Sight Distance Guidelines
Transcript Of Sight Distance Guidelines
SIGHT DISTANCE GUIDELINES
According to the 2011 AASHTO, 2011 MMUTCD, and Michigan Department of Transportation Guidelines
PREPARED BY GEOMETRICS AND OPERATIONS UNIT
TRAFFIC AND SAFETY April 22, 2015
“Providing the highest quality transportation services for economic benefit and improved quality of life.”
INDEX
PAGE NUMBER ACKNOWLEDGEMENTS ...............................................................................................iii
TYPES OF SIGHT DISTANCE....................................................................................... iii
STOPPING SIGHT DISTANCE ...................................................................................... 1 Quick Charts for Stopping Sight Distance .............................................................. 3 STOPPING SIGHT DISTANCE ................................................................................... 5 Horizontal Stopping Sight Distance......................................................................... 6 Vertical Curves ........................................................................................................ 10 Crest Vertical Curves .............................................................................................. 11 Sag Vertical Curves ................................................................................................. 13 Design Controls: Stopping Sight Distance .......................................................... 16 General Control for Vertical Alignment ................................................................. 18
PASSING SIGHT DISTANCE ....................................................................................... 19 Quick Charts for Passing Sight Distance .............................................................. 21 PASSING SIGHT DISTANCE (Two-Lane, Two-Way Highways) ............................ 23 Measurement of Passing Sight Distance.................................................... .......... 24 Passing Sight Distance on Multilane Roadways................................................... 25 Passing Sight Distance for Horizontal Curves...................................................... 25 Passing Sight Distance for Vertical Curves .......................................................... 26 Passing Sight Distance - Pavement Markings ...................................................... 27
DECISION SIGHT DISTANCE...................................................................................... 30 Quick Chart for Decision Sight Distance ............................................................... 31 DECISION SIGHT DISTANCE .................................................................................. 33
INTERSECTION SIGHT DISTANCE ............................................................................ 37 Quick Charts for Intersection Sight Distance ....................................................... 39 INTERSECTION SIGHT DISTANCE......................................................................... 41 Intersections with Stop-Control on the Minor Road ............................................. 42 Intersection Sight Distance Considerations for Signalized Intersections .......... 48 Determination and Measurement of Intersection Sight Distance........................ 48 Field Measurement of Intersection Sight Distance............................................... 51
REFERENCES.............................................................................................................. 52
MDOT Traffic & Safety
i
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
MDOT Traffic & Safety
i
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
ACKNOWLEDGEMENTS
The Michigan Department of Transportation (MDOT) practices regarding sight distance measurement are based almost exclusively and entirely upon the AASHTO sight distance principles, theories, and methodologies. Therefore, it was not possible to produce this reference document without utilizing significant portions of the A Policy on Geometric Design of Highways and Streets, 2011, by the American Association of State Highway and Traffic Officials (AASHTO), Washington, D.C. MDOT would like to acknowledge the AASHTO publication (used by permission) as the major source material within this document. As a result, several sections of the AASHTO publication were incorporated into this document, either directly and intact, or paraphrased for ease of explanation and/or understanding. Acknowledgements are also extended to the Michigan Manual on Uniform Traffic Control Devices (MMUTCD), 2011 Edition, for additional source material.
In general, the information in this document can be found in Chapters 3 and 9 of the AASHTO publication, and in Part 3 of the MMUTCD publication. For all references used in this guide, the document and page number is provided, i.e.
(2011 AASHTO, 3-1).
TYPES OF SIGHT DISTANCE
“Sight distance is the distance along a roadway throughout which an object of specified height is continuously visible to the driver. This distance is dependent on the height of the driver’s eye above the road surface, the specified object height above the road surface, and the height and lateral position of sight obstructions within the driver’s line of sight.” (2011 AASHTO, 3-14)
Following are the four types of sight distance:
• Stopping Sight Distance
• Passing Sight Distance
• Decision Sight Distance
• Intersection Sight Distance
Each of the different types of sight distance will be further detailed in the next four sections.
MDOT Traffic & Safety
iii
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
STOPPING SIGHT
DISTANCE
MDOT Traffic & Safety
Page 1 of 52
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
Quick Charts for Stopping Sight Distance
Design
Stopping Rate of Vertical Curvature, K*
Speed (mph)
Sight Distance (ft)
Calculated
Design
15
80
3.0
3
20
115
6.1
7
25
155
11.1
12
30
200
18.5
19
35
250
29.0
29
40
305
43.1
44
45
360
60.1
61
50
425
83.7
84
55
495
113.5
114
60
570
150.6
151
65
645
192.8
193
70
730
246.9
247
75
820
311.6
312
80
910
383.7
384
Design Controls for Stopping Sight Distance and Crest Vertical Curves
(2011 AASHTO, Exhibit 3-34, 3-155)
Design
Stopping Rate of Vertical Curvature, K*
Speed (mph)
Sight Distance (ft)
Calculated
Design
15
80
9.4
10
20
115
16.5
17
25
155
25.5
26
30
200
36.4
37
35
250
49.0
49
40
305
63.4
64
45
360
78.1
79
50
425
95.7
96
55
495
114.9
115
60
570
135.7
136
65
645
156.5
157
70
730
180.3
181
75
820
205.6
206
80
910
231.0
231
Design Controls for Stopping Sight Distance and Sag Vertical Curves
(2011, AASHTO, Exhibit 3-36, 3-161)
*Rate of vertical curvature, K, is the length of curve (L) per percent Algebraic difference on intersecting grades (A). K= L/A
MDOT Traffic & Safety
Page 3 of 52
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
MDOT Traffic & Safety
Page 4 of 52
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
According to the 2011 AASHTO, 2011 MMUTCD, and Michigan Department of Transportation Guidelines
PREPARED BY GEOMETRICS AND OPERATIONS UNIT
TRAFFIC AND SAFETY April 22, 2015
“Providing the highest quality transportation services for economic benefit and improved quality of life.”
