Designing for Pedestrian Safety

Transcription

1 Designing for Pedestrian Safety Intersection Geometry Presented by: John LaPlante T.Y. Lin International, Inc Keith Sinclair FHWA Resource Center September 9, 2010

2 Learning Outcomes At the end of this module, you will be able to: Explain why tight/right angle intersections are best Describe why pedestrians need access to all corners Assess good crosswalk placement: where peds want to cross & where drivers can see them Explain how islands can break up complex intersections 4 2

3 Intersection Crashes Some basic facts: 1. Most (urban) crashes occur at intersections 2. Most occur at signalized intersections 3. Most are associated with turning movements 4. Geometry matters: keeping intersections tight, simple & slow speed make them safer for everyone 4 3

4 Small, tight intersections best for pedestrians Simple, few conflicts, slow speeds 4 4

5 Large intersections can work for pedestrians with mitigation 4 5

6 Skewed intersections Skew increases crossing distance & speed of turning cars 4 6

7 Cars can turn at high speed 4 7

8 Skew increases crosswalk length, decreases visibility 4 8

9 Right angle decreases crosswalk length, increases visibility 4 9

10 Skewed intersection reduces visibility Driver looks left, doesn t see pedestrian on right 4 10

11 Adjust skew by bringing out curb 4 11

12 Result: driver behavior change 4 12

13 Curb radius small radii are safer for pedestrians Large radii: 1. Increase crossing distance and 2. Make crosswalk & ramp placement more difficult 4 13

14 Effect of large radius on crosswalk: Additional area to cross + Higher speed turns It adds to crossing distance 4 14

15 Effect of large radius on crosswalk: Note right turning vehicle and makes it hard to figure out where to cross 4 15

16 Effect of large radius on drivers They drive fast 4 16

17 Effect of large radius on drivers ignoring pedestrians 4 17

18 Minimize curb radius 1. Calculate effective radius: Larger than built radius if travel lanes offset from curb with parking and/or bike lane 4 18

19 Minimize curb radius 2. At one way streets, corner with no turns can have tight radius 4 19

20 Minimize curb radius 3. Don t choose larger design vehicle than necessary (Bus makes turn several times an hour) 4 20

21 Minimize curb radius 4. Don t choose larger design vehicle than necessary (Moving van, once or twice a year; peds cross every day) 4 21

22 Minimize curb radius 5. Where appropriate, let trucks use 2nd lane 4 22

23 Minimize curb radius 6. Trucks can make very tight turns at slow speeds 4 23

24 Minimize curb radius 7. Turn common Single Unit truck (SU 30) into near lane 4 24

25 Minimize curb radius 7. Turn less common Semi (WB 50) into 2nd lane 4 25

26 CRF for curb radii: not yet known Although an exact number has not been determined, a study conducted by Zegeer et al. in Florida showed a correlation between large radii and higher pedestrian crash rates with right turning vehicles 4 26

27 Discussion: What are your policies & practices regarding corner radii? 4 27

28 Curb extensions Most focus is on reduced crossing distance Other advantages: Better visibility between peds and motorists Traffic calming Room for street furniture Curb extensions should be the width of the parking lane and not encroach on bike lanes or travel lanes 4 28

29 Better Visibility 4 29

30 Pedestrians wait where they can see, in front of parked cars Curb ext. places pedestrian where he can see and be seen 4 30

31 Before: high speed right turns 4 31

32 After: slow speed right turns Curb extension and new corner radius must be designed together see earlier radius discussion 4 32

33 Curb ext. increases likelihood drivers will yield to peds 4 33

34 Public art Newspaper boxes Bike parking Street trees Curb extensions allow room for street furniture But use care not to block sight lines 4 34

35 Curb extensions enable signs to be moved in 4 35

36 Curb extensions enable signs to be moved in 4 36

37 Curb extensions enable signs to be moved in 4 37

38 Drainage solutions 1. Additional inlet 4 38

39 Drainage solutions 2. Slotted drain 4 39

40 Drainage solutions 3. Leave original curb + islands 4 40

41 Drainage solutions 4. Same as before + plate 4 41

42 Curb Extension Integrated with the Sidewalk Parking pockets in furniture zone have similar surface materials as the sidewalk 4 42

