Office of the Administrator 1200 New Jersey Ave., SE

 Washington, D.C. 20590

ACTION MEMORANDUM TO THE DEPUTY SECRETARY

From: Shailen P. Bhatt

Administrator

X62240 

Through: Victoria Wassmer

Assistant Secretary for Budget and Programs and 

Chief Financial Officer

Prepared by: Cheryl J. Walker

Associate Administrator for Safety

X66378 

Subject: Report to Congress on Guidance for the Setting of Speed Limits

ACTION REQUESTED

I request that you approve and authorize me to send the attached report to Congress on Guidance 

for the Setting of Speed Limits as required by the Joint Explanatory Statement and House of 

Representatives Report 116-452 accompanying the 2021 Appropriations Act. 

SUMMARY

The report summarizes the findings on how speed limits are set, from the National Cooperative 

Highway Research Program (NCHRP) Project 17-76, “Guidance for the Setting of Speed 

Limits.” The NCHRP Project 17-76 research team investigated the factors that influence 

operating speed and its impacts on safety. In addition, the research team conducted a thorough 

review of different methods and tools that have been developed for the setting of posted speed 

limits. The Federal Highway Administration (FHWA) also introduces a recently initiated project 

to create a handbook on approaches to determining appropriate speed limits for all roads and 

streets to advance speed management practices in support of the Safe System Approach. 

This report to Congress relates directly to the U.S. Department of Transportation’s National 

Roadway Safety Strategy. Speed limits, how they are set and how they are obeyed, are an 

important component in the safety of our roads. We expect the Hill, State and local officials 

involved in highway safety, and advocacy groups to respond positively to the report. 
2

The attached report summarizes the findings from NCHRP Project 17-76 with respect to the 

following aspects: 

• States establish statutory speed limits for specific types of roads—such as freeways, rural

highways, or urban streets—which are applicable even if the speed limit sign is not

posted. This report focuses on the setting of posted speed limits.

• The process of selecting a posted speed limit value for a roadway segment can be

influenced by many factors, including safety concerns, roadway geometry and

characteristics, and human factors such as the way drivers react to the roadway.

• The predominant method used in the United States is the operating speed approach. It

typically relies on the 85th percentile speed with adjustments used to account for existing

roadway geometry or crash experience. Many States and some local agencies have their

own laws and criteria for setting speed limits. Professionals who conduct studies to

determine the appropriate posted speed limit rarely relies solely on the 85th percentile

speed (i.e., they use several other factors).

• Using approaches other than the 85th percentile speed to determine the posted speed limit

is gaining popularity nationwide. Several cities – such as Boston, Massachusetts; New

York City, New York; and Seattle, Washington – have recently campaigned to be able to

set lower citywide default speed limits. Some State legislatures have passed laws giving

these cities the ability to set a 25 or 20 mph default speed limit citywide. For example,

Portland, Oregon, has gained the authority to set residential streets at 20 mph. Other

countries are also exploring or implementing citywide speed limits.

• The speed limit setting procedure (SLS-Procedure) uses fact-based decision rules that

consider both driver speed choice and safety associated with the roadway. Employing the

SLS-Procedure and the accompanying tool has the potential to help State, local, and

Tribal transportation agencies make informed decisions and communicate how speed

limits can be set to State/local/Tribal leadership and citizens.

BACKGROUND

The Joint Explanatory Statement and House of Representatives Report 116-452 accompanying 

the Departments of Transportation, Housing and Urban Development, and Related Agencies 

Appropriations Act, 2021, tasked the Federal Highway Administration to summarize the findings 

of two NCHRP research projects and report to the House and Senate Committees on 

Appropriations detailing findings within those reports. Specifically, the applicable language 

states:

Design speeds. - The Committee is concerned about the relationship between design 

speed, posted speed, and operating speed. The Committee is looking forward to the

results of two upcoming projects underway by the National Cooperative Highway 

Research Program (NCHRP), NCHRP Project 17-76, “Guidance for the Setting of Speed 

Limits” and NCHRP Project 15-76, “Designing for Target Speed”. Following the 

completion of each study, the Department should summarize the findings and report to 

the House and Senate Committees on Appropriations detailing findings on how speed 

limits are set, how they impact roadway design, and the implications for enforcement and 

crashes where posted speeds and design speeds deviate. 
3

The NCHRP Project 17-76 produced two research reports: 1) NCHRP Research Report 966: 

Posted Speed Limit Setting Procedure and Tool: User Guide, which contains a procedure for 

setting speed limits and a user manual explaining the SLS-Procedure, and 2) NCHRP Web-Only 

Document 291: Development of a Posted Speed Limit Setting Procedure and Tool, which details 

the research activities and methods.

This report summarizes and documents the findings in NCHRP Project 17-76. At the time of 

preparing this report, NCHRP Project 15-76 has not been completed. Once it is completed, 

FHWA will submit a separate report to Congress summarizing the findings of NCHRP Project 

15-76, including the implications for enforcement and crashes where posted speed limits and

design speeds deviate.

RECOMMENDATION

I recommend that you approve the attached summary report to Congress on Guidance for the 

Setting of Speed Limits. With your concurrence, FHWA will transmit the report to the House 

and Senate Committees on Appropriations and the transportation subcommittees of the 

Appropriations Committees.

The Deputy Secretary

APPROVED: _______________________

DATE: _August 31, 2023_

COMMENTS:

Attachments:

• Letters to Members of Congress

• Report to Congress
 Office of the Administrator 1200 New Jersey Ave., SE

 Washington, D.C. 20590

September 5, 2023 

The Honorable Patty Murray

Chair

Committee on Appropriations 

United States Senate 

Washington, DC 20510 

Dear Chair Murray: 

This letter provides the report requested by the Joint Explanatory Statement and House of 

Representatives Report 116-452 accompanying the Departments of Transportation, Housing and 

Urban Development, and Related Agencies Appropriations Act, 2021, tasking the Federal 

Highway Administration (FHWA) to provide findings of two projects underway by the National 

Cooperative Highway Research Program (NCHRP): NCHRP Project 17-76, Guidance for the 

Setting of Speed Limits; and NCHRP Project 15-76, Designing for Target Speed. House Report 

116-452 specifically requests that following the completion of each study, “the Department

should summarize the findings and report to the House and Senate Committees on

Appropriations detailing findings on how speed limits are set, how they impact roadway design,

and the implications for enforcement and crashes where posted speeds and design speeds

deviate.”

Promoting safe traffic speeds and reducing speeding-related fatalities and serious injuries is a 

focus of the U.S. Department of Transportation’s National Roadway Safety Strategy, which 

officially adopts the Safe System Approach principles to guide safety actions. One of those 

principles is to recognize that humans are vulnerable and have a limited ability to tolerate crash 

impacts. The FHWA will use resources such as NCHRP Projects 17-76 and 15-76 and recently 

initiated work to produce a handbook providing guidance to States and localities on approaches 

to determining appropriate speed limits for all roads and streets to advance speed management 

practices in support of the Safe System Approach. 

This enclosed report summarizes and documents the findings in NCHRP Project 17-76 and 

introduces the recently initiated project to produce a handbook on speed limits. At the time of 

preparing this report, NCHRP Project 15-76 has not been completed. Once it is completed, 

FHWA will submit a separate report to Congress summarizing the findings of NCHRP Project 

15-76, including the implications for enforcement and crashes where posted speed limits and

design speeds deviate.

The objectives of NCHRP Project 17-76 were (i) to identify factors that influence a driver’s 

operating speed and (ii) to develop a speed limit setting procedure and a speed limit setting tool 
The Honorable Patty Murray

Page 2 

that would automate the procedure used in making informed decisions related to establishing 

speed limits for any roadway type. The project was completed in June 2021 and produced two 

research reports: 1) NCHRP Research Report 966: Posted Speed Limit Setting Procedure and 

Tool: User Guide, which contains a procedure for setting speed limits and a user manual 

explaining the speed limit setting procedure (SLS-Procedure), and 2) NCHRP Web-Only 

Document 291: Development of a Posted Speed Limit Setting Procedure and Tool, which details 

the research activities and methods. 

The attached report summarizes the findings from NCHRP Project 17-76 with respect to the 

following aspects: 

• States establish statutory speed limits for specific types of roads—such as freeways, rural

highways, or urban streets—which are applicable even if the speed limit sign is not

posted. This report focuses on the setting of posted speed limits.

• The process of selecting a posted speed limit value for a roadway segment can be

influenced by many factors, including safety concerns, roadway geometry and

characteristics, and human factors such as the way drivers react to the roadway.

• The predominant method used in the United States is the operating speed approach. It

typically relies on the 85th percentile speed with adjustments used to account for existing

roadway geometry or crash experience. Many States and some local agencies have their

own laws and criteria for setting speed limits. Professionals who conduct studies to

determine the appropriate posted speed limit rarely relies solely on the 85th percentile

speed (i.e., they use several other factors).

• Using approaches other than the 85th percentile speed to determine the posted speed limit

is gaining popularity nationwide. Several cities – such as Boston, Massachusetts; New

York City, New York; and Seattle, Washington – have recently campaigned to be able to

set lower citywide default speed limits. Some State legislatures have passed laws giving

these cities the ability to set a 25 or 20 mph default speed limit citywide. For example,

Portland, Oregon, has gained the authority to set residential streets at 20 mph. Other

countries are also exploring or implementing citywide speed limits.

