introducción al manual de seguridad en carreteras, hsm...
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Introducción al Manual de Seguridad en Carreteras, HSM 2010
Benjamín Colucci Ríos, PhD, PE, JD, [email protected]ático
Auspiciado Por:Centro de Transferencia de Tecnología en Transportación
17 y 20 de octubre de 2014
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Buenos Días
Temas a cubrir: HSM Día 2
TALLER/WORKSHOP AM: RURAL
•Estimar los choques esperadosen carreteras rurales doscarriles en dos direcciones(Cap. 10 HSM)
•Uso de aplicación desarrolladaen Excel para estimar choquesaplicando metodología HSM
TALLER/WORKSHOP PM: URBANO
•Estimar los choques esperadospara arterias urbanas y sub-urbanas (Cap. 12 HSM)
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Temas a cubrir: HSM Día 2 (cont.)
•Site Selection Criteria for Determining Local Calibration Factors (Cr)
•Crash Modification Factor (CMF) Clearinghouse –FHWA http://www.cmfclearinghouse.org
•The future of HSM• New Changes in HSM 2010 (NCHRP 17-45)
•How the HSM fits within the Puerto Rico Strategic Highway Safety Plan (SHSP-PR): 2014-2018
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Workshop # 1 AMRural two way-two lane road
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Situation
Highway PR-114, a rural two-lane, two-way road segment located in the Municipality of Cabo Rojothat was treated with center-line rumble strips in 2012.
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Situation (cont.)•This segment is currently being investigated for alleged significant crash frequency during the past year 2013. Specifically, it consists of the following 3 segments: ◦ a 1.5 mile tangent segment followed by
◦ a 6.5° horizontal curve with an intersection angle of 60 °and
◦ a 1.0 mile tangent segment after the point of tangency.
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Situation (cont.)•Concrete utility poles (not shown in thephotograph) with a longitudinal spacing of 150 ft.were located at 3 ft. from the pavement edge whenthe crashes occurred in 2013.
•The concrete poles were removed by theDepartment of Transportation and Public Worksdue to the high incidents of “single vehicle run-offthe road” crashes that impacted the utility poles.
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Situation (cont.)•The proportion of total night time crashes forunlighted roadway segments that involve a fatalityor injury is 38% and the remaining 62% involveproperty damage only.
•The proportion of total crashes that occur at nightfor unlighted roadway segments is 37%.
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Rural Two-lane, Two-way Road Segment
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Pertinent Data:•Design speed: 50 mph
•AADT: 1,800 veh/day
•Lane width: 11 ft.
•Shoulder width: 2 ft.
•Shoulder type: gravel
•Vertical Alignment: 3.0 %
•AASHTO Green Book superelevation rate: 0.065 ft/ft
•Maximum (actual) superelevation rate: 0.08 ft/ft
•Coefficient of side friction: 0.14 ft/ft
•CMF for Centerline Rumble Strips in PR: 0.91
•Driveways ◦ North Bound: 2
◦ South Bound: 1
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Assumptions•Calibration Factor equal to 1.0.
•There is no spiral transition present in this horizontal alignment.
•There are no guardrails installed in the roadside.
•No left-turn lanes are provided.
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Required•Radius of curvature
•Minimum radius of curvature for the design speed
•Does the horizontal curve satisfy minimum AASHTO requirements?
•Length of horizontal curve
•Predicted total crash frequency for roadway segment base conditions
•Superelevation Variance
•Driveway Density
•Roadside Hazard Rating
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Required (cont.)•Crash Modification Factors (CMF’s) applicable only to the horizontal curves segment
1. CMF for the effect of lane width on total crashes2. CMF for the effect of lane width on related crashes3. CMF for the effect of shoulder width and type on total crashes4. CMF for related crashes based on shoulder width5. CMF for related crashes based on shoulder type6. CMF for the effect of horizontal alignment on total crashes7. CMF for the effect of superelevation variance on total crashes8. CMF for the effect of driveway density on total crashes9. CMF for effect of roadside design10. CMF for the effect of lighting of total crashes
•Combined Crash Modification Factor (CMF)
•Predicted Average Crash Frequency
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Workshop # 1 AMRural two way-two lane road
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Solution
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Solution
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Workshop #2 PM Urban
URBAN AND SUBURBAN ARTERIAL ROADS
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Urban Arterial RoadsUrban = an area typified by high densities of development or concentrations of population (population > 5,000 people)
Arterial = road that provides high level of service at a great speed for uninterrupted distance, with some degree of access control.
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Urban Arterial Predicted CrashesAs per Highway Safety Manual Chapter 12
Example utilizing:HSM worksheets
HSM Excel Spreadsheet
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HSM Worksheets…
Found in Appendix A of the Highway Safety Manual 2010
Multiple sheets arranged in a logical order
Organizes the information needed to calculate the crash frequency
Provides the equation and table references for guidance
Online Excel spreadsheet version available on the HSM website
How to obtain the Excel Tool:
22www.highwaysafetymanual.org
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Tools
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Choose the Excel Spreadsheet that pertains to your road characteristics:
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Now, let’s try some sample problems…
Beta Versions…
A Two-Lane Undivided Arterial Roadway Segment•2.5 mile length of Calle Méndez Vigo, Dorado, PR
•15,000 veh/day
•2.0 mi of parallel on-street commercial parking on each side of street
•50 driveways (30 minor commercial, 1 major commercial, 5 majorresidential, 10 minor residential, 4 minor industrial/institutional)
•Utility poles located 5 feet from the side of the road (12 poles per mile)
•Lighting present
•30-mph posted speed
•Collision type distributions are the default values in HSM 2010
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Example of Two-Lane Undivided Urban Arterial: Calle Méndez Vigo (Dorado, PR)
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Required:•Crash Modification Factors (CMF’s) applicable
1. CMF for the effect of on-street parking
2. CMF for the effect of roadside fixed objects
3. CMF for the effect of the median width
4. CMF for the effect of lighting
5. CMF for the effect of automated speed enforcement
•Combined Crash Modification Factor (CMF)
•Predicted Average Crash Frequency
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Situation:•A 2.5 mile long road segment located on an arterial in the urban City of Dorado
•What is the predicted crash frequency of the road segment?
