Traffic Engineering

Traffic Controls

Traffic control measures become necessary when the individual drivers along roadways experience conflict points as they each attempt to reach their destinations and cross paths at intersecting points. At these intersections where two or more roadways cross paths, City Traffic Engineers work to minimize the risk to drivers and pedestrians by increasing the safety within the intersection with the most efficient means available. 

The type of traffic control used within an intersection is determined by a variety of factors. There are strict guidelines outlined in the Federal Highway Administration’s Manual on Uniform Traffic Control Devices (MUTCD). The type of intersection traffic control is determined by a variety of factors including: traffic volumes, sight distance, crash histories, speed limits, and street classifications.

Uncontrolled intersections are the most minimal form of intersection traffic control. These intersections are low traffic volumes, low speed roadways typically in residential neighborhoods that rely on the Uniform Vehicle Code (UVC) to determine right-of-way. The code states that “the driver of the vehicle on the left shall yield the right-of-way to all vehicles approaching from the right that are close enough to constitute an immediate hazard”. More simply stated; a driver must yield to the vehicles on their right. Occasionally, uncontrolled intersections need additional traffic control, but do not warrant the higher levels of traffic control shown below. In these special cases, various forms of “traffic calming” can be used to aid in the neighborhood traffic. Traffic calming is discussed in more detail in the Traffic Engineering Section of this page.

When the traffic increases to a point where the UVC can no longer safely pass traffic, right-of-way for approaching vehicles is assigned with the use of signs. Prior to installation, an engineering study is performed to determine the need and type of signage. STOP or YIELD signs are the commonly used signs to assign this priority.

Traffic signals and/or roundabouts are used for the more complex intersections along heavily traveled roadways. Both traffic signals and roundabouts have advantages/disadvantages over the other. However, both intersection treatments are used to progress higher level traffic through intersections in the safest, most efficient way possible. Traffic engineers have to take into account a variety of factors when determining whether to use a traffic signal or a roundabout.

The City is constantly monitoring problematic intersections for potential solutions. Each intersection presents unique characteristics that can be better handled with one intersection treatment over the others. A roundabout may work at one intersection, whereas a traffic signal or 4-way stop signs are a better fit at another intersection. The City takes our role in solving traffic problems very seriously, yet the ultimate burden of safety rests with you, the motorist.

Stop Signs

The purpose of stop signs is generally misunderstood by the public. The purpose of the stop sign is provide safe and orderly operation at an intersection that is otherwise compromised without the signs.

Reasons for Stop Sign Installation

The City receives many citizen requests for installing stop signs for a number of different reasons.

The most common inquiry is to install a stop sign to slow traffic through their neighborhood. However, research shows that other measures are often more effective than adding "nuisance" stop signs. Additional Information is available in under Traffic Engineering.

Some of the other reasons for requests include crash reduction, intersection visibility concerns, and travel time delay reduction. These requests are more fitting with the intended purpose of stop signs and are investigated by the City on a case-by-case basis.

Installation Policies

The Federal Highway Administration publishes the Manual on Uniform Traffic Control Devices (MUTCD). This publication dictates all aspects of signing and striping within public roadways. The MUTCD dictates the size, shape, and color for traffic signs, signals, and other traffic control devices.

Included within the MUTCD are guidelines for where signs and signals are installed that create uniformity from city to city and state to state. The City of Billings is required by State law to comply with the guidelines contained within the MUTCD. A stop sign will only be installed after careful engineering evaluation complying with the MUTCD guidelines of the existing conditions indicates that the installation is appropriate.

MUTCD Guidelines

The guidelines outlined for stop sign installations are dependent on a number of factors. When a citizen request is made, each of these factors are researched and analyzed to determine if a stop sign is justified for installation. Some of these factors are listed below:

• Volume of traffic on both intersecting roadways
• Recorded crash history
• Sight distance from one street to the other
• Prevailing traffic speeds
• Roadway classification (i.e. hierarchy of roadway network)
• Temporary installation prior to signal installation

This process will also look to optimize the intersection without the use of signs. 

Stop Sign Visibility & Overuse
Our experience has shown that improving the intersection sight distance by prohibiting parking near the intersection or trimming trees and shrubs is often more effective in reducing traffic accidents. This often eliminates the need to install more restrictive intersection controls. 

The overuse of stops signs can reduce their effectiveness. Studies have also shown that adding unwarranted stop signs can actually increase speeds as drivers try to make up for perceived "lost time".

More information on the MUTCD and its guidelines can be found at the MUTCD website.

Intersection Revision Requests

Please contact the Engineering Services Office to request a stop sign, or other revision for an intersection.

