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Systemic
Approach to
Safety in Texas
Srinivas Reddy Geedipally, PhD, PE
June 9, 2015
What is “Systemic Approach”?
 Focuses on high-risk roadway features
 Selects low-cost effective countermeasures
 Reduces fatal/severe crashes in rural areas
 Also beneficial for crash types less likely clustered
in urban area.
An approach that focuses on roadway safety
features to prevent high severe crashes
 Severe crashes are widely distributed
 Few locations experience a high number of
sustained occurrences
 Crash locations are somewhat random
 Addresses crashes across the network
Why “Systemic Approach”?
Systemic Project Selection Tool
Systemic Widening Program
 Rural
 2-Lane – 2-Way Highway
 ADT ≥ 400 vehicles per day
 Less than 24 foot paved surface width
 Widening to a maximum paved surface width of 28 foot
CRITERIA
Systemic Widening Program
 Head-On
 Single Vehicle Run Off Road
K & A Crashes
SVROR Crashes
Single Vehicle
8439
Urban
758 (11%)
Rural
6030 (89%)
Overturned
2485 (37%)
Fixed Object
4138 (61%)
Tree, Shrub, Landscaping - 1090 (26%)
Fence - 642 (16%)
Culvert-Headwall - 620 (15%)
Guardrail - 302 (7%)
Embankment- 260 (6%)
Ditch- 259 (6%)
Highway Sign - 224 (5%)
Other Fixed Object - 193 (4%)
Utility Pole - 150 (4%)
Mailbox - 148 (4%)
Others - 250 (6%)
Fatal and Incapacitating Injury Crashes Only
Two-lane Two-way Highways
Source: TxDOT CRIS, 2009-2013
Other/Unknown
165 (2%)
Minor Arterial - 342 (45%)
Collector - 215 (28%)
Principal Arterial - 196 (26%)
Others - 5 (1%)
Major Collector - 3327 (55%)
Minor arterials - 1386 (23%)
Minor Collector - 751 (12%)
Principal Arterial - 557 (9%)
Local - 9 (1%)
Total Paved Width
18-20: 1187 (20%)
21-22: 487 (8%)
23-24: 927 (15%)
25-26: 313 (5%)
27-28: 483 (8%)
29-30: 304 (5%)
31-40: 1142 (19%)
>40: 1187 (20%)
On Roadway
1651 (20%)
ROR
6788 (80%)
Fatal - 2167 (26%)
Incap. injury- 6272 (74%)
ADT
0-399: 768 (13%)
400-999: 1277 (21%)
1000-1999: 1432 (24%)
2000-2999: 887 (15%)
3000-3999: 554 (9%)
4000-4999: 356 (6%)
5000-5999: 250 (4%)
6000-6999: 182 (3%)
7000-7999: 99 (2%)
8000-8999: 79 (1%)
9000-9999: 46 (1%)
>=10000: 100 (2%)
Head-on Crashes
Head-on
2023
Fatal and Incapacitating Injury Crashes Only
Two-lane Two-way Highways
Source: TxDOT CRIS, 2009-2013
Minor Arterial - 160 (45%)
Principal Arterial - 120 (34%)
Collector - 69 (19%)
Others - 9 (2%)
Major Collector - 633 (38%)
Minor arterials - 584 (35%)
Principal Arterial - 376 (23%)
Minor Collector - 72 (4%)
ADT
0-399: 37 (2%)
400-999: 113 (7%)
1000-1999: 253 (15%)
2000-2999: 282 (17%)
3000-3999: 229 (14%)
4000-4999: 199 (12%)
5000-5999: 152 (9%)
6000-6999: 141 (8%)
7000-7999: 80 (5%)
8000-8999: 62 (4%)
9000-9999: 31 (2%)
>=10000: 86 (5%)
Urban
358 (18%)
Rural
1665 (82%)