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First, find out what is site type from Table 12-1:
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Worksheet 1A: Let’s Get Started
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AADTMAX = 53,800 (veh/day)
30
1.00
Offset to roadside fixed objects (ft) [If greater than 30 or Not Present, input 30]
Calibration Factor, Cr
Minor commercial driveways (number) --
Other driveways (number)
Speed Category
Roadside fixed object density (fixed objects / mi)
--
0
Minor residential driveways (number) --
--
--
Worksheet 1A -- General Information and Input Data for Urban and Suburban Roadway Segments
General Information Location Information
Agency or Company Roadway Section
Analyst Roadway
JurisdictionDate Performed
Input Data Base Conditions Site Conditions
Analysis Year
Length of segment, L (mi) --
None
Roadway type (2U, 3T, 4U, 4D, ST) --
--
Proportion of curb length with on-street parking --
Type of on-street parking (none/parallel/angle)
AADT (veh/day)
Major residential driveways (number)
Auto speed enforcement (present / not present) Not Present
Median width (ft) - for divided only 15
Lighting (present / not present) Not Present
--
Major commercial driveways (number) --
Major industrial / institutional driveways (number)
Minor industrial / institutional driveways (number)
--
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Worksheet 1A: General Input for Urban & Suburban Roadway Segments
AADTMAX = 32,600 (veh/day)
530
1.00 1.00
Offset to roadside fixed objects (ft) [If greater than 30 or Not Present, input 30]
Calibration Factor, Cr
Minor commercial driveways (number) -- 30
Other driveways (number)
Speed Category
Roadside fixed object density (fixed objects / mi)
0
4
--
12
10
0
Minor residential driveways (number) --
Posted Speed 30 mph or Lower
--
--
0
Worksheet 1A -- General Information and Input Data for Urban and Suburban Roadway Segments
General Information Location Information
Agency or Company T2 Center Roadway Section MP 0.0 to MP 1.5
Analyst YR Roadway 2-Lane Undivided Arterial Segment
Jurisdiction Puerto RicoDate Performed 10/17/14
Input Data Base Conditions Site Conditions
Analysis Year 2014
Length of segment, L (mi) -- 2.5
None
Roadway type (2U, 3T, 4U, 4D, ST) -- 2U
-- 15,000
Proportion of curb length with on-street parking -- 0.8
Type of on-street parking (none/parallel/angle) Parallel (Comm/Ind)
AADT (veh/day)
Major residential driveways (number)
Auto speed enforcement (present / not present) Not Present Not Present
Median width (ft) - for divided only 15 Not Present
Lighting (present / not present) Not Present Present
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--
Major commercial driveways (number) -- 1
Major industrial / institutional driveways (number)
Minor industrial / institutional driveways (number)
--
Next Calculate the CMF’s
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Where is the CMF information?
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On Street Parking CMF (Equation 12-32)𝐶𝑀𝐹1𝑟 = 1 + 𝑝𝑝𝑘 × (𝑓𝑝𝑘 −1.0))
Where:CMF1r = crash modification factor for the effect of on-street parking on total crashesfpk = factor from Table 12-19ppk = proportion of curb length with on-street parking = (0.5 Lpk / L)Lpk = sum of curb length with on-street parking for both sides of the road combined (miles)L = length of roadway segment (miles)
On Street Parking CMF (Equation 12-32)
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𝑝𝑝𝑘 =0.5 2 𝑚𝑖𝑙𝑒𝑠 + 2 𝑚𝑖𝑙𝑒𝑠
2.5 𝑚𝑖𝑙𝑒𝑠
𝑝𝑝𝑘 = 0.8
𝐶𝑀𝐹1𝑟 = 1 + 0.8 ∗ (2.074 − 1.0)
𝐶𝑀𝐹1𝑟=1.86
𝐶𝑀𝐹1𝑟 = 1 + 𝑝𝑝𝑘 × (𝑓𝑝𝑘 − 1.0)
Where:CMF1r = crash modification factor for the effect of on-street parking on total crashesfpk = factor from Table 12-19ppk = proportion of curb length with on-street parking = (0.5 Lpk / L)Lpk = sum of curb length with on-street parking for both sides of the road combined (miles)L = length of roadway segment (miles)
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Roadside Fixed Objects CMF (Eqn 12-33)
Where:
CMF2r = crash modification factor for the effect of roadside fixed objects on total crashes
foffset = fixed-object offset factor from Table 12-20
Dfo = fixed-object density (fixed objects/ mile) for both sides of the road combined
pfo = fixed-object collisions as a proportion of total crashes from Table 12-21
𝐶𝑀𝐹2𝑟 = 𝑓𝑜𝑓𝑓𝑠𝑒𝑡 × 𝐷𝑓𝑜 × 𝑝𝑓𝑜 + (1.0 − 𝑝𝑓𝑜)
Roadside Fixed Objects CMF (Equation 12-33)
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𝑓𝑜𝑓𝑓𝑠𝑒𝑡 = 0.133
𝑃𝑓𝑜 = 0.059
𝐶𝑀𝐹2𝑟 = 0.133 ∗ 12 ∗ 0.059 + (1.0 − 0.059)
𝐶𝑀𝐹2𝑟 = 1.03
𝐶𝑀𝐹2𝑟 = 𝑓𝑜𝑓𝑓𝑠𝑒𝑡 × 𝐷𝑓𝑜 × 𝑝𝑓𝑜 + (1.0 − 𝑝𝑓𝑜)
Where:
CMF2r = crash modification factor for the effect of roadside fixed objects on total crashes
Foffset = fixed-object offset factor from Table 12-20
Dfo = fixed-object density (fixed objects/ mile) for both sides of the road combined
Pfo = fixed-object collisions as a proportion of total crashes from Table 12-21
Median Width CMF (Table 12-22)
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CMF=1 is used for:• Medians without traffic
