relationship of winter road weather monitoring to winter driving crash ...
1 Robert Koeberlein, Dennis Jensen, Miranda Forcier 1 2
RELATIONSHIP OF WINTER ROAD WEATHER MONITORING TO WINTER DRIVING CRASH STATISTICS
3
October 24, 2014
4
3229 Words
5
AUTHORS:
Robert Koeberlein, P.E. (corresponding author)
6
[email protected]
7
Mobility Services Engineer
8
Idaho Transportation Department
9
208 334 8487
phone
10 11 12 13
208 334 4429
fax
14
[email protected]
15
Winter Maintenance Coordinator
16
Idaho Transportation Department
17
208 334 8472
phone
18
208 334 4429
fax
Dennis Jensen
19 20
Miranda Forcier
21
[email protected]
22
Winter Performance Analyst
23
Six Mile Engineering (Consultant)
24
208.334.8850
phone
25
208 334 4429
fax
26
2 Robert Koeberlein, Dennis Jensen, Miranda Forcier 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52
1.
ABSTRACT:
The deployment of Road Weather Information Systems (RWIS) using state of the art non-invasive pavement sensors together with the atmospheric sensors has advanced the capabilities of the Idaho Transportation Department (ITD) maintenance crews to better plan their winter storm response, both in treatment chemical selection and application timing. The results of the winter maintenance activities are now measured through a Winter Performance Measurement program that evaluates how well each maintenance crew is doing with regards to achieving and maintaining safe grip roads during and after storm events. The results of this recent focus towards data driven maintenance operations has revolutionized the level of service ITD provides its customers in terms of year round safety and mobility. ITD has developed a quantitative data collection procedure to measure the effectiveness of the RWIS and Winter Performance Measure program in improving safety, which was evaluated through a benefit/cost study. This paper compares winter driving crash statistics on road segments prior to the deployment of RWIS sites to crash statistics after winter road condition data became available through RWIS deployment and then calculates a benefit/cost metric. For the study period (20102013) the benefit/cost is 22, which concludes that strategically deployed RWIS sites and proper utilization of the data easily justifies the investment in infrastructure and operations. For the 3-year study period and the highway segments being analyzed, winter driving fatalities dropped from 5 in the baseline season to 1 in the second season to zero in the third season.
3 Robert Koeberlein, Dennis Jensen, Miranda Forcier 53 54 55 56
2.
57 58 59 60 61 62
In each of these studies the researchers developed and used mathematical models to estimate the benefits of the tool or maintenance practice. Instead of developing a mathematical model for calculating estimated benefits and costs for the three year study period, this paper used crash data extracted from the Idaho statewide crash report database to calculate the benefits of avoided crashes, and collected associated deployment and operations costs for the Road Weather Information Systems (RWIS) sites in the study area.
63 64 65 66 67 68 69 70 71 72 73 74
Over the past five years the Idaho Transportation Department (ITD) has invested over $15 Million in expanding and modernizing its RWIS network at strategic locations statewide. Noninvasive pavement sensors have been included at nearly every site that report pavement temperature, layer type (water, ice, snow), layer thickness, and “grip” (the coefficient of friction). The current RWIS inventory statewide is 125 sites with an additional new site under construction. ITD has developed a winter performance management program to quantify how well the maintenance crews are maintaining safe roads during and after winter storm events. The winter performance measures track the success of the road treatments, and the percentage of time the grip measurement was maintained in the safe driving range (grip >0.6) when the road surface temperature was below freezing and precipitation is present. ITD asserts that the measured grip value is the most useful indicator of the condition and safety of the road surface during winter weather conditions.
75 76
This deployment of winter performance reporting RWIS sites has enabled the following improvements to occur that all can contribute to safety:
77 78 79 80 81 82 83 84 85 86 87 88 89
BACKGROUND
There have been several studies performed that examine the benefits of various aspects of winter operations, including (a), (b), and (c).
