What Is a Speed Recording Device

A Speed Recording Device is a small, discreet unit temporarily placed along a roadway. It records the number of vehicles passing by and their speeds, without being noticeable to drivers. Because it does not influence driver behavior, the data reflects how motorists naturally travel on that roadway.

Why We Conduct Speed Studies

Speed Recording Device Studies provide reliable speed data in real‑world conditions. The information collected helps the Police Department determine the most appropriate safety response so that enforcement is efficient, fair, and evidence‑based. Depending on study results, the Department may:

• Conduct targeted speed enforcement by police officers;
• Deploy speed cameras when conditions also meet Maryland’s legal criteria;
• Implement public awareness tools, such as speed display sign boards; or
• Take no further action when speeds are within safe limits.

Key Data Points Collected

Each study generates several metrics used to guide enforcement decisions:

• Location of the study and direction of travel.
• Dates and times when data was collected.
• Total number of vehicles recorded.
• Posted speed limit.
• Number of vehicles traveling 12 mph or more above the speed limit (enforcement threshold under Maryland law).
• Average speed of all recorded vehicles.
• Percentage of enforceable violations.
• Enforcement Rating: Based on the data collected, the analysis assigns a categorization of the enforcement need:

• Low: 0–10% enforceable violations detected.
• Medium: 11–20% enforceable violations detected.
• High: 21% or more enforceable violations detected.

Speed Recording Data by Area

Speed Recording Devices are deployed on a scheduled basis and in response to community concerns. Results are organized by Council and Community Areas within the City of Gaithersburg.

Enlarge Map

 View Speed Recording Data by Area

Speed Recording Device Deployment Limitations

Speed Recording Devices help collect accurate traffic‑speed data; however, they can only function correctly in certain environments. While the police department makes every effort to honor community requests, deployment is dependent on location conditions. Some areas simply cannot support the device due to technical and safety limitations.

To ensure accurate data collection, the following conditions must be met before a device can be installed:

• Proper Setback and Height: The device must be positioned 6–10 feet from the roadway and mounted at least 6 feet above the ground, aimed at an angle toward traffic for optimal accuracy.
• Lane Requirements: The roadway must consist of no more than two undivided lanes. This may be one lane in each direction or two lanes traveling in the same direction.
• Straight, Free‑Flowing Roadway: The device requires a clear, straight segment of roadway where traffic moves normally without frequent stops.
• Seasonal Limitations: The device cannot be deployed during winter months due to freezing temperatures that affect equipment performance.
• Mounting Surface Needs: A stable mounting surface, such as a street signpost (perpendicular to the roadway), a light pole, or a tree is required. The device cannot be attached to square wooden street‑name posts.
• Clear Sightlines: Installations cannot occur at intersections, near parked cars, in areas where parking is common, or anywhere visibility of the travel lanes is obstructed.
• Distance Range: The farthest lane must be within 50 feet of the device to ensure accurate readings.

These limitations help ensure the Speed Recording Device collects reliable, high‑quality data. If the requested location does not meet these conditions, staff may recommend an alternate placement nearby that still reflects local traffic patterns or deny the request due to the location conditions.