barriers• For undivided facilities
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Lighting CMF (Equation 12-34)
CMF4r = crash modification factor for the effect of roadway segment lighting on total crashespinr = proportion of total nighttime crashes for unlighted roadway segments that involve a fatality or injuryppnr = proportion of total nighttime crashes for unlighted roadway segments that involve property damage onlyPnr = proportion of total crashes for unlighted roadway segments that occur at night
𝐶𝑀𝐹4𝑟 = 1.0 − (𝑝𝑛𝑟 × (1.0 − 0.72 × 𝑝𝑖𝑛𝑟 − 0.83 × 𝑝𝑝𝑛𝑟))
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Lighting CMF (Equation 12-34)
pinr=0.424 ppnr=0.576 pnr=0.316
𝐶𝑀𝐹4𝑟 = 1.0 − (0.316 × 1.0 − 0.72 × 0.424 − 0.83 × 0.576 )
𝐶𝑀𝐹4𝑟 = 0.93
𝐶𝑀𝐹4𝑟 = 1.0 − (𝑝𝑛𝑟 × (1.0 − 0.72 × 𝑝𝑖𝑛𝑟 − 0.83 × 𝑝𝑝𝑛𝑟))
CMF4r = crash modification factor for the effect of roadway segment lighting on total crashespinr = proportion of total nighttime crashes for unlighted roadway segments that involve a fatality or injuryppnr = proportion of total nighttime crashes for unlighted roadway segments that involve property damage onlyPnr = proportion of total crashes for unlighted roadway segments that occur at night
Automated Speed Enforcement CMFNo automated speed enforcement (base condition):◦ CMF=1
If there is automated speed enforcement:◦ Fatal and Injury Crashes – CMF=0.83
◦ Non-injury (PDO) – CMF=0.95
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Combined CMFs𝐶𝑀𝐹(𝑐𝑜𝑚𝑏𝑖𝑛𝑒𝑑) = 𝐶𝑀𝐹1𝑟 ×
𝐶𝑀𝐹2𝑟 × 𝐶𝑀𝐹3𝑟 × 𝐶𝑀𝐹4𝑟 ×𝐶𝑀𝐹5
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𝐶𝑀𝐹 𝑐𝑜𝑚𝑏𝑖𝑛𝑒𝑑 = 1.86 × 1.03 × 1.00 × 0.93 × 1.00
𝐶𝑀𝐹 𝑐𝑜𝑚𝑏𝑖𝑛𝑒𝑑 = 1.79
Worksheet 1B: CMF’s
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CMF combCMF 2r CMF 3r CMF 4r CMF 5r
(1)*(2)*(3)*(4)*(5)
CMF 1r
CMF for On-Street
Parking
CMF for Roadside
Fixed Objects
from Section 12.7.1
CMF for Automated Speed
Enforcement
from Equation 12-32 from Equation 12-33 from Table 12-22 from Equation 12-34
(6)
Combined CMF
(5)
Worksheet 1B -- Crash Modification Factors for Urban and Suburban Roadway Segments
(1) (2) (3)
CMF for Median Width
(4)
CMF for Lighting
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Next calculate SPFs By Collision Type
Multiple-vehicle collision – two or more moving motor vehicles involved in the crash in the following manners:• rear-end
• head-on
• angle
• sideswipe
• other
Single-vehicle collision – one moving motor vehicle involved in a crash in the following manners: collision with parked vehicle, collision with animal, collision with fixed object, collision with other object, non-collision, other
Worksheet 1C: Multiple-Vehicle Nondriveway
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(6) (7) (8) (9)
a b
Predicted
Nbrmv
SPF Coefficients
Initial Nbrmv
Proportion of Total
Crashes
Calibration
Factor, Cr
from Table 12-3
Overdispersion
Parameter, k
Combined
CMFs
(6) from
Worksheet 1B
(2)
Crash Severity
Level
Adjusted
Nbrmv
Total
Fatal and Injury
(FI)
(1)
Worksheet 1C -- Multiple-Vehicle Nondriveway Collisions by Severity Level for Urban and Suburban Roadway Segments
(3) (4) (5)
from Table 12-3 from Equation 12-10 (4)TOTAL*(5)
(4)FI/((4)FI+(4)PDO)
(6)*(7)*(8)
Property
Damage Only
(PDO)
(5)TOTAL-(5)FI
Table 12-3
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Equation 12-10𝑁𝑏𝑟𝑚𝑣 = exp(𝑎 + 𝑏 × ln 𝐴𝐴𝐷𝑇 + ln(𝐿))
Where:
AADT=average annual daily traffic volume (veh/day) on roadway segment
L= length of roadway segment (mi)
a, b = regression coefficients
Nbrmv (total)= exp (-15.22+1.68 x ln(15,000)+ln(2.5) )=6.365
Nbrmv (FI)=exp (-16.22+1.66 x ln(15,000)+ln(2.5) )= 1.932
Nbrmv (PDO)=exp(-15.62+1.69 x ln(15,000)+ln(2.5) )= 4.697
But wait! 1.932+4.697≠ 6.365 Not finished yet…
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Equations 12-11 and 12-12
In order to adjust the values…
𝑁𝑏𝑟𝑚𝑣 = 6.365(1.932
1.932+4.697)= 1.855
𝑁𝑏𝑟𝑚𝑣= 6.365 – 1.855 = 4.510
*Multiply these values by the combined CMFs (1.79) and the calibration factor (1.0)
𝑁𝑏𝑟𝑚𝑣(𝐹𝐼) = 𝑁𝑏𝑟𝑚𝑣(𝑡𝑜𝑡𝑎𝑙)𝑁′𝑏𝑟𝑚𝑣(𝐹𝐼)
𝑁′𝑏𝑟𝑚𝑣 𝐹𝐼 +𝑁′𝑏𝑟𝑚𝑣(𝑃𝐷𝑂)Equation 12-11
𝑁𝑏𝑟𝑠𝑣(𝑃𝐷𝑂) = 𝑁𝑏𝑟𝑠𝑣(𝑡𝑜𝑡𝑎𝑙) − 𝑁𝑏𝑟𝑠𝑣 𝐹𝐼 Equation 12-12
Worksheet 1C: Multiple Vehicle Nondriveway Crashes by Severity
(6) (7) (8) (9)
a b
-15.22 1.68 6.365 1.79 1.00 11.410
Predicted
Nbrmv
SPF Coefficients
Initial Nbrmv
Proportion of Total
Crashes
Calibration
Factor, Cr
from Table 12-3
Overdispersion
Parameter, k
Combined
CMFs
(6) from
Worksheet 1B
(2)
6.365
1.855
Crash Severity Level
-15.62 1.69 0.87
Adjusted
Nbrmv
Total
Fatal and Injury (FI) -16.22 1.66
(1)
Worksheet 1C -- Multiple-Vehicle Nondriveway Collisions by Severity Level for Urban and Suburban Roadway Segments
(3) (4) (5)
from Table 12-3 from Equation 12-10 (4)TOTAL*(5)
0.65
0.84
1.00
3.325
8.085
(4)FI/((4)FI+(4)PDO)
1.000
0.2911.00
(6)*(7)*(8)
1.932 1.79
Property Damage Only (PDO)0.709
(5)TOTAL-(5)FI4.697 4.510 1.79
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Nbrmv (total) = 11.410 crashes/ yrNbrmv (FI) = 3.325 crashes/ yrNbrmv (PDO) = 8.085 crashes/ yr
