JCE 4600 Transportation Engineering. Traffic Control

Transcription

1 JCE 4600 Transportation Engineering Traffic Control

2 Human Factors Primary Driving Tasks NAVIGATION GUIDANCE CONTROL

3 What makes a Traffic Control Device Effective? Fulfill a need Command Attention Convey a Clear, Simple Meaning Command Respect of Road Users Give adequate time for a proper response MUTCD; Section 1A.02

4 Design and Location of Traffic Control Devices 1. Timing: Provide information at a steady rate Spread out lower priority information 2. Primacy: Place sufficient target value on more urgent devices Example: Flashing light on warning sign 3. Expectancy: Drivers respond more correctly to expected situations Give advance notice of an unexpected situation 4. Redundancy: Provide critical information in more than one way Pavement markings supplement signs

5 Timing: What s wrong with this picture? Source: PTOE Refresher Course

6 Primacy: What s wrong with this picture? Camden County Courthouse

7 Primacy: What s wrong with this picture? Source: PTOE Refresher Course

8 Expectancy: What s wrong with this picture? Tipperary Hill in western Syracuse

9 Expectancy: What s wrong with this picture? Source: PTOE Refresher Course

10 Expectancy: What s wrong with this picture?

11 Redundancy: What s wrong with this picture? Forest Park

12 Redundancy: What s wrong with this picture? Source: PTOE Refresher Course

13 Promotes Uniformity in Design and Application

14 Why do we need an MUTCD?

15 MUTCD DEFINITIONS 1A-13 (Shall) Standard a statement of required, mandatory, or specifically prohibitive practice regarding a traffic control device. The verb shall is typically used. Standard statements shall not be modified or compromised based on engineering judgment or engineering study.

16 MUTCD DEFINITIONS (Should) 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. The verb should is typically used.

17 MUTCD DEFINITIONS (May) Option a statement of practice that is a permissive condition and carries no requirement or recommendation. Option statements sometime contain allowable modifications to a Standard or Guidance statement. The verb may is typically used.

18 Color Code how many colors do we use? Section 1A-12

19 Shape/Color

20 Sign Size

21

22 Typical Standards, Guidance, and Options

23

24 Destination Signs

25

26 General Service Signs

27

28

29 Typical Application

30

31 Placement

32 PAVEMENT MARKINGS

33

34 Work Zones Advance Warning Area Transition Area Activity Area Work Space Traffic Space Buffer Space Termination Area

35

36 Design Criteria is Provided

37 Example Problem What is the minimum merging taper length for a 12-foot lane with a design speed of 55 mph?

38 Traffic Signal Warrants

39

40

41

42

43 Warrant 5 School Crossing

44 Warrant 6 Coordinated Signal System

45 Warrant 7 Crash Experience

46 Warrant 8 Roadway Network

47 Warrant 9 Grade Crossing

48 DESIGN ISSUES Turning Path Sight Distance Channelization Access Management Intersection Configurations Traffic calming

49 Turning Templates

50 Turning Path Issues

51 Results of Poor Turning Paths Maryland Heights, Missouri

52 Results of Poor Turning Paths

53 Sight Distance Route M in Jefferson County, Missouri

54 Forest Park Parkway, St. Louis 250 feet Advanced Flashers

55 150 feet Upper Bottom Road, St. Charles

56 9 Principles of Channelization Discourage or prohibit undesirable or wrong-way movements Clearly define desirable vehicle paths Encourage desirable and safe vehicle speeds Separate points of conflict Traffic streams should cross at near-right angles and merge at flat angles. Facilitate the movement of high priority traffic flows. Facilitate the traffic control scheme. Accommodate decelerating, slow, or stopped vehicles outside higher-speed through traffic lanes. Provide safe refuge ( e.g., pedestrians and handicapped)

57 Near Eglin AFB Florida

58 Access Management Source: Indiana

59 What is Access Management? Access Management is the process that provides access to land development while simultaneously preserving the flow of traffic on the surrounding road system in terms of safety, capacity, and speed. (Federal Highway Administration) Access Management seeks to limit and consolidate access along major roadways, while promoting a supporting street system and unified access and circulation systems for development. The result is a roadway that functions safely and efficiently for its useful life, and a more attractive corridor. (Transportation Research Board)

