Traffic Control Devices: The Same Message No Matter Where You Travel

Linda Brown and Scott Wainwright and Kevin Sylvester
Institute of Transportation Engineers. ITE Journal

Feb 29, 2008 19:00 EST

TRAFFIC CONTROL DEVICES ARE signs, signals, pavement markings and other features that instruct the traveling public as it traverses the United States' most vital asset-its transportation system. This system includes an extensive and sophisticated network of streets, highways and shared-use facilities open to public travel. It moves the nation's economy and affords one of the most basic forms of freedom: mobility-of people, goods and services.

Serving such a critical role requires a uniform set of traveler cues so that those devices appear the same no matter where people travel throughout the United States. The developers of the Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) have recognized this need for more than 70 years. The principles that have guided the development and evolution of MUTCD have remained the same-that effective traffic control devices must fulfill an operational need; command attention and respect by the traveler; convey a clear meaning; and be placed in a manner that provides for adequate response.

Although MUTCD has been the national standard for designing and installing traffic control devices for more than 70 years, it is dynamic and responsive to changes in the way Americans travel; the special needs of travelers; safety and security concerns; and advances in technology. Over the years, eight full editions of MUTCD have been published. Amendments to MUTCD are made through the Federal Register rule-making process. This process is designed to encourage public involvement. After a proposed set of MUTCD changes is published, any interested person or organization may provide input to the rule-making process by submitting comments to the Federal Register docket.

The Federal Highway Administration (FHWA) is preparing for the next edition of MUTCD, which is scheduled for publication in 2009. A Notice of Proposed Amendments (NPA) for the next edition was published in the Federal Register on January 2, 2008. This NPA is accessible via mutcd.fhwa.dot.gov/res-notices.htm.

The details of all of the proposed changes to MUTCD text, figures and tables also can be viewed on the MUTCD Web site. The many significant proposed changes are too numerous to describe in this feature; however, die following sections summarize some of die major MUTCD changes proposed in die NPA.

PART 2-SIGNS

The number of older drivers on streets and highways will continue to increase gready in die coming years. Research has identified a variety of sign improvements diat can enhance safety and convenience for older drivers and, thereby, for all drivers. One such change is FHWA's proposed revision of die minimum ratio for letter height from 1 inch for every 40 feet of legibility distance to 1 inch for every 30 feet of legibility distance.

FHWA proposes this change to be consistent with older driver research recommendations that sign legibility be based on 20/40 vision.1 Most states allow drivers with 20/40 corrected vision to obtain driver's licenses and, with the increasing numbers of older drivers, FHWA believes that 20/40 vision should be the basis of letter heights used on signs. As a result, increases in the sizes of some regulatory and warning signs are proposed, particularly when used on multi-lane arterial roads.

Also based on older driver research, FHWA proposes to eliminate the option of all uppercase letters for names of places, streets and highways and to require that these names comprise lowercase letters with an initial uppercase letter. Mixed-case sign legends for destinations have significant legibility and recognition distance benefits versus all uppercase letters.

For multi-lane exits that have an optional exit lane that also carries the throughroad, and for freeway splits that include ah optional lane, FHWA proposes requiring a new type of diagrammatic guide sign design that features an upward arrow above each lane, similar to standard European practice. The existing diagrammatic sign design, which attempts to illustrate optional lane use by depicting lane lines on an arrow shaft, has been found too subtle to be easily recognized and understood by many road users, especially older drivers. The new design is intended to reduce unnecessary lane changes by more positively conveying lane use and highlighting the presence of the optional lane.

Because of the wide variety of geometric designs, many drivers also experience difficulties on conventional road approaches to freeway interchanges. FHWA is proposing that the existing MUTCD recommendations be changed to a mandatory requirement that guide signs be provided to identify which direction of turn is to be made for ramp access and/or which specific lane is to be used to enter each direction of the freeway.

NPA includes a proposed new MUTCD section regarding methods that may be used to enhance the conspicuity of standard regulatory, warning, or guide signs to provide improved uniformity of such treatments to benefit road users. A variety of conspicuity enhancement methods such as header panels, flags and background panels are proposed, reflecting widespread and successful practices by state and local agencies.