• The speed limit setting procedure (SLS-Procedure) uses fact-based decision rules that

consider both driver speed choice and safety associated with the roadway. Employing the

SLS-Procedure and the accompanying tool has the potential to help State, local, and

Tribal transportation agencies make informed decisions and communicate how speed

limits can be set to State/local/Tribal leadership and citizens.
The Honorable Patty Murray

Page 3

A similar letter has been sent to the Vice Chair of the Senate Committee on Appropriations; the 

Chair and Ranking Member of the House Committee on Appropriations; the Chairman and 

Ranking Member of the Senate Subcommittee on Transportation, Housing and Urban 

Development, and Related Agencies; and the Chairman and Ranking Member of the House 

Subcommittee on Transportation, Housing and Urban Development, and Related Agencies.

Sincerely,

Shailen P. Bhatt

Administrator 

Enclosure 
 Office of the Administrator 1200 New Jersey Ave., SE

 Washington, D.C. 20590

September 5, 2023 

The Honorable Susan Collins 

Vice Chair

Committee on Appropriations 

United States Senate

Washington, DC 20510 

Dear Vice Chair Collins: 

This letter provides the report requested by the Joint Explanatory Statement and House of 

Representatives Report 116-452 accompanying the Departments of Transportation, Housing and 

Urban Development, and Related Agencies Appropriations Act, 2021, tasking the Federal 

Highway Administration (FHWA) to provide findings of two projects underway by the National 

Cooperative Highway Research Program (NCHRP): NCHRP Project 17-76, Guidance for the 

Setting of Speed Limits; and NCHRP Project 15-76, Designing for Target Speed. House Report 

116-452 specifically requests that following the completion of each study, “the Department

should summarize the findings and report to the House and Senate Committees on

Appropriations detailing findings on how speed limits are set, how they impact roadway design,

and the implications for enforcement and crashes where posted speeds and design speeds

deviate.”

Promoting safe traffic speeds and reducing speeding-related fatalities and serious injuries is a 

focus of the U.S. Department of Transportation’s National Roadway Safety Strategy, which 

officially adopts the Safe System Approach principles to guide safety actions. One of those 

principles is to recognize that humans are vulnerable and have a limited ability to tolerate crash 

impacts. The FHWA will use resources such as NCHRP Projects 17-76 and 15-76 and recently 

initiated work to produce a handbook providing guidance to States and localities on approaches 

to determining appropriate speed limits for all roads and streets to advance speed management 

practices in support of the Safe System Approach. 

This enclosed report summarizes and documents the findings in NCHRP Project 17-76 and 

introduces the recently initiated project to produce a handbook on speed limits. At the time of 

preparing this report, NCHRP Project 15-76 has not been completed. Once it is completed, 

FHWA will submit a separate report to Congress summarizing the findings of NCHRP Project 

15-76, including the implications for enforcement and crashes where posted speed limits and

design speeds deviate.

The objectives of NCHRP Project 17-76 were (i) to identify factors that influence a driver’s 

operating speed and (ii) to develop a speed limit setting procedure and a speed limit setting tool 
The Honorable Susan Collins 

Page 2

that would automate the procedure used in making informed decisions related to establishing 

speed limits for any roadway type. The project was completed in June 2021 and produced two 

research reports: 1) NCHRP Research Report 966: Posted Speed Limit Setting Procedure and 

Tool: User Guide, which contains a procedure for setting speed limits and a user manual 

explaining the speed limit setting procedure (SLS-Procedure), and 2) NCHRP Web-Only 

Document 291: Development of a Posted Speed Limit Setting Procedure and Tool, which details 

the research activities and methods. 

The attached report summarizes the findings from NCHRP Project 17-76 with respect to the 

following aspects: 

• States establish statutory speed limits for specific types of roads—such as freeways, rural

highways, or urban streets—which are applicable even if the speed limit sign is not

posted. This report focuses on the setting of posted speed limits.

• The process of selecting a posted speed limit value for a roadway segment can be

influenced by many factors, including safety concerns, roadway geometry and

characteristics, and human factors such as the way drivers react to the roadway.

• The predominant method used in the United States is the operating speed approach. It

typically relies on the 85th percentile speed with adjustments used to account for existing

roadway geometry or crash experience. Many States and some local agencies have their

own laws and criteria for setting speed limits. Professionals who conduct studies to

determine the appropriate posted speed limit rarely relies solely on the 85th percentile

speed (i.e., they use several other factors).

• Using approaches other than the 85th percentile speed to determine the posted speed limit

is gaining popularity nationwide. Several cities – such as Boston, Massachusetts; New

York City, New York; and Seattle, Washington – have recently campaigned to be able to

set lower citywide default speed limits. Some State legislatures have passed laws giving

these cities the ability to set a 25 or 20 mph default speed limit citywide. For example,

Portland, Oregon, has gained the authority to set residential streets at 20 mph. Other

countries are also exploring or implementing citywide speed limits.

• The speed limit setting procedure (SLS-Procedure) uses fact-based decision rules that

consider both driver speed choice and safety associated with the roadway. Employing the

SLS-Procedure and the accompanying tool has the potential to help State, local, and

Tribal transportation agencies make informed decisions and communicate how speed

limits can be set to State/local/Tribal leadership and citizens.
The Honorable Susan Collins 

Page 3

A similar letter has been sent to the Chair of the Senate Committee on Appropriations; the Chair 

and Ranking Member of the House Committee on Appropriations; the Chairman and Ranking 

Member of the Senate Subcommittee on Transportation, Housing and Urban Development, and 

Related Agencies; and the Chairman and Ranking Member of the House Subcommittee on 

Transportation, Housing and Urban Development, and Related Agencies.

Sincerely,

Shailen P. Bhatt

Administrator 

Enclosure 
 Office of the Administrator 1200 New Jersey Ave., SE

 Washington, D.C. 20590

September 5, 2023 

The Honorable Kay Granger

Chair

Committee on Appropriations 

U.S. House of Representatives

Washington, DC 20515 

Dear Chair Granger: 

This letter provides the report requested by the Joint Explanatory Statement and House of 

Representatives Report 116-452 accompanying the Departments of Transportation, Housing and 

Urban Development, and Related Agencies Appropriations Act, 2021, tasking the Federal 

Highway Administration (FHWA) to provide findings of two projects underway by the National 

Cooperative Highway Research Program (NCHRP): NCHRP Project 17-76, Guidance for the 

Setting of Speed Limits; and NCHRP Project 15-76, Designing for Target Speed. House Report 

116-452 specifically requests that following the completion of each study, “the Department

should summarize the findings and report to the House and Senate Committees on

Appropriations detailing findings on how speed limits are set, how they impact roadway design,

and the implications for enforcement and crashes where posted speeds and design speeds

deviate.”

Promoting safe traffic speeds and reducing speeding-related fatalities and serious injuries is a 

focus of the U.S. Department of Transportation’s National Roadway Safety Strategy, which 

officially adopts the Safe System Approach principles to guide safety actions. One of those 

principles is to recognize that humans are vulnerable and have a limited ability to tolerate crash 

impacts. The FHWA will use resources such as NCHRP Projects 17-76 and 15-76 and recently 

initiated work to produce a handbook providing guidance to States and localities on approaches 

to determining appropriate speed limits for all roads and streets to advance speed management 

practices in support of the Safe System Approach. 

This enclosed report summarizes and documents the findings in NCHRP Project 17-76 and 

introduces the recently initiated project to produce a handbook on speed limits. At the time of 

preparing this report, NCHRP Project 15-76 has not been completed. Once it is completed, 

FHWA will submit a separate report to Congress summarizing the findings of NCHRP Project 

15-76, including the implications for enforcement and crashes where posted speed limits and

design speeds deviate.

The objectives of NCHRP Project 17-76 were (i) to identify factors that influence a driver’s 

operating speed and (ii) to develop a speed limit setting procedure and a speed limit setting tool 
The Honorable Kay Granger

Page 2 

that would automate the procedure used in making informed decisions related to establishing 

speed limits for any roadway type. The project was completed in June 2021 and produced two 

research reports: 1) NCHRP Research Report 966: Posted Speed Limit Setting Procedure and 

Tool: User Guide, which contains a procedure for setting speed limits and a user manual 

explaining the speed limit setting procedure (SLS-Procedure), and 2) NCHRP Web-Only 

Document 291: Development of a Posted Speed Limit Setting Procedure and Tool, which details 

the research activities and methods. 

The attached report summarizes the findings from NCHRP Project 17-76 with respect to the 

following aspects: 

• States establish statutory speed limits for specific types of roads—such as freeways, rural

highways, or urban streets—which are applicable even if the speed limit sign is not

posted. This report focuses on the setting of posted speed limits.

• The process of selecting a posted speed limit value for a roadway segment can be

influenced by many factors, including safety concerns, roadway geometry and

characteristics, and human factors such as the way drivers react to the roadway.

• The predominant method used in the United States is the operating speed approach. It

typically relies on the 85th percentile speed with adjustments used to account for existing

roadway geometry or crash experience. Many States and some local agencies have their

own laws and criteria for setting speed limits. Professionals who conduct studies to

determine the appropriate posted speed limit rarely relies solely on the 85th percentile

speed (i.e., they use several other factors).

• Using approaches other than the 85th percentile speed to determine the posted speed limit

is gaining popularity nationwide. Several cities – such as Boston, Massachusetts; New

York City, New York; and Seattle, Washington – have recently campaigned to be able to

set lower citywide default speed limits. Some State legislatures have passed laws giving

these cities the ability to set a 25 or 20 mph default speed limit citywide. For example,

Portland, Oregon, has gained the authority to set residential streets at 20 mph. Other

countries are also exploring or implementing citywide speed limits.