43 Before: road looks and feels wide 4 43

44 After: curb extension integral to sidewalk Street looks narrow even with no parked cars 4 44

45 Reminder crosswalks are provided: 1. To tell pedestrians where to cross 2. To tell drivers where to expect pedestrians 4 45

46 Crosswalks should normally be placed on all legs of an intersection 4 46

47 Should there be a crosswalk here? Of course! Closing a crosswalk is not the answer Large intersection is capacity driven, pedestrian unfriendly 4 47

48 Will she wait? Is crossing 15 lanes safer than crossing 5 lanes? Here s what pedestrians are expected to do 4 48

49 Crosswalk placement requires balancing several goals that sometimes compete: Shortest crosswalk length Minimal crosswalk setback to: Reduce out of direction travel Provide good sight lines between peds and motorists Proper ramp placement: Ramps entirely contained in crosswalk Two ramps preferred whenever possible 4 49

50 Small corner radii allow two ramps, shortest crosswalks, direct travel paths 4 50

51 Larger radii create large undefined areas 4 51

52 Crosswalks at shortest crossing = longer walking distance 4 52

53 Crosswalks at shortest crossing = longer walking distance Right & left turning drivers don t see crosswalk 4 53

54 Single ramp reduces crosswalk setback but lengthens crosswalk 4 54

55 Balancing the goals works best Note: Crosswalk length and setback are greater with large radii than with small radii 4 55

56 Balancing the goals works best Note: 3 curb exposure between ramps allows them to be close together 4 56

57 Pedestrian crossing Crosswalk Crosswalk placement: Observe pedestrians 4 57

58 Crosswalk placement: Think like a pedestrian 4 58

59 When in doubt, paint it out! Crosswalks can have odd shapes to take pedestrians where they want to go 4 59

60 Discussion: What are your policies & practices regarding crosswalk placement? 4 60

61 Pedestrian Islands Benefits: Separate conflicts & decision points Reduce crossing distance Improve signal timing Reduce crashes 4 61

62 Imagine the signal timing without island 4 62

63 Right-Turn Slip Lane: Design for Pedestrians High speed, head turner = low visibility of pedestrians Slow speed, good angle = good visibility of pedestrians 4 63

64 Right-Turn Slip Lane - Details 4 64

65 Drivers naturally trace the right island shape 4 65

66 Peds could start crossing here 4 66

67 instead of here 4 67

68 Should we mark this crosswalk? 4 68

69 Yes: It s a yield controlled approach, and it may not be clear where peds cross. 4 69

70 Raised islands can improve a large multi-lane intersection 4 70

71 Raised islands can improve a large multi-lane intersection 1. Build raised islands between thru & RT lanes to separate ped/driver conflicts. Consolidate two crosswalks into one. 4 71

72 Raised islands can improve a large multi-lane intersection 1. Build raised islands between thru & RT lanes to separate ped/driver conflicts. Consolidate two crosswalks into one. 2. Move stop bar forward to improve capacity and safety for motorists 4 72

73 Island Design Details Cut through preferred over ramps Truncated domes at cut throughs 8 or more preferred width 6 minimum 4 73

74 48 With ramps, provide at least 48 level area 4 74

75 NOT Okay 4 75

76 Not acceptable Acceptable, not great 4 76

77 Best: Bullet nose protects pedestrians from highspeed left turning cars 4 77

78 How to place a crosswalk at porkchop island 1. Place crosswalks to island 4 78

79 How to place a crosswalk at porkchop island 2. Trace 3rd line where they meet 4 79

80 How to place a crosswalk at porkchop island 3. Place 3rd crosswalk there 4 80

81 Discussion: What are your policies & practices regarding providing pedestrian islands? 4 81

82 Intersection Geometry: Recap of Design Measures Should pedestrians have access to all corners? Yes Why? Otherwise peds will dash across anyway Intersection geometry should be? Tight (small radii); right angles How do you break up complex intersections? With islands Where should you place crosswalks? Where pedestrians want to cross and where drivers can see them 4 82

83 Intersection Geometry Learning Outcomes You should now be able to: 1. Explain why tight/right angle intersections are best 2. Describe why pedestrians need access to all corners 3. Assess good crosswalk placement: where peds want to cross & where drivers can see them 4. Explain how islands break up complex intersections 4 83

84 Questions? 4 84