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Chapter 1C. Definitions, Acronyms, and Abbreviations Used in This Manual

§1C.01 Definitions of Headings Used in this Manual

Standard

01. When used in this Manual, the text headings of Standard, Guidance, Option, and Support shall be defined as follows:

  • A. Standard—a statement of required, mandatory, or specifically prohibitive practice regarding a traffic control device. In limited, location-specific cases, the results of a documented engineering study (see Section 1D.03) might indicate a deviation from one or more requirements of a Standard provision to be appropriate. All Standard statements are labeled, and the text appears in bold type. The verb “shall” is typically used. The verbs “should” and “may” are not used in Standard statements. Standard statements are sometimes modified by Option statements.
  • B. Guidance—a statement of recommended practice in typical situations, with deviations allowed if engineering judgment or engineering study (see Section 1D.03) indicates the deviation to be appropriate. All Guidance statements are labeled, and the text appears in unbold italic type. The verb “should” is typically used. The verbs “shall” and “may” are not used in Guidance statements. Guidance statements are sometimes modified by Option statements.
  • C. Option—a statement of practice that is a permissive condition and carries no requirement or recommendation. Option statements sometimes contain allowable modifications to a Standard or Guidance statement. All Option statements are labeled, and the text appears in unbold type. The verb “may” is typically used. The verbs “shall” and “should” are not used in Option statements.
  • D. Support—an informational statement that does not convey any degree of mandate, recommendation, authorization, prohibition, or enforceable condition. Support statements are labeled, and the text appears in unbold type. The verbs “shall,” “should,” and “may” are not used in Support statements.

§1C.02 Definitions of Words and Phrases Used in this Manual

Colorado-modified

Amended by the Colorado Supplement (January 2026). This section shows Colorado's text; sections without this flag are the unmodified National MUTCD.

Standard

01. Definitions contained in this Section, or other Parts of this Manual, shall apply unless otherwise defined by C.R.S Sec. 42-1-102 or in other parts of Title 42, C.R.S, in which case the C.R.S definitions are adopted by reference. Unless otherwise defined by the statutory definitions or herein, the definitions contained in the most recent edition of the “AASHTO Transportation Glossary (Highway Definitions),” and other appropriate publications specified in this section are incorporated and adopted by reference. January 2026 Part 1

03. The following words and phrases, when used in this Manual, shall have the following meanings:

  • 103. Highway Traffic Signal—a power-operated traffic control device by which traffic is warned or directed to take some specific action. These devices do not include power-operated signs (except as provided in Chapters 4S and 4T), steadily-illuminated raised pavement markers, gates, flashing-light signals (see Section 8D.02), warning lights (see Section 6L.07), or steady- burning electric lamps. Highway traffic signals include: (a) Flashing Beacon—see Beacon. (b) In-Roadway Warning Lights—a special type of highway traffic signal installed in the roadway surface to warn road users that they are approaching a condition on or adjacent to the roadway that might not be readily apparent and might require the road users to reduce speed and/or come to a stop. (c) Lane-Use Control Signal—a signal face or comparable display on a full-matrix Changeable Message Sign (see Chapters 2L and 4T) displaying indications to permit or prohibit the use of specific lanes of a roadway or a shoulder where driving is sometimes permitted, or to indicate the impending prohibition of such use. (d) Traffic Control Signal (Traffic Signal)—a highway traffic signal placed at intersections, movable bridges, fire stations, midblock crosswalks, alternating one-way sections of a single lane road, private driveways, or other locations that require conflicting traffic to be directed to stop and permitted to proceed in an orderly manner. These devices do not include pedestrian hybrid beacons (see Chapter 4J) or emergency-vehicle hybrid beacons (see Chapter 4N). Traffic control signals include vehicular signal indications, pedestrian signal indications, and bicycle symbol signal indications. Special traffic control signals include: (1) Emergency-Vehicle Traffic Control Signal—a traffic control signal that directs all conflicting traffic to stop in order to permit the driver of an authorized emergency vehicle to proceed into the roadway or intersection. (2) Movable Bridge Traffic Control Signal—a traffic control signal installed at a movable bridge to notify traffic to stop during periods when the roadway is closed to allow the bridge to open. (3) Portable Traffic Control Signal—a temporary component of a traffic control signal on a mobile support with one or more signal faces that is designed so that it can be easily transported, deployed, or relocated as part of a temporary traffic control signal, or during construction and maintenance as a temporary part of a permanent traffic control signal installation. (4) Pre-Signal—traffic control signal faces that are located upstream from a signalized intersection and are operated in conjunction with the traffic control signal faces at the downstream signalized intersection in a manner that is designed to keep the area between the stop line for the upstream traffic control signal faces and the stop line for the downstream signalized intersection clear of queued vehicles. When used in conjunction with a grade crossing, the pre-signal is operated for the purpose of preventing vehicles from queuing within the minimum track clearance distance. Supplemental near-side traffic control signal faces for the downstream signalized intersection are not considered to be pre-signals. (5) Queue Cutter Signal—an independently-controlled traffic control signal (not operated in conjunction with the traffic control signal faces at a downstream signalized intersection) located at a grade crossing that controls traffic in one direction only on the roadway for the purpose of keeping the minimum track clearance distance clear of vehicles. The display of red signal indications is activated from a downstream queue detection system, by time of day, by approaching rail traffic, by an approaching bus on a busway, or by a combination of any of these methods. January 2026 Part 1 (6) Ramp Control Signal (Ramp Meter)—a traffic control signal installed to control the merging flow of traffic onto a freeway at an entrance ramp or at a freeway-to-freeway ramp connection. (7) Temporary Traffic Control Signal—a traffic control signal that is installed for a limited time period using fixed or portable traffic control signal units.
  • 219. Shared-Use Path—a bikeway outside the traveled way and physically separated from motorized vehicular traffic by an open space or barrier and either within the highway right-of- way or within an independent alignment. Shared-use paths are also used by pedestrians (including skaters, users of manual and motorized wheelchairs, and joggers) and other authorized motorized and non-motorized users. A shared-use path shall be paved and be a minimum of 10 feet wide. TRAFFIC CONTROL DEVICES IN GENERAL