Worksheet 1D: Multiple Nondriveway Crashes by Type
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Predicted N brmv ( PD O)
(crashes/year)
from Table 12-4(9)PDO from Worksheet
1C(9)FI from Worksheet 1C
Predicted N brmv ( F I)
(crashes/year)
Proportion of
Collision Type ( F I)
from Table 12-4
Total
(2)*(3)FI (4)*(5)PDO (3)+(5)
(2) (4) (6)
Predicted N brmv (TOTAL)
(crashes/year)
Worksheet 1D -- Multiple-Vehicle Nondriveway Collisions by Collision Type for Urban and Suburban Roadway Segments
(3)(1)
Collision Type Proportion of
Collision Type (PDO)
Sideswipe, same direction
Rear-end collision
Head-on collision
Angle collision
Sideswipe, opposite direction
Other multiple-vehicle collision
(5)
(9)TOTAL from Worksheet 1C
Table 12-4
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Worksheet 1D: Multiple Nondriveway Crashes by Type
Predicted N brmv ( PD O)
(crashes/year)
from Table 12-4(9)PD O from Worksheet
1C
(9)F I from Worksheet
1C
Predicted N brmv ( F I)
(crashes/year)
Proportion of Collision
Type( F I)
from Table 12-4
1.000 1.000Total 3.325 8.085 11.410
(2)*(3)FI (4)*(5)PDO (3)+(5)
(2) (4) (6)
Predicted N brmv (TOTAL) (crashes/year)
Worksheet 1D -- Multiple-Vehicle Nondriveway Collisions by Collision Type for Urban and Suburban Roadway Segments
(3)(1)
Collision Type Proportion of Collision
Type (PDO)
Sideswipe, same direction
Rear-end collision
Head-on collision
Angle collision
Sideswipe, opposite direction
Other multiple-vehicle collision
0.730
0.068
0.085
0.015
0.073
0.029
(5)
(9)TOTA L from Worksheet 1C
8.7176.290
0.226
0.283
0.050
0.243
0.096
2.427
0.445
0.428
0.778
0.004
0.079
0.031
0.055
0.258
0.921
0.300
0.687
0.5250.053
0.032
0.639
0.251
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Worksheet 1E: Single Vehicle Crashes by Severity
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(6) (7) (8) (9)
a b
Combined
CMFs
Calibration
Factor, Cr
Predicted
Nbrsv
(5)TOTAL-(5)FIProperty Damage Only (PDO)
Fatal and Injury (FI)(4)FI/((4)FI+(4)PDO)
Total
Crash Severity Level
SPF Coefficients Overdispersion
Parameter, k Initial Nbrsv
Worksheet 1E -- Single-Vehicle Collisions by Severity Level for Urban and Suburban Roadway Segments
(1) (2) (3) (4) (5)
Proportion of Total
Crashes
Adjusted
Nbrsv
from Table 12-5from Table 12-5 from Equation 12-13 (4)TOTAL*(5)
(6) from
Worksheet 1B(6)*(7)*(8)
Table 12-5
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13
Equation 12-13𝑁𝑁 𝑏𝑟s𝑣=exp(𝑎+𝑏×ln(𝐴𝐴𝐷𝑇)+ln〖(𝐿)〗
Where:
AADT=average annual daily traffic volume (veh/day) on roadway segment
L= length of roadway segment (mi)
a, b = regression coefficients
Nbrsv (total)= exp (-5.47+0.56 x ln(15,000)+ln(2.5)) =2.296
Nbrsv (FI)=exp (-3.96+0.23 x ln(15,000)+ln(2.5)) = 0.435
Nbrsv (PDO)=exp(-6.51+0.64 x ln(15,000)+ln(2.5)) = 1.751
Next…
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Equations 12-14 and 12-15
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In order to adjust the values…
𝑁𝑏𝑟𝑠𝑣 = 2.2960.435
0.435+1.751= 0.457
𝑁𝑏𝑟s𝑣= 2.296 – 0.457 = 1.839
Multiply these values by the combined CMFs (1.79) and the calibration factor (1.0)
𝑁𝑏𝑟𝑠𝑣(𝐹𝐼) = 𝑁𝑏𝑟𝑠𝑣(𝑡𝑜𝑡𝑎𝑙)𝑁′𝑏𝑟𝑠𝑣(𝐹𝐼)
𝑁′𝑏𝑟𝑠𝑣 𝐹𝐼 +𝑁′𝑏𝑟𝑠𝑣(𝑃𝐷𝑂)Equation 12-14
𝑁𝑏𝑟𝑠𝑣(𝑃𝐷𝑂) = 𝑁𝑏𝑟𝑠𝑣(𝑡𝑜𝑡𝑎𝑙) − 𝑁𝑏𝑟𝑠𝑣 𝐹𝐼 Equation 12-15
Worksheet 1E: Single Vehicle Crashes by Severity
(6) (7) (8) (9)
a b
-5.47 0.56 2.296 1.79 1.00 4.115
Combined
CMFs
Calibration
Factor, Cr
Predicted
Nbrsv
(5)TOTAL-(5)FI 1.839 1.79 1.00 3.2960.801
0.457 1.79 0.8190.199
Property Damage Only (PDO) -6.51 0.64 0.87 1.751
Fatal and Injury (FI) -3.96 0.23 0.50 0.435(4)FI/((4)FI+(4)PDO)
Total 0.81 2.296 1.000
Crash Severity Level
SPF Coefficients Overdispersion
Parameter, k Initial Nbrsv
1.00
Worksheet 1E -- Single-Vehicle Collisions by Severity Level for Urban and Suburban Roadway Segments
(1) (2) (3) (4) (5)
Proportion of Total
Crashes
Adjusted
Nbrsv
from Table 12-5from Table 12-5 from Equation 12-13 (4)TOTAL*(5)
(6) from
Worksheet 1B(6)*(7)*(8)
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Nbrsv (total) = 4.115 crashes/ yrNbrsv (FI) = 0.819 crashes/ yrNbrsv (PDO) = 3.296 crashes/ yr
Worksheet 1F: Single Vehicle Crashes by Type
60
Other single-vehicle collision
Collision with fixed object
Collision with other object
(4)*(5)PDO (3)+(5)
Collision with animal
(2)*(3)FI
Total
Proportion of
Collision Type (PDO)
Predicted N brsv ( PD O)
(crashes/year)Predicted N brsv (TOTAL)
(crashes/year)Collision Type
Proportion of
Collision Type ( F I)
Predicted N brsv ( F I)
(crashes/year)
from Table 12-6
(2) (3) (4) (5) (6)
(9)FI from Worksheet 1E from Table 12-6(9)PDO from Worksheet
1E(9)TOTAL from Worksheet 1E
Worksheet 1F -- Single-Vehicle Collisions by Collision Type for Urban and Suburban Roadway Segments
(1)
Table 12-6
61
Worksheet 1F: Single Vehicle Crashes by Type
0.010 0.008
Other single-vehicle collision 0.241 0.197 0.162 0.534 0.731
0.013 0.043 0.051
Collision with fixed object 0.723 0.592 0.759 2.502 3.094
Collision with other object
(4)*(5)PDO (3)+(5)
Collision with animal 0.026 0.021 0.066 0.218 0.239
