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Traffic Engineering

To report a traffic signal malfunction or outage, down signage, or faded pavement markings please contact Traffic Services at 678-512-3200 or contact Traffic Services.
 

Traffic Engineering

The Johns Creek Traffic Services Division is focused on getting the most out of the City’s roads. That means the City’s traffic engineers are constantly looking for new and innovative ways to move traffic efficiently and safely.

traffic engineeringThanks to Traffic Services, Johns Creek was the first city in Georgia to employ flashing yellow arrows, to partner with Waze to learn more about traffic patterns, and to install back-up batteries at traffic signals to keep them operational during power outages.

Traffic Services maintains and operates the City’s traffic control system, which includes signals, signs, and striping. It also reviews, manages and conducts safety and traffic studies that help shape the City’s overall transportation system.

ITS

The City of Johns Creek has developed one of the most advanced Intelligent Traffic Systems (ITS) in the country. The City’s synchronized signal timing system uses sophisticated software to help balance traffic flow throughout the city.  ITS ties 72 traffic signals in five separately coordinated systems, which are each uniquely timed, to a Traffic Control Center (TCC) at City Hall. 
 
For example, during rush hour, the traffic signals at intersections along Medlock Bridge Road/SR 141 are set to cycle every 160 seconds.  Each plan determines how much time each light is allowed.  The lights do not always receive the same amount of time to remain green within this 160 second cycle.  ITS determines the time based on how much volume it can allow to go any one direction at a time.  For example, when traffic volume is heavy in the direction of Gwinnett County from Johns Creek along Abbotts Bridge Road, the traffic signal timing for a left turn from Medlock Bridge Road/SR 141 south will be significantly shorter than it will be for traffic moving both north and south along Medlock Bridge Road/SR 141.  Motorists attempting a left turn onto States Bridge Road from Medlock Bridge Road/SR 141 north also experience shorter green signal times when ITS determines that is necessary to allow for more time to keep the flow of traffic moving north and south along Medlock Bridge Road/SR 141. 
 
Sensors continuously monitor the flow of traffic, speed and direction throughout the city, and then feed that information into the ITS.  As a result, ITS understands what time it is and what normal traffic patterns can be expected from the data it collects and stores.  The information it receives is instantly analyzed and compared to pre-scripted signal lighting plans to help determine the optimum cycle to keep traffic moving.  The plans are selected by the computer based on stored data, which includes the history of traffic volumes at every hour of the day and night.  The sensors then provide real time traffic volume and speed information to ITS, which ITS then uses to determine the plan programmers have previously calculated as the optimum for thru-put.
 
ITS maintains many programmed traffic signal plans with their own set of planned intervals. ITS maintains separate plans based on the time of day, weekend vs week day, and peak hours vs non-peak hours.  For example, weekends and holidays have different traffic signal plans as traffic volumes and speeds differ from normal work week traffic.  ITS also has plans that can be initiated when traffic accidents occur and automatically end when the accident and affected lanes are clear.  Nearly every variable imaginable has been programmed to include rain and snow events.
 
As sophisticated as ITS is, traffic light synchronization is not a 100 percent solution for the daily work-week congestion the city experiences as traffic exceeds the capacity for which the roads were designed.  More than 50 percent of the traffic Johns Creek experiences during the week both originates and ends outside of its borders.  As a result, most of our major intersections are well over their capacity during peak traffic times.   
 
Traffic Engineers at City Hall’s TCC monitor both morning and evening rush hour traffic each day. The engineers monitor live traffic screens as well as a computer street map, which indicates what patterns are being run and if there are any issues.  They continuously assess the ITS timing plans based on the level of congestion and can manually make adjustments if necessary.  As a result of continuous refinement of the plans, ITS maintains enough plans to make decisions without traffic engineers present after hours and on holidays and weekends.          
 
Johns Creek’s engineers continue to work to identify the latest innovations in traffic management to incorporate into the ITS system to help ensure the city can keep pace with rapid population growth in surrounding counties and cities.