60 Why Implement Access Management? Up to 50% crash reduction 23-45% capacity increase 40-60% delay reduction Better business environment Improved quality of life Save tax dollars Camdenton Source: Michigan DOT

61 Access Management Tools Access rights Intersection spacing Access management standards/guidelines Driveway controls Turning restrictions Frontage/backage roads Shared/cross access Comprehensive planning Zoning ordinances Site plan development Permitting

62 Planning Example Maryland Heights Howard Bend Levee District 25M ft 2 planned development Regional park Comprehensive plan 6-lane expressway Parallel collector roadway Extensive Coordination: Developers, Land Owners, Levee District, Existing Businesses, St. Louis County and MoDOT

63 Backage Roads Near US12/18 in Madison, WI

64 Intersection Configurations

65 New Jersey Near Side Jug Handle

66 New Jersey Far Side Jug Handle

67 New Jersey Far Side Jug Handle

68 Three/Quarter Access Intersection

69 Three/Quarter Access Intersection

70 Median U-turns

71 Median U-turns

72 Median U-turns Advantages Reduced Crash Potential Increased Cross-street Capacity Easily Retrofitted Medium/Low Cost Disadvantages Indirect Movements Unfamiliar to Drivers Public Education Mainline Weaving

73 New Designs I-270 and Olive Boulevard, St. Louis

74 Continuous Flow Intersection

75 St. Louis CFI Route 30 at Summit Photo courtesy of MoDOT

76 DDI at I-270 and Dorsett Road

77 DDI at I-70 and 5 th Street

78 DDI at I-70 and Mid Rivers Mall Drive

79 DDI at I-270 and Dorsett Road

80 Forest Park Traffic Calming

81 Traffic Calming Tools Available Vertical Deflections, Horizontal Shifts, and Roadway Narrowings are intended to reduce speed and enhance the street environment for non-motorists Closures (diagonal diverters, half closures, full closures, and median barriers) are intended to reduce cut-through traffic by obstructing traffic movements.

82 Chokers and Neck Downs Potential Impacts: can impact parking and driveway access reduces pedestrian crossing width and increases visibility of pedestrian speeds reduced on average by 4% for twolane chokers and 14% for one lane chokers bicyclists prefer not to have the travelway narrowed into path of motor vehicles Emergency Response Issues: preferred traffic calming device by many emergency response agencies

83 Raised Intersections Potential Impacts: reduction in through movement speeds at intersection reduction in midblock speeds typically less than 10% access not effected entire intersection more pedestrian-friendly no data available on safety impacts Emergency Response Issues: slows emergency vehicles to approximately 15 mph

84 Full and Partial Closures Potential Impacts: concern over effects on emergency response, street network connectivity, and parallel local streets that carry diverted traffic may divert significant traffic volumes no significant effect on vehicle speeds beyond the full street closure Emergency Response Issues: can be designed to allow emergency vehicle access

85 Turn Restrictions and One Way Systems

86 Diverters

87 MUTCD Homework Due next class 1. Using the 2009 MUTCD, create a design to provide drivers with advanced warning about an isolated signal on rural 2-lane road with moderate ADT and 55 miles per hour posted speed limit. Specifically address: What signage/markings should be used? (give the MUTCD code and show a picture). If you use any signs, How large should they be? How far should they be placed upstream of the traffic signal? Where should it be mounted in relationship to the driving lanes? Are there any other special considerations that should be taken into account Provide references (page numbers, table numbers, etc) for all of your work. 2. Provide a typical traffic control scheme for a Lane Closure on a Minor Street. Base your drawing on the MUTCD. 3. What special considerations should be taken into account when installing traffic calming measures such as partial closures and diverters? 4. Under what conditions are Diverging Diamond Interchanges best suited? 5. When used appropriately, list 5 reasons that roundabouts can improve intersection safety.