National Academies Press: OpenBook

Roundabouts: An Informational Guide – Second Edition (2010)

Chapter: Appendix C - Rules of the Road

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Suggested Citation:"Appendix C - Rules of the Road." National Academies of Sciences, Engineering, and Medicine. 2010. Roundabouts: An Informational Guide – Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22914.
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Suggested Citation:"Appendix C - Rules of the Road." National Academies of Sciences, Engineering, and Medicine. 2010. Roundabouts: An Informational Guide – Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22914.
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Suggested Citation:"Appendix C - Rules of the Road." National Academies of Sciences, Engineering, and Medicine. 2010. Roundabouts: An Informational Guide – Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22914.
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Suggested Citation:"Appendix C - Rules of the Road." National Academies of Sciences, Engineering, and Medicine. 2010. Roundabouts: An Informational Guide – Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22914.
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Suggested Citation:"Appendix C - Rules of the Road." National Academies of Sciences, Engineering, and Medicine. 2010. Roundabouts: An Informational Guide – Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22914.
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Appendix C Page C-1 Roundabouts: An Informational Guide APPENDIX C RULES OF THE ROAD CONTENTS C.1 RULES OF THE ROAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2 C.1.1 Definition of “Intersection” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2 C.1.2 Right-of-Way between Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3 C.1.3 Required Lane Position at Intersections . . . . . . . . . . . . . . . . . . . . . . . C-3 C.1.4 Priority within the Circulatory Roadway . . . . . . . . . . . . . . . . . . . . . C-3 C.1.5 Pedestrians . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4 C.1.6 Parking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4 C.2 EXAMPLE LEGISLATIVE ACTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-5 C.3 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-5

Roundabouts: An Informational Guide Page C-2 Appendix C C.1 RULES OF THE ROAD The following sections discuss several of the important legal issues that should be considered for roundabouts. These have been based on the provisions of the 2000 Uniform Vehicle Code (1), which has been adopted to varying degrees by each state, as well as examples from various states and international legislation on roundabouts. Note that the information in the following sections does not con- stitute specific legal opinion; each jurisdiction should consult with its attorneys on specific legal issues. C.1.1 DEFINITION OF “INTERSECTION” The central legal issue around which all other issues are derived is the rela- tionship between a roundabout and the legal definition of an “intersection.” A roundabout could be legally defined one of two ways: • As a single intersection or • As a series of T-intersections. The UVC does not provide clear guidance on the appropriate definition of an intersection with respect to roundabouts. The UVC generally defines an inter- section as the area bounded by the projection of the boundary lines of the approaching roadways (UVC §1-46a). It also specifies that where a highway includes two roadways 30 ft (9.1 m) or more apart, each crossing shall be regarded as a separate intersection (UVC §1-146b). This may imply that most circular inter- sections should be regarded as a series of T-intersections. This distinction has ramifications in the interpretation of the other elements identified in this section. Some states have codified the legal definition of a roundabout. For example, the State of Oregon has defined a roundabout as follows: “Roundabout” means an intersection characterized by a circulatory roadway, channelized approaches and yield control of entering traffic. A roundabout encompasses the area bounded by the outermost curb line or, if there is no curb, the edge of the pavement, and includes crosswalks on any entering or exiting roadway. (2) Furthermore, the State of Oregon has defined the circulatory roadway as follows: “Circulatory roadway” means the portion of a highway within a roundabout that is used by vehicles to travel counterclockwise around a central island. A circulatory roadway does not have a crosswalk. (3) This guide recommends that a roundabout be specifically defined as a single intersection, regardless of the size of the roundabout. This intersection should be defined as the area bounded by the limits of the pedestrian crossing areas around the perimeter of a single central island. Closely spaced roundabouts with multiple central islands should be defined as separate intersections since each roundabout is typically designed to operate independently. Roundabouts are recommended to be defined as a single inter- section; the area bounded by the limits of the pedestrian crossing areas.

