear omss,
Can you picture the world without traffic signals? I imagine life without traffic signals would be similar to rush hour traffic in Los Angeles, immobile. Properly designed and installed traffic signals not only help promote mobility but can reduce the number and severity of accidents. And considering the number of factors that impact our roadways - vehicles, transit operations, bicyclists, pedestrians - I maintain that traffic signals are one of the better ways for us to safely and politely share the road.
In honor of the traffic signal, this month we take a look back at its invention and a few of the great advancements over the past 100 years. |
| Traffic Signals, The Beginning Traffic signs and signals were first used for rail systems to relay information about conditions ahead to train engineers. This idea quickly translated into providing the right-of-way to horse-drawn carriages, streetcars and pedestrians. The first traffic signals were manually operated and generally consisted of simple signs that read "stop" and "go". It wasn't until the early 1900s that the first electric signal made its debut in Cleveland, OH.
One of the major benefits of an electric signal and motivators behind its design, was the ability to operate the signal (i.e. change the signal direction) from a distance. Until this point, signal operation required police officers to stand adjacent to the signal, most often in the center of an intersection. |
| Traffic Signals, The Evolution Traffic signals have come a long way since horses and buggies. In particular, there are two major areas of advancement that continue to mandate their inclusion in our infrastructure: visibility and control. |
| Advancements for Improved Visibility
During the early years, impaired visibility was one of the largest obstacles in achieving safe and efficient intersection control. Lights were small, difficult to see and easily blocked by other vehicles. The following advancements not only helped overcome these visibility concerns, but with an aging U.S. population - 20% will be over 65 in the next ten years - will prove to be valuable for years to come. - Signal heads doubled in size, from 4" to 8", in the early 1900s with modern signal heads most often 12" to promote even greater visibility. With ever increasing traffic speeds, signals must be seen from farther away in order to give drivers the necessary time to react.
- Signal mounting & framework originally limited placement of traffic signals to the center of the intersection since they had to be mounted to the top of poles and be visible from all angles. Today's framework provides a wide array of mounting options allowing signals to stretch above the road, improving safety and promoting visibility.
- Programmable signals address the issue of too much visibility in specific instances like an intersection that is closely preceded by another intersection. Programmable signals aim visibility to only the intersection to which the signal applies, avoiding driver confusion and increasing safety.
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| Progressive Traffic Control
As aforementioned, the earliest traffic signals were hand operated by policemen. Though timers would eventually take over, it wasn't until the mid-20th century that computers were introduced. Traffic controllers are now an integral part of signal operations thanks to their ability to monitor traffic flow and optimize signal timing.
Since traffic controllers have advanced by leaps-and-bounds since the 1960s, we thought we'd focus on only the latest models: - 2070E Controller is the latest 2070 controller platform promoted by Caltrans in compliance with 2009 TEES.
- ATC eX 2070 allows users to upgrade existing intersections based on the 2070 to an advanced, modern, high-performance platform by a simple module and software upgrade to existing 2070s or via new installations with a fully configured ATC 2070.
- ATC eX NEMA capitalizes on the modular advantages of ATC standards allowing it to be compatible with all NEMA TS 1 and TS 2 requirements making it fully adaptable to a range of cabinets and control applications.
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| Signal Alternatives, The Roundabout While I am a huge proponent of the traffic signal, by no means is it a cure-all solution for maximizing the safety and efficiency of the world's transportation infrastructure and in fact, in some cases, it may hinder rather than promote traffic flow.
Roundabouts are becoming an option experiencing growing popularity in the United States. Long successful throughout Europe, when properly deployed, roundabouts are a great alternative to traffic signals and offer a multitude of benefits including: - Slowing traffic without impeding traffic flow
- Reduced installation costs due to greatly reduced infrastructure requirements
- Reduced long-term operational costs due to limited or no electrical and maintenance costs
- More aesthetically pleasing than traditional intersections
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| Add McCain to your growing social network. |
The latest, Caltrans approved 2070 controller. |
| Vancouver, Canada
August 8-10, 2010 Boston, MA
October 11-14, 2010 |
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| | August marks the 11th Annual Happiness Happens Month. Join the movement; learn more by visiting the Secret Society of Happy People's website at www.sohp.com. |
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