INDEX
PAGE NUMBER ACKNOWLEDGEMENTS ...............................................................................................iii
TYPES OF SIGHT DISTANCE....................................................................................... iii
STOPPING SIGHT DISTANCE ...................................................................................... 1 Quick Charts for Stopping Sight Distance .............................................................. 3 STOPPING SIGHT DISTANCE ................................................................................... 5 Horizontal Stopping Sight Distance......................................................................... 6 Vertical Curves ........................................................................................................ 10 Crest Vertical Curves .............................................................................................. 11 Sag Vertical Curves ................................................................................................. 13 Design Controls: Stopping Sight Distance .......................................................... 16 General Control for Vertical Alignment ................................................................. 18
PASSING SIGHT DISTANCE ....................................................................................... 19 Quick Charts for Passing Sight Distance .............................................................. 21 PASSING SIGHT DISTANCE (Two-Lane, Two-Way Highways) ............................ 23 Measurement of Passing Sight Distance.................................................... .......... 24 Passing Sight Distance on Multilane Roadways................................................... 25 Passing Sight Distance for Horizontal Curves...................................................... 25 Passing Sight Distance for Vertical Curves .......................................................... 26 Passing Sight Distance - Pavement Markings ...................................................... 27
DECISION SIGHT DISTANCE...................................................................................... 30 Quick Chart for Decision Sight Distance ............................................................... 31 DECISION SIGHT DISTANCE .................................................................................. 33
INTERSECTION SIGHT DISTANCE ............................................................................ 37 Quick Charts for Intersection Sight Distance ....................................................... 39 INTERSECTION SIGHT DISTANCE......................................................................... 41 Intersections with Stop-Control on the Minor Road ............................................. 42 Intersection Sight Distance Considerations for Signalized Intersections .......... 48 Determination and Measurement of Intersection Sight Distance........................ 48 Field Measurement of Intersection Sight Distance............................................... 51
REFERENCES.............................................................................................................. 52
MDOT Traffic & Safety
i
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
MDOT Traffic & Safety
i
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
ACKNOWLEDGEMENTS
The Michigan Department of Transportation (MDOT) practices regarding sight distance measurement are based almost exclusively and entirely upon the AASHTO sight distance principles, theories, and methodologies. Therefore, it was not possible to produce this reference document without utilizing significant portions of the A Policy on Geometric Design of Highways and Streets, 2011, by the American Association of State Highway and Traffic Officials (AASHTO), Washington, D.C. MDOT would like to acknowledge the AASHTO publication (used by permission) as the major source material within this document. As a result, several sections of the AASHTO publication were incorporated into this document, either directly and intact, or paraphrased for ease of explanation and/or understanding. Acknowledgements are also extended to the Michigan Manual on Uniform Traffic Control Devices (MMUTCD), 2011 Edition, for additional source material.
In general, the information in this document can be found in Chapters 3 and 9 of the AASHTO publication, and in Part 3 of the MMUTCD publication. For all references used in this guide, the document and page number is provided, i.e.
(2011 AASHTO, 3-1).
TYPES OF SIGHT DISTANCE
“Sight distance is the distance along a roadway throughout which an object of specified height is continuously visible to the driver. This distance is dependent on the height of the driver’s eye above the road surface, the specified object height above the road surface, and the height and lateral position of sight obstructions within the driver’s line of sight.” (2011 AASHTO, 3-14)
Following are the four types of sight distance:
• Stopping Sight Distance
• Passing Sight Distance
• Decision Sight Distance
• Intersection Sight Distance
Each of the different types of sight distance will be further detailed in the next four sections.
MDOT Traffic & Safety
iii
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
STOPPING SIGHT
DISTANCE
MDOT Traffic & Safety
Page 1 of 52
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
Quick Charts for Stopping Sight Distance
Design
Stopping Rate of Vertical Curvature, K*
Speed (mph)
Sight Distance (ft)
Calculated
Design
15
80
3.0
3
20
115
6.1
7
25
155
11.1
12
30
200
18.5
19
35
250
29.0
29
40
305
43.1
44
45
360
60.1
61
50
425
83.7
84
55
495
113.5
114
60
570
150.6
151
65
645
192.8
193
70
730
246.9
247
75
820
311.6
312
80
910
383.7
384
Design Controls for Stopping Sight Distance and Crest Vertical Curves
(2011 AASHTO, Exhibit 3-34, 3-155)
Design
Stopping Rate of Vertical Curvature, K*
Speed (mph)
Sight Distance (ft)
Calculated
Design
15
80
9.4
10
20
115
16.5
17
25
155
25.5
26
30
200
36.4
37
35
250
49.0
49
40
305
63.4
64
45
360
78.1
79
50
425
95.7
96
55
495
114.9
115
60
570
135.7
136
65
645
156.5
157
70
730
180.3
181
75
820
205.6
206
80
910
231.0
231
Design Controls for Stopping Sight Distance and Sag Vertical Curves
(2011, AASHTO, Exhibit 3-36, 3-161)
*Rate of vertical curvature, K, is the length of curve (L) per percent Algebraic difference on intersecting grades (A). K= L/A
MDOT Traffic & Safety
Page 3 of 52
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015
MDOT Traffic & Safety
Page 4 of 52
PW Ref Docs\T&S\Typicals\Final\Geometrics\mdot_Guidelines_Sight_Distance.doc
April 22, 2015