Appendix C Page C-3 Roundabouts: An Informational Guide C.1.2 RIGHT-OF-WAY BETWEEN VEHICLES The UVC specifies that “when two vehicles approach or enter an intersection from different highways at approximately the same time, the driver of the vehicle on the left shall yield the right-of-way to the vehicle on the right” (UVC §11-401). This runs contrary to the default operation of a roundabout, which assigns the right-of-way to the vehicle on the left and any vehicle in front. This requires the use of yield signs and yield lines at all approaches to a roundabout to clearly define right-of-way. This guide recommends that right-of-way at a roundabout be legally defined such that an entering vehicle shall yield the right-of-way to the vehicle on the left. This definition does not change the recommendation for appropriately placed yield signs and yield lines. C.1.3 REQUIRED LANE POSITION AT INTERSECTIONS At a typical intersection with multilane approaches, vehicles are required by the UVC to use the right-most lane to turn right and the left-most lane to turn left, unless specifically signed or marked lanes allow otherwise (e.g., double left-turn lanes) (UVC §11-601). Because multilane roundabouts can be used at intersections with more than four legs, the concept of “left turns” and “right turns” becomes more difficult to legally define. The following language (1) is recommended: Unless official traffic control devices indicate otherwise, drivers must make lane choices according to the following rules: • If a driver intends to exit the roundabout less than halfway around it, the right lane must be used. • If a driver intends to exit the roundabout more than halfway around it, the left lane must be used. The Australian Road Rules (2008) Traffic Act (4) gives no guidance for straight through movements (movements leaving the roundabout exactly halfway), and the general Australian practice is to allow drivers to use either lane unless signed or marked otherwise. On multilane roundabouts, when the intersecting roadways are not at 90° angles or there are more than four legs to the roundabout, special consideration should be given to assisting driver understanding through advance diagrammatic guide signs or lane markings on approaches showing the appropriate lane choices. C.1.4 PRIORITY WITHIN THE CIRCULATORY ROADWAY For multilane roundabouts, the issue of priority within the circulatory road- way is important, as it directly affects the exit—circulating conflict. Any vehicle on the inside lane of the circulatory roadway (e.g., a vehicle making a left turn) ultimately needs to exit. This may cause conflicts with other vehicles in the circulatory roadway. In the United States, this issue is generally addressed through the use of circu- latory roadway striping that guides vehicles toward the correct exit (see Chapter 7). In this manner, lane selection takes place before entering the intersection. Any Because of yield-to-the-right laws, yield signs and lines must be used on roundabout entries to assign right-of-way to the circulatory roadway.

Roundabouts: An Informational Guide Page C-4 Appendix C lane changes that take place within the roundabout clearly put the onus on the driver changing lanes to yield the right-of-way to conflicting vehicles. Therefore, the use of circulatory roadway markings as recommended makes the issue of overtaking within the circulatory roadway or priority between circulating and exiting vehicles largely moot. For unmarked, multilane roundabouts, the issue is less clear. Due to its com- mon use of unmarked multilane roundabouts, the United Kingdom requires drivers to “watch out for traffic crossing in front of you on the roundabout, espe- cially vehicles intending to leave by the next exit. Show them consideration” (5, §125). This is generally interpreted as meaning that a vehicle at the front of a group of vehicles within the circulatory roadway has the right-of-way, regardless of the track it is on, and following vehicles on any track must yield to the front vehicle as it exits. C.1.5 PEDESTRIANS The legal definition of a roundabout as one intersection or a series of intersec- tions also has implications for pedestrians, particularly with respect to marked and unmarked crosswalks. A portion of the UVC definition of a crosswalk is as follows: “ . . . in the absence of a sidewalk on one side of the roadway, that part of a roadway included within the extension of the lateral lines of the existing side- walk at right angles to the centerline” [UVC §1-118(a)]. Under the definition of a roundabout as a series of T-intersections, this portion of the definition could be interpreted to mean that there are unmarked crosswalks between the perimeter and the central island at every approach. The recommended definition of a round- about as a single intersection simplifies this issue, for the marked or unmarked crosswalks around the perimeter as defined are sufficient and complete. This is also another reason to provide landscaping between sidewalks and the circulatory roadway; it is more difficult to make a legal argument that crosswalks exist across the circulatory roadway if the sidewalks do not extend to the edge of the circula- tory roadway. In all states, drivers are required to either yield or stop for pedestrians in a crosswalk, including crosswalks at roundabouts. C.1.6 PARKING Many states prohibit parking within a specified distance of an intersection; others allow parking right up to the crosswalk. The degree to which these laws are in place will govern the need to provide supplemental signs and/or curb mark- ings showing parking restrictions. This guide recommends that parking be restricted immediately upstream of the pedestrian crosswalks to provide the necessary sight distances for safe crossings to occur. The legal need to mark parking restrictions within the circulatory roadway may be dependent on the definition of a roundabout as a single intersection or as a series of T-intersections. Using the recommended definition of a roundabout as a single intersection, the circulatory roadway would be completely contained within the intersection, and the UVC currently prohibits parking within an intersection (UVC §11-1003).