Overview 

Traffic signals, similar to stop signs and roundabouts, are designed to provide safe, and efficient passage through intersections by assigning right-of-way to individual traffic movements. In a perfect environment, traffic signals promote orderly movement of traffic while minimizing excessive delay.

Installation Policies

The Federal Highway Administration publishes the Manual on Uniform Traffic Control Devices (MUTCD). This publication dictates all aspects of signing and striping within public roadways. The MUTCD dictates the size, shape, and color for traffic signs, signals, and other traffic control devices. Included within the MUTCD are guidelines for where signs and signals are installed that create uniformity from city to city and state to state. The City of Billings is required by State law to comply with the guidelines contained within the MUTCD. A traffic signal will only be installed after careful engineering evaluation complying with the MUTCD guidelines of the existing conditions indicates that the installation is appropriate. This analysis must balance the following, sometimes conflicting goals:

• Moving traffic in an orderly fashion
• Minimizing delay to vehicles and pedestrians
• Reducing crash-producing conflicts
• Maximizing capacity for each intersection approach

The MUTCD has very specific requirements of the existing traffic data in order for an intersection to be “warranted” for the installation of a traffic signal. These requirements include justification based on traffic volumes; pedestrian volumes; proximity to other signals, schools, and railroads; crash history; and roadway classification (i.e. hierarchy of roadway network). While any one of these factors may justify the installation of a traffic signal, it does not require the installation of the traffic signal.

More information on the MUTCD and its guidelines can be found HERE.

Drawbacks of Traffic Signals 

When installed correctly, signals provide safe and efficient traffic flow through complex intersections. However, traffic signals are often considered a cure-all for traffic problems at intersections. This can lead to unwarranted installations that end up doing more harm than good. Even if an intersection is warranted for a traffic signal, improper design and operation of the signal can adversely impact the effectiveness of the signal. This can lead to excessive travel time delays, disobedience of signal indications, increased use of less adequate roadways, increases to certain crash types (particularly rear-end crashes), and costs. In an effort to minimize these adverse impacts, the City is actively trying to improve the traffic signal system in the City. 

Combating Traffic Signal Drawbacks

There are a variety of ways that the City remedies traffic signal deficiencies. These methods range from simple modifications to the signal timing parameters to complete replacement of the traffic signals. The City is currently replacing all traffic signal controllers (which are the computers that run the signal) to modern technology. A master traffic signal software program was also installed to allow for quicker diagnosis of signal problems. This software will also allow the City to implement solutions and update signal timing parameters more quickly and efficiently from City offices.
Left turn crashes can be particularly troublesome at signalized intersections. Safely progressing left turning traffic directly impacts the efficiency of passing the oncoming through traffic. As such, traffic engineers have implemented various types of protected turn movements (green arrows). The latest safety measure for the left turning problem is the Flashing Yellow Arrow.

Another alternative that combats the traffic signal inadequacies are Roundabouts.

Citizen Requests

The City is constantly monitoring both existing traffic signals and intersections for potentially new installations. Further, the City takes our role in solving traffic problems very seriously, yet the ultimate burden of safety rests with you, the motorist. Please use the contact information below to request a stop sign for an intersection in your neighborhood:
City Engineering Division
2224 Montana Avenue
Billings, MT 59101
(406) 657-8231 (phone)

Signal Technology

High 


Intensity Activated Crosswalk Signal

The HAWK Signal is a relatively new style  of traffic signal designed to help pedestrians cross busy streets. HAWK stands for High-intensity Activated crossWalK (it is also known as a Pedestrian Hybrid Beacon). HAWK signals operate only when a pedestrian activates it. This allows traffic to move freely for most of the day, while providing a safe crossing when needed.  The schematic on the left shows the relationship between what drivers see during the phases of what pedestrians see.  The schematic also describes the appropriate driver and pedestrian behavior during a HAWK Signal activation.

Montana’s first HAWK signal was installed at the intersection of 4th Avenue North and N 20th Street in conjunction with the opening of the General Services Administration (GSA) Federal Building.  The City has since installed HAWK Signals at multiple locations across the City including the multi-lane roundabouts along Grand and Central Avenues

How to Read Flashing Yellow Arrow

In an effort to minimize the safety concerns with left turn movements, a national study was conducted to determine the most effective way to alert drivers when to yield to oncoming traffic. This study showed the Flashing Yellow Arrow (FYA) was safer and more effective than a simple circular green ball that is typically used. As such, cities across the country are installing FYAs, and the City of Billings is no exception.

With the installation of FYAs, traffic will be able to perform the left turn movement more safely and with less confusion.