Treatment timing Material selection Scenario review and critique Performance Measurement-Mobility Index Higher quality road condition traveler information Automated road condition and alerts reporting on 511 traveler information websites
3. STUDY ITD wanted to analyze the relationship of utilizing the winter road condition data to winter driving crash statistics to determine what the benefit/cost is for deploying RWIS sites. A study was begun in 2014 that covered winter driving seasons starting in the fall of 2010 and examined the new deployments of RWIS sites (33 total, 2011 and 2012) and the crash statistics associated with this group. See map of RWIS locations below in Figure 1.
4 Robert Koeberlein, Dennis Jensen, Miranda Forcier
90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114
Yellow = 2011 RWIS Deployment (9) Blue = 2012 RWIS Deployment (24) FIGURE 1 RWIS locations added 2011-2012 The bases for this study were the following: 1. The seasonal winter storm frequency and severity was not significantly different during the 3 year study window 2. Data sets consist of reported winter driving crashes 3. Traffic volumes were constant or slightly increasing during the study period 4. Benefits are the avoided societal costs represented by crash reductions. During the study period (2010-2013) the statewide winter operational costs decreased in succeeding years, however these savings were not included in the benefit/cost calculation. 5. The global average cost per crash is calculated using NHTSA values for serious injury and fatality crashes plus Idaho law enforcement estimated property damage values, covering 674 recorded crashes on the highway segments studied 6. A grip value < 0.6 determines winter driving conditions (post RWIS deployment) 7. Winter driving conditions for pre-RWIS deployment locations based on crash report causes noted by law enforcement officers 8. Each of the 33 RWIS sites has associated segments of highway that it represents. A total of 885 lane miles are associated with the 33 RWIS sites. Only winter driving condition crashes reported on these segments are counted in the calculations The approach used in analyzing the road condition data and crash data is to annualize the benefits and costs as follows:
5 Robert Koeberlein, Dennis Jensen, Miranda Forcier 115 116
Crash Reduction (CR) = Crash totals (before data) – Crash totals (after data)
117
Benefits = CR x average cost of crash
118 119
The average cost of a winter driving crash is $72,700 based on 674 reported crashes involving fatalities, serious injury, and property damage
120 121
Costs = annualized capital and operating costs of RWIS network
122
Costs = ∑capital/n + annual network operating cost
123
Where n is the service life of an RWIS site, which is assumed to average 10 years
124
The average capital cost per site is $125,000, covering design and construction
125 126
The RWIS site operating costs average $5,500 per year and cover repair, maintenance, communications and data management
127
Therefore the annual operating cost per site is $18,000.
128
Note that benefits and costs are calculated using constant 2014 dollars
129 130 Season
131 132 133 134 135 136 137 138 139 140
4.
TABLE 1 RWIS Inventory by Winter Season RWIS Sites Deployed Total
2010-2011
Pre-deployment season (Baseline)
0
2011-2012
9
9
2012-2013
24
33
RESULTS The reported winter driving crash events for the highway segments associated with the 33 RWIS sites are shown on Chart 1, and the corresponding calculated societal costs avoided are shown on Chart 2. The 2010-2011 season is the baseline for crash statistics and used to compare results from the next two succeeding years as 9 RWIS sites were deployed in 2011 and then 24 RWIS sites added in 2012.
6 Robert Koeberlein, Dennis Jensen, Miranda Forcier
Chart 1 Crashes 350
9 Sites
Number of Crashes
300 250
33 Sites
200 150 100 50 0
2010-2011 301
Crashes
2011-2012 226
2012-2013 147
141 142
Chart 2 Value of Crashes Avoided $12,000,000 Societal Value
$10,000,000 $8,000,000 $6,000,000 $4,000,000 $2,000,000 $0
20102011 $0
Value of Crashes Avoided
20112012 $5,452,500
20122013 $11,195,800
143 144 145 146
Table 2 shows the capital and operating costs for the two RWIS Groups.
147
TABLE 2 RWIS Capital and Operating Costs ($) RWIS Site Group
Capital
Operating
Capital
Operating
2011-2012
2011-2012
2012-2013
2012-2013
9
112,500
49,500
112,500
49,500
24
0
0
300,000
132,000
Totals
112,500
49,500
412,500
181,500
7 Robert Koeberlein, Dennis Jensen, Miranda Forcier 148 149
Table 3 shows the calculated benefit/cost for the two year span.