• The speed limit setting procedure (SLS-Procedure) uses fact-based decision rules that

consider both driver speed choice and safety associated with the roadway. Employing the

SLS-Procedure and the accompanying tool has the potential to help State, local, and

Tribal transportation agencies make informed decisions and communicate how speed

limits can be set to State/local/Tribal leadership and citizens.
The Honorable Kay Granger

Page 3

A similar letter has been sent to the Ranking Member of the House Committee on 

Appropriations; the Chair and Vice Chair of the Senate Committee on Appropriations; the 

Chairman and Ranking Member of the Senate Subcommittee on Transportation, Housing and 

Urban Development, and Related Agencies; and the Chairman and Ranking Member of the 

House Subcommittee on Transportation, Housing and Urban Development, and Related 

Agencies.

Sincerely,

Shailen P. Bhatt

Administrator

Enclosure 
 Office of the Administrator 1200 New Jersey Ave., SE

 Washington, D.C. 20590

September 5, 2023 

The Honorable Rosa DeLauro

Ranking Member 

Committee on Appropriations 

U.S. House of Representatives

Washington, DC 20515 

Dear Ranking Member DeLauro: 

This letter provides the report requested by the Joint Explanatory Statement and House of 

Representatives Report 116-452 accompanying the Departments of Transportation, Housing and 

Urban Development, and Related Agencies Appropriations Act, 2021, tasking the Federal 

Highway Administration (FHWA) to provide findings of two projects underway by the National 

Cooperative Highway Research Program (NCHRP): NCHRP Project 17-76, Guidance for the 

Setting of Speed Limits; and NCHRP Project 15-76, Designing for Target Speed. House Report 

116-452 specifically requests that following the completion of each study, “the Department

should summarize the findings and report to the House and Senate Committees on

Appropriations detailing findings on how speed limits are set, how they impact roadway design,

and the implications for enforcement and crashes where posted speeds and design speeds

deviate.”

Promoting safe traffic speeds and reducing speeding-related fatalities and serious injuries is a 

focus of the U.S. Department of Transportation’s National Roadway Safety Strategy, which 

officially adopts the Safe System Approach principles to guide safety actions. One of those 

principles is to recognize that humans are vulnerable and have a limited ability to tolerate crash 

impacts. The FHWA will use resources such as NCHRP Projects 17-76 and 15-76 and recently 

initiated work to produce a handbook providing guidance to States and localities on approaches 

to determining appropriate speed limits for all roads and streets to advance speed management 

practices in support of the Safe System Approach. 

This enclosed report summarizes and documents the findings in NCHRP Project 17-76 and 

introduces the recently initiated project to produce a handbook on speed limits. At the time of 

preparing this report, NCHRP Project 15-76 has not been completed. Once it is completed, 

FHWA will submit a separate report to Congress summarizing the findings of NCHRP Project 

15-76, including the implications for enforcement and crashes where posted speed limits and

design speeds deviate.

The objectives of NCHRP Project 17-76 were (i) to identify factors that influence a driver’s 

operating speed and (ii) to develop a speed limit setting procedure and a speed limit setting tool 
The Honorable Rosa DeLauro

Page 2

that would automate the procedure used in making informed decisions related to establishing 

speed limits for any roadway type. The project was completed in June 2021 and produced two 

research reports: 1) NCHRP Research Report 966: Posted Speed Limit Setting Procedure and 

Tool: User Guide, which contains a procedure for setting speed limits and a user manual 

explaining the speed limit setting procedure (SLS-Procedure), and 2) NCHRP Web-Only 

Document 291: Development of a Posted Speed Limit Setting Procedure and Tool, which details 

the research activities and methods. 

The attached report summarizes the findings from NCHRP Project 17-76 with respect to the 

following aspects: 

• States establish statutory speed limits for specific types of roads—such as freeways, rural

highways, or urban streets—which are applicable even if the speed limit sign is not

posted. This report focuses on the setting of posted speed limits.

• The process of selecting a posted speed limit value for a roadway segment can be

influenced by many factors, including safety concerns, roadway geometry and

characteristics, and human factors such as the way drivers react to the roadway.

• The predominant method used in the United States is the operating speed approach. It

typically relies on the 85th percentile speed with adjustments used to account for existing

roadway geometry or crash experience. Many States and some local agencies have their

own laws and criteria for setting speed limits. Professionals who conduct studies to

determine the appropriate posted speed limit rarely relies solely on the 85th percentile

speed (i.e., they use several other factors).

• Using approaches other than the 85th percentile speed to determine the posted speed limit

is gaining popularity nationwide. Several cities – such as Boston, Massachusetts; New

York City, New York; and Seattle, Washington – have recently campaigned to be able to

set lower citywide default speed limits. Some State legislatures have passed laws giving

these cities the ability to set a 25 or 20 mph default speed limit citywide. For example,

Portland, Oregon, has gained the authority to set residential streets at 20 mph. Other

countries are also exploring or implementing citywide speed limits.

• The speed limit setting procedure (SLS-Procedure) uses fact-based decision rules that

consider both driver speed choice and safety associated with the roadway. Employing the

SLS-Procedure and the accompanying tool has the potential to help State, local, and

Tribal transportation agencies make informed decisions and communicate how speed

limits can be set to State/local/Tribal leadership and citizens.
The Honorable Rosa DeLauro

Page 3

A similar letter has been sent to the Chair of the House Committee on Appropriations; the Chair 

and Vice Chair of the Senate Committee on Appropriations; the Chairman and Ranking Member 

of the Senate Subcommittee on Transportation, Housing and Urban Development, and Related 

Agencies; and the Chairman and Ranking Member of the House Subcommittee on 

Transportation, Housing and Urban Development, and Related Agencies.

Sincerely,

Shailen P. Bhatt

Administrator

Enclosure 
 Office of the Administrator 1200 New Jersey Ave., SE

 Washington, D.C. 20590

September 5, 2023 

The Honorable Brian Schatz 

Chairman, Subcommittee on Transportation, Housing 

 and Urban Development, and Related Agencies

Committee on Appropriations 

United States Senate

Washington, DC 20510 

Dear Chairman Schatz: 

This letter provides the report requested by the Joint Explanatory Statement and House of 

Representatives Report 116-452 accompanying the Departments of Transportation, Housing and 

Urban Development, and Related Agencies Appropriations Act, 2021, tasking the Federal 

Highway Administration (FHWA) to provide findings of two projects underway by the National 

Cooperative Highway Research Program (NCHRP): NCHRP Project 17-76, Guidance for the 

Setting of Speed Limits; and NCHRP Project 15-76, Designing for Target Speed. House Report 

116-452 specifically requests that following the completion of each study, “the Department

should summarize the findings and report to the House and Senate Committees on

Appropriations detailing findings on how speed limits are set, how they impact roadway design,

and the implications for enforcement and crashes where posted speeds and design speeds

deviate.”

Promoting safe traffic speeds and reducing speeding-related fatalities and serious injuries is a 

focus of the U.S. Department of Transportation’s National Roadway Safety Strategy, which 

officially adopts the Safe System Approach principles to guide safety actions. One of those 

principles is to recognize that humans are vulnerable and have a limited ability to tolerate crash 

impacts. The FHWA will use resources such as NCHRP Projects 17-76 and 15-76 and recently 

initiated work to produce a handbook providing guidance to States and localities on approaches 

to determining appropriate speed limits for all roads and streets to advance speed management 

practices in support of the Safe System Approach. 

This enclosed report summarizes and documents the findings in NCHRP Project 17-76 and 

introduces the recently initiated project to produce a handbook on speed limits. At the time of 

preparing this report, NCHRP Project 15-76 has not been completed. Once it is completed, 

FHWA will submit a separate report to Congress summarizing the findings of NCHRP Project 

15-76, including the implications for enforcement and crashes where posted speed limits and

design speeds deviate.
The Honorable Brian Schatz

Page 2 

The objectives of NCHRP Project 17-76 were (i) to identify factors that influence a driver’s 

operating speed and (ii) to develop a speed limit setting procedure and a speed limit setting tool 

that would automate the procedure used in making informed decisions related to establishing 

speed limits for any roadway type. The project was completed in June 2021 and produced two 

research reports: 1) NCHRP Research Report 966: Posted Speed Limit Setting Procedure and 

Tool: User Guide, which contains a procedure for setting speed limits and a user manual 

explaining the speed limit setting procedure (SLS-Procedure), and 2) NCHRP Web-Only 

Document 291: Development of a Posted Speed Limit Setting Procedure and Tool, which details 

the research activities and methods. 

The attached report summarizes the findings from NCHRP Project 17-76 with respect to the 

following aspects: 

• States establish statutory speed limits for specific types of roads—such as freeways, rural

highways, or urban streets—which are applicable even if the speed limit sign is not

posted. This report focuses on the setting of posted speed limits.

• The process of selecting a posted speed limit value for a roadway segment can be

influenced by many factors, including safety concerns, roadway geometry and

characteristics, and human factors such as the way drivers react to the roadway.

• The predominant method used in the United States is the operating speed approach. It

typically relies on the 85th percentile speed with adjustments used to account for existing

roadway geometry or crash experience. Many States and some local agencies have their

own laws and criteria for setting speed limits. Professionals who conduct studies to

determine the appropriate posted speed limit rarely relies solely on the 85th percentile

speed (i.e., they use several other factors).

• Using approaches other than the 85th percentile speed to determine the posted speed limit

is gaining popularity nationwide. Several cities – such as Boston, Massachusetts; New

York City, New York; and Seattle, Washington – have recently campaigned to be able to

set lower citywide default speed limits. Some State legislatures have passed laws giving

these cities the ability to set a 25 or 20 mph default speed limit citywide. For example,

Portland, Oregon, has gained the authority to set residential streets at 20 mph. Other

countries are also exploring or implementing citywide speed limits.

