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1、Chapter 7Traffic and Safety Control Devices A.General 1.Traffic Signs,Marking,and Signal-Signs-Markings-Signals-Example 2.Purpose of Traffic Control Devices-The purpose of traffic control devices is to promote highway safety and efficiency by providing for the orderly movement of all road users on s
2、treets and highways throughout the nation.-Traffic control devices notify road users of regulations and provide warning and guidance needed for the safe,uniform,and efficient operation of all elements of the traffic stream.-Traffic control devices or their supports shall not bear any advertising mes
3、sage or any other message that is not related to traffic control.3.Principles of Traffic Control Devices-Guidance:To be effective,a traffic control device should meet five basic requirements:-Fulfill a need,-Command attention,-Convey a clear,simple meaning,-Command respect from road users,and-Give a
4、dequate time for proper response.4.Design of Traffic Control Devices-Devices should be designed so that features such as size,shape,and color,composition,lighting or retroreflection,and contrast are combined to draw attention to the devices;that size,shape,color,and simplicity of message combine to
5、produce a clear meaning;that legibility and size combine with placement to permit adequate time for response;and that uniformity,size,legibility,and reasonableness of the message combine to command respect.5.Placement and Operation of Traffic Control Devices-Placement of a traffic control device sho
6、uld be within the road users view so that maximum visual acuity is provided.To aid in conveying the proper meaning,the traffic control device should be appropriately positioned with respect to the location,object,or situation to which it applies.The location and legibility of the traffic control dev
7、ice should be such that a road user has adequate time to make the proper response in both day and night conditions.-Traffic control devices should be placed and operated in a uniform and consistent manner.-Unnecessary traffic control devices should be removed.6.Maintenance of Traffic Control Devices
8、-Traffic control devices should be reviewed periodically to determine if they meet current traffic conditions.-Traffic control devices should be maintained to ensure that legibility is retained,that the device is visible,and that it functions properly in relation to other traffic control devices in
9、the vicinity during both day and night conditions.7.Uniformity of Traffic Control Devices-Uniformity of devices simplifies the task of the road user because it aids in recognition and understanding,thereby reducing perception/reaction time.-Uniformity assists road users,police officers,and traffic c
10、ourts by giving everyone the same interpretation.-Uniformity assists public highway officials through efficiency in manufacture,installation,maintenance,and administration.-Uniformity means treating similar situations in a similar way.8.Color Codes9.Abbreviations Used on Traffic Control Devices-The
11、abbreviations for the words listed in Table 1A-2 should not be used in connection with traffic control devices unless the prompt word shown in Table 1A-2 either precedes or follows the abbreviation.-The abbreviations shown in Table 1A-3 shall not be used in connection with traffic control device bec
12、ause of their potential to be misinterpreted by road users.B.Traffic Signs 1.Function and Purpose of Signs-The functions of signs are to provide regulations,warnings,and guidance information for road users.-Types of Signs:-Regulatory Signs-Warning Signs-Guide Signs(Conventional Roads)-Guide Signs(Fr
13、eeways and Expressways)-Specific Service(Logo)Signs-Tourist-Oriented Direction Signs-Recreational and Cultural Interest Area Signs-Emergency Management Signs2.Standardization of Application-It is recognized that urban traffic conditions differ from those in rural environments,and in many instances s
14、igns are applied and located differently.-Signs should be used only where justified by engineering judgment or studies.-Roadway geometric design and sign application should be coordinated so that signing can be effectively placed to give the road user any necessary regulatory,warning,guidance,and ot
15、her information.-Regulatory and warning signs should be used conservatively because these signs,if used to excess,tend to lose their effectiveness.If used,route signs and directional signs should be used frequently because they promote safe and efficient operations by keeping road users informed of
16、their location.3.Design of Signs-The basic requirements of a highway sign are that it be legible to those for whom it is intended and that it be understandable in time to permit a proper response.Desirable attributes include:-High visibility by day and night,and -High legibility(adequately sized let
17、ters or symbols,and a short legend for quick comprehension by a road user approaching a sign).-Standardized colors and shapes are specified so that the several classes of traffic signs can be promptly recognized.Simplicity and uniformity in design,position,and application are important.-Regulatory,w
18、arning,and guide signs shall be retroreflective or illuminated to show the same shape and similar color by both day and night.4.Location and Height of Signs5.Regulatory Signs-Regulatory signs shall be used to inform road users of selected traffic laws or regulations and indicate the applicability of
