How InSync Works



Public transportation agencies use InSync as a toolbox for fixing a wide range of traffic challenges. Learn about some of the most common InSync applications. We’ve classified them under three broad categories: roadway geometries, traffic conditions and integrating non-vehicular traffic.

“Typical coordinated systems have been around for decades with little or no changes in basic functionality and fewer alternatives for trying to accomplish the same end result. [InSync] is a fresh look at how to handle the age-old problem of how to move traffic more efficiently.”

Roadway Geometries

Many traffic engineering challenges relate directly to the arrangement, or geometry, of the intersections. See how InSync solves these challenges.

Arterial Corridors

Arterial CorridorsMotorists who travel on arterial corridors can experience many stops, much delay and unnecessary frustration if the traffic signals are not synchronized. Those waiting on the side streets often feel they are being ignored.

InSync’s greatest  strength is coordinating progression along a corridor while simultaneously minimizing delay for the side streets at each individual intersection. The technology is not affected by challenges such as odd spacing of the intersections, variable traffic flow, achieving progression in both directions or the need to balance main and side street needs.

See Example: Lee’s Summit, MO

Intersection Networks

InSync can optimize entire traffic signal networks, or groups of non-linear signals. Currently InSync is used in multiple networks of more than 50 signals and additional networks involving intersecting arterials or other unique, non-linear geometries.

To accomplish signal optimization in a network, InSync relies on its digital and dynamic capabilities to precisely coordinate multiple movements within the network. Being unconstrained by fixed cycle lengths, sequences and splits, InSync is the best option for customizing signal operations to unique and/or complex geometries and traffic objectives.

See Example: Columbia County, GA

See Example: Grapevine, TX

Intersecting Arterials

Intersecting Arterials

Arterial corridors that intersect present a challenge because both roadways experience heavy traffic volume and their need for progression is equal. If not perfectly engineered, the needs of the two arterials can be at odds with each other.

Columbia County, GA’s deployment is a prime example of how InSync uses its artificial intelligence and adaptive capabilities to solve this problem. The county installed InSync along two corridors in Evans, GA: Washington Road and North Belair Road. Both corridors experience heavy retail and residential traffic, and both average more than 40,000 vehicles daily. The InSync system coordinates and guarantees progression along both corridors including at their common intersection.

See Example: Columbia County, GA

See Example: Grapevine, TX

Freeway Interchanges

Freeway InterchangesFreeway interchanges affect traffic due to the heavy volume of vehicles trying to get on via an entrance ramp or get off via an exit ramp, especially during rush hour.

InSync works in this situation because it flexibly serves the sequences and amount of green time needed to intelligently progress traffic through a left-turn onto an entrance ramp, or from an exit ramp left-turn through the entire interchange. Frequently re-serving the approaches with the highest demand, such as the left-turn bays, increases storage capacity, clears queues of vehicles and keeps vehicles moving through and out of the network.


See Example: San Ramon, CA

See Example:Grapevine, TX

See Example:Wichita, KS 

Atypical Geometries

Atypical Geometries

Many agencies deploying InSync have unusual geometries that cause challenges in managing traffic. InSync handles traffic in atypical geometries because of the system’s five adaptive capabilities and the configuration flexibility available through our CentralSync software.

Since InSync understands the relationship between the intersections and knows on a second-by-second basis what the adjacent signals are doing, it can make decisions for the entire network of intersections.

Traffic Conditions

InSync solves even the toughest traffic engineering challenges. Wherever better signalization has the potential to improve conditions on your roads, InSync is proven the single most effective engineering intervention to intelligently optimize signal operations with noticeable results.



When there are too many vehicles and not enough road capacity, an agency can do a couple things. They can build additional lanes or roads, or they can find a way to maximize every inch and second of existing capacity.

InSync is the sustainable, technology alternative to multimillion dollar road construction projects. By having greater flexibility and intelligence than traditional traffic control systems, InSync increases throughput, freeing up existing road capacity and reducing the duration and severity of saturation.