• The speed limit setting procedure (SLS-Procedure) uses fact-based decision rules that

consider both driver speed choice and safety associated with the roadway. Employing the

SLS-Procedure and the accompanying tool has the potential to help State, local, and

Tribal transportation agencies make informed decisions and communicate how speed

limits can be set to State/local/Tribal leadership and citizens.
The Honorable Brian Schatz 

Page 3

A similar letter has been sent to the Ranking Member of the Senate Subcommittee on 

Transportation, Housing and Urban Development, and Related Agencies; the Chair and Vice 

Chair of the Senate Committee on Appropriations; the Chair and Ranking Member of the House 

Committee on Appropriations; and the Chairman and Ranking Member of the House 

Subcommittee on Transportation, Housing and Urban Development, and Related Agencies.

Sincerely,

Shailen P. Bhatt

Administrator

Enclosure 
 Office of the Administrator 1200 New Jersey Ave., SE

 Washington, D.C. 20590

September 5, 2023 

The Honorable Cindy Hyde-Smith

Ranking Member, Subcommittee on Transportation, Housing 

 and Urban Development, and Related Agencies

Committee on Appropriations 

United States Senate 

Washington, DC 20510 

Dear Ranking Member Hyde-Smith: 

This letter provides the report requested by the Joint Explanatory Statement and House of 

Representatives Report 116-452 accompanying the Departments of Transportation, Housing and 

Urban Development, and Related Agencies Appropriations Act, 2021, tasking the Federal 

Highway Administration (FHWA) to provide findings of two projects underway by the National 

Cooperative Highway Research Program (NCHRP): NCHRP Project 17-76, Guidance for the 

Setting of Speed Limits; and NCHRP Project 15-76, Designing for Target Speed. House Report 

116-452 specifically requests that following the completion of each study, “the Department

should summarize the findings and report to the House and Senate Committees on

Appropriations detailing findings on how speed limits are set, how they impact roadway design,

and the implications for enforcement and crashes where posted speeds and design speeds

deviate.”

Promoting safe traffic speeds and reducing speeding-related fatalities and serious injuries is a 

focus of the U.S. Department of Transportation’s National Roadway Safety Strategy, which 

officially adopts the Safe System Approach principles to guide safety actions. One of those 

principles is to recognize that humans are vulnerable and have a limited ability to tolerate crash 

impacts. The FHWA will use resources such as NCHRP Projects 17-76 and 15-76 and recently 

initiated work to produce a handbook providing guidance to States and localities on approaches 

to determining appropriate speed limits for all roads and streets to advance speed management 

practices in support of the Safe System Approach. 

This enclosed report summarizes and documents the findings in NCHRP Project 17-76 and 

introduces the recently initiated project to produce a handbook on speed limits. At the time of 

preparing this report, NCHRP Project 15-76 has not been completed. Once it is completed, 

FHWA will submit a separate report to Congress summarizing the findings of NCHRP Project 

15-76, including the implications for enforcement and crashes where posted speed limits and

design speeds deviate.
The Honorable Cindy Hyde-Smith

Page 2

The objectives of NCHRP Project 17-76 were (i) to identify factors that influence a driver’s 

operating speed and (ii) to develop a speed limit setting procedure and a speed limit setting tool 

that would automate the procedure used in making informed decisions related to establishing 

speed limits for any roadway type. The project was completed in June 2021 and produced two 

research reports: 1) NCHRP Research Report 966: Posted Speed Limit Setting Procedure and 

Tool: User Guide, which contains a procedure for setting speed limits and a user manual 

explaining the speed limit setting procedure (SLS-Procedure), and 2) NCHRP Web-Only 

Document 291: Development of a Posted Speed Limit Setting Procedure and Tool, which details 

the research activities and methods. 

The attached report summarizes the findings from NCHRP Project 17-76 with respect to the 

following aspects: 

• States establish statutory speed limits for specific types of roads—such as freeways, rural

highways, or urban streets—which are applicable even if the speed limit sign is not

posted. This report focuses on the setting of posted speed limits.

• The process of selecting a posted speed limit value for a roadway segment can be

influenced by many factors, including safety concerns, roadway geometry and

characteristics, and human factors such as the way drivers react to the roadway.

• The predominant method used in the United States is the operating speed approach. It

typically relies on the 85th percentile speed with adjustments used to account for existing

roadway geometry or crash experience. Many States and some local agencies have their

own laws and criteria for setting speed limits. Professionals who conduct studies to

determine the appropriate posted speed limit rarely relies solely on the 85th percentile

speed (i.e., they use several other factors).

• Using approaches other than the 85th percentile speed to determine the posted speed limit

is gaining popularity nationwide. Several cities – such as Boston, Massachusetts; New

York City, New York; and Seattle, Washington – have recently campaigned to be able to

set lower citywide default speed limits. Some State legislatures have passed laws giving

these cities the ability to set a 25 or 20 mph default speed limit citywide. For example,

Portland, Oregon, has gained the authority to set residential streets at 20 mph. Other

countries are also exploring or implementing citywide speed limits.

• The speed limit setting procedure (SLS-Procedure) uses fact-based decision rules that

consider both driver speed choice and safety associated with the roadway. Employing the

SLS-Procedure and the accompanying tool has the potential to help State, local, and

Tribal transportation agencies make informed decisions and communicate how speed

limits can be set to State/local/Tribal leadership and citizens.
The Honorable Cindy Hyde-Smith

Page 3

A similar letter has been sent to the Chairman of the Senate Subcommittee on Transportation, 

Housing and Urban Development, and Related Agencies; the Chair and Vice Chair of the Senate 

Committee on Appropriations; the Chair and Ranking Member of the House Committee on 

Appropriations; and the Chairman and Ranking Member of the House Subcommittee on 

Transportation, Housing and Urban Development, and Related Agencies. 

Sincerely,

Shailen P. Bhatt

Administrator

Enclosure
 Office of the Administrator 1200 New Jersey Ave., SE

 Washington, D.C. 20590

September 5, 2023 

The Honorable Tom Cole 

Chairman, Subcommittee on Transportation, Housing 

 and Urban Development, and Related Agencies

Committee on Appropriations 

U.S. House of Representatives 

Washington, DC 20515 

Dear Chairman Cole: 

This letter provides the report requested by the Joint Explanatory Statement and House of 

Representatives Report 116-452 accompanying the Departments of Transportation, Housing and 

Urban Development, and Related Agencies Appropriations Act, 2021, tasking the Federal 

Highway Administration (FHWA) to provide findings of two projects underway by the National 

Cooperative Highway Research Program (NCHRP): NCHRP Project 17-76, Guidance for the 

Setting of Speed Limits; and NCHRP Project 15-76, Designing for Target Speed. House Report 

116-452 specifically requests that following the completion of each study, “the Department

should summarize the findings and report to the House and Senate Committees on

Appropriations detailing findings on how speed limits are set, how they impact roadway design,

and the implications for enforcement and crashes where posted speeds and design speeds

deviate.”

Promoting safe traffic speeds and reducing speeding-related fatalities and serious injuries is a 

focus of the U.S. Department of Transportation’s National Roadway Safety Strategy, which 

officially adopts the Safe System Approach principles to guide safety actions. One of those 

principles is to recognize that humans are vulnerable and have a limited ability to tolerate crash 

impacts. The FHWA will use resources such as NCHRP Projects 17-76 and 15-76 and recently 

initiated work to produce a handbook providing guidance to States and localities on approaches 

to determining appropriate speed limits for all roads and streets to advance speed management 

practices in support of the Safe System Approach. 

This enclosed report summarizes and documents the findings in NCHRP Project 17-76 and 

introduces the recently initiated project to produce a handbook on speed limits. At the time of 

preparing this report, NCHRP Project 15-76 has not been completed. Once it is completed, 

FHWA will submit a separate report to Congress summarizing the findings of NCHRP Project 

15-76, including the implications for enforcement and crashes where posted speed limits and

design speeds deviate.
The Honorable Tom Cole 

Page 2 

The objectives of NCHRP Project 17-76 were (i) to identify factors that influence a driver’s 

operating speed and (ii) to develop a speed limit setting procedure and a speed limit setting tool 

that would automate the procedure used in making informed decisions related to establishing 

speed limits for any roadway type. The project was completed in June 2021 and produced two 

research reports: 1) NCHRP Research Report 966: Posted Speed Limit Setting Procedure and 

Tool: User Guide, which contains a procedure for setting speed limits and a user manual 

explaining the speed limit setting procedure (SLS-Procedure), and 2) NCHRP Web-Only 

Document 291: Development of a Posted Speed Limit Setting Procedure and Tool, which details 

the research activities and methods. 

The attached report summarizes the findings from NCHRP Project 17-76 with respect to the 

following aspects: 

• States establish statutory speed limits for specific types of roads—such as freeways, rural

highways, or urban streets—which are applicable even if the speed limit sign is not

posted. This report focuses on the setting of posted speed limits.

• The process of selecting a posted speed limit value for a roadway segment can be

influenced by many factors, including safety concerns, roadway geometry and

characteristics, and human factors such as the way drivers react to the roadway.

• The predominant method used in the United States is the operating speed approach. It

typically relies on the 85th percentile speed with adjustments used to account for existing

roadway geometry or crash experience. Many States and some local agencies have their

own laws and criteria for setting speed limits. Professionals who conduct studies to

determine the appropriate posted speed limit rarely relies solely on the 85th percentile

speed (i.e., they use several other factors).