Appendix C Page C-5 Roundabouts: An Informational Guide C.2 EXAMPLE LEGISLATIVE ACTION In addition to the definitions described previously, the State of Oregon added language to the Oregon Vehicle Code in 2001 to address right-of-way and the use of turn signals as follows: 811.292. Failure to yield right-of-way within roundabout; exception; penalty. (1) A person commits the offense of failure to yield right-of-way within a round- about if the person operates a motor vehicle upon a multilane circulatory roadway and does not yield the right-of-way to a second vehicle lawfully exiting the roundabout from a position ahead and to the left of the person’s vehicle. (2) This section does not apply if a traffic control device indicates that the operator of a motor vehicle should take other action. (3) The offense described in this section, failure to yield right-of-way within a roundabout, is a Class C traffic violation. (2001 c.464 §5) 811.400. Failure to use appropriate signal for turn, lane change, stop, or exit from roundabout; penalty. (1) A person commits the offense of failure to use an appropriate signal for a turn, lane change, or stop or for an exit from a roundabout if the person does not make the appropriate signal under ORS 811.395 by use of signal lamps or hand signals and the person is operating a vehicle that is: (a) Turning, changing lanes, stopping, or suddenly decelerating; or (b) Exiting from any position within a roundabout. (2) This section does not authorize the use of only hand signals to signal a turn, change of lane, stop, or deceleration when the use of signal lights is required under ORS 811.405. (3) The offense described in this section, failure to use appropriate signal for a turn, lane change, or stop or for an exit from a roundabout, is a Class B traffic violation. (1983 c.338 §634; 1995 c.383 §66; 2001 c.464 §6) C.3 REFERENCES 1. National Committee on Uniform Traffic Laws and Ordinances (NCUTLO). Uniform Vehicle Code and Model Traffic Ordinance. Evanston, Illinois: NCUTLO, 2000. 2. State of Oregon. Oregon Revised Statute 801.451. http://www.leg.state.or.us/ ors/801.html. Accessed March 2010. 3. State of Oregon. Oregon Revised Statute 801.187. http://www.leg.state.or.us/ ors/801.html. Accessed March 2010. 4. Australia. Traffic Act, Part 6A, 1962. 5. Department of Transport (United Kingdom). The Highway Code. Department of Transport and the Central Office of Information for Her Majesty’s Stationery Office, 1996.

Next: Appendix D - Design Supplemental Materials »
Roundabouts: An Informational Guide – Second Edition Get This Book
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TRB’s National Cooperative Highway Research Program (NCHRP) Report 672: Roundabouts: An Informational Guide – Second Edition explores the planning, design, construction, maintenance, and operation of roundabouts. The report also addresses issues that may be useful in helping to explain the trade-offs associated with roundabouts.

This report updates the U.S. Federal Highway Administration’s Roundabouts: An Informational Guide, based on experience gained in the United States since that guide was published in 2000.

Errata

Equation 6-3 on page 6-58 incorrectly contains an addition sign (+) as an operator. The correct operator should be a subtraction sign (-).

Errata #2

Exhibit 5-23 on page 5-29 of NCHRP Report 672 contains an incorrect calculation of estimated injury crashes.

There is a summary document, Paths to Practice, available.

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