Fatal - 1015 (50%)
Incap. injury- 1008 (50%)
Total Paved Width
18-20: 139 (8%)
21-22: 85 (5%)
23-24: 151 (9%)
25-26: 43 (3%)
27-28: 121 (7%)
29-30: 66 (4%)
31-40: 413 (25%)
>40: 647 (39%)
Evaluate Risk Factors
Average Daily Traffic
Highways are categorized into:
 Low volume: 400 < ADT <700
 Moderate volume: 700 < ADT <1500
 High volume: ADT > 1500
Evaluate Risk Factors
Cross-sectional width
- Crash Total
- Crash Over-Representation
a) SVROR crashes
b) Head-on crashes
60.7%
6.4%
32.8%
53.3%
6.6%
40.2%
0.0%
20.0%
40.0%
60.0%
80.0%
<=10+0 10+1 11+0
Percent
Lane Width + Shoulder Width (ft)
Length
KA Crashes
60.7%
6.4%
32.8%
63.1%
7.1%
29.8%
0.0%
20.0%
40.0%
60.0%
80.0%
<=10+0 10+1 11+0
Percent
Lane Width + Shoulder Width (ft)
Length
KA Crashes
Evaluate Risk Factors
Truck Volume
a) SVROR crashes
b) Head-on crashes
49.6%
32.9%
17.5%
56.2%
30.0%
13.8%
0.0%
15.0%
30.0%
45.0%
60.0%
75.0%
0-8% 9-15% >15%
Percent
Truck Presence
Length
KA Crashes
49.6%
32.9%
17.5%
59.8%
18.9% 21.3%
0.0%
15.0%
30.0%
45.0%
60.0%
75.0%
0-8% 9-15% >15%
Percent
Truck Presence
Length
KA Crashes
Evaluate Risk Factors
Alignment
a) SVROR crashes
b) Head-on crashes
3.7%
18.2%
78.1%
14.8%
22.1%
63.1%
0.0%
20.0%
40.0%
60.0%
80.0%
100.0%
Curve (R <1000ft) Curve (R >=1000ft) Straight
Percent
Alignment
Length
KA Crashes3.7%
18.2%
78.1%
10.6%
19.0%
70.4%
0.0%
20.0%
40.0%
60.0%
80.0%
100.0%
Curve (R <1000ft) Curve (R >=1000ft) Straight
Percent
Alignment
Length
KA Crashes
Evaluate Risk Factors
Risk Factor Weights
Category
Weight (points)
0 1 2 3 4 5 6 7 8 9 10
Crash Total
≥0%
and
<10%
≥10
and
<20%
≥20
and
<30%
≥30
and
<40%
≥40
and
<50%
≥50
and
<60%
≥60
and
<70%
≥70
and
<80%
≥80
and
<90%
≥90
and
<100%
100%
Crash Over-
Representation
0%
>0%
and
<2%
≥2%
and
<3%
≥3%
and
<4%
≥4%
and
<5%
≥5%
and
<6%
≥6%
and
<7%
≥7%
and
<8%
≥8%
and
<9%
≥9%
and
<10%
≥10%
and
≤100%
Evaluate Risk Factors
SVROR Risk Factor
Weight (points)
Low Volume
(400≤ADT≤700)
Moderate
Volume
(700<ADT≤1,500)
High Volume
(ADT>1,500)
Lane & Shoulder
Width
10+0 7 8 8
10+1 0 1 1
11+0 6 2 2
Truck Percentage
≤8% 2 7 11
9-15% 10 3 3
>15% 3 2 1
Alignment
Curve (R
<1000ft)
8 8 7
Curve (R
≥1000ft)
1 3 2
Straight 7 6 7
Evaluate Risk Factors
Head-on Risk Factor
Weight (points)
Low Volume
(400≤ADT≤700)
Moderate Volume
(700<ADT≤1,500)
High Volume
(ADT>1,500)
Lane & Shoulder
Width
10+0 7 6 5
10+1 4 2 1
11+0 2 6 11
Truck Percentage
≤8% 2 2 15
9-15% 4 6 1
>15% 6 2 5
Alignment
Curve (R
<1000ft)
12 11 11
Curve (R
≥1000ft)
1 2 5
Straight 6 6 6
Evaluate Risk Factors
We now have
 Weight for SVROR (Ws)
 Weight for Head-on (Wh)
Total Weight
𝑊𝑡 = 𝑊𝑠 + 𝑝 ∗ 𝐶 ∗ 𝑊ℎ
Where
• 𝑝= proportion of the number of head-on crashes with respect to
SVROR and
• 𝐶 = proportion of the crash cost of head-on crashes with respect
to SVROR.