(2)*(3)FI
Total 1.000 0.819 4.115
Proportion of Collision
Type (PDO)
Predicted N brsv ( PD O)
(crashes/year) Predicted N brsv (TOTAL) (crashes/year)
Collision Type
Proportion of Collision
Type( F I)
Predicted N brsv ( F I)
(crashes/year)
from Table 12-6
(2) (3) (4) (5)
1.000 3.296
(6)
(9)F I from Worksheet
1Efrom Table 12-6
(9)PD O from Worksheet
1E(9)TOTA L from Worksheet 1E
Worksheet 1F -- Single-Vehicle Collisions by Collision Type for Urban and Suburban Roadway Segments
(1)
62
Column (3) Nbrsv (FI) = 0.819 crashes/ yrColumn (5) Nbrsv (PDO) = 3.296 crashes/ yrColumn (6) Nbrsv (total) = 4.115 crashes/ yr
Worksheet 1G: Multiple Vehicle Driveway Related by Driveway Type
63
Minor residential
Other
Total
Major residential
Minor commercial
Major industrial/institutional
Minor industrial/institutional
from Table 12-7from Table 12-7
Number of
driveways, nj Equation 12-16Driveway Type
Major commercial
Worksheet 1G -- Multiple-Vehicle Driveway-Related Collisions by Driveway Type for Urban and Suburban Roadway Segments
(1) (2) (3)
from Table 12-7
Crashes per driveway
per year, Nj
(4) (5) (6)
Coefficient for traffic
adjustment, tInitial Nbrdwy
Overdispersio
n parameter, k
nj * Nj * (AADT/15,000)t
--
Table 12-7
64
Worksheet 1G: Multiple Vehicle Driveway Related by Driveway Type
Minor residential
Other
Total
1
30
0
4
Major residential 5
10
Minor commercial
Major industrial/institutional
Minor industrial/institutional
from Table 12-7from Table 12-7
Number of driveways,
nj Equation 12-16
0.000
0.092
Driveway Type
Major commercial
Worksheet 1G -- Multiple-Vehicle Driveway-Related Collisions by Driveway Type for Urban and Suburban Roadway Segments
(1) (2) (3)
from Table 12-7
Crashes per driveway
per year, Nj
(4) (5) (6)
Coefficient for traffic
adjustment, tInitial Nbrdwy
Overdispersion
parameter, k
nj * Nj * (AADT/15,000)t
0
--
0.158
0.050
0.172
0.023
0.083
0.016
0.025
--
1.000
--
0.000
2.325 0.81
--
0.158
0.415
0.160
1.000
1.000
1.000
1.000
1.000
1.000
1.500
65
N taken from the given information
Worksheet 1G: Multiple Vehicle Driveway Related by Driveway Type
Minor residential
Other
Total
1
30
0
4
Major residential 5
10
Minor commercial
Major industrial/institutional
Minor industrial/institutional
from Table 12-7from Table 12-7
Number of driveways,
nj Equation 12-16
0.000
0.092
Driveway Type
Major commercial
Worksheet 1G -- Multiple-Vehicle Driveway-Related Collisions by Driveway Type for Urban and Suburban Roadway Segments
(1) (2) (3)
from Table 12-7
Crashes per driveway
per year, Nj
(4) (5) (6)
Coefficient for traffic
adjustment, tInitial Nbrdwy
Overdispersion
parameter, k
nj * Nj * (AADT/15,000)t
0
--
0.158
0.050
0.172
0.023
0.083
0.016
0.025
--
1.000
--
0.000
2.325 0.81
--
0.158
0.415
0.160
1.000
1.000
1.000
1.000
1.000
1.000
1.500
66
Variables Nj and t taken from Table 12-7
Equation 12-16𝑁𝑁 𝑏𝑟dwy=exp (a+b x ln(AADT) + ln(L))
Where:
AADT=average annual daily traffic volume (veh/day) on roadway segment
L= length of roadway segment (mi)
a, b = regression coefficients
Nbrdwy (total)= exp (-5.47+0.56 x ln(15,000)+ln(2.5) =2.296
Nbrdwy (FI)=exp (-3.96+0.23 x ln(15,000)+ln(2.5) = 0.435
Nbrdwy (PDO)=exp(-6.51+0.64 x ln(15,000)+ln(2.5) = 1.751
Next…
67
68
Equations 12-17 and 12-18
In order to adjust the values…
𝑁𝑏𝑟𝑠𝑣 = 2.2960.435
0.435+1.751= 0.457
𝑁𝑏𝑟s𝑣= 2.296 – 0.457 = 1.839
Multiply these values by the combined CMFs (1.79) and the calibration factor (1.0)
𝑁𝑑𝑟𝑤𝑦(𝐹𝐼) = 𝑁𝑏𝑟𝑑𝑤𝑦(𝑡𝑜𝑡𝑎𝑙) × 𝑓𝑑𝑤𝑦 (12-17)
𝑁𝑏𝑟𝑑𝑤𝑦(𝑃𝐷𝑂) = 𝑁𝑏𝑟𝑑𝑤𝑦(𝑡𝑜𝑡𝑎𝑙) − 𝑁𝑏𝑟𝑑𝑤𝑦(𝐹𝐼) (12-18)
Where:Fdwy = proportion of driveway-related collisions that involve fatalities or injuries
Worksheet 1H: Multiple Vehicle Driveway Related Crashes by Severity
69
(4) (5) (6) (7)
(4)*(5)*(6)
Proportion of total
crashes (fdwy)
Adjusted
Nbrdwy
Combined CMFsPredicted
Nbrdwy
Worksheet 1H -- Multiple-Vehicle Driveway-Related Collisions by Severity Level for Urban and Suburban Roadway Segments
(1) (2) (3)
Total
Crash Severity Level
Initial Nbrdwy
from Table 12-7
Fatal and injury (FI)
Property damage only (PDO)
--
--
(5)TOTAL from
Worksheet 1G(2)TOTAL * (3)
(6) from
Worksheet 1B
Calibration factor, Cr
70
Table 12-7 (for severity proportions)
Worksheet 1H: Multiple Vehicle Driveway Related Crashes by Severity
(4)
2.325
0.751
1.574
(5) (6) (7)
(4)*(5)*(6)
Proportion of total
crashes (fdwy)
Adjusted
Nbrdwy
Combined CMFs Predicted Nbrdwy
Worksheet 1H -- Multiple-Vehicle Driveway-Related Collisions by Severity Level for Urban and Suburban Roadway Segments
(1) (2) (3)
Total
Crash Severity Level
Initial Nbrdwy
1.000 4.168
from Table 12-7
Fatal and injury (FI)
Property damage only (PDO)
2.325
--
--
(5)TOTAL from Worksheet
1G
0.677
1.79
1.79
1.79
1.00
1.00
1.00
1.346
2.821
(2)TOTAL * (3)(6) from Worksheet
1B
Calibration factor, Cr
0.323
71
Worksheet 1I: Vehicle-Pedestrian Crashes
72
(6) (7)
fpedr
-- 0.00
Worksheet 1I -- Vehicle-Pedestrian Collisions for Urban and Suburban Roadway Segments
(1) (8)(2) (3) (4) (5)
Predicted Nbrdwy Predicted Nbr Predicted Npedr
from Table
12-8
Calibration
factor, Cr (5)*(6)*(7)(2)+(3)+(4)(7) from
