Stop Signs vs. Traffic Lights: How Do Engineers Decide?

How Traffic Engineers Decide to use Stop Signs or Signals

Planning or optimizing intersections is one of the most challenging areas of street design. One of the questions traffic engineers and urban planners face in street design is whether to use stop signs or traffic lights to control the flow of traffic.

Traffic Lights (signalized intersections)

Pros	Cons
Handles high traffic volumes, coordinating multiple lanes and directions.	Expensive to install, maintain, and repair; requires power and advanced technology.
Provides dedicated pedestrian crossing phases, improving safety.	More complex, requiring ongoing engineering assessments for optimal timing and function.
Can be timed or adjusted to optimize traffic flow based on real-time conditions.	Requires energy to operate, increasing carbon footprint.
Provides clearer guidance during low visibility periods like night.	Can cause confusion die to complex or unclear phasing, especially in older systems.
Can be equipped with preemption for emergency vehicles, improving response times.	May cause delays during off peak hours when unnecessary stops or waits are enforced.
Elimination of barriers to pedestrians created by arterials bisecting adjacent neighborhoods.	Bulky infrastructure can be visually unappealing and rake up space in urban landscapes.

Stop Signs (unsignalized intersections)

Pros	Cons
Low-cost and easy to install, requiring minimal maintenance and no power source.	Can be overwhelmed by high traffic, leading to congestion.
Simple design, requiring minimal engineering oversight or adjustment.	Pedestrians must judge gaps in traffic, which can be less safe in busy areas.
Functions well in low traffic situations without extra energy or maintenance.	No adaptive mechanism; vehicles and pedestrians always follow the same rules.
Environmentally friendly due to no energy consumption.	Rolling stops and non-compliance can reduce safety and traffic flow in busy intersections.
Minimal visual impact, fitting easily into the built environment.	Cannot adjust for emergency vehicles without adding special measures (flashing beacons)

Due to it's considerable implications, engineers are typically required to conduct a thorough engineering analysis and a study of the location in order to make the best possible decision and allocate resources wisely. The first step in this planning is collecting intersection data (not an exhaustive list):

Intersection Data (not an exhaustive list)

• Number and turning movement of vehicles • Physical roadway attributes (e.g., number of lanes, approach grade) • Vehicles’ classification, especially specialty vehicles (e.g., school buses) • Number of pedestrians • Number of bicyclists • Speed study of each approach • Knowledge of the region, such as surrounding development (e.g., reasons for traffic) • Location of transit stops and facilities • Field observations of peak hours [CRITICAL]

Here’s a look at how engineers make the call between stop signs and traffic signals.

Traffic Volume and Flow

One of the first considerations is traffic volume. Intersections with low vehicle volume, especially in residential areas, are typically controlled by stop signs. They’re simpler, less costly to install, and effective when fewer cars are passing through. On the other hand, high-traffic intersections in urban areas often require traffic signals to manage the larger volume of cars and minimize congestion.

Accident History

Another factor engineers analyze is the accident history of the intersection. If an area has experienced multiple crashes, especially those related to poor visibility or confusion over who has the right of way, traffic signals may be preferred over stop signs. Signals help organize the flow of traffic more systematically, reducing the chance of collisions.

Pedestrian and Bicycle Activity

Engineers also evaluate pedestrian and bicycle traffic at intersections. In areas with a lot of foot or bike traffic, traffic signals offer better protection than stop signs by giving clear and dedicated phases for crossing. Signals reduce the risk of accidents involving vulnerable road users.

Speed Limits and Road Type

Higher-speed roads often need traffic signals rather than stop signs to prevent sudden stops that could lead to rear-end collisions. Traffic signals allow for smoother transitions and provide more time for vehicles to slow down.

Making Roads Safer with Data

In the end, traffic engineers rely on data—traffic counts, accident reports, and pedestrian activity—to decide between stop signs and traffic signals. For companies like Hivemapper, which provide real-time mapping data, this information becomes invaluable. Accurate road data can help city planners and engineers make informed decisions to improve road safety.

How we Can Help

If you’re an urban planner or traffic engineer looking for reliable road mapping tools, learn how Bee Maps, powered by Hivemapper, can provide updated map feature data to optimize your traffic management strategies.