Advanced signal warning systems

Safer Signals

The Nevada Department of Transportation is evaluating and updating the use and placement of ASWS, or Advance Signal Warning Systems, across the state.

About the Project

ASWS include the yellow signs stationed over the roadway that often feature flashing yellow lights to warn of a traffic signal ahead. ASWS are used to alert drivers of upcoming traffic conditions, especially the potential need to stop at a signalized intersection.

The goal is to develop a unified approach statewide that promotes uniformity and consistency in the treatment of ASWS specific to each intersection’s individual needs. This will enhance the safety of the traveling public and promote safer driver behavior. Similar modifications in other states have shown a reduction in crashes, including severe crashes and crashes from drivers running red lights.

Life-Saving Benefits

One of the behaviors this effort aims to reduce is red light running, one of the most serious traffic problems in the nation. Estimates show vehicles running red lights result in more than 200,000 people being injured and approximately 900 deaths nationwide per year. Between 2013 and 2017, the average number of deaths on Nevada’s roads was 303 (Nevada Department of Public Safety, Office of Traffic Safety Annual Performance Report FFY 2018).

Advance Signal Warning Systems

Advance warning signs are often placed where roadway curves or other factors limit visibility or expectation of a signal. They are also placed on highways connecting rural and urban areas, such as Pyramid Highway, Mt. Rose Highway and State Route 160.

There are three types of systems and each has unique benefits depending on the characteristics of the intersection.

Static System

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Static System

Only includes signage alerting drivers to an upcoming traffic signal or intersection.

Best used if signal is visible from an adequate distance but there is still a need to provide some advance warning.

Passive System Active System

Passive System

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Passive System

Includes signage and a continuously flashing beacon.

Best used if signal is visible from an adequate distance but drivers are transitioning from a rural to an urban area or if signal is isolated, unexpected, and/or road speeds are above 45mph.

Static System
Active System

Active System

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Active System

Includes signage and a flashing beacon that is connected to the signal controller, and only flashes during a signal change, such as from green to yellow, or when a signal is red.

Best used if signal has limited sight distance that doesn’t provide proper reaction time, if the area has heavy truck traffic, or if there are winter or other conditions that require additional stopping distance or reaction time.

Static System Passive System

What Does this Mean for Me?

NDOT conducted an engineering study in 2019 to establish guidelines for the most effective use of different types of ASWS, compliant with federal guidelines. Following thorough engineering review, some of the advance signals throughout the state are changing from flashing at the onset of an upcoming yellow signal to either a static sign or a continuously flashing signal. Timing of flashing signals may also be modified to enhance safety. Some advance signals may be removed due to the updated guidance.

Most ASWS systems throughout the state are currently active systems. New guidance will allow for the use of all three systems based on field conditions and an engineering study. This will enhance uniformity and improve operations and safety.

Project Details

Project Maps

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Construction Updates

Project Timeline

ASWS Guideance Study & Engineering

Completed 2019

Construction Begins

Fall/Winter 2020

Construction Completion

Fall/Winter 2022

Continued Engineering
Review of ASWS

Continuing

What impacts can I expect during construction?

Motorists should always heed warnings and pay attention to the road ahead.

During construction, access to businesses and residences will remain open at all times. Where needed, flaggers will be stationed at designated areas to maintain safe travel.

Construction activities could include:

Lane Closures

Traffic Delays

Detours

Noise, Dust and Vibration

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