• Using approaches other than the 85th percentile speed to determine the posted speed limit

is gaining popularity nationwide. Several cities – such as Boston, Massachusetts; New

York City, New York; and Seattle, Washington – have recently campaigned to be able to

set lower citywide default speed limits. Some State legislatures have passed laws giving

these cities the ability to set a 25 or 20 mph default speed limit citywide. For example,

Portland, Oregon, has gained the authority to set residential streets at 20 mph. Other

countries are also exploring or implementing citywide speed limits.

• The speed limit setting procedure (SLS-Procedure) uses fact-based decision rules that

consider both driver speed choice and safety associated with the roadway. Employing the

SLS-Procedure and the accompanying tool has the potential to help State, local, and

Tribal transportation agencies make informed decisions and communicate how speed

limits can be set to State/local/Tribal leadership and citizens.
The Honorable Tom Cole 

Page 3

A similar letter has been sent to the Ranking Member of the House Subcommittee on 

Transportation, Housing and Urban Development, and Related Agencies; the Chair and Vice 

Chair of the Senate Committee on Appropriations; the Chair and Ranking Member of the House 

Committee on Appropriations; and the Chairman and Ranking Member of the Senate 

Subcommittee on Transportation, Housing and Urban Development, and Related Agencies. 

Sincerely,

Shailen P. Bhatt 

Administrator

Enclosure
 Office of the Administrator 1200 New Jersey Ave., SE

 Washington, D.C. 20590

September 5, 2023 

The Honorable Mike Quigley

Ranking Member, Subcommittee on Transportation, Housing 

 and Urban Development, and Related Agencies

Committee on Appropriations 

U.S. House of Representatives

Washington, DC 20515 

Dear Ranking Member Quigley: 

This letter provides the report requested by the Joint Explanatory Statement and House of 

Representatives Report 116-452 accompanying the Departments of Transportation, Housing and 

Urban Development, and Related Agencies Appropriations Act, 2021, tasking the Federal 

Highway Administration (FHWA) to provide findings of two projects underway by the National 

Cooperative Highway Research Program (NCHRP): NCHRP Project 17-76, Guidance for the 

Setting of Speed Limits; and NCHRP Project 15-76, Designing for Target Speed. House Report 

116-452 specifically requests that following the completion of each study, “the Department

should summarize the findings and report to the House and Senate Committees on

Appropriations detailing findings on how speed limits are set, how they impact roadway design,

and the implications for enforcement and crashes where posted speeds and design speeds

deviate.”

Promoting safe traffic speeds and reducing speeding-related fatalities and serious injuries is a 

focus of the U.S. Department of Transportation’s National Roadway Safety Strategy, which 

officially adopts the Safe System Approach principles to guide safety actions. One of those 

principles is to recognize that humans are vulnerable and have a limited ability to tolerate crash 

impacts. The FHWA will use resources such as NCHRP Projects 17-76 and 15-76 and recently 

initiated work to produce a handbook providing guidance to States and localities on approaches 

to determining appropriate speed limits for all roads and streets to advance speed management 

practices in support of the Safe System Approach. 

This enclosed report summarizes and documents the findings in NCHRP Project 17-76 and 

introduces the recently initiated project to produce a handbook on speed limits. At the time of 

preparing this report, NCHRP Project 15-76 has not been completed. Once it is completed, 

FHWA will submit a separate report to Congress summarizing the findings of NCHRP Project 

15-76, including the implications for enforcement and crashes where posted speed limits and

design speeds deviate.

The objectives of NCHRP Project 17-76 were (i) to identify factors that influence a driver’s 

operating speed and (ii) to develop a speed limit setting procedure and a speed limit setting tool 
The Honorable Mike Quigley 

Page 2

that would automate the procedure used in making informed decisions related to establishing 

speed limits for any roadway type. The project was completed in June 2021 and produced two 

research reports: 1) NCHRP Research Report 966: Posted Speed Limit Setting Procedure and 

Tool: User Guide, which contains a procedure for setting speed limits and a user manual 

explaining the speed limit setting procedure (SLS-Procedure), and 2) NCHRP Web-Only 

Document 291: Development of a Posted Speed Limit Setting Procedure and Tool, which details 

the research activities and methods. 

The attached report summarizes the findings from NCHRP Project 17-76 with respect to the 

following aspects: 

• States establish statutory speed limits for specific types of roads—such as freeways, rural

highways, or urban streets—which are applicable even if the speed limit sign is not

posted. This report focuses on the setting of posted speed limits.

• The process of selecting a posted speed limit value for a roadway segment can be

influenced by many factors, including safety concerns, roadway geometry and

characteristics, and human factors such as the way drivers react to the roadway.

• The predominant method used in the United States is the operating speed approach. It

typically relies on the 85th percentile speed with adjustments used to account for existing

roadway geometry or crash experience. Many States and some local agencies have their

own laws and criteria for setting speed limits. Professionals who conduct studies to

determine the appropriate posted speed limit rarely relies solely on the 85th percentile

speed (i.e., they use several other factors).

• Using approaches other than the 85th percentile speed to determine the posted speed limit

is gaining popularity nationwide. Several cities – such as Boston, Massachusetts; New

York City, New York; and Seattle, Washington – have recently campaigned to be able to

set lower citywide default speed limits. Some State legislatures have passed laws giving

these cities the ability to set a 25 or 20 mph default speed limit citywide. For example,

Portland, Oregon, has gained the authority to set residential streets at 20 mph. Other

countries are also exploring or implementing citywide speed limits.

• The speed limit setting procedure (SLS-Procedure) uses fact-based decision rules that

consider both driver speed choice and safety associated with the roadway. Employing the

SLS-Procedure and the accompanying tool has the potential to help State, local, and

Tribal transportation agencies make informed decisions and communicate how speed

limits can be set to State/local/Tribal leadership and citizens.
The Honorable Mike Quigley 

Page 3

A similar letter has been sent to the Chairman of the House Subcommittee on Transportation, 

Housing and Urban Development, and Related Agencies; the Chair and Vice Chair of the Senate 

Committee on Appropriations; the Chair and Ranking Member of the House Committee on 

Appropriations; and the Chairman and Ranking Member of the Senate Subcommittee on 

Transportation, Housing and Urban Development, and Related Agencies.

Sincerely,

Shailen P. Bhatt

Administrator

Enclosure 
Report to Congress: National Cooperative 

Highway Research Program (NCHRP) 

Project 17-76 “Guidance for the Setting of 

Speed Limits”

U.S. Department of Transportation

Federal Highway Administration
Table of Contents

1. INTRODUCTION................................................................................................................................. 2 

2. BACKGROUND.................................................................................................................................... 2 

3. OBJECTIVES AND SCOPE OF NCHRP PROJECT 17-76 ............................................................ 3 

4. DEVELOPMENT OF RESULT: SPEED LIMIT SETTING PROCEDURE AND TOOL.......... 4 

4.1 SPEED LIMIT SETTING APPROACHES ....................................................................................... 4 

4.2 RELATIONSHIPS AMONG ROADWAY CHARACTERISTICS, POSTED SPEED LIMIT, 

OPERATING SPEED, AND CRASHES ........................................................................................ 6 

4.2.1 Traffic Variables ...................................................................................................................... 6 

4.2.2 TCD Variables ......................................................................................................................... 7 

4.2.3 Roadway Geometry Variables ................................................................................................. 8 

4.2.4 Roadway Surrounding Variables ............................................................................................. 9 

4.3 DEVELOPMENT OF SPEED LIMIT SETTING PROCEDURE AND TOOL ............................. 10 

5. CONCLUSIONS OF NCHRP PROJECT 17-76 ..............................................................................11

6. SUGGESTED RESEARCH FROM NCHRP PROJECT 17-76 .....................................................12

7. CONCLUSION....................................................................................................................................12
EXECUTIVE SUMMARY

There is broad consensus among global roadway safety experts that speed control is one of the 

most important methods for reducing fatalities and serious injuries. Speeding, whether driving in 

excess of the posted speed limit or driving too fast for conditions, has played a role in more than 

a quarter of traffic deaths – killing nearly 100,000 people in the United States – over the past 

decade. Moreover, as noted in this report, speed influences both the severity of crashes and the 

number of crashes, which underscores the need for setting safer speed limits as a critical tool for 

reducing fatalities and serious injuries. The U.S. Department of Transportation’s (DOT) 

National Roadway Safety Strategy emphasizes that methods for setting speed limits should be 

customized to the context of the roadway. This report summarizes recent work done on speedlimit setting. 

This report to Congress is prepared in response to the Joint Explanatory Statement and House of 

Representatives Report 116-452 accompanying the Departments of Transportation, Housing and 

Urban Development, and Related Agencies Appropriations Act, 2021, tasking the Federal 

Highway Administration (FHWA) to provide findings and results of two projects underway by 

the National Cooperative Highway Research Program (NCHRP): NCHRP Project 17-76, 

Guidance for the Setting of Speed Limits and NCHRP Project 15-76, Designing for Target Speed. 

This report summarizes and documents the results of NCHRP Project 17-76, which was 

completed in June 2021 and produced two research reports: 

1) NCHRP Research Report 966: Posted Speed Limit Setting Procedure and Tool: User

Guide, which contains a procedure for setting speed limits and a user manual

explaining the speed limit setting procedure (SLS-Procedure), and

2) NCHRP Web-Only Document 291: Development of a Posted Speed Limit Setting

Procedure and Tool, which details the research activities and methods.

The NCHRP Project 15-76 has been delayed during the pandemic, with completion anticipated 

in 2023. The report to Congress summarizing the findings of NCHRP Project 15-76 will be 

prepared once that project is complete. 

