Prompted by increased concerns from citizens and local officials, the Georgia Department of 

Transportation (GDOT) used an engineering speed study supplemented by a tool developed by 

Federal Highway Administration (FHWA) called USLIMITS2 to evaluate the existing speed limits 

in Greenville, Georgia. 

Located approximately 55 miles southwest of Atlanta, the small city of Greenville is the county 

seat in Meriwether County. The city’s main roadway network feeds into a traffic circle, which 

encircles the Meriwether County Courthouse at the center of town. US Highway 27 and State 

Highways 100 and 109 bring motorists through this city’s town center and typically carry a fairly 

large amount of truck traffic. The area around the courthouse contains on-street parking, and 

with the town hall, a police station, and several businesses nearby, it often brings a high-level of 

pedestrian activity. Outside the city limits, speed limits are 55 mph and rapidly drop in 10 mph 

increments to 25 mph leading into the city’s center. Many motorists felt the speed limits dropped 

too suddenly and were unrealistic, setting them up to receive speeding tickets, calling the area 

a potential speed trap.

USLIMITS2

is a web-based tool 

designed to help 

practitioners set 

reasonable, safe, and 

consistent speed 

limits for specific 

segments of roads. 

It is applicable to all 

types of facilities, from 

rural local roads and 

residential streets 

to urban freeways. 

The tool provides a 

suggested speed limit 

value based on 50th 

and 85th percentile 

speeds, roadway 

characteristics, and 

(optional) crash data.

Georgia Department of Transportation 

Setting Speed Limits with Help from USLIMITS2

?

Meriwether County Courthouse and sign showing surrounding roadway network.

Source: Max Dromgoole, GDOT

Case Study

SPEED MANAGEMENT
http://safety.fhwa.dot.gov

EVALUATING THE SPEED LIMIT

GDOT’s standard procedure for evaluating speed limits includes performing a thorough speed 

study for both directions of traffic and collecting three years of crash data for the section of 

the roadway under review. Staff typically complete several test drives to gauge “driver feel and 

expectation” and collect curve data, as necessary. In addition to these steps, traffic engineers 

at GDOT then use FHWA’s online tool, USLIMITS2. They find that USLIMITS2 is easy to use and 

provides an objective, unbiased recommendation that gives them confidence in the original 

speed study results and helps them defend and explain their decisions for setting speed limits.

In early 2015, GDOT followed the process described above 

and evaluated the speed limits on the roadways leading 

into Greenville’s town center to determine whether 

they were properly set. GDOT’s initial conclusion after 

reviewing the existing speeds and crash data was that the 

25 mph speed limit on the approaching highways was set 

too low. The operating speed, or 85th percentile speed, 

was measured to be closer to 35 mph, and the crash data 

revealed no existing speed-related safety issues. USLIMITS2 supported this by confirming the 

findings of their engineering speed study. With these results, GDOT increased the 25 mph 

speed limit to 35 mph on the approaches into the city’s center. They also adjusted the speed 

limits within the transition zone between 55 mph and the new 35 mph, using incremental 

drops of 5 or 10 miles per hour to make the transition less sudden.

RESULTS

Initially, some residents living along these roadways had concerns regarding the speed limit 

changes, but GDOT staff described the results of the speed and crash analyses, explained the 

concept of the 85th percentile speed, and pointed out that motorists were already traveling 

at 35 mph. The USLIMITS2 data lent further support for the speed limit changes. 

After the speed limits were adjusted, motorists reported that the speed limits felt more 

appropriate and provided a smoother transition from a 55 mph speed zone to the town 

center’s 25 mph speed zone. GDOT received several messages of thanks from citizens. A speed 

study showed that the 85th percentile speeds are now in line with the posted speed limit. 

Perhaps most importantly, there has been no increase in the number of crashes. 

While using USLIMITS2 is a step beyond a standard speed study, the traffic engineers at GDOT 

believe it provides a fair and unbiased opinion based on sound engineering practices. Overall, 

they report that it is a valuable tool that augments the credibility of their speed studies and 

has often helped address concerns from local government officials and private citizens when 

speed limits are adjusted.

FOR MORE INFORMATION

To learn more about USLIMITS2, visit the USLIMITS2 website.

For additional speed management resources, visit the Speed Management Safety website.

Also, check out FHWA’s fact sheets: Speed Limit Basics and Speed Management: More than Just 

Speed Humps.

“The USLIMITS2

tool takes out all the 

emotion and politics, 

and it provides us with 

something that we 

could show to others 

that is concrete and 

easy to understand.” GDOT Traffic Engineer

“USLIMITS2 acts as 

an external, impartial, 

second set of eyes.”

GDOT Traffic Engineer

Since USLIMITS2 

software became 

available in 2007, 

GDOT estimates it 

has used the tool to 

complement the State’s 

engineering speed 

studies on nearly 500 

speed limits statewide. 

FHWA-SA-16-078

Source: Max Dromgoole, GDOT

Source: Max Dromgoole, GDOT