Based on FHWA research, many new signs are being proposed throughout MUTCD to provide road users with a uniform message for commonly-encountered conditions (see Figure I).2

The use of roundabouts has increased over the past 10 years. It is important that more detailed information on effective signing of roundabouts be included in MUTCD to have consistent traffic control devices for roadways with this unique geometric design. New information is proposed in MUTCD to provide for pavement markings as well as regulatory, warning and guide signs at roundabouts.

FHWA also is seeing an increase in the use of roadway designs that use jughandles as a method to improve safety and operations at intersections. Appropriate regulatory and guide signs at jughandles are critical because the roadway geometry typically requires left turns and U-turns to be made via a right turn, either in advance of or beyond die intersection. This type of traffic pattern might be contrary to typical driver expectations. Therefore, uniform provisions for signs at jughandles also are included in the MUTCD proposed changes. Figure 2 provides examples of proposed diagrammatic signs for an approach to a roundabout.

Demand for highway travel by Americans continues to grow as the U.S. population increases. Highway congestion has resulted because traffic demand has approached and, in many cases, exceeded the available capacity of the highway system. Experience has shown that the evolution of electronic toll collection (ETC) technology has the potential to improve traffic capacity and reduce congestion at toll plazas. In addition to ETC, the transportation industry is seeing the evolution of a variety of technology applications based on the managed lane concept, such as high-occupancy vehicle lanes, highoccupancy toll lanes, express lanes and interstate system toll conversion programs.

Figure 3 shows proposed guide signs for open road ETC lanes and toll plaza approach lanes. Proposed symbols for payment methods also are illustrated.

FHWA proposes to include new information in MUTCD to provide consistency and uniformity of traffic control devices used for toll facilities, managed lanes and other forms of preferential lanes. Examples of proposed MUTCD changes to address the needs of these types of facilities include: guide signs for toll plazas, open road tolling and entrances to managed lanes; updated and expanded provisions for preferential lane signing; special regulatory and warhing signs; designation of purple as the standard sign color for ETC-only lanes; several new symbols including ones for exact change and attended lanes at toll plazas; toll plaza pavement markings; and toll plaza lane-use signals.

The proposed provisions reflect available guidance on the state of the art of managed lanes from the report entided, "State of the Practice and Recommendations on Traffic Control Strategies at Toll Plazas."3

New uniform provisions are proposed for the design and locations of community wayfinding guide signs to direct tourists and other road users to key civic, cultural, visitor and recreational attractions and other destinations within a city or a local urbanized or downtown area. These provisions are based on accepted sign design principles to achieve consistency for road users.

The Specific Service Sign Program (also known as the Logo Program) is a statesponsored program that provides information to the traveling public about specific motorist services available at approaching interchanges. Eligible service facilities can use their business identification logo for services and attractions. FHWA recognizes diat the demand for logo space on the specific service signs on U.S. freeways has increased dramatically and that there is significant competition for logo panels.

Based on a study done by the Virginia Department of Transportation, FHWA proposes to allow states the option of displaying up to 12 logo panels for any one specific service type (gas, food, lodging, camping, attraction, or 24-hour pharmacy). However, the existing limit of six logos per sign and four signs per interchange approach will be retained.

To recognize the importance of electronic display changeable message signs (CMS) as a means of enhancing traffic operations, FHWA proposes to add a completely new section of uniform provisions for their design and application (see Figure 4). Information is provided on how to develop effective message content and the maximum amount of information that should be displayed; the number of messages and display time for each; and minimum letter heights and brightness levels to maintain legibility under both daytime and nighttime conditions. These provisions would apply to both permanent and portable CMS installations. Additional provisions for their specific applications in work zones are provided in Part 6.

PART 3-MARKINGS

FHWA proposes to add new language to require that dotted lane lines, rather than normal broken lane lines, are used for noncontinuing lanes, including acceleration lanes, deceleration lanes, auxiliary lanes, lane drops at interchanges and intersections and other lane reductions. As documented in National Cooperative Highway Research Program (NCHRP) Synthesis 356, a number of states and other jurisdictions currendy follow this practice, which also is the standard practice in Europe and most other developed countries.5 FHWA believes dial a normal broken line does not provide enough information to the road user for these conditions and that a dotted lane line provides a clear message to the road user that a lane does not continue.