Worksheet 1H
Crash Severity Level
Total
Fatal and injury (FI) --
Predicted Nbrsv
(9) from
Worksheet 1E
Predicted Nbrmv
-- -- --
(9) from
Worksheet 1C
0.000
Table 12-8
73
Worksheet 1I: Vehicle-Pedestrian Crashes(6) (7)
fpedr
0.036 1.00
-- 1.00
Worksheet 1I -- Vehicle-Pedestrian Collisions for Urban and Suburban Roadway Segments
(1) (8)(2) (3) (4) (5)
Predicted Nbrdwy Predicted Nbr Predicted Npedr
from Table
12-8
Calibration
factor, Cr (5)*(6)*(7)(2)+(3)+(4)(7) from Worksheet 1HCrash Severity Level
Total
Fatal and injury (FI)
11.410
--
Predicted Nbrsv
(9) from Worksheet 1E
Predicted Nbrmv
--
4.168
--
19.693
--
(9) from Worksheet 1C
0.709
0.709
4.115
74
(6) (7)
fpedr
0.036 1.00
-- 1.00
Worksheet 1I -- Vehicle-Pedestrian Collisions for Urban and Suburban Roadway Segments
(1) (8)(2) (3) (4) (5)
Predicted Nbrdwy Predicted Nbr Predicted Npedr
from Table
12-8
Calibration
factor, Cr (5)*(6)*(7)(2)+(3)+(4)(7) from Worksheet 1HCrash Severity Level
Total
Fatal and injury (FI)
11.410
--
Predicted Nbrsv
(9) from Worksheet 1E
Predicted Nbrmv
--
4.168
--
19.693
--
(9) from Worksheet 1C
0.709
0.709
4.115
(6) (7)
fpedr
0.036 1.00
-- 1.00
Worksheet 1I -- Vehicle-Pedestrian Collisions for Urban and Suburban Roadway Segments
(1) (8)(2) (3) (4) (5)
Predicted Nbrdwy Predicted Nbr Predicted Npedr
from Table
12-8
Calibration
factor, Cr (5)*(6)*(7)(2)+(3)+(4)(7) from Worksheet 1HCrash Severity Level
Total
Fatal and injury (FI)
11.410
--
Predicted Nbrsv
(9) from Worksheet 1E
Predicted Nbrmv
--
4.168
--
19.693
--
(9) from Worksheet 1C
0.709
0.709
4.115
Worksheet 1J: Vehicle-Bicycle Crashes
75
(6) (7)
fbiker
-- 0.00
Worksheet 1J -- Vehicle-Bicycle Collisions for Urban and Suburban Roadway Segments
(1) (2) (3) (4) (5) (8)
Crash Severity Level
Predicted Nbrmv Predicted Nbrsv Predicted Nbrdwy Predicted Nbr Calibration
factor, Cr
Predicted Nbiker
(9) from
Worksheet 1C
(9) from
Worksheet 1E
(7) from
Worksheet 1H(2)+(3)+(4)
from Table
12-9(5)*(6)*(7)
Total
Fatal and injury (FI) -- -- -- -- 0.000
Table 12-9
76
Worksheet 1J: Vehicle-Bicycle Crashes(6) (7)
fbiker
0.018 1.00
-- 1.00
Worksheet 1J -- Vehicle-Bicycle Collisions for Urban and Suburban Roadway Segments
(1) (2) (3) (4) (5) (8)
Crash Severity Level
Predicted Nbrmv Predicted Nbrsv Predicted Nbrdwy Predicted Nbr Calibration
factor, Cr
Predicted Nbiker
(9) from Worksheet 1C (9) from Worksheet 1E (7) from Worksheet 1H (2)+(3)+(4)from Table
12-9(5)*(6)*(7)
Total 11.410 4.115 4.168 19.693 0.354
Fatal and injury (FI) -- -- -- -- 0.354
77
Worksheet 1K: Crash Severity Distribution
78
(3) (4)(1)
(8) from Worksheet 1I and 1J
(5) from Worksheet 1D and 1F; and
(7) from Worksheet 1H
(6) from Worksheet 1D and 1F;
(7) from Worksheet 1H; and
Fatal and injury (FI) Property damage only (PDO) Total
MULTIPLE-VEHICLE
Rear-end collisions (from Worksheet 1D)
Head-on collisions (from Worksheet 1D)
(3) from Worksheet 1D and 1F;
(7) from Worksheet 1H; and
Collision with other object (from Worksheet 1F)
Other single-vehicle collision (from Worksheet 1F)
Collision with bicycle (from Worksheet 1J)
Collision with pedestrian (from Worksheet 1I)
SINGLE-VEHICLE
Subtotal
Total
Angle collisions (from Worksheet 1D)
Sideswipe, same direction (from Worksheet 1D)
Sideswipe, opposite direction (from Worksheet 1D)
Driveway-related collisions (from Worksheet 1H)
Other multiple-vehicle collision (from Worksheet 1D)
Subtotal
Collision with animal (from Worksheet 1F)
Collision with fixed object (from Worksheet 1F)
Worksheet 1K -- Crash Severity Distribution for Urban and Suburban Roadway Segments
(2)
(8) from Worksheet 1I and 1J
Collision type
Worksheet 1K: Crash Severity Distribution
(3) (4)(1)
(8) from Worksheet 1I and 1J
(5) from Worksheet 1D and 1F; and
(7) from Worksheet 1H
(6) from Worksheet 1D and 1F;
(7) from Worksheet 1H; and
Fatal and injury (FI) Property damage only (PDO) Total
MULTIPLE-VEHICLE
Rear-end collisions (from Worksheet 1D)
Head-on collisions (from Worksheet 1D)
8.717
0.258
(3) from Worksheet 1D and 1F;
(7) from Worksheet 1H; and
6.290
0.0320.226
Collision with other object (from Worksheet 1F)
Other single-vehicle collision (from Worksheet 1F)
10.906
Collision with bicycle (from Worksheet 1J)
Collision with pedestrian (from Worksheet 1I) 0.709
SINGLE-VEHICLE
0.283
0.050
0.243
1.346
0.354
4.671
0.921
0.197
0.096
Subtotal
Total
2.427
0.300
0.687
4.168
0.525
0.639
0.251
0.445
2.821
0.428
0.000
Angle collisions (from Worksheet 1D)
Sideswipe, same direction (from Worksheet 1D)
Sideswipe, opposite direction (from Worksheet 1D)
Driveway-related collisions (from Worksheet 1H)
Other multiple-vehicle collision (from Worksheet 1D)
Subtotal
1.882
Collision with animal (from Worksheet 1F)
Collision with fixed object (from Worksheet 1F)
15.577
Worksheet 1K -- Crash Severity Distribution for Urban and Suburban Roadway Segments
(2)
6.554
0.218
2.502
0.043
0.534
0.000
3.296 5.179
20.756
0.709
0.354
0.239
3.094
0.051
0.731
(8) from Worksheet 1I and 1J
14.203
Collision type
0.021
0.592
0.008
79