150 151
TABLE 3 Benefit/Cost for the Two Winter Seasons Season
Crash Reduction
Value per Crash ($)
Benefit ($)
Cost ($)
Benefit/Cost
2011-2012
75
72,700
5,452,500
162,000
33.7
2012-2013
154
72,700
11,195,800
594,000
18.8
16,648,300
756,000
22.0
Totals 152 153 154
The crash reduction trend is also reflected in fatality statistics for the highway segments considered in this study as shown in Table 4.
155 156
TABLE 4 Highway Fatalities During Winter Driving Conditions
Fatalities
2010-2011 5
2011-2012 1
2012-2013 0
157 158
5.
CONCLUSIONS
159 160 161 162
The Idaho Transportation Department has concluded that the capital and operating investments in strategically placed RWIS sites and proper utilization of the observation data is easily justified by the societal benefits in significant reductions in winter driving crashes and fatalities.
163 164 165
Also, the safety improvements experienced are the result of improved winter maintenance operations and better and more comprehensive winter traveler information, both of which are enabled by the availability of road weather observation data.
166 167 168 169 170 171 172 173 174 175 176 177 178 179
6.
REFERENCES a. Ye, Z, C. K. Strong, X. Shi, S. M. Conger and D. L. Huft, Benefit-Cost Analysis of Maintenance Decision Support System, , Transportation Research Record: Journal of the Transportation Research Board No. 2107, Transportation Research Board of the National Academies, Washington, DC, 2009, pp: 95-103 b. Strong, C. K., and X. Shi, Benefit-Cost Analysis of Weather Information for Winter Maintenance, Transportation Research Record: Journal of the Transportation Research Board No. 2055, Transportation Research Board of the National Academies, Washington, DC, 2008, pp: 119-127 c. Ye, Z., D. Veneziano, X. Shi, and L. Fay, Methods for Estimating the Benefits of Winter Maintenance Operations, NCHRP Project 20-07, Task 300, National Cooperative Highway Research Program, Transportation Research Board, 2012
RELATIONSHIP OF WINTER ROAD WEATHER MONITORING TO WINTER DRIVING CRASH STATISTICS
3
October 24, 2014
4
3229 Words
5
AUTHORS:
Robert Koeberlein, P.E. (corresponding author)
6
[email protected]
7
Mobility Services Engineer
8
Idaho Transportation Department
9
208 334 8487
phone
10 11 12 13
208 334 4429
fax
14
[email protected]
15
Winter Maintenance Coordinator
16
Idaho Transportation Department
17
208 334 8472
phone
18
208 334 4429
fax
Dennis Jensen
19 20
Miranda Forcier
21
[email protected]
22
Winter Performance Analyst
23
Six Mile Engineering (Consultant)
24
208.334.8850
phone
25
208 334 4429
fax
26
2 Robert Koeberlein, Dennis Jensen, Miranda Forcier 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52
1.
ABSTRACT:
The deployment of Road Weather Information Systems (RWIS) using state of the art non-invasive pavement sensors together with the atmospheric sensors has advanced the capabilities of the Idaho Transportation Department (ITD) maintenance crews to better plan their winter storm response, both in treatment chemical selection and application timing. The results of the winter maintenance activities are now measured through a Winter Performance Measurement program that evaluates how well each maintenance crew is doing with regards to achieving and maintaining safe grip roads during and after storm events. The results of this recent focus towards data driven maintenance operations has revolutionized the level of service ITD provides its customers in terms of year round safety and mobility. ITD has developed a quantitative data collection procedure to measure the effectiveness of the RWIS and Winter Performance Measure program in improving safety, which was evaluated through a benefit/cost study. This paper compares winter driving crash statistics on road segments prior to the deployment of RWIS sites to crash statistics after winter road condition data became available through RWIS deployment and then calculates a benefit/cost metric. For the study period (20102013) the benefit/cost is 22, which concludes that strategically deployed RWIS sites and proper utilization of the data easily justifies the investment in infrastructure and operations. For the 3-year study period and the highway segments being analyzed, winter driving fatalities dropped from 5 in the baseline season to 1 in the second season to zero in the third season.