See Example: Upper Merion, PA

Special Events

Special Events Traffic

Even the best coordinated timing plans cannot adapt to the dramatic shift in traffic caused by special events such as concerts, sporting events, weather-related evacuations or holiday shopping traffic. Traffic always fluctuates a few percentage points up or down, but some special events cause traffic volume to quadruple. Perhaps more importantly, events send an unpredictable rush of single-direction traffic along a route that does not often experience such demand.

InSync adjusts traffic signals to serve these changes in traffic demand as they occur. It is not burdened by the conventions of fixed sequences, fixed cycle lengths or lags in responsiveness. InSync intelligently changes its phasing, sequencing and green times.

See Example: Columbia, MO

Road Diet

A road diet, or lane reduction, reduces the number of travel lanes and/or effective width of a road in order to achieve systemic improvements. Reducing road capacity can also negatively impact traffic flow, leading to congestion. However, InSync proves a valuable tool in successfully implementing a road diet with more positive results than negative.

One example of this is the Borough of Carlisle, PA’s deployment of InSync along 23 intersections. The purpose of this project was to take the four lanes of Hanover and High Streets down to two lanes with a center turning lane and bicycle lanes on each side. Having fewer lanes was expected to slow traffic through the downtown, preserving the community’s heritage while making it safer for pedestrians. By detecting real-time traffic demand and changing the lights accordingly, InSync keeps the flow of traffic on the main roads moving at the design velocity without stopping, more than offsetting the effects of the decrease in capacity.

Variable Traffic Flow

Some signal networks are prone to substantial, unpredictable variations in traffic volumes. This is a common occurrence around high schools and universities. Due to the irregular timing of day and evening classes, final exams, summer and seasonal breaks, basketball and football games, concerts, theater productions and more, it can be impossible to accommodate the unpredictable nature of campus traffic with signal timing plans.

In contrast, InSync easily handles variable traffic flow because adapting to actual, real-time demand is its very nature. The system has no timing plan to rely on; it must constantly take stock of actual demand at every approach in order to make signalization decisions.

Bi-Directional Progression

Often times, a traffic engineer’s objective is to progress traffic in two directions at the same time. InSync makes it easier to achieve bi-directional progression, especially on oddly spaced intersections. The precision of the InSync digital state machine initiates green signals for the coordinated movement at the exact desired time because it is not inhibited by common cycle lengths or fixed sequences.

One example of this is the City of San Ramon, CA’s deployment of InSync along two busy corridors, Crow Canyon Road and Bollinger Canyon Road. Odd signal spacing and uneven demand made bidirectional progression a challenge. By deploying InSync, the city achieved its goal to keep traffic moving both eastbound and westbound with as few stops as possible.

See Example: San Ramon, CA

Serving Non-Vehicular Demand

Non-vehicular demand such as that caused by pedestrians, trains and emergency vehicle preemption are important factors to consider when optimizing a signal network.  In some cases they are significant contributors to congestion, while in almost all cases they at least represent a roadway user that must be adequately planned for.

Pedestrian Traffic

Pedestrian Traffic

InSync minimizes the impact of pedestrian push buttons on vehicular service levels. By intercepting the pedestrian call and waiting until it can coordinate the pedestrian movement along with vehicular traffic, InSync refrains from interrupting the progression of dozens of vehicles passing through an intersection. In nearly all cases, this creates no noticeable difference for the pedestrian.

The City of Salinas, CA installed InSync at five intersections to manage the high pedestrian and vehicle traffic along Main Street. InSync incorporates pedestrian calls into its local optimization and global coordination to ensure that pedestrians can cross the street safely without disrupting traffic flow.

See Example: Salinas, CA


InSync integrates seamlessly with preemption, such as emergency vehicle preemption or rail preemption. This is because InSync’s calls to the controller are passive and therefore overridden by higher priority calls such as preemption. The controller performs the signalization for the preemption per its existing programmed instructions. Once the preemption call subsides, control returns to InSync. The system is completely compatible with all forms of preemption without any special modifications or upgrades needed.


Not only does InSync accommodate preemption, but it substantially improves the negative effects of transition caused by preemption. InSync immediately recognizes the demand and volume of each approach and alters signalization to remedy the transition effects caused by preemption. Since InSync does not operate on fixed cycles, sequences, cycle lengths and offsets, InSync has the flexibility to do what is necessary to resolve traffic challenges.