"Do Not Block Intersection" markings are being used more widely across the United States to improve traffic flow at intersections that may be impacted by queues from downstream locations. FHWA is proposing a new section in MUTCD to foster uniformity in the design and application of these markings.

FHWA proposes to add a new section in MUTCD for speed-reduction markings. These proposed transverse markings may be placed on roadways within a lane in a pattern that gives drivers the impression that their speed is increasing. FHWA proposes this new section to reflect the Traffic Control Devices Pooled Fund Study on speedreduction markings, which found that these markings can be effective in reducing speeds at certain locations, and to provide a standardized design for uniformity.6

A new recommendation proposes that delineators should be used whenever guardrail or other longitudinal barriers are present to provide for consistency in application. Guardrail and barriers typically are located close to the roadway, and delineation of these features will help road users be aware of the potential to collide with them during conditions of darkness.

PART 4-TRAFFIC SIGNALS

FHWA proposes to replace the two existing criteria for the pedestrian volume signal warrant with two new criteria that will be based on vehicular and pedestrian volumes. FHWA also proposes to require that only one of the two criteria be met. The proposed criteria and the associated volume curves are derived from other vehicle-based traffic signal warrants and supplemented with data gathered during a Transit Cooperative Research Program/NCHRP study.7

For many years, some engineers have had concerns that drivers turning left on a permissive circular green signal indication might inadvertendy mistake that indication as implying the left turn has the right of way over opposing traffic. Research contained in NCHRP Report 493 found that the flashing yellow arrow (FYA) is the best overall alternative to the circular green as the permissive signal display for a left-turn movement.8

The FYA has a high level of understanding and correct response by left-turn drivers and a lower fail-critical rate than the circular green, and the FYA display in a separate signal face for the left-turn movement offers more versatility in field application.

Based on this research study, FHWA proposes to add the optional use of an FYA indication for left-turn movements during permissive turn intervals. The optional use of a flashing red arrow for permissive turn movements also is being proposed but only for certain unusual circumstances where an engineering study determines that each successive vehide must come to a full stop before making the turn permissively.

For approaches to signalized locations having a speed limit greater than 40 miles per hour, guidance is proposed that signal faces should be located overhead on the far side; one overhead signal face per through lane should be used when there is more than one through lane; supplemental near- or far-side post-mounted faces should be considered for added visibility; and backplates should be included on the signal faces.

As documented in the FHWA report "Making Intersections Safer: A Toolbox of Engineering Countermeasures to Reduce Red-Light Running," numerous studies have found significant safety benefits from implementing these design practices.9 FHWA also proposes that these recommended practices be considered for any major urban or suburban arterial street with four our more lanes.

To help clarify appropriate pedestrian pushbutton locations for all users under different geometric conditions, revisions are proposed to the requirements for the location of pedestrian pushbuttons and for accessible pedestrian signal pushbuttons. Also, it is proposed that the legends on the signs clearly indicate which crosswalk signal is activated by which pushbutton.

For calculating the duration of the time for pedestrian clearance after the walk interval, FHWA proposes reducing the recommended walking speed from 4 feet per second (ft./sec.) to 3.5 ft./sec. (except where extended pushbutton presses or passive pedestrian detection have been installed for slower pedestrians to request additional crossing time.)

A recommendation also would be added that the total of the walk interval and pedestrian clearance time be long enough to allow a pedestrian to walk from the pedestrian detector to the opposite edge of the traveled way at a speed of 3 ft./sec. These changes are proposed to better accommodate the increasing numbers of slower-walking individuals, including wheelchair users.

To provide enhanced pedestrian safety and convenience, FHWA proposes to change the existing option of using pedestrian countdown displays to a requirement for use with all new installations of pedestrian signals, except where the duration of the pedestrian change interval (flashing don't walk) is less than 3 seconds. This proposed change is based on a comprehensive multiyear research study in San Francisco, CA, USA, which showed substantial reduction in the number of pedestrian-vehicle crashes where the countdowns were installed.