Evaluate Risk Factors
Combined Risk Factor
Weight (points)
Low Volume
(400≤ADT≤700)
Moderate
Volume
(700<ADT≤1,500)
High Volume
(ADT>1,500)
Lane & Shoulder
Width
≤10+0 8.93 9.66 9.38
10+1 1.10 1.55 1.28
11+0 6.55 3.66 5.04
Truck Presence
≤8% 2.55 7.55 15.14
9-15% 11.10 4.66 3.28
>15% 4.66 2.55 2.38
Alignment
Curve (R
<1000ft)
11.31 11.04 10.04
Curve (R
≥1000ft)
1.28 3.55 3.38
Straight 8.66 7.66 8.66
Practical Application
DFO = 1.68
DFO = 1.73
DFO = 1.76
DFO = 1.8
𝐿 𝑐 = 0.03 mi
𝐿𝑡1 = 0.05 mi
𝐿𝑡2 = 0.04 mi
Highway: BS0121D
District: Paris
County: Fayette
DFO: 1.68 to 1.8
Total Length :0.12 miles
ADT (in 2013): 516 vpd
Truck %: 8.9
Lane Width: 10 ft
Shoulder Width: 0 ft
R = 110 ft
Evaluate Risk Factors
Combined Risk Factor
Weight (points)
Low Volume
(400≤ADT≤700)
Moderate
Volume
(700<ADT≤1,500)
High Volume
(ADT>1,500)
Lane & Shoulder
Width
≤10+0 8.93 9.66 9.38
10+1 1.10 1.55 1.28
11+0 6.55 3.66 5.04
Truck Presence
≤8% 2.55 7.55 15.14
9-15% 11.10 4.66 3.28
>15% 4.66 2.55 2.38
Alignment
Curve (R
<1000ft)
11.31 11.04 10.04
Curve (R
≥1000ft)
1.28 3.55 3.38
Straight 8.66 7.66 8.66
Weight Calculations
Section Weight
Curve (𝐿 𝑐 = 0.03 mi) 𝑊 𝑐 = 8.93+11.10+11.31
= 31.34
Tangent (𝐿 𝑇 = 0.09 mi) 𝑊 𝑇 = 8.93+11.10+8.66
= 28.69
Total (𝐿 = 0.12 mi) 𝑊 =
𝑊𝑐 𝐿 𝑐+𝑊 𝑇 𝐿 𝑇
𝐿
=29.35
Prioritize Locations
DI CO HWY ADT_CUR TRK_AADT FRM_DFO TO_DFO PAVED_WID length weight
1 75 BS0121D 516 8.9 1.68 1.8 20 0.12 29.35
1 75 BU0069B 1101 22.7 0.52 0.61 20 0.09 19.87
1 75 BU0069B 1101 22.7 0.61 0.96 20 0.35 19.87
1 194 BU0271D 1100 9 1.07 1.15 21 0.08 21.98
1 194 BU0271D 1100 9 1.64 1.65 20 0.01 13.87
1 92 BU0377B 2164 3.1 1.28 1.51 22 0.23 27.98
1 92 BU0377B 2164 3.1 1.51 4.29 22 2.78 28.41
1 92 BU0377B 2164 3.1 4.29 4.89 22 0.6 28.93
1 117 FM0006 2387 4.4 7.88 8.52 20 0.64 33.18
THANK YOU

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Project Selection for Highway Widening: A Systemic Approach

  • 1. Systemic Approach to Safety in Texas Srinivas Reddy Geedipally, PhD, PE June 9, 2015
  • 2. What is “Systemic Approach”?  Focuses on high-risk roadway features  Selects low-cost effective countermeasures  Reduces fatal/severe crashes in rural areas  Also beneficial for crash types less likely clustered in urban area. An approach that focuses on roadway safety features to prevent high severe crashes
  • 3.  Severe crashes are widely distributed  Few locations experience a high number of sustained occurrences  Crash locations are somewhat random  Addresses crashes across the network Why “Systemic Approach”?