19、 the legal requirements.-Size of Regulatory Signs6.Warning Signs-Warning signs call attention to unexpected conditions on or adjacent to a highway or street and to situations that might not be readily apparent to road users.Warning signs alert road users to conditions that might call for a reduction
20、 of speed or an action in the interest of safety and efficient traffic operations.-Applications of Warning Signs:The use of warning signs should be kept to a minimum as the unnecessary use of warning signs tends to breed disrespect for all signs.In situations where the condition or activity is seaso
21、nal or temporary,the warning sign should be removed or covered when the condition or activity does not exist.7.Guide Signs(Conventional Roads)-Standards for conventional road guide signs shall apply to any road or street other than low-volume roads,expressways,and freeways.-Guide signs are essential
22、 to direct road users along streets and highways,to inform them of intersecting routes,to direct them to cities,towns,villages,or other important destinations,to identify nearby rivers and streams,parks,forests,and historical sites,and generally to give such information as will help them along their
23、 way in the most simple,direct manner possible.-Except where otherwise specified herein for individual signs or groups of signs,guide signs on streets and highways shall have a white message and border on a green background.-The standard lettering for conventional road guide signs shall be all capit
24、al letters,or a combination of lower-case letters with initial upper-case letters.-Guide signs should be limited to three lines of principal legend.Where two or more signs are included in the same overhead display,the amount of legend should be minimized.The principal legend should include only plac
25、e names,route numbers,and street names.8.Guide Signs(Freeways and Expressways)-Signs are designed so that they are legible to road users approaching them and readable in time to permit proper responses.Desired design characteristics include:(a)long visibility distances,(b)large lettering and symbols
26、,and(c)short legends for quick comprehension.-The development of a signing system for freeways and expressways is approached on the premise that the signing is primarily for the benefit and direction of road users who are not familiar with the route or area.-Road users should be guided with consiste
27、nt signing on the approaches to interchanges,as they drive from one state to another,and when driving through rural or urban areas.-Guide signs on freeways and expressways should serve distinct functions as follows:(1)Give directions to destinations,or to streets or highway routes,at intersections o
28、r interchanges,(2)Furnish advance notice of the approach to intersections or interchanges,(3)Direct road users into appropriate lanes in advance of diverging or merging movements,(4)Identify routes and directions on those routes,(5)Show distances to destinations,(6)Indicate access to general motoris
29、t services,rest,scenic,and recreational areas,(7)Provide other information of value to the road user.-Guide signs on freeways and expressways,except as noted herein,shall have white letters,symbols,and borders on a green background.C.Traffic Markings 1.General-Major marking types include pavement an
30、d curb markings,object markers,delineators,colored pavements,barricades,channelizing devices and islands.-Before any new highway,paved detour,or temporary route is opened to traffic,all necessary markings should be in place.-Markings that are no longer applicable for roadway conditions or restrictio
31、ns and that might cause confusion for the road user shall be removed or obliterated to be unidentifiable as a marking as soon as practical.-Pavement and curb markings are commonly placed by using paints or thermoplastics;however,other suitable marking materials,including raised pavement markers and
32、colored pavements,are also used.Delineators,object markers,barricades,and channelizing devices are visibly placed in a vertical position similar to signs above the roadway.-Markings shall be yellow,white,red,or blue.The colors for markings shall conform to the standard highway colors.2.Pavement and
33、Curb Markings-Yellow Centerline and Left Edge Line Pavement Markings-No-Passing Zone Pavement Markings and Warrants-Edge Line Pavement Markings-Extensions Through Intersections or Interchanges-Crosswalk Markings-Parking Space Markings-Pavement Word and Symbol Markings3.Object Markers-Markings for Ob
34、jects in the Roadway:Obstructions within the roadway shall be marked with a Type 1 or Type 3 object marker.-Markings for Objects Adjacent to the Roadway:Type 2 or Type 3 object markers may be used.-End-of-Roadway Markings4.DelineatorsD.Traffic Signals 1.Types-Traffic control signals;pedestrian signa
35、ls;emergency-vehicle traffic control signals;traffic control signals for one-lane,two-way facilities;traffic control signals for freeway entrance ramps;traffic control signals for movable bridges;lane-use control signals;flashing beacons;and in-roadway lights.-Definition2.Traffic Control Signals Gen
36、eral3.-The selection and use of traffic control signals should be based on an engineering study of roadway,pedestrian,bicyclist,and other conditions.4.-Advantages of Traffic Control Signals:5.-Improper or unjustified traffic control signals can result in one or more of the following disadvantages:6.