§1C.03 Meanings of Acronyms and Abbreviations Used in this Manual

Standard

01. The following acronyms and abbreviations, when used in this Manual, shall have the following meanings:

  • 1. AADT—annual average daily traffic
  • 2. AASHTO—American Association of State Highway and Transportation Officials
  • 3. AC—alternating current
  • 4. ADA—Americans with Disabilities Act
  • 5. ADAS—Advanced Driver Assistance Systems
  • 6. ADS—Automated Driving System
  • 7. ADT—average daily traffic
  • 8. AFAD—Automated Flagger Assistance Device
  • 9. ANSI—American National Standards Institute
  • 10. AREMA—American Railway Engineering and Maintenance-of-Way Association
  • 11. AV—automated vehicle
  • 12. cd/lx/m²—candelas per lux per square meter
  • 13. CFR—Code of Federal Regulations
  • 14. CMS—changeable message sign
  • 15. dBA—A-weighted decibels
  • 16. DC—direct current
  • 17. DDT—Dynamic Driving Task
  • 18. EPA—Environmental Protection Agency
  • 19. ETC—electronic toll collection
  • 20. EV—electric vehicle
  • 21. FHWA—Federal Highway Administration
  • 22. FRA—Federal Railroad Administration
  • 23. ft—foot or feet
  • 24. FTA—Federal Transit Administration
  • 25. HOV—high-occupancy vehicle
  • 26. IEEE—Institute of Electrical and Electronics Engineers
  • 27. IES—Illuminating Engineering Society
  • 28. ILEV—inherently low emission vehicle
  • 29. in—inch(es)
  • 30. ISEA—International Safety Equipment Association
  • 31. ITE—Institute of Transportation Engineers
  • 32. ITS—intelligent transportation systems
  • 33. L—taper length
  • 34. LED—light-emitting diode
  • 35. LP—liquified petroleum
  • 36. LRT—light rail transit
  • 37. mi—mile(s)
  • 38. MPH or mph—miles per hour
  • 39. MUTCD—Manual on Uniform Traffic Control Devices for Streets and Highways
  • 40. N—length of one line segment plus one gap of a broken line
  • 41. NCEES—National Council of Examiners for Engineering and Surveying
  • 42. NCHRP—National Cooperative Highway Research Program
  • 43. ODD—Operational Design Domain
  • 44. OPM—U.S. Office of Personnel Management
  • 62. ORT—open-road tolling PCMS—portable changeable message sign PRT—perception-response time RRFB—rectangular rapid-flashing beacon RV—recreational vehicle SAE—Society of Automotive Engineers SHV—Specialized Hauling Vehicle SPF—safety performance function TA—Typical Application TDD—telecommunication device for the deaf TRB—Transportation Research Board TTC—temporary traffic control U.S.—United States U.S.C.—United States Code USDOT—United States Department of Transportation UVC—Uniform Vehicle Code VPH or vph—vehicles per hour V2I—vehicle-to-infrastructure