3 Robert Koeberlein, Dennis Jensen, Miranda Forcier 53 54 55 56
2.
57 58 59 60 61 62
In each of these studies the researchers developed and used mathematical models to estimate the benefits of the tool or maintenance practice. Instead of developing a mathematical model for calculating estimated benefits and costs for the three year study period, this paper used crash data extracted from the Idaho statewide crash report database to calculate the benefits of avoided crashes, and collected associated deployment and operations costs for the Road Weather Information Systems (RWIS) sites in the study area.
63 64 65 66 67 68 69 70 71 72 73 74
Over the past five years the Idaho Transportation Department (ITD) has invested over $15 Million in expanding and modernizing its RWIS network at strategic locations statewide. Noninvasive pavement sensors have been included at nearly every site that report pavement temperature, layer type (water, ice, snow), layer thickness, and “grip” (the coefficient of friction). The current RWIS inventory statewide is 125 sites with an additional new site under construction. ITD has developed a winter performance management program to quantify how well the maintenance crews are maintaining safe roads during and after winter storm events. The winter performance measures track the success of the road treatments, and the percentage of time the grip measurement was maintained in the safe driving range (grip >0.6) when the road surface temperature was below freezing and precipitation is present. ITD asserts that the measured grip value is the most useful indicator of the condition and safety of the road surface during winter weather conditions.
75 76
This deployment of winter performance reporting RWIS sites has enabled the following improvements to occur that all can contribute to safety:
77 78 79 80 81 82 83 84 85 86 87 88 89
BACKGROUND
There have been several studies performed that examine the benefits of various aspects of winter operations, including (a), (b), and (c).
Treatment timing Material selection Scenario review and critique Performance Measurement-Mobility Index Higher quality road condition traveler information Automated road condition and alerts reporting on 511 traveler information websites
3. STUDY ITD wanted to analyze the relationship of utilizing the winter road condition data to winter driving crash statistics to determine what the benefit/cost is for deploying RWIS sites. A study was begun in 2014 that covered winter driving seasons starting in the fall of 2010 and examined the new deployments of RWIS sites (33 total, 2011 and 2012) and the crash statistics associated with this group. See map of RWIS locations below in Figure 1.
4 Robert Koeberlein, Dennis Jensen, Miranda Forcier
90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114
Yellow = 2011 RWIS Deployment (9) Blue = 2012 RWIS Deployment (24) FIGURE 1 RWIS locations added 2011-2012 The bases for this study were the following: 1. The seasonal winter storm frequency and severity was not significantly different during the 3 year study window 2. Data sets consist of reported winter driving crashes 3. Traffic volumes were constant or slightly increasing during the study period 4. Benefits are the avoided societal costs represented by crash reductions. During the study period (2010-2013) the statewide winter operational costs decreased in succeeding years, however these savings were not included in the benefit/cost calculation. 5. The global average cost per crash is calculated using NHTSA values for serious injury and fatality crashes plus Idaho law enforcement estimated property damage values, covering 674 recorded crashes on the highway segments studied 6. A grip value < 0.6 determines winter driving conditions (post RWIS deployment) 7. Winter driving conditions for pre-RWIS deployment locations based on crash report causes noted by law enforcement officers 8. Each of the 33 RWIS sites has associated segments of highway that it represents. A total of 885 lane miles are associated with the 33 RWIS sites. Only winter driving condition crashes reported on these segments are counted in the calculations The approach used in analyzing the road condition data and crash data is to annualize the benefits and costs as follows:
5 Robert Koeberlein, Dennis Jensen, Miranda Forcier 115 116
Crash Reduction (CR) = Crash totals (before data) – Crash totals (after data)
117
Benefits = CR x average cost of crash
118 119
The average cost of a winter driving crash is $72,700 based on 674 reported crashes involving fatalities, serious injury, and property damage
120 121
Costs = annualized capital and operating costs of RWIS network
122
Costs = ∑capital/n + annual network operating cost
123
Where n is the service life of an RWIS site, which is assumed to average 10 years
124
The average capital cost per site is $125,000, covering design and construction
125 126
The RWIS site operating costs average $5,500 per year and cover repair, maintenance, communications and data management
127
Therefore the annual operating cost per site is $18,000.