This schematic displays the sequence of operations for the FYA in comparison to existing signal operations. 

Additional Information is available at:

Montana Department of Transportation FYA Website

National Cooperative Highway Research Program Report 493: Evaluation of Traffic Signal
Displays for Protected/Permissive Left-Turn Control

Overview

Roundabouts are circular-flow intersections that have proven to move traffic through an intersection at a steadier rate of speed than a conventional intersection, as well as reduce the accident severity for crashes that occur in the intersection. In a roundabout, traffic flows counter-clockwise and the traffic entering the roundabout must yield to the traffic currently in the roundabout.

Tips for Driving a Roundabout

• Choose the appropriate lane before entering
• Slowdown
• Yield to pedestrians at the crosswalk
• Yield to traffic in the roundabout
• Merge into the roundabout when traffic is clear
• Proceed in correct lane until you have reached your exit
• If you missed your exit, proceed around the roundabout                until your exit arrives
• Signal right blinker, indicating the intent to exit roundabout
• When exiting, yield to pedestrians at the crosswalk
• DO not STOP IN ROUNDABOUT AT ANY TIME

Conflicts at Standard Intersections vs. Roundabouts 

Roundabouts are designed specifically to be safer intersections than conventional intersections. Roundabouts have fewer conflict points in comparison to conventional intersections. The potential for hazardous conflicts, such as right-angle and left-turn head-on crashes is eliminated with roundabout use. The images at right depict potential conflict points of a conventional four-legged intersection, and the same for a roundabout.

The circular nature of the roundabout requires drivers to slowly traverse the roundabout’s curves. This allows drivers more time to react to potential conflicts, while also limiting the severity of any crashes. The decreased speeds and severity typically leads to decreased injury-related accidents.

Drawbacks of Roundabouts

When designed and constructed correctly, roundabouts are extremely effective at calming traffic at major intersections. By design, they can lower speeds, provide arterial access with minimal conflict points, increase efficiency, and most importantly, decrease severe crashes. However, there are some drawbacks that prevent the use of roundabouts at every intersection. These drawbacks include the following:

• Pedestrian crossing are not controlled with signal operations
• Maintenance of center roundabout island
• Right-of-way limitations (overall size of the intersection is larger than signals)
• Initial cost (primarily due to the right-of-way purchases needed)
• Interaction with nearby traffic signals

Helpful Information

• ROUNDABOUT PAMPHLET
• ROUNDABOUT VIDEO

Overview

There are two types of crosswalks: “marked” and “unmarked”. A marked crosswalk consists of white paint outlining the traveled path of pedestrians. An unmarked crosswalk is the portion of the street that connects two aligned sidewalks across the intersection. The formal definition of a crosswalk from State law is shown below:

“The part of a roadway at an intersection included within the connections of the lateral lines of the sidewalks on opposite sides of the highway measured from the curbs or, in the absence of curbs, from the edges of the traversable roadway; or

Any portion of a roadway at an intersection or elsewhere distinctly indicated for pedestrians crossing by lines or other markings on the surface.”

At any and all crosswalks (marked or unmarked; at an intersection or midblock), drivers are required by State law to yield the right-of-way, slowing down or stopping if need be, to pedestrians. However, this is not happening in Billings. The Engineering Division has implemented a number of different crossing treatments in an effort to draw attention of the drivers to crossing pedestrians to improve both the compliance rate and safety of the intersections. 

Pedestrian Crossing Enhancements

In an effort to draw attention to both pedestrians and crosswalks and aid in the vehicular compliance rate, the City has used a number of different enhancements. These enhancements include the following:

Ladder-style crosswalks These crosswalks use more paint to highlight the crossing and have been reserved for school crossings or trail crossings.

Pedestrian refuge island This treatment provides a “safety” island for pedestrians to rest as they cross one direction of traffic at a time. This enhancement also minimizes the crossing distance and the exposure of the pedestrians within the traveled way.

School crossings These crosswalks are unique in their proximity to schools and come with their own sign clusters. 

Overhead signage and lighting The signage and lighting enhances the visibility of the crossing and thus gives the driver advanced warning that pedestrians may be present.

Rapid Rectangular Flashing Beacon (RRFB) These are pedestrian activated flashers located beneath the crossing signage. The unique pattern in which the beacons flash has proven to better alert drivers to the presence of pedestrians. This enhancement has been reserved for trail crossings of major roadways.

HAWK Signals This is a relatively new and effective crosswalk treatment in the City. 

The City takes our role in solving traffic problems very seriously, yet the ultimate burden of safety rests with you, the motorist. State law requires drivers to yield the right-of-way to pedestrians within a crosswalk.