A pedestrian hybrid signal (also called a "HAWK" signal) is a special type of signal used to warn and control traffic at an unsignalized location to assist pedestrians in crossing a street or highway at a marked crosswalk. FHWA proposes to add a new chapter to describe the application, design and operation of pedestrian hybrid signals. This type of device has been researched and found to be highly effective.10

PART 6-TEMPORARY TRAFFIC CONTROL DEVICES

FHWA proposes to incorporate into MUTCD the provisions of 23 CFR Part 634 (published in the Federal Register on November 24, 2006) regarding the use of high-visibility safety apparel by workers and flaggers within the public right of way.11 The CFR now requires this on all federal-aid streets and highways. Including these provisions in MUTCD will make them apply to all roads open to public travel regardless of federal-aid status. FHWA also proposes adding an option that allows first responders and law enforcement personnel to use safety apparel meeting a newly developed ANSI standard for "public safety vests."

Automated flagger assistance devices (AFADs) are optional devices that enable a flagger to be positioned out of the traffic lane and are used to control road users through temporary traffic control zones. Based on FHWA's revised Interim Approval dated January 28,2005, FHWA proposes to add a new section to MUTCD that contains provisions describing the use of AFADs.12 FHWA also proposes to add a statement that flaggers shall use a STOP/SLOW paddle, flag, or AFAD to control road users and that the use of hand movements alone is prohibited.

FHWA proposes adding an alternating diamond display as one of the options for a flashing caution display on arrow panels. This type of display has been found effective by experimentation in Utah.13

Several existing sections in MUTCD Part 6 contain language about non-traffic control devices used in work zones. Because it is not appropriate to have regulatory language regarding their design or use in MUTCD, and sufficient guidance is available in other documents, FHWA proposes deleting the sections on floodlights, crash cushions, vehicle arresting systems and glare screens.

PART 7-TRAFFIC CONTROL FOR SCHOOL AREAS

The use of fluorescent yellow-green (FYG) as the background color for all school warning signs and plaques currently is an option. FHWA proposes to change this to a requirement because use of this color has become the predominant practice in most jurisdictions. FYG provides enhanced conspicuity for these critical signs, especially in dusk and dawn periods, and uniform use for all school warning signs and plaques will enhance safety and road user recognition (see Figure 5).

A new option is being added that die in-street pedestrian sign may use the school children symbol rather dian the pedestrian symbol when used at a school crossing.14

A new symbol sign is proposed to replace the existing SCHOOL BUS STOP AHEAD word message sign and, instead of a specific distance for placement of this sign, FHWA proposes to reference the distances given in Table 2C-4.15

The existing requirement regarding the use of either a speed limit sign or an END SCHOOL ZONE sign at the end of an authorized and posted school speed zone is proposed to change a requirement that the end of a designated school zone be marked with both an END SCHOOL ZONE sign and a speed limit sign for the section of highway that follows. It is important and sometimes legally necessary to mark the end points of designated school zones, and the use of a speed limit sign showing the speed limit for the following section of highway is required by existing section 2B.13.

PART 8-TRAFFIC CONTROLS FOR HIGHWAY-RAIL GRADE CROSSINGS

A new provision is proposed that requires a YIELD sign or STOP sign to be installed at all passive highway-rail grade crossings, except where train crews always provide flagging of the crossing to road users. Although the crossbuck sign is a regulatory sign that requires vehicles to yield to trains and stop if necessary, recent research indicates insufficient road user understanding of and compliance with that regulatory requirement when just die crossbuck sign is present at passive crossings.16

FHWA proposes to add a requirement that a supplemental plaque describing the type of traffic control at highway-rail grade crossings be used. FHWA proposes to require the use of a "No Signal" supplemental plaque in advance of passive crossings and the use of a new "Signal Ahead" plaque in advance of active crossings. This change also is proposed for Part 10, Highway Light-Rail Transit Grade Crossings.

A proposal also is included that the stripes on gate arms be vertical instead of at a diagonal, 45-degree angle. This change is proposed because the diagonal stripes might tend to encourage road users to drive around the gates. Diagonal stripes are used on other devices such as barricades and object markers to indicate the direction in which road users are expected to change their path of travel. This change is also proposed for Part 10, Highway Light-Rail Transit Grade Crossings.