FI Crashes = 6.554 PDO Crashes = 14.203 Total Crashes = 20.756
Worksheet 1L: Summary of Results
80
(4)
Predicted average crash
frequency, N predicted rs
(crashes/year)
Roadway segment length, L
(mi)
(Total) from Worksheet 1K
Total
Fatal and injury (FI)
(1)
Crash Severity Level
(2)
Property damage only (PDO)
Crash rate (crashes/mi/year)
(2) / (3)
(3)
Worksheet 1L -- Summary Results for Urban and Suburban Roadway Segments
Worksheet 1L: Summary of Results
(4)
Predicted average crash
frequency, N predicted rs
(crashes/year)Roadway segment length, L (mi)
(Total) from Worksheet 1K
Total
Fatal and injury (FI)
2.50
2.50
(1)
Crash Severity Level
(2)
Property damage only (PDO)
20.8
6.6
14.2
Crash rate (crashes/mi/year)
(2) / (3)
2.50
8.3
2.6
5.7
(3)
Worksheet 1L -- Summary Results for Urban and Suburban Roadway Segments
81
Urban 4 Leg Signalized Intersection(This example using the Excel Tool)
82
Pertinent Data:•1 left-turn lane on each of the two major road approaches
•No right-turn lanes
•Protected left-turn signal phasing on major road (both approaches)
•AADT (major rd) = 20,000 veh/ day
•AADT (minor rd) = 8,000 veh/ day
•Lighting is present
83
Pertinent Data (cont.):•1 bus stop 400 ft from the intersection
•A high school is located 800 ft from the intersection
•Coqui Bar, Coco Bar, Fiesta Bar, and Margarita Bar located within 1,000 ft of the intersection
•No approaches with prohibited right-turn-on-red
•4-lane undivided major road
•2-lane undivided minor road
•Pedestrian volume = 1,200 ped/day
84
Assumptions:•The calibration factor = 1.00
•The maximum number of lanes crossed by a pedestrian is assumed to be 4
•Collision type distributions are the default values from HSM 2010
85
86
Required:•Crash Modification Factors (CMF’s) applicable only to the four-leg signalized intersections
1. CMF for the effect of left-turn lanes
2. CMF for the effect of left-turn signal phasing
3. CMF for the effect of right-turn lanes
4. CMF for the effect of right-turn-on-red
5. CMF for the effect of lighting
6. CMF for the effect of red-light cameras
7. CMF for the effect of bus stops
8. CMF for the effect of schools
9. CMF for the effect of alcohol sales establishments
•Combined Crash Modification Factor (CMF)
•Predicted Average Crash Frequency
First, find out what is the site type from Table 12-1:
87
Safety Performance Functions for Urban and Suburban Arterials (Table 12-2)
88
89
AADTMAX = 67,700 (veh/day)
AADTMAX = 33,400 (veh/day)
Type of left-turn signal phasing for Leg #4 (if applicable) --
Number of alcohol sales establishments within 300 m (1,000 ft) of the intersection 0
Not PresentSchools within 300 m (1,000 ft) of the intersection (present/not present)
Number of approaches with left-turn lanes (0,1,2,3,4) [for 3SG, use maximum value of 3]
0
--
Number of approaches with right-turn lanes (0,1,2,3,4) [for 3SG, use maximum value of 3]
Intersection red light cameras (present/not present)
--
Type of left-turn signal phasing for Leg #1
Maximum number of lanes crossed by a pedestrian (nlanesx)
Sum of all pedestrian crossing volumes (PedVol) -- Signalized intersections only
Type of left-turn signal phasing for Leg #2
Intersection lighting (present/not present) Not Present
Calibration factor, Ci
AADT minor (veh/day)
Number of bus stops within 300 m (1,000 ft) of the intersection 0
Type of left-turn signal phasing for Leg #3 --
0
--
Number of approaches with left-turn signal phasing [for 3SG, use maximum value of 3]
Permissive
Not Present
Number of approaches with right-turn-on-red prohibited [for 3SG, use maximum value of 3] 0
Data for signalized intersections only: --
Worksheet 2A -- General Information and Input Data for Urban and Suburban Arterial Intersections
General Information Location Information
Analyst Roadway
Intersection type (3ST, 3SG, 4ST, 4SG) --
Analysis Year
Input Data Base Conditions Site Conditions
Number of major-road approaches with left-turn lanes (0,1,2) 0
Number of major-road approaches with right-turn lanes (0,1,2) 0
Agency or Company Intersection
Date Performed Jurisdiction
--AADT major (veh/day)
1.00
Data for unsignalized intersections only: --
--
Worksheet 2A – Urban and Suburban Arterial Intersections
Worksheet 2B – Double Check the Values!
90
CMF Intersection Left-Turn Lane (Table 12-24):
CMF Intersection Left-Turn Lane = 0.81
91
CMF Left-Turn Phasing Signal (Table 12-25):
2 approaches, therefore must multiply 0.94 x 0.94 = 0.88
CMF Left-Turn Phasing Signal = 0.88
92
CMF of Right-Turn Lanes (Table 12-26):Are there right-turn lanes?
CMF Right-Turn Lanes = 1.0 (Base Condition)
93
CMF for Right Turn on RedRight turn on red is not prohibited (base condition)
Therefore CMF 4i = 1.00
If the movement was prohibited, use Equation 12.35
94
CMF of lighting (Table 12-27):
Equation 12-36: CMF (lighting)=1-0.38 x P (night)
P (night): 1 - 0.38 x 0.235 = 0.91
CMF 5i = 0.91
95
CMF for Red Light CamerasNo cameras (base condition)
CMF6i Red Light Cameras = 1.00
If there were cameras, use Equation 12-37
96
Worksheet 2C – Double Check the Values!
