Back to Blog

Signs for Managing Traffic Flow

August 15, 2019

Keeping traffic flow under control surrounding and within your property is an important social and business responsibility. If you run a popular business then you either need a large enough parking lot or adequate parking should be available for patrons. Here are some issues regarding signs that can help make life easier at your organization’s location.

Speed, Flow and Concentration

The main variables that shape traffic conditions are speed, flow and concentration. Speed can be managed with signs that post the speed limit. The flow and concentration are more difficult to control since it may change on a daily basis. Traffic flow is considered “free” when the road is occupied by less than 12 vehicles per mile. Conditions are called “stable” when the number of vehicles per mile increases to the 12-30 range. When density exceeds 30 cars per mile, conditions are considered “unstable.”

When too many cars are jammed in each lane it may call for traffic control personnel. Many cities, however, use signs and the three-phase traffic theory to manage conditions. The theory, developed by Boris Kerner in the late nineties, emphasizes how congestion develops on highways in the three phases of 1) free flow, 2) synchronized flow and 3) wide moving jam. A jam has a front, in which the width affects overall traffic flow.

In a sychronized flow, the downstream front is often fixed at the bottleneck within a wide moving jam where there isn’t any stoppage. Synchronized flow is the tendency for vehicles to synchronize at similar speeds, which reduces passing.

During minimal density, the flow rate of number of vehicles per unit of time directly affects vehicle density, but during congestion, this relationship disappears. Congestion can be divided into synchronized flow and wide moving jam scenarios.

Choosing the Right Signs

By breaking down traffic jams into components, conditions are easier to predict. Theories on transportation science can be applied when planning on posting specific signs in an area. Proper signage often depends on traffic analysis so that bottlenecks can be avoided. Understanding the causes of traffic congestion in a specific area is the key to controlling it. The number of lanes on a main road will play a crucial role in traffic flow, as will the amount of space devoted to bike lanes. Public transit systems also affect the level of traffic congestion.

The main reasons for congestion include road work, lane closures due to road work and accidents. Other reasons for congestion may include big events that attract many pedestrians and when too many trucks are on the road, slowing down the general flow of traffic.

Construction work signs are needed during times when road crews work on lanes otherwise used by traffic. Signs that remind drivers when a road narrows are helpful at reducing speed. Sometimes temporary signs are needed during big events to block off certain streets or keep traffic contained in a specific area. Detour signs and alternative routes can help limit bottlenecks.


Traffic flow is a science that can be managed with a series of signs designed to keep vehicles separated by a certain distance. Contact Zumar at our Arizona, California and Washington location to learn more about selecting the proper signage.

Product Added

Go to Quote Request Form

Continue Product Search