Shared-use paths and other similar facilities often cross railroad tracks. It is important that suitable traffic control devices be used to provide for safe and effective operation of such crossings. A new chapter is proposed to provide information for traffic control devices used on pathways at railroad-grade crossings. This change also is proposed for Part 10, Highway LightRail Transit Grade Crossings.

PART 9-TRAFFIC CONTROLS FOR BICYCLE FACILITIES

Two new bicycle pushbutton signs are proposed to inform bicyclists that they need to press a pushbutton to receive a green indication at a traffic signal. Several new bicycle guide signs are proposed that may be used to provide direction, destination and distance information for bicycle travel (see Figure 6).

Instead of the existing option, FHWA is recommending that where a designated bicycle route extends through two or more states, the affected states should submit a request to the American Association of State Highway and Transportation Officials (AASHTO) for a designated U.S. Bicycle Route number. The design of die U.S. Bicycle Route sign also is proposed to be revised to better present an immediate impression of a "bicycle numbered route" rather than a "highway numbered route which can also be used by bicyclists."

Reference location signs (formerly called milepost markers) placed along a highway have proven extraordinarily valuable for traveler information, maintenance operations and emergency response. Because the linear nature of many shared-use paths would seem to naturally lend itself to the application of reference location signs, FHWA proposes adding a new section in MUTCD to discuss the design, application and placement of reference location signs when used on shared-use paths.

FHWA also proposes adding a new section for shared lane markings. This proposed new pavement marking symbol indicates the legal and appropriate bicycle lane of travel and cues motorists to pass with sufficient clearance. This proposed change is based on research conducted in San Francisco that showed that this proposed new marking can reduce the number and severity of bicycle-vehicular crashes, particularly crashes involving bicycles colliding with suddenly opened doors of parked vehicles.17

PART 10-HIGHWAY LIGHT-RAIL TRANSIT GRADE CROSSINGS

In addition to the proposed changes already discussed for Part 8 that would also apply to Part 10, FHWA. proposes to change the option of using audible devices to a requirement to use audible devices if flashing light signals or traffic control signals are in operation at a light-rail crossing that is used by pedestrians. The reason for this proposed change is that light-rail transit vehicles often are nearly silent and blind pedestrians cannot see flashing lights. Requiring the use of an audible warning device would assure that information about the approach of a light-rail transit vehicle is available to persons with visual disabilities.

FHWA also proposes that for signals to control only light-rail transit movements, the light-rail transit signal indications illustrated in the current edition of MUTCD should be used. The existing MUTCD indicates that these signals are only examples of indications that could be used, and currently there is no requirement or recommendation to use these particular indications. As a result, there is no uniformity in the light-rail transit signal indications used around the United States. FHWA believes that such uniformity is needed.

CONCLUSION

In addition to the proposed items discussed here for the 2009 edition of MUTCD, many more important new requirements and recommendations are intended to enhance uniformity, safety and mobility for road users. To minimize adverse impacts on state or local highway agencies, NPA includes proposed target compliance dates for various significant changes ranging from 2 to 15 years. FHWA encourages all interested parties to visit the MUTCD Web site to review the Federal Register notice as well as the proposed MUTCD text and figures.

All comments must be submitted to the Federal Register docket either by mail to the U.S. Department of Transportation, Dockets Management Facility, 1200 New Jersey Avenue, SE, Washington, DC 20590; electronically at www.regulations. gov; or by fax to 202-493-2251.

The docket will be open until July 31, 2008 to provide sufficient time for submitting comments. After the docket doses, FHWA will analyze the comments and develop a Final Rule for the 2009 MUTCD. States and other federal agencies will have two years from the effective date of the Final Rule to adopt the changes issued by FHWA that do not have target compliance dates.

We hope this highlight of the proposed changes and discussion of the rule-making process is helpful. We look forward to receiving valuable input from our partners and stakeholders in this open process of developing changes to MUTCD.

© 2008 Institute of Transportation Engineers Provided by ProQuest LLC. All Rights Reserved.

Source: Institute of Transportation Engineers. ITE Journal