37、-Engineering studies of operating traffic control signals should be made to determine whether the type of installation and the timing program meet the current requirements of traffic.-Since vehicular delay and the frequency of some types of crashes are sometimes greater under traffic signal control
38、than under STOP sign control,consideration should be given to providing alternatives to traffic control signals even if one or more of the signal warrants has been satisfied.3.Traffic Control Signals Needs Study-Warrants-A traffic control signal should not be installed unless one or more of the warr
39、ants are met.-The satisfaction of a traffic signal warrant or warrants shall not in itself require the installation of a traffic control signal.-A traffic control signal should not be installed if it will seriously disrupt progressive traffic flow.-A traffic control signal should not be installed un
40、less an engineering study indicates that installing a traffic control signal will improve the overall safety and/or operation of the intersection.EndHomework No.5 Standard:A.Yellow-warning B.Red-stop or prohibition C.Blue-road user services guidance,tourist information,and evacuation route D.Green-i
41、ndicated movements permitted,direction guidance E.Brown-recreational and cultural interest area guidance F.Orange-temporary traffic control G.Black-regulation H.White-regulation I.Fluorescent Yellow-Green-pedestrian warning,bicycle warning,school bus and school warning J.Purple-unassigned K.Light Bl
42、ue-unassigned L.Coral-unassigned(Continued from previous page)(Continued from previous page)(Continued from previous page)(Continued from previous page)(Continued from previous page)Definitions Relating to Highway Traffic Signals1.Accessible Pedestrian Signal-a device that communicates information a
43、bout pedestrian timing in non-visual format such as audible tones,verbal messages,and/or vibrating surfaces.2.Active Grade Crossing Warning System-the flashing-light signals,with or without warning gates,together with the necessary control equipment used to inform road users of the approach or prese
44、nce of trains at highway-rail grade crossings.3.Actuated Operation-a type of traffic control signal operation in which some or all signal phases are operated on the basis of actuation.4.Actuation-initiation of a change in or extension of a traffic signal phase through the operation of any type of de
45、tector.5.Approach-all lanes of traffic moving towards an intersection or a midblock location from one direction,including any adjacent parking lane(s).6.Average Day-a day representing traffic volumes normally and repeatedly found at a location,typically a weekday when volumes are influenced by emplo
46、yment or a weekend when volumes are influenced by entertainment or recreation.7.Backplate-a thin strip of material that extends outward from and parallel to a signal face on all sides of a signal housing to provide a background for improved visibility of the signal indications.8.Beacon-a highway tra
47、ffic signal with one or more signal sections that operates in a flashing mode.9.Conflict Monitor-a device used to detect and respond to improper or conflicting signal indications and improper operating voltages in a traffic controller assembly.10.Controller Assembly-a complete electrical device moun
48、ted in a cabinet for controlling the operation of a highway traffic signal.11.Controller Unit-that part of a controller assembly that is devoted to the selection and timing of the display of signal indications.12.Crosswalk-(a)that part of a roadway at an intersection included within the connections
49、of the lateral lines of the sidewalks on opposite sides of the highway measured from the curbs or in the absence of curbs,from the edges of the traversable roadway,and in the absence of a sidewalk on one side of the roadway,the part of a roadway included within the extension of the lateral lines of
50、the sidewalk at right angles to the centerline;(b)any portion of a roadway at an intersection or elsewhere distinctly indicated for pedestrian crossing by lines or other markings on the surface.13.Cycle Length-the time required for one complete sequence of signal indications.14.Dark Mode-the lack of