97
Table 12-10
98
Worksheet 2D – Double Check the Values!
99
Table 12-11
100
Worksheet 2E – Double Check the Values!
101
102
Table 12-12
Worksheet 2F – Double Check the Values!
103
Table 12-13
104
Worksheet 2G – Does not apply to intersections
105
Worksheet 2H – Double Check the Values!
106
Table 12-28 (CMF Bus Stops) :
CMF Bus Stops = 2.78
107
Table 12-29 (CMF Presence of Schools) :CMF School = 1.35
108
Table 12-30 (CMF Alcohol Sales):CMF Alcohol Sales = 1.12
109
Worksheet 2I – Double Check the Values!
110
Table 12-14:
111
Worksheet 2J – Double Check the Values!
112
113
Table 12-17
Worksheets 2K & 2L – Crash Summaries
114
115
Crash severity level
Worksheet 2L -- Summary Results for Urban and Suburban Arterial Intersections
(1) (2)
Property damage only (PDO) 2.5
Total
Fatal and injury (FI)
4.1
1.6
Predicted average crash frequency, Npredicted int
(crashes/year)
(Total) from Worksheet 2K
Empirical Bayes Method116
Empirical Bayes Method:
117
Evaluate the predicted number ofcrashes using the Empirical BayesMethod
Empirical Bayes Method:
118
Used to combined observed crashfrequency data for a given site withpredicted crash frequency data frommany similar sites to estimate itsexpected crash frequency.
The advantages of using EB Method for crash data analysis
119
“The Empirical Bayes method addresses two problems of safety estimation;
1. it increases the precision of estimates beyond what is possible when one is limited to the use of a two-three year history accidents, and
2. it corrects for the regression-to-mean bias.
The increase in precision is important when the usual estimate is too imprecise to be useful. The elimination of the regression to mean bias is important whenever the accident history of the entity is in some way connected with the reason why its safety is estimated.”
Hauer, et al. Estiating Safety by the Empirical Bayes Method: A Tutorial, website: http://www.ctre.iastate.edu/educweb/ce552/docs/Bayes_tutor_hauer.pdf
The project – Using EmpiricalBayes Method•What is the expected crash frequency of the project for a particular yearusing the site-specific EB Method?• The following is the breakdown of the observed crashes per section type:
2U Segment
•Multiple-vehicle non-driveway = 4
•Single-vehicle = 6
•Multiple-vehicle driveway related = 1
4SG Segment
•Multiple-vehicle = 8
•Single-vehicle = 2
120
Worksheet 3A: Predicted Crashes by Severity & Type Using EB Method (Segment)
121
Worksheet 3A: Predicted Crashes by Severity & Type Using EB Method (Intersection)
122
Column#7: Weighted Adjustment, w
𝑤 =1
1+𝑘× 𝑎𝑙𝑙 𝑠𝑡𝑢𝑑𝑦 𝑦𝑒𝑎𝑟𝑠 𝑁𝑝𝑟𝑒𝑑𝑖𝑐𝑡𝑒𝑑
123
Multiple-vehicle non-driveway (segment):
𝑤 =1
1+0.84×11.41= 0.094
Column#8: Expected Average Crash Frequency, Nexpected
124
𝑁𝑒𝑥𝑝𝑒𝑐𝑡𝑒𝑑 = 𝑤 × 𝑁𝑝𝑟𝑒𝑑𝑖𝑐𝑡𝑒𝑑 + (1 − 𝑤) × 𝑁𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑
Multiple-vehicle Non-driveway Collisions (Segment):
𝑁𝑒𝑥𝑝𝑒𝑐𝑡𝑒𝑑 = 0.094 × 11.41 + 1 − 0.094 × 7 = 7.417 𝑐𝑟𝑎𝑠ℎ𝑒𝑠/𝑦𝑟
Worksheet 3B: Predicted Pedestrian & Bicycle Crashes
125
Worksheet 1I, Column 8
Worksheet 2J, Column 7Worksheet 2I, Column 7
Worksheet 1J, Column 8
Worksheet 3C: Site Specific EB Method Results
126
Calibration Factor (Cr) Formula
Where:
Cr = constant used to multiply the base SPF to correct the number of expected crashes at the applied location
Nobserved = number of observed crashes for the selected set of sites
Npredicted = number of predicted crashes
Note:
Appendix A in Part C of the HSM contains a detailed procedure to obtain the c-factor.
𝐶𝑟 = 𝑁𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑 𝑁𝑝𝑟𝑒𝑑𝑖𝑐𝑡𝑒𝑑
127
Site Selection Criteria to Determine the Calibration Factor (Cr)
1. Between 30-50 sites minimum should be selected through random sampling
2. Sites should be long enough to be representative of a roadway section, but no shorter than 0.10 mile in length
3. Sites must exhibit at least 100 crashes per year
4. A minimum of three years of historical crash data must be used
128
Crash Modification Factors Clearinghouse Website http://www.cmfclearinghouse.org
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New Changes for the HSM 2010
NCHRP 17-45, May 2012
The Enhanced Safety Prediction Methodology And Analysis Tool For
Freeways And Interchanges
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PRSHSP
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• Available: http://www.carreterasegurapr.com/Content/docs/Puerto_Rico_SHSP_2014-2018_English.pdf
• Strategic Plan for years 2014 - 2018
Topics Covered:
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• Highway Safety in the Commonwealth of Puerto Rico
• The planning and development process
• The emphasis areas• Future steps in the
implementation• Evaluation of the Strategic
Highway Safety Plan
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Flowchart of the 2014 Puerto Rico SHSP Developmentand Implementation Process
Predictive Model for Freeway Segments (NCHRP 17-45)
1. Rural freeway◦ with four through lanes,
◦ with six through lanes,
◦ with eight through lanes,
2. Urban freeway ◦ with four through lanes,
◦ with six through lanes,
◦ with eight through lanes, and
◦ with ten through lanes.
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Predictive Model for Ramp and Collector Distributor (C-D) Road Segments
RURAL
1. Entrance ramp with one lane,
2. Exit ramp with one lane,
3. C-D road with one lane
URBAN
1. C-D road with one lane,
2. C-D road with two lanes,
3. Entrance ramp with one lane,
4. Entrance ramp with two lanes,
5. Exit ramp with one lane, and
6. Exit ramp with two lanes.
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Gracias por su atención