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Roadways 33 With respect to road design, the positive guidance approach emphasizes: · Expectation--Design roadway configurations and geometrics and traffic operations in accor- dance with driver expectations. Design should conform to long-term expectancies (e.g., there are no traffic signals on freeways, freeway exits are on the right) as well as short-term expectan- cies (e.g., all curves on this road are gradual). With respect to traffic control devices, the positive guidance approach emphasizes the following: · Primacy--Determine the placement of signs according to the importance of their informa- tion (e.g., stop signs are more important than parking payment signs, or in an airport envi- ronment, terminals are more important than cargo areas), and in such a way as to avoid presenting the driver with information when and where it is not essential. · Spreading--Where all the information required by the driver cannot be placed on one sign or on a number of signs at one location, spread it out along the road so that information is given in small chunks, thereby reducing the information load on the driver. · Coding--Where possible, organize pieces of information into larger units. Color and shape coding of traffic signs accomplish this by representing specific information about the message based on the color of the sign background and the shape of the sign panel (e.g., warning signs are yellow and typically diamond shaped). · Repetition--Say the same thing in more than one way (e.g., shape, color). The same infor- mation may also be given with two different devices (e.g., "no passing" indicated with a sign and pavement markings), or by two identical devices (e.g., STOP signs on both sides of a wide intersection). 3.2 Applicable Federal Standards The Federal Highway Administration (FHWA) oversees the standards and practices for traffic signs, signals, and markings. They produce the MUTCD under 23 Code of Federal Regulations (CFR), Part 655, Subpart F. The MUTCD defines the standards used by road managers nation- wide to install and maintain traffic control devices on all public streets, highways, bikeways, and private roads open to public traffic. The MUTCD approved by the Federal Highway Administration is the national standard for all traffic control devices installed on any street, highway, or bicycle trail open to public travel. For the purpose of MUTCD applicability, open to public travel includes toll roads and roads within shopping centers, airports, sports arenas, and other similar business and/or recreation facilities that are privately owned but where the public is allowed to travel without access restrictions54. Each state must adopt the Federal MUTCD or a state-specific alternative manual or supplemen- tal material that is in substantial conformance to the National manual. The recommendations in this document refer to the 2009 Edition of the MUTCD. 3.2.1 MUTCD Organization and Terms Before addressing MUTCD applicability in airport roadway systems, it is important to under- stand how the MUTCD is organized and terminology used. For many sign applications, the MUTCD distinguishes between "Freeways and Expressways" and "Conventional Roads." The main thing that distinguishes these two road classes from each other is operating speed and the presence of driveways and intersections. For most situations, airport roads (including terminal curbside roads) would be considered "Conventional Roads" because they typically have operating speeds lower than 45 mph, and they have frequent drive-
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34 Wayfinding and Signing Guidelines for Airport Terminals and Landside ways and at-grade intersections and may have pedestrian activity along and/or across them. Air- ports may also own and operate freeway or expressway-type roadways with limited or partially controlled access and operating speeds higher than 45mph. In those cases, the sign designer should consider use of the principles and guidance in the "Freeways and Expressways" section of the Manual to address the likely higher speeds, volumes and entrance/exit ramp conditions. The MUTCD refers to signs by their function or class, such as regulatory, warning and guide signs. Each sign class is addressed in a separate chapter of the Manual. In addition, there are addi- tional chapters dedicated to school areas, highway-rail crossings, bicycle facilities, and light-rail transit grade crossings which are less likely to be used by airports. Throughout the MUTCD, the headings Standard, Guidance, Option, and Support are used to classify the nature of the text that follows. Designers should understand and pay close attention to these definitions and requirements as listed in the MUTCD and defined as the following: · Standard--a statement of required, mandatory, or specifically prohibitive practice regarding a traffic control device. Standard statements are sometimes modified by options. Standard statements shall not be modified or compromised based on engineering judgment or engineer- ing study. · Guidance--a statement of recommended, but not mandatory, practice in typical situations, with deviations allowed if engineering judgment or engineering study indicates the deviation to be appropriate. Guidance statements are sometimes modified by options. · Option--a statement of practice that is a permissive condition. · Support--an informational statement which provides background and rationale for a stan- dard, guidance, or option statement. 3.2.2 Airport Roadways and the MUTCD The MUTCD contains little guidance on how to apply MUTCD principles and standards to airport roadways as a unique category although it does specifically state that airport roads open to public travel shall comply with the MUTCD. This lack of detailed guidance does not, how- ever, give airport sign designers and operators permission to avoid compliance with these road- way signing standards. Airports should retain the services of licensed professional engineers who are experienced in roadway design, including roadway signing design, and are therefore able to exercise engineering judgment for particular site and traffic flow characteristics. In Section 1A.09 of the MUTCD, the Manual addresses the issue of engineering judgment by stating as a Standard Statement, "This Manual describes the application of traffic control devices, but shall not be a legal requirement for their installation." It provides further guidance which states that engineering judgment should be exercised in the selection and application of traffic control devices. Engineering judgment does not mean, in this context, that substitution of alter- native devices can take place at will. The formal request for experimentation process, including the evaluation, described herein should be followed. The MUTCD does allow some flexibility in interpretation through engineering judgment and study. It is important to note, however, that the Manual clearly states any Standard statement cannot be ignored or overruled by engineering judgment. Only Guidance and Option statements can be interpreted through engineering judgment (see Section 1A.13, definition of a Standard; also reference Official Ruling No. 1(09)1(I) issued October 1, 2010). FHWA has made provision for agencies to request interpretations of MUTCD language to par- ticular situations. An agency can also request experimentation with a new traffic control device or application of an existing device to a new situation. Experimentations require a formal evaluation of the device to demonstrate that the new device provides an improvement over the current stan-