Speed Limits: Frequently Asked Questions

All speed limits must be declared and posted to be enforceable. Declarations must be established either by state statutes or through ordinances by the respective roadway authority or municipality. Regulatory speed limits are absolute speed limits, above which it is unlawful to drive regardless of roadway conditions, traffic volumes or other factors. Advisory speed limits are not enforceable in Wisconsin courts, except when driving too fast for conditions.

Typically, there is little change in speed patterns after posting a lower speed limit unless there are significant changes in the roadway environment and context. Drivers are much more influenced by physical changes to the roadway, its environment and driving conditions.

Lower speed limits are often viewed as a quick fix to traffic safety, but this is not the case. Crashes are most often the result of other factors. In many cases, posting a lower speed limit creates a greater speed variance between the slowest and fastest vehicles. This speed variance, also called “speed differential,” can contribute to crashes and make the roadway less safe.

This theory is only effective when law enforcement resources are available to commit. Voluntary driver compliance and respect for appropriate regulatory speed limits is the ultimate goal. The availability of police officers is typically limited for dedicated speed enforcement on a consistent basis. If speed limits are posted well below what most people are typically driving and not vigorously enforced, there will be varying speeds of traffic, which will increase the potential for crashes. In general, setting unreasonably low speed limits will also lead to a disregard of speed limits.

No. Several states utilize automated speed enforcement through speed safety cameras to help enforce speed limits on roadways. Wisconsin ss. 349.02 currently prohibits the use of any type of automated enforcement technology.

Yes. Speed limits are established with optimal conditions in mind. Further, Wisconsin ss. 346.57(3) defines conditions requiring reduced speeds. In situations such as approaching and crossing an intersection or railroad crossing, approaching or going around a curve, passing school children, highway construction or maintenance workers or by reason of weather or highway conditions, an operator of every vehicle shall drive at an appropriate reduced speed.

All speed limits in Wisconsin must be based an engineering and traffic investigation. If a speed limit modification is proposed to lower (or raise) a posted speed limit to meet statutory speed limits, an engineering and traffic investigation should document this decision. Statutory limits are established to ensure that every roadway has a speed limit, but decisions on adjusting speed limits should consider the roadway’s context, function and existing driving behaviors to determine the appropriate and safe speed. Setting speed limits without consideration of these factors may lead to compliance and safety issues without significant interventions (e.g., design changes, heavy enforcement).

Any requests to modify speed limits on the State Highway System must come through a local roadway authority, such as a city, village or township. If existing speeding issues are the primary concern, the best solution would be to work with law enforcement. WisDOT does not entertain requests to modify speed limits from individual citizens or advocacy groups. Local governmental authorities (e.g., Director of Public Works, village/town president/administrator, police chief) must submit a request to WisDOT with current regulatory speed limit information, the requested speed, begin/end points and reasoning for the request. WisDOT will then determine if a review of the speed limit is appropriate.

To initiate a request for WisDOT to review a speed limit for potential modifications on the State Highway System (e.g., US 12, WIS 64):

• Local authority (e.g., town/village/city government official) submits a written request to WisDOT. The request should include reasoning for why the location should be investigated within an engineering and traffic investigation (i.e., engineering study).
• WisDOT determines if an engineering study is appropriate for the location or if other changes are needed. If a study is completed, WisDOT reviews the results and makes a determination for potential changes.
• WisDOT informs the local authority of the results. If changes are supported, WisDOT coordinates with the county highway department to install new roadway signs with the modified speed limits.

It's important to note the department will not consider modifications solely based on any of the following:

• Noise complaints
• Accommodating specialty vehicles (e.g., ATV/UTV)
• Correcting spot safety concerns
• Future concerns that have not yet occurred
• Future development

Local authorities can initiate action to modify a speed limit and create a new regulatory speed zone on a local road through an engineering and traffic investigation. Local officials have a key role in setting limits. They must balance the competing concerns and opinions of drivers, residents and law enforcement agencies with statutory requirements and traffic safety. Any change must be supported by an engineering and traffic investigation adhering to the Wisconsin state statutes. This should be conducted by a professional engineer with appropriate traffic engineering expertise through the application of procedures and criteria established by an engineer (e.g., Wisconsin's speed limit guidance).

WisDOT recommends that local authorities coordinate with WisDOT prior to completing an engineering and traffic investigation to verify study requirements and approval authorities. For questions, please reach out to the appropriate co​ntact.

When changes to the local roadway system require WisDOT coordination and approval, follow the steps below:

1. Local authority (e.g., town/village/city government official) receives request from citizen or another constituent.
2. Local authority determines if an engineering and traffic investigation (i.e., engineering study) is appropriate for the location or if other changes are needed.
3. Local authority prepares engineering study based on guidance provided by WisDOT.
4. Local authority submits written request to WisDOT. Request should include reasoning for why the location is being investigated and provide a copy of the engineering study.
5. WisDOT reviews the results and makes a determination for potential changes.
6. If approved by WisDOT, modified speed limit is posted by local roadway employees.

For situations where speed zone modifications are not justified, there are several options to stay engaged and make roadways safer for both vehicles and other roadway users.

• Stay active through public involvement or county traffic safety commission meetings to voice concerns and issues within your community.
• Improve visibility of reduced speed zones. Examples of this include:
• Signing Improvements
• Double marking the first instance of the reduced speed zone sign
• Increasing the size and frequency of speed limit signs
• Installing temporary or permanent flags on reduced speed zone ahead signs, or regulatory speed limit signs
• Providing dynamic speed display devices at transitional areas. These are most effective when used at variable times and not as a permanent installation. Examples include:
• Portable Speed Radar Trailer
• Dynamic speed display signs
• Providing dedicated traffic enforcement at variable times
• Consider adjusting the roadway design through short-term or long-term changes.