  • 5. Systemic Widening Program  Rural  2-Lane – 2-Way Highway  ADT ≥ 400 vehicles per day  Less than 24 foot paved surface width  Widening to a maximum paved surface width of 28 foot CRITERIA
  • 6. Systemic Widening Program  Head-On  Single Vehicle Run Off Road K & A Crashes
  • 7. SVROR Crashes Single Vehicle 8439 Urban 758 (11%) Rural 6030 (89%) Overturned 2485 (37%) Fixed Object 4138 (61%) Tree, Shrub, Landscaping - 1090 (26%) Fence - 642 (16%) Culvert-Headwall - 620 (15%) Guardrail - 302 (7%) Embankment- 260 (6%) Ditch- 259 (6%) Highway Sign - 224 (5%) Other Fixed Object - 193 (4%) Utility Pole - 150 (4%) Mailbox - 148 (4%) Others - 250 (6%) Fatal and Incapacitating Injury Crashes Only Two-lane Two-way Highways Source: TxDOT CRIS, 2009-2013 Other/Unknown 165 (2%) Minor Arterial - 342 (45%) Collector - 215 (28%) Principal Arterial - 196 (26%) Others - 5 (1%) Major Collector - 3327 (55%) Minor arterials - 1386 (23%) Minor Collector - 751 (12%) Principal Arterial - 557 (9%) Local - 9 (1%) Total Paved Width 18-20: 1187 (20%) 21-22: 487 (8%) 23-24: 927 (15%) 25-26: 313 (5%) 27-28: 483 (8%) 29-30: 304 (5%) 31-40: 1142 (19%) >40: 1187 (20%) On Roadway 1651 (20%) ROR 6788 (80%) Fatal - 2167 (26%) Incap. injury- 6272 (74%) ADT 0-399: 768 (13%) 400-999: 1277 (21%) 1000-1999: 1432 (24%) 2000-2999: 887 (15%) 3000-3999: 554 (9%) 4000-4999: 356 (6%) 5000-5999: 250 (4%) 6000-6999: 182 (3%) 7000-7999: 99 (2%) 8000-8999: 79 (1%) 9000-9999: 46 (1%) >=10000: 100 (2%)
  • 8. Head-on Crashes Head-on 2023 Fatal and Incapacitating Injury Crashes Only Two-lane Two-way Highways Source: TxDOT CRIS, 2009-2013 Minor Arterial - 160 (45%) Principal Arterial - 120 (34%) Collector - 69 (19%) Others - 9 (2%) Major Collector - 633 (38%) Minor arterials - 584 (35%) Principal Arterial - 376 (23%) Minor Collector - 72 (4%) ADT 0-399: 37 (2%) 400-999: 113 (7%) 1000-1999: 253 (15%) 2000-2999: 282 (17%) 3000-3999: 229 (14%) 4000-4999: 199 (12%) 5000-5999: 152 (9%) 6000-6999: 141 (8%) 7000-7999: 80 (5%) 8000-8999: 62 (4%) 9000-9999: 31 (2%) >=10000: 86 (5%) Urban 358 (18%) Rural 1665 (82%) Fatal - 1015 (50%) Incap. injury- 1008 (50%) Total Paved Width 18-20: 139 (8%) 21-22: 85 (5%) 23-24: 151 (9%) 25-26: 43 (3%) 27-28: 121 (7%) 29-30: 66 (4%) 31-40: 413 (25%) >40: 647 (39%)
  • 9. Evaluate Risk Factors Average Daily Traffic Highways are categorized into:  Low volume: 400 < ADT <700  Moderate volume: 700 < ADT <1500  High volume: ADT > 1500
  • 10. Evaluate Risk Factors Cross-sectional width - Crash Total - Crash Over-Representation a) SVROR crashes b) Head-on crashes 60.7% 6.4% 32.8% 53.3% 6.6% 40.2% 0.0% 20.0% 40.0% 60.0% 80.0% <=10+0 10+1 11+0 Percent Lane Width + Shoulder Width (ft) Length KA Crashes 60.7% 6.4% 32.8% 63.1% 7.1% 29.8% 0.0% 20.0% 40.0% 60.0% 80.0% <=10+0 10+1 11+0 Percent Lane Width + Shoulder Width (ft) Length KA Crashes
  • 11. Evaluate Risk Factors Truck Volume a) SVROR crashes b) Head-on crashes 49.6% 32.9% 17.5% 56.2% 30.0% 13.8% 0.0% 15.0% 30.0% 45.0% 60.0% 75.0% 0-8% 9-15% >15% Percent Truck Presence Length KA Crashes 49.6% 32.9% 17.5% 59.8% 18.9% 21.3% 0.0% 15.0% 30.0% 45.0% 60.0% 75.0% 0-8% 9-15% >15% Percent Truck Presence Length KA Crashes
  • 12. Evaluate Risk Factors Alignment a) SVROR crashes b) Head-on crashes 3.7% 18.2% 78.1% 14.8% 22.1% 63.1% 0.0% 20.0% 40.0% 60.0% 80.0% 100.0% Curve (R <1000ft) Curve (R >=1000ft) Straight Percent Alignment Length KA Crashes3.7% 18.2% 78.1% 10.6% 19.0% 70.4% 0.0% 20.0% 40.0% 60.0% 80.0% 100.0% Curve (R <1000ft) Curve (R >=1000ft) Straight Percent Alignment Length KA Crashes
  • 13. Evaluate Risk Factors Risk Factor Weights Category Weight (points) 0 1 2 3 4 5 6 7 8 9 10 Crash Total ≥0% and <10% ≥10 and <20% ≥20 and <30% ≥30 and <40% ≥40 and <50% ≥50 and <60% ≥60 and <70% ≥70 and <80% ≥80 and <90% ≥90 and <100% 100% Crash Over- Representation 0% >0% and <2% ≥2% and <3% ≥3% and <4% ≥4% and <5% ≥5% and <6% ≥6% and <7% ≥7% and <8% ≥8% and <9% ≥9% and <10% ≥10% and ≤100%
  • 14. Evaluate Risk Factors SVROR Risk Factor Weight (points) Low Volume (400≤ADT≤700) Moderate Volume (700<ADT≤1,500) High Volume (ADT>1,500) Lane & Shoulder Width 10+0 7 8 8 10+1 0 1 1 11+0 6 2 2 Truck Percentage ≤8% 2 7 11 9-15% 10 3 3 >15% 3 2 1 Alignment Curve (R <1000ft) 8 8 7 Curve (R ≥1000ft) 1 3 2 Straight 7 6 7
  • 15. Evaluate Risk Factors Head-on Risk Factor Weight (points) Low Volume (400≤ADT≤700) Moderate Volume (700<ADT≤1,500) High Volume (ADT>1,500) Lane & Shoulder Width 10+0 7 6 5 10+1 4 2 1 11+0 2 6 11 Truck Percentage ≤8% 2 2 15 9-15% 4 6 1 >15% 6 2 5 Alignment Curve (R <1000ft) 12 11 11 Curve (R ≥1000ft) 1 2 5 Straight 6 6 6
  • 16. Evaluate Risk Factors We now have  Weight for SVROR (Ws)  Weight for Head-on (Wh) Total Weight 𝑊𝑡 = 𝑊𝑠 + 𝑝 ∗ 𝐶 ∗ 𝑊ℎ Where • 𝑝= proportion of the number of head-on crashes with respect to SVROR and • 𝐶 = proportion of the crash cost of head-on crashes with respect to SVROR.
  • 17. Evaluate Risk Factors Combined Risk Factor Weight (points) Low Volume (400≤ADT≤700) Moderate Volume (700<ADT≤1,500) High Volume (ADT>1,500) Lane & Shoulder Width ≤10+0 8.93 9.66 9.38 10+1 1.10 1.55 1.28 11+0 6.55 3.66 5.04 Truck Presence ≤8% 2.55 7.55 15.14 9-15% 11.10 4.66 3.28 >15% 4.66 2.55 2.38 Alignment Curve (R <1000ft) 11.31 11.04 10.04 Curve (R ≥1000ft) 1.28 3.55 3.38 Straight 8.66 7.66 8.66
  • 18. Practical Application DFO = 1.68 DFO = 1.73 DFO = 1.76 DFO = 1.8 𝐿 𝑐 = 0.03 mi 𝐿𝑡1 = 0.05 mi 𝐿𝑡2 = 0.04 mi Highway: BS0121D District: Paris County: Fayette DFO: 1.68 to 1.8 Total Length :0.12 miles ADT (in 2013): 516 vpd Truck %: 8.9 Lane Width: 10 ft Shoulder Width: 0 ft R = 110 ft
  • 19. Evaluate Risk Factors Combined Risk Factor Weight (points) Low Volume (400≤ADT≤700) Moderate Volume (700<ADT≤1,500) High Volume (ADT>1,500) Lane & Shoulder Width ≤10+0 8.93 9.66 9.38 10+1 1.10 1.55 1.28 11+0 6.55 3.66 5.04 Truck Presence ≤8% 2.55 7.55 15.14 9-15% 11.10 4.66 3.28 >15% 4.66 2.55 2.38 Alignment Curve (R <1000ft) 11.31 11.04 10.04 Curve (R ≥1000ft) 1.28 3.55 3.38 Straight 8.66 7.66 8.66
  • 20. Weight Calculations Section Weight Curve (𝐿 𝑐 = 0.03 mi) 𝑊 𝑐 = 8.93+11.10+11.31 = 31.34 Tangent (𝐿 𝑇 = 0.09 mi) 𝑊 𝑇 = 8.93+11.10+8.66 = 28.69 Total (𝐿 = 0.12 mi) 𝑊 = 𝑊𝑐 𝐿 𝑐+𝑊 𝑇 𝐿 𝑇 𝐿 =29.35
  • 21. Prioritize Locations DI CO HWY ADT_CUR TRK_AADT FRM_DFO TO_DFO PAVED_WID length weight 1 75 BS0121D 516 8.9 1.68 1.8 20 0.12 29.35 1 75 BU0069B 1101 22.7 0.52 0.61 20 0.09 19.87 1 75 BU0069B 1101 22.7 0.61 0.96 20 0.35 19.87 1 194 BU0271D 1100 9 1.07 1.15 21 0.08 21.98 1 194 BU0271D 1100 9 1.64 1.65 20 0.01 13.87 1 92 BU0377B 2164 3.1 1.28 1.51 22 0.23 27.98 1 92 BU0377B 2164 3.1 1.51 4.29 22 2.78 28.41 1 92 BU0377B 2164 3.1 4.29 4.89 22 0.6 28.93 1 117 FM0006 2387 4.4 7.88 8.52 20 0.64 33.18