The NCHRP Project 17-76 investigated the factors that influence operating speed and safety 

through a review of the literature and an analysis of the relationships of speed, safety, and 

roadway characteristics on urban/suburban roadways. The variables identified that influence 

either operating speeds or crashes were grouped into five categories: 

1) Traffic;

2) Traffic Control Devices (TCD);

3) Roadway Geometry;

4) Roadway Surroundings; and

5) Other.

This research also considered the breadth of approaches available for the setting of speed limits 

and the need to develop a methodology that could be used for any roadway type. An 
2 

investigation into the factors that influence operating speed and safety and a review of existing 

speed limit setting practices were used in developing the SLS-Procedure and accompanying 

SLS-Tool. Detailed information is provided in the NCHRP Research Report 966: Posted Speed 

Limit Setting Procedure and Tool: User Guide, and NCHRP Web-Only Document 291: 

Development of a Posted Speed Limit Setting Procedure and Tool. The goal of the 

SLS-Procedure and SLS-Tool is to produce an objective suggested speed limit value, based on 

factors specific to the roadway. Practitioners are able to use the procedure and/or tool to 

communicate with the public or government officials to explain the general procedures behind 

setting speed limits.

1. INTRODUCTION

The FHWA submits this report to the House and Senate Committees on Appropriations in 

response to the following committee recommendations in the House Report 116-452, Page 45: 

Design speeds. - The Committee is concerned about the relationship between design 

speed, posted speed, and operating speed. The Committee is looking forward to the 

results of two upcoming projects underway by the [NCHRP], NCHRP Project 17-76, 

“Guidance for the Setting of Speed Limits” and NCHRP Project 15-76, “Designing for 

Target Speed”. Following the completion of each study, the Department should 

summarize the findings and report to the House and Senate Committees on 

Appropriations detailing findings on how speed limits are set, how they impact roadway 

design, and the implications for enforcement and crashes where posted speeds and design 

speeds deviate.

This report summarizes and documents the results of NCHRP Project 17-76. However, it does 

not contain results from NCHRP Project 15-76 because that project had not been completed at 

the time of preparing this report. The FHWA will submit another report to Congress on NCHRP 

Project 15-76, including the implications for enforcement and crashes where posted speed limits 

and design speeds deviate. 

2. BACKGROUND

Speed influences both the severity of crashes – particularly in pedestrian crashes – and the 

number of crashes. The increase in crash severity is not linear with respect to the increase in 

speed. Instead, the severity of a crash tends to increase exponentially at higher speeds. It is 

unclear whether knowledge of the increased risks associated with higher speeds would influence 

drivers’ speed choice. In the United States (U.S.), the predominant method for setting speed 

limits has been based on the 85th percentile speed, which is defined as the speed at or below 

which 85 percent of all vehicles are observed to travel under free-flowing conditions. However, 

the use of the 85th percentile method has come under scrutiny for the following reasons: 

• Drivers may not see or be aware of all the conditions present along the roadway, so

setting the posted speed limit based on existing driver behavior may create unsafe road

conditions.
3 

• Setting the speed limit based on existing driver behavior rather than the roadway context

may not adequately consider vulnerable roadway users such as pedestrians, bicyclists,

other cyclists, and persons on personal conveyance. Drivers are not always reasonable

and prudent, or they may consider only what is reasonable and prudent for themselves but

not for all users of the roadway. Drivers frequently select speeds at a certain increment

above the posted speed limit; if this occurs, posting the speed limit based on measured

operating speeds results in increases to the posted speed limit over time.

• Most of the early research justifying the use of the 85th percentile speed was conducted

on rural roadways; therefore, it may not be appropriate for the urban roadway system.

• Changes to roadway design features and the context of the roadway have direct impacts

on operating speeds.

Two recent publications have influenced the discussion about practices used to establish speed 

limits: 

1) In March 2017, the National Association of City Transportation Officials (NACTO)

released a policy statement.1

 One of the action items in that policy statement is to “permit

local control of city speed limits.” The NACTO also recommends that “state rules or laws

that set speed limits at the 85th percentile speed should be repealed.”

2) In July 2017, the National Transportation Safety Board (NTSB) published a report

“Reducing Speeding-Related Crashes Involving Passenger Vehicles.”2 The NTSB report

contains several recommendations to reduce speeding-related crashes, including the following

two recommended changes:

• Revise Section 2B.13 of the Manual on Uniform Traffic Control Devices so that the

factors currently listed as optional for all engineering studies are required, require that an

expert system such as USLIMITS be used as a validation tool, and remove the guidance

that speed limits in speed zones should be within 5 mph of the 85th percentile speed.

(H-17-27)

• Revise Section 2B.13 of the Manual on Uniform Traffic Control Devices to, at a

minimum, incorporate the safe system approach for urban roads to strengthen protection

for vulnerable road users. (H-17-28)

While the highway geometric design practice has historically focused on design speed and 

posted speed, the concept of “target speed” is now central to many discussions related to 

roadways in urban, suburban, and rural towns. The target speed is simply the operating speed 

intended for drivers to travel on a given roadway facility. While NCHRP Project 15-76 is still 

underway, it is expected to give design engineers updated information about how to design 

roadways such that drivers naturally travel at the target speed. 

3. OBJECTIVES AND SCOPE OF NCHRP PROJECT 17-76

1 See https://nacto.org/wp-content/uploads/2017/03/NACTO-Policy-2017.pdf 2 See https://www.ntsb.gov/safety/safety-studies/Documents/SS1701.pdf 
4 

The objectives of NCHRP Project 17-76, “Guidance for the Setting of Speed Limits,” were to 

identify factors that influence a driver’s operating speed, and develop an SLS-Procedure and 

SLS-Tool that automates the procedure for making informed decisions related to establishing 

speed limits for any roadway type. The research efforts and findings of NCHRP 17-76 are 

published in NCHRP Research Report 966: Posted Speed Limit Setting Procedure and Tool: 

User Guide,3 which contains a procedure for setting speed limits and a practitioner ready user 

manual explaining SLS-Procedure, and NCHRP Web-Only Document 291: Development of a 

Posted Speed Limit Setting Procedure and Tool,

4 which details the research activities and 

methods. 

This project was carried out in two phases. During Phase I, the research team collected insights 

into how the roadway environment influences operating speed and safety through a literature 

review, and identified the factors or variables used in current speed setting practices.

Using those insights along with an understanding of different methods currently being 

considered for the setting of posted speed limits, the research team developed the SLS-Procedure 

in Phase II. The SLS-Procedure is based on fact-based decision rules that consider both driver 

speed choice and the safety associated with the roadway features. Then, Phase II involved the 

automation of that procedure to develop the SLS-Tool. As a part of the Phase II efforts, the 

research team collected data for urban and suburban roads in Austin, Texas, and Washtenaw 

County, Michigan, and built a database to investigate the relationships among crashes, roadway 

characteristics, and posted speed limits on city streets. 

4. DEVELOPMENT OF RESULT: SPEED LIMIT SETTING

PROCEDURE AND TOOL

4.1 SPEED LIMIT SETTING APPROACHES

The research team found that a number of approaches are used in setting speed limits. Speed 

limit is the maximum speed a driver is legally permitted for a given roadway segment. Several 

types of speed limits exist, including statutory speed limit, posted speed limit (PSL), school zone 

speed limit, work zone speed limit, variable speed limit, and advisory speed. States establish 

statutory speed limits for specific types of roads—such as freeways, rural highways, or urban 

streets—which are applicable even if the speed limit sign is not posted. 

The primary purpose of setting speed limits is to inform and advise drivers of the appropriate and 

safe driving speeds under favorable conditions. Because drivers often ignore posted speed 

limits, simply setting a speed limit without considering the factors that affect operating speed 

will rarely achieve the intended operating speed (known as the target speed). In part because 

States and some local agencies have their own speed-limit-setting laws and criteria; various 

approaches and factors are used to set speed limits.

The research team conducted a literature review of current domestic and international practices 

on setting speed limits and summarized the following six approaches: 1) Operating Speed, 

3 See https://www.nap.edu/catalog/26216/posted-speed-limit-setting-procedure-and-tool-user-guide 4 See https://www.nap.edu/catalog/26200/development-of-a-posted-speed-limit-setting-procedure-and-tool
5 

2) Road Risk, 3) Expert System, 4) Injury Minimization/Safe System, 5) Citywide or Default,

and 6) Slow Zones.

• Operating Speed: This approach uses the 85th percentile speed, with adjustments used

to account for existing roadway geometry or crash experience. A review of 31 State

Websites by the research team found that all 31 States use the operating speed approach.

More than half of the States reviewed consider roadside development or land use, traffic

condition or volume, sight distances, the maximum or minimum speed allowed in the

State, as additional factors, while at least three States also consider alignment or crosssectional factors such as horizontal/vertical curves, lane width, and pavement width.

• Road Risk: This approach is primarily used in Canada and New Zealand and determines

the speed limit based on the risks associated with the physical design of the road and the

expected traffic conditions. Essentially, the speed limits are set according to the function

or classification of the roads, and then adjustments to the speed limit are made based on

the relative risk introduced by road and roadside design features. Since this method may

result in speed limits well below the 85th percentile speeds, additional enforcement may

be needed if countermeasures to reduce operating speeds are not employed.

• Expert System: This approach recommends a speed limit based on a computer

algorithm that uses knowledge and inference procedures that simulate the judgment and

behavior derived from knowledgeable people, i.e., the “experts.” The first expert system

approach was developed in the late 1980s by Australia, and currently USLIMITS2, a

Web-based tool developed by FHWA, is used on a limited basis as an expert system in

the United States.

• Injury Minimization/Safe System: This approach sets speed limits based on collision

types that are likely to occur, the resulting impact forces, and the human body’s tolerance

to withstand those forces. This approach is based on the scientific link between speed

limits and serious crash prevention, placing a high priority on road safety. It is used in

Australia, the Netherlands, and Sweden but is not commonly used in the United States.

This may be due to lack of exposure to this method, or because the resulting low speed

limits are not viewed as appropriate by some jurisdictions.

• Citywide or Default: This approach sets speed limits by government actions. The

report discusses city efforts to set uniform speed limits for safety, such as a 20 mph speed

limit on residential streets. States generally control statutory speed limits, and several

U.S. cities have recently campaigned to gain the authority from their state legislatures to

set lower citywide default speed limits. For example, Boston, Massachusetts; New York

City, New York; and Seattle, Washington, now have the ability to set a 25 mph speed

limit citywide. Portland, Oregon, has the authority to set residential streets at 20 mph.

Other countries are also implementing citywide speed limits.

• Slow Zones: This approach is a community-based program to set lower speed limits for

specifically designated corridors or areas than the speed limits on surrounding roadways

of the same type. For example, New York City has implemented a “Neighborhood Slow

Zones Program” to reduce crash frequency and severity and to enhance quality of life by

reducing cut-through traffic and traffic noise in residential neighborhoods. Within the
6 

Slow Zone area, speed limits are reduced from 25 mph to 20 mph, and traffic calming 

treatments are added with the intention of changing driver behavior. 

4.2 RELATIONSHIPS AMONG ROADWAY CHARACTERISTICS, POSTED SPEED LIMIT, 

OPERATING SPEED, AND CRASHES

The relationships among roadway characteristics, posted speed limit, operating speed, and 

crashes, are very complex, and the association among those variables is known to vary widely. 

The research team reviewed the findings reported in the literature, and conducted a data-driven 

analysis to identify those relationships based on data collected for urban and suburban road 

segments located in Austin, Texas, and Washtenaw County, Michigan (which includes the city of 

Ann Arbor). 

The research team identified variables that influence either operating speed or crash potential, 

and these variables were grouped by the research team into five categories: 1) Traffic, 2) TCD, 

3) Roadway Geometry, 4) Roadway Surroundings, and 5) Other. A short synthesis on key

variables follows.

4.2.1 Traffic Variables 

The volume of traffic and the characteristics of that traffic – including vehicle mix and operating 

speed – have a clear relationship with both speed and safety. Traffic variables include:

• Average Annual Daily Traffic (AADT)

Traffic flow measure AADT is considered the most determinant variable for the

occurrence of crashes. Many safety performance functions consider only traffic flow and

segment length in the model development. The relationship between traffic volume and

crashes can be affected by whether the section is undivided or divided. The effect of this

variable on crash frequencies differs based on the facility type. Usually, roadways with

higher AADT values are associated with higher operating speeds on both urban and rural

roadways. However, one study found lower operating speeds to be associated with higher

AADT roadways. The researchers of that study commented that motorists may view

increases in traffic volume as a motivation to slow down.

• Operating Speed

Operating speeds reflect the speed behavior of drivers affected by roadway geometry,

surroundings, traffic, and other variables. On urban roads, average speed, traffic volume,

segment length, median presence, and horizontal curves have significant impacts on

operating speeds, and roadways with higher average operating speeds are anticipated to have

higher crash frequency. Vehicle characteristics, such as vehicle class and vehicle age,

impact speed choice as well. For rural highways, one study found that the number of injury

crashes increased with an increase in the segment mean speed. Another study reviewed

several previous studies to identify factors, especially traffic and road-related factors, related

to crashes. The research literature generally suggests that increased operating speeds would
7 

likely lead to an increase in the overall crash rate and would also shift the severity 

distribution toward crashes of greater severity. 

• Congestion

Congestion has a positive direct relationship with total crashes, i.e., congestion increases the

risk that a crash will occur. Also, traffic flow fluctuation on congested roadways can cause

increased crashes.

• Percentage of Trucks

The percentage of trucks has a mixed effect on operating speeds. On urban/suburban streets,

crashes involving cars decrease as truck percentages increase and drivers of heavy vehicles

generally choose a higher speed than drivers of passenger cars. On the other hand, the

frequency of truck-involved crashes and car-truck-involved crashes increases as the truck

percentage increases.

4.2.2 TCD Variables 

The type of TCDs present can influence operating speeds and crashes because, when signalized 

intersections are present, drivers tend to select their operating speed to avoid stopping at such 

signalized intersections that have optimized progression along a corridor. The TCD variables 

are:

• Posted Speed Limit

Several studies have found that the posted speed limit has a significant effect on free-flow

speeds on urban arterials; higher average vehicle speeds are associated with higher posted

speed limits. Vehicular operating speeds along tangent sections of rural two-lane highways

have also been shown to be impacted by the posted speed limit, with vehicular speeds

increasing as the posted speed limit increases. The magnitude of the change in operating

speed when there is an increase (or decrease) in posted speed is typically only a fraction of

the amount of the actual speed limit change. For undivided high-speed rural roadways,

mean speeds are generally 3 to 5 mph higher for every 10-mph increase in speed limit above

55 mph, with smaller increases at higher speed limits. Increasing speed limits can lead to an

increase in the overall crash rate and would also shift the severity distribution toward

crashes of greater severity. One urban street study noted that “it is the higher speeds on

roads with higher speed limits that cause collisions and not the speed limits (i.e., posted

speed limits affect collisions through their effects on speeds).”

• Signalized Intersection

For urban roadways, the presence of a signalized intersection is associated with higher crash

frequencies and lower operating speeds.

• Passing Lane

Passing lanes are effective in crash reduction on rural roadways. However, passing lanes are

associated with higher intersection-related crash frequency on rural roadways.
8 

4.2.3 Roadway Geometry Variables

The geometric design of the roadway and appurtenance can influence either operating speed or 

crashes in select cases. Roadway geometry variables include: 

• Horizontal Alignment

On rural highways, horizontal curves are identified as having the most influence on driver

speed behavior and crash risk among the geometric variables. Crash frequency increases

with the length and/or degree of horizontal curvature. On two-lane rural highways, design

speed at horizontal curves inconsistent with a driver’s desired speed could create operating

speed irregularities by increasing the driver’s workload, which may incur higher crash

potential. However, past studies have shown mixed results regarding the safety effects of

horizontal curves because the measurements used in the studies varied, including degree of

curve, length of curve, deflection angle, and/or superelevation rate. While several studies

found that the presence of horizontal curvature increases the likelihood of a crash

occurrence, others found that sharper horizontal curves were negatively related to crash

frequency since drivers tend to drive slowly on those segments.

• Vertical Alignment

Studies showed that roadways with vertical alignment experience lower operating speeds

once the vertical alignment exceeds a certain value. Typically, total crash rates increase

with the degree of vertical alignment, especially in the presence of hidden horizontal curves,

intersections, or driveways. Safety risks also associated with higher speed limits increased

on segments with steeper vertical alignments.

• Presence of Median

Median barriers are associated with severe crash reduction on urban arterials but have also

been found to be associated with more Property-Damage-Only (PDO) crashes. Speeds are

lower when either the median with a Two-Way Left Turn Lane (TWLTL) or no median was

present as compared to when a raised median was present. Using data from Austin, Texas,

and Washtenaw County (which includes Ann Arbor), Michigan, the NCHRP 17-76 Project

team found that median type was significant for all severity level crashes, with the presence

of a raised median being associated with fewer crashes than either a TWLTL or no median.

On rural highways, the presence of a median on multilane, non-freeway facilities could

decrease expected crash rates. A Michigan study found that the presence of a TWLTL was

associated with a significant increase in total and injury crashes but was also associated with

a significant decrease in fatal crashes.

• Number of Lanes

The number of lanes is positively associated with crash frequency and operating speed. For

instance, one study found that rural four-lane, undivided facilities tended to experience

significantly more crashes across all severity levels compared to two-lane, undivided

facilities.
9 

• Lane Width

Lane width is one of the significant variables affecting operating speeds and the number of

crashes on rural highways. On rural highways, the width of travel lanes is related to the

safety performance of both two-lane and multilane highways. Wider lanes in particular have

been associated with reductions in single-vehicle run-off-the-road, head-on, and sideswipe

type crashes. It is important to note that the effect of lane width on safety performance is

reduced for multilane highways compared to two-lane highways. For two-lane rural

highways, several studies found that operating speeds increase with wider lane width.

• Shoulder Width

On urban freeways, increasing the outside shoulder width could reduce the total, rear-end,

and fatal and injury crashes, and the presence of curb/shoulders leads to lower operating

speeds on low-speed urban roads.

• Bike Lanes

On urban/suburban streets, installation of bike lanes has positive safety effects on reducing

four crash types: total crashes, injury crashes, bike crashes, and bike injury crashes.

• Intersection Angle

On urban/suburban streets, intersection skew angle is associated with increased car, cartruck, and truck crash frequencies.

• Intersection Lighting

On urban/suburban streets, the presence of intersection lighting appears to significantly

decrease car, car-truck, and truck crash frequencies.

4.2.4 Roadway Surrounding Variables

The characteristics of the road’s surroundings, including the neighboring land use, affect both 

operating speed and crashes. Variables associated with roadway surroundings include: 

• Access Density (driveways and intersections)

On urban/suburban streets, higher densities of driveways, unsignalized intersections, and

urban interchange ramp density have a positive correlation with crash frequency. Higher

density of driveways and T-intersections result in lower operating speeds, and speed

variation increases as the access density increases on urban arterials.

• School Zones

The presence of a school zone requires drivers to slow down. In studies examining different

factors associated with school-zone-related crashes, the dominant factors are the type of

school zones, type of schools, number of roadway lanes, and length of speed zone. Larger

numbers of schools near a roadway segment have been found to be associated with a greater

number of crashes. School zones are used to reduce operating speeds during select times of

the day when students are moving between home and school. While operating speeds are
10 

typically lower during an active school zone, drivers are often still not in full compliance 

with the speed limit.

• Parking

The presence of on-street parking is associated with an increase in PDO crashes, but there is

no statistically significant association with severe crashes. The presence of on-street parking

is associated with lower operating speed.

• Liquor Stores

The presence of licensed liquor stores is associated with higher severe and PDO crashes.

• Sidewalk Presence

The presence of sidewalks on urban/suburban streets is generally associated with lower

operating speeds, but the results varied by study. Setback sidewalks seem to result in higher

operating speeds while sidewalks attached to curbs result in lower operating speeds.

• Development (surrounding land and use)

One study of urban streets found that commercial and residential land use is positively

correlated with operating speed. Type of development (land use) has a significant influence

on operating speed. Generally, mixed low-density areas have the highest operating speeds,

while the mixed high-to-medium density areas have the lowest operating speeds. Land use

plays a role in driver perception of a safe speed. Another study found lower speed to be

associated with residential development for two-lane rural highways

• Transit stops

Transit stops and transit vehicle activities within a roadway segment are associated with

higher pedestrian and bicyclist activities.

4.3 DEVELOPMENT OF SPEED LIMIT SETTING PROCEDURE AND TOOL

The NCHRP 17-76 Project developed the SLS-Procedure and an accompanying SLS-Tool, a 

spreadsheet which automates the procedure, based on the identified factors influencing operating 

speed and safety, and a review of existing speed limit setting practices. The SLS-Procedure is 

designed to apply a set of unique decision rules that consider both driver speed choice and safety 

to four collapsed Speed Limit Setting Groups5

: Limited-Access, Undeveloped, Developed and 

Full-Access facilities based on roadway types and roadway contexts. The guiding principles 

applied to the SLS-Procedure included the following: 

• Use a data-driven approach with research-based decision rules.

• Produce consistent results for a given set of conditions.

• Incorporate contemporary policies, guidelines, and practices.

• Consider drivers’ speed choice and roadway safety.

• Provide transparency in the decision process.

• Consider all roadway types and roadway contexts.

5 See https://www.nap.edu/catalog/24775/an-expanded-functional-classification-system-for-highways-and-streets
11 

• Vary the decision rules to account for the diverse characteristics of each Speed Limit

Setting Group.

• Consider agency data and human resource constraints.

• Include inputs and outputs on the same screen to demonstrate the relationship between

each roadway characteristic and selection of the suggested speed limit.

• Allow for future modifications to accommodate new knowledge.

• Create efficiencies in the decision process, where possible.

For the SLS-Procedure, the research team recommended considering the measured operating 

speed as the starting point for selecting a posted speed limit, but with the measured operating 

speed being adjusted based on roadway conditions and consideration of the crash experience on 

the segment. Overall, the development of the suggested speed limit involves the following steps: 

the user identifies the roadway segment’s context and type; then the user enters the existing 

operating speed to consider the speed drivers are selecting for the segment; next, the crash 

experience or potential is considered; and the result is a final suggested speed limit for the 

segment. Safety is considered through the observed crash data and/or risk factors. It is also 

considered in the decision rules when a geometric variable has been shown through other 

research to be associated with more crashes. The goal of the SLS-Procedure and SLS-Tool is to 

produce an objective suggested speed limit value, based on factors specific to the roadway. 

Practitioners are able to use the procedure and/or tool to communicate with the public or 

government officials to explain the general procedures behind setting speed limits. 

5. CONCLUSIONS OF NCHRP PROJECT 17-76

Selecting a posted speed limit value for a roadway segment can be influenced by many factors, 

including engineering concerns, roadway characteristics, human factors such as the way drivers 

react to the roadway environment in terms of the speed they select, and policies including 

established State/local/Tribal agency laws or protocols along with political pressures. 

The operating speed approach is the most common method for selecting a posted speed limit 

used in the U.S. It typically relies on the 85th percentile speed, with adjustments used to account 

for existing roadway geometry or crash experience. Many States/local agencies have their own 

laws/criteria for setting speed limits, many of which are quite detailed. Professionals who 

conduct studies to determine the appropriate posted speed limit rarely use only the 85th 

percentile speed (i.e., they use several other factors).

Using techniques other than the 85th percentile speed to select the posted speed limit is gaining 

in popularity in other countries. Several cities in the U.S. – such as Boston, Massachusetts; New 

York City, New York; Portland, Oregon; Seattle, Washington; and others – are using alternative 

speed limit setting approaches for city streets.

The SLS-Procedure uses fact-based decision rules that consider both driver speed choice and 

safety features associated with the roadway. Employing the SLS-Procedure and the SLS-Tool 

has potential to help State and/or local transportation agencies make informed decisions and 

communicate how speed limits are set to leadership and citizens.
12 

6. SUGGESTED RESEARCH FROM NCHRP PROJECT 17-76

Among suggestions for additional research identified in NCHRP Project 17-76 include the 

following: 

• Investigate current statutory speeds in all 50 States and develop a roadmap of how a uniform

set of best-practice statutory speeds could be established across the country.

• Determine needed collaboration among engineering, enforcement, and judicial industries that

will result in more uniform setting, enforcement, and adjudication of reasonable speed limits.

• Identify comprehensive definitions of the other factors used in setting speed limits such that

they lead to more uniform application.

• Conduct outreach to the most experienced State and local personnel who have conducted

engineering in setting speed limits, to help refine the speed limit setting process to be efficient

and effective.

• Perform additional research on the relationships among operating speed, roadway

characteristics, posted speed limit, and crashes for city streets to confirm the findings in

Austin, Texas.

• Conduct similar research for roads with other speed ranges, such as freeways (generally

55 mph and greater), rural highways (subdivided into two speed groups of higher speeds and

lower speeds), and local/residential streets.

• Conduct focus groups to identify other variables that could be considered within the SLSProcedure, and investigate those variables for suitability for integration into the SLS-Tool.

7. CONCLUSION

This report was developed based on the research reports of NCHRP Project 17-76. The project 

team investigated how the roadway environment influences both operating speed and safety and 

also identified the factors used in current speed setting practices. In addition, the research team 

conducted a thorough review of different methods and tools that have been developed for setting 

posted speed limits, and developed an SLS-Procedure and an accompanying SLS-Tool. Detailed 

information is provided in the NCHRP Research Report 966: Posted Speed Limit Setting 

Procedure and Tool: User Guide, and NCHRP Web-Only Document 291: Development of a 

Posted Speed Limit Setting Procedure and Tool. 

Reducing traffic speeds and speeding-related fatalities and serious injuries is a focus of DOT’s

National Roadway Safety Strategy, which officially adopts the Safe System Approach principles 

to guide safety actions. The FHWA aims to achieve safe mobility for all road users through the 

Safe System Approach and is developing guidance and resources as speed management practices 

shift toward applying the Safe System Approach. In addition, FHWA promotes several 

strategies and treatments known as the Proven Safety Countermeasures, including methods and 

practices for setting appropriate speed limits for all road users. The FHWA is developing 

materials to assist with the implementation of the Proven Safety Countermeasures. The FHWA

is committed to championing the Safe System Approach and continuing to work with our 

stakeholders to achieve safe speeds for all road users. This approach will be comprehensive and 

will incorporate equity into all efforts to achieve zero roadway fatalities and injuries.
13 

The FHWA has initiated a project to develop a handbook to provide guidance on determining 

appropriate speed limits for all roads and streets. The purpose of this project is to provide a 

single, inclusive source of informational guidance on a variety of different approaches to 

determining appropriate posted speed limits that are safe for all road users. The project will:

• Present the advantages and disadvantages of different current speed limit setting

approaches.

• Provide guidance regarding the application of an engineering study in determining

which factors need to be considered in setting appropriate non-statutory speed

limits and ways to consider those factors. This effort will draw upon the

advantages of different methods of speed limit setting. Practitioners can use the

developed guidance to make informed decisions regarding the setting of

appropriate speed limits for all road users.

• Provide technical guidance and assistance to agencies to determine appropriate

speed limit setting.

• Provide resources for re-engineering roads and creating roadways that help to

“self-enforce” speed limits to achieve a target speed and slow down vehicles

rather than relying primarily on enforcement to achieve the posted speed limits.

• Develop training and outreach resources for speed limit setting.

The Bipartisan Infrastructure Law (BIL), also known as the Infrastructure Investment and Jobs 

Act (Public Law 117-58)) provides new funding resources that allow State and local 

governments to address speeding-related fatalities and serious injuries in their jurisdictions. The 

FHWA released guidance for the Highway Safety Improvement Program, which received an 

additional $4 billion in funding under BIL. The BIL also created a new $5-$6 billion Safe 

Streets and Roads for all competitive grant program for metropolitan planning organizations, 

local governments, and Tribal governments. In addition, BIL provides funding for safety-related 

activities through the National Highway Performance Program, the Surface Transportation Block 

Grant Program funds, and the Tribal Transportation Program Safety. 

As noted in the introduction section, once the NCHRP 15-76 study is completed, FHWA will 

provide a summary of the report, including the implications for enforcement practices and safety 

where posted speed limits and design speeds deviate.