128
Note that benefits and costs are calculated using constant 2014 dollars
129 130 Season
131 132 133 134 135 136 137 138 139 140
4.
TABLE 1 RWIS Inventory by Winter Season RWIS Sites Deployed Total
2010-2011
Pre-deployment season (Baseline)
0
2011-2012
9
9
2012-2013
24
33
RESULTS The reported winter driving crash events for the highway segments associated with the 33 RWIS sites are shown on Chart 1, and the corresponding calculated societal costs avoided are shown on Chart 2. The 2010-2011 season is the baseline for crash statistics and used to compare results from the next two succeeding years as 9 RWIS sites were deployed in 2011 and then 24 RWIS sites added in 2012.
6 Robert Koeberlein, Dennis Jensen, Miranda Forcier
Chart 1 Crashes 350
9 Sites
Number of Crashes
300 250
33 Sites
200 150 100 50 0
2010-2011 301
Crashes
2011-2012 226
2012-2013 147
141 142
Chart 2 Value of Crashes Avoided $12,000,000 Societal Value
$10,000,000 $8,000,000 $6,000,000 $4,000,000 $2,000,000 $0
20102011 $0
Value of Crashes Avoided
20112012 $5,452,500
20122013 $11,195,800
143 144 145 146
Table 2 shows the capital and operating costs for the two RWIS Groups.
147
TABLE 2 RWIS Capital and Operating Costs ($) RWIS Site Group
Capital
Operating
Capital
Operating
2011-2012
2011-2012
2012-2013
2012-2013
9
112,500
49,500
112,500
49,500
24
0
0
300,000
132,000
Totals
112,500
49,500
412,500
181,500
7 Robert Koeberlein, Dennis Jensen, Miranda Forcier 148 149
Table 3 shows the calculated benefit/cost for the two year span.
150 151
TABLE 3 Benefit/Cost for the Two Winter Seasons Season
Crash Reduction
Value per Crash ($)
Benefit ($)
Cost ($)
Benefit/Cost
2011-2012
75
72,700
5,452,500
162,000
33.7
2012-2013
154
72,700
11,195,800
594,000
18.8
16,648,300
756,000
22.0
Totals 152 153 154
The crash reduction trend is also reflected in fatality statistics for the highway segments considered in this study as shown in Table 4.
155 156
TABLE 4 Highway Fatalities During Winter Driving Conditions
Fatalities
2010-2011 5
2011-2012 1
2012-2013 0
157 158
5.
CONCLUSIONS
159 160 161 162
The Idaho Transportation Department has concluded that the capital and operating investments in strategically placed RWIS sites and proper utilization of the observation data is easily justified by the societal benefits in significant reductions in winter driving crashes and fatalities.
163 164 165
Also, the safety improvements experienced are the result of improved winter maintenance operations and better and more comprehensive winter traveler information, both of which are enabled by the availability of road weather observation data.
166 167 168 169 170 171 172 173 174 175 176 177 178 179
6.
REFERENCES a. Ye, Z, C. K. Strong, X. Shi, S. M. Conger and D. L. Huft, Benefit-Cost Analysis of Maintenance Decision Support System, , Transportation Research Record: Journal of the Transportation Research Board No. 2107, Transportation Research Board of the National Academies, Washington, DC, 2009, pp: 95-103 b. Strong, C. K., and X. Shi, Benefit-Cost Analysis of Weather Information for Winter Maintenance, Transportation Research Record: Journal of the Transportation Research Board No. 2055, Transportation Research Board of the National Academies, Washington, DC, 2008, pp: 119-127 c. Ye, Z., D. Veneziano, X. Shi, and L. Fay, Methods for Estimating the Benefits of Winter Maintenance Operations, NCHRP Project 20-07, Task 300, National Cooperative Highway Research Program, Transportation Research Board, 2012
