Limited Use Document This presentation is provided in the interest of the free exchange of ideas but may not represent the final or complete results

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1 Limited Use Document This presentation is provided in the interest of the free exchange of ideas but may not represent the final or complete results of the research. The presentation is regarded as fully privileged and dissemination of the information included herein must be approved by the authors.

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3 Many thanks to the Washington Department of Transportation for providing the data for this analysis and for their thoughtful comments in the preparation of this paper. Slide 3

4 Generally, the goal of roadside design is to minimize, in so far as practical, the chance of fatal or incapacitating injury crashes on the roadside. Slide 4

5 applicable to new construction or major reconstruction projects. concepts cannot, and should not, be included in their totality on every single project. Slide 5

6 How much can risk be minimize while maintaining agreements for access with utility companies? This study developed a quantitative approach for measuring the risk of different pole location alternatives such that poles can be located where the greatest risk reduction can be realized. Slide 6

7 Benefit-cost methods have been used in roadside safety for over 40 years. Benefit-cost methods compare the risk reduction to the capital cost increase for each viable alternative. Issue: the risk reduction benefits and direct improvement costs do not accrue to the same entities. Slide 7

8 Separate the risk assessment from the benefit-cost assessment. Consider of risk reduction across alternatives. