Chapter 3. Traffic Laws and Regulations
This chapter provides an overview of traffic laws and regulations and identifies existing traffic laws and traffic regulation databases, if any, or current forms and inventory of traffic regulation data.
For constitutional and historical reasons, traffic regulations in the United States are enacted and administered by the States rather than the Federal government. The first statewide traffic regulations were enacted in Connecticut in 1901,13 before automobiles were common on roadways. Other States enacted their own regulations as need and custom dictated. The first version of the Uniform Vehicle Code (UVC) appeared in 1926.14 The first Manual on Uniform Traffic Control Devices (MUTCD) was compiled by the American Association of State Highway Officials (AASHTO) in 1935.15 The U.S. Department of Transportation (USDOT) was not established until 1966.
Although not directly responsible for traffic regulation, USDOT nonetheless oversees the safety of the nation’s roadways. As described in , Title 23 of the United States Code , the Secretary of USDOT “Is authorized and directed to assist and cooperate with other Federal departments and agencies, State and local governments, private industry, and other interested parties, to increase highway safety.”16 This authority is then exercised through the department’s review and approval of the States’ highway safety programs. The National Highway Transportation Safety Administration (NHTSA) and the Federal Highway Administration (FHWA) Office of Safety administer highway safety programs within USDOT.
Most aspects of the national body of traffic regulations are consistent as a result of historical practices, institutional collaborations, and modern Federal oversight. The UVC17 represents a working consensus, though it has no formal standing as a body of law and has not been updated since 2000. As a starting point for this analysis, however, the UVC provides a common reference for the definition of terms used in framing traffic regulations and the user categories to which the regulations apply. The structure of UVC, shown in table 1, has also been echoed in many of the States’ traffic codes, forming a de facto standard for indexing of the regulations. Similarly, the UVC and State traffic codes generally point to the MUTCD, or the State’s version, for the definition of particular traffic controls with which drivers are to comply.
Source: Uniform Vehicle Code, 2000.
The advent of automated vehicles (AV) creates multiple challenges for traffic regulations. Much of the body of traffic safety regulation concerns licensure of vehicles and drivers, and not specifically their behaviors. In the broadest sense, however, AVs blur the distinction between driver and vehicle, since driving automation systems reside in the vehicle and depend on its sensors. Recent regulation of AVs views AVs as a hybrid of vehicles and drivers and is largely limited to their licensure for operation design domains (ODD) in particular jurisdictions under the presumption that existing regulations on driver behavior will remain applicable.
Existing Traffic Laws and Traffic Regulation Databases
As noted earlier, the body of traffic laws across the United States varies from State to State and among local jurisdictions within those States. The UVC itself is not a normative source of traffic regulations. It was developed from the larger body of traffic laws being developed by state and local governments as a means of documenting common aspects of those sets of laws, and has become the common reference for uniformity of traffic codes. Reviewing existing traffic laws and traffic regulation databases, therefore, requires consideration of a compilation of, State, and local perspectives.
Since there are no national statutes requiring conformance to a single standard, and consequently no normative statutes, there have been various other efforts to document the actual diversity of traffic laws across the country. Particular perspectives and use cases for the resulting traffic regulation compilation or database have driven each effort.
Justia provides a seemingly complete compilation of laws, codes, and statutes at the Federal and State levels, implicitly including traffic regulations. It appears to have been built as a portal for linking individual legal research to legal counsel. It does not address local government codes. It is primarily a set of links to documents in portable document format (PDF) and Hypertext Markup Language (HTML) format. For example: https://law.justia.com/codes/kansas/2018/chapter-8/article-15/.18
The American Automobile Association (AAA) Digest of Motor Laws19 provides summaries of traffic laws within individual States and across the country. It categorizes traffic laws, largely along the outline of the UVC, to list summaries of relevant laws across the nation. It also provides the same summaries for all categories within a particular State. It is not a complete representation of the traffic codes and does not link to the text of the actual statutes and codes. It does not address local variability within States.
The National Council of State Legislatures (NCSL) maintains a database of current legislation relating to traffic safety. It provides a view of the delineation of existing laws, the impacts of emerging technologies, and changes in public policy. It links to, but does not directly provide, the underlying and enacted bodies of traffic regulations. For additional resources, visit the following websites:
NCSL also provides a database of legislation directly related to AVs. For more information, visit the NCSL Autonomous Vehicles, Self-Driving Vehicles Enacted Legislation website.22
The National District Attorneys Association (NDAA) maintains a National Traffic Laws Center to provide support to district attorneys in enforcement of traffic law. It does not specifically provide a database of laws.
Visit the National Traffic Law Center, for more information.23
The FindLaw website operated by Thomson Reuters provides summaries and links for some State traffic laws. It appears to be intended for individual research on traffic law enforcement and penalties for traffic law violations. It does not specifically provide a database of laws.
For more resources, visit the FindLaw website.24
The American Road and Transportation Builders Association (ARTBA) maintains a National Work Zone Safety Information Clearinghouse25 of links to work zone safety laws across States and territories. In many cases it provides direct links to State laws, but notes in a disclaimer at the bottom of the web page, it is for information only and does not necessarily include all relevant statutes.
State vehicle and traffic regulations are in all cases within the authority of the State legislatures. Execution and enforcement of those laws reside with the State motor vehicle administration, transportation, and police/patrol agencies, which may be separate or combined in various ways. Publishing the enacted vehicle and traffic statutes is a legislative function. State transportation agencies are as much users of those statutes as drivers within those States.
Although traffic laws across the United States are largely consistent and, in many cases, based on the UVC, available publications and databases of State traffic laws vary in structure, format, and wording. As described in the previous section, and shown in Table 2, electronic access to State traffic laws ranges from PDFs of entire sections of the statutes to searchable records of individual statutes.
The MUTCD provides another layer of consistency in traffic control deployments that complements the influence of the UVC. The State traffic codes prescribe that the State must have a standard for uniform traffic control and that drivers must obey the instructions of any official traffic control device. FHWA maintains an informational web page on the status of the States’ traffic control device specifications at https://mutcd.fhwa.dot.gov/resources/state_info/index.htm.27
Some States may provide detail beyond the State traffic code with databases of information on deployed traffic control. For example, Ohio provides records of permits to local agencies for traffic controls such as speed zones, traffic signals, and signs on State routes.28 However, no national databases of traffic control deployments exist.
HTML = Hypertext Markup Language. PDF = portable document format. RTF = rich text format. TBD = to be determined. XML = Extensible Markup Language.
Vehicle and traffic laws may be subject to additional local regulation where allowed (or not disallowed) by State authority. These local authorities may include counties, parishes, cities, villages, townships, or other such entities as identified in the respective states. The number and diversity of such local authorities and their transportation agencies preclude cataloging their traffic regulations databases for this analysis, other than anecdotally.
In general, the local regulations reference the State laws with which the local law conform. Where allowed, local regulations may modify or take exception to the State traffic regulations. The City of Overland Park, Kansas, for example, provides its municipal code online at http://online.encodeplus.com/regs/overlandpark-ks/index.aspx.82 The code is searchable by keyword or browsable by section. Title 12 of that code contains traffic regulations. Exceptions to the State code would generally be described as such. For example, Section 12.04.011 states, “All traffic control devices shall conform to the manual and specifications as adopted by the State department of transportation with the exception of handicapped parking signs as defined in 12.04.087” [italics added for emphasis]. Extensions to the referenced State regulations may not be noted as such. For example, in its traffic control signal legend, Overland Park includes a flashing yellow arrow indication, even though such an indication is not part of the code for the State of Kansas.
13 State of Connecticut, “An Act Regulating the Speed of Motor Vehicles,” in Public Acts Passed by the General Assembly of the State of Connecticut, in the Year 1901, Chapter 69. [ Return to note 13. ]
14 J. Allen Davis, The California Vehicle Code and the Uniform Vehicle Code, 14 Hastings L.J. 377 (1963). Available at: https://repository.uchastings.edu/hastings_law_journal/vol14/iss4/3. [ Return to note 14. ]
18 “2018 Kansas Statutes :: Chapter 8 AUTOMOBILES AND OTHER VEHICLES :: Article 15 UNIFORM ACT REGULATING TRAFFIC; RULES OF THE ROAD,” Justia Law, accessed May 12, 2020, https://law.justia.com/codes/kansas/2018/chapter-8/article-15/. [ Return to note 18. ]
20 Ann Kitch and Gretchenn DuBois, Traffic Safety State Bill Tracking, accessed May 12, 2020, http://www.ncsl.org/research/transportation/state-traffic-safety-legislation-database.aspx. [ Return to note 20. ]
21 Administration, State Legislative Websites Directory, accessed May 12, 2020, https://www.ncsl.org/aboutus/ncslservice/state-legislative-websites-directory.aspx. [ Return to note 21. ]
22 Douglas Shinkle and Gretchenn Dubois, “Autonomous Vehicles: Self-Driving Vehicles Enacted Legislation,” Autonomous Vehicles | Self-Driving Vehicles Enacted Legislation, accessed May 12, 2020, http://www.ncsl.org/research/transportation/autonomous-vehicles-self-driving-vehicles-enacted-legislation.aspx. [ Return to note 22. ]
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25 “State Work Zone Laws,” The National Work Zone Safety Information Clearinghouse, October 25, 2019, https://www.workzonesafety.org/data-resources/laws-regulations-and-standards/state-work-zone-laws/. [ Return to note 25. ]
27 “MUTCDs & Traffic Control Devices Information by State,” Information by State - FHWA MUTCD, accessed May 12, 2020, https://mutcd.fhwa.dot.gov/resources/state_info/index.htm. [ Return to note 27. ]
28 http://www.dot.state.oh.us/Divisions/Operations/Traffic-Management/Pages/Regulations.aspx, accessed 12/31/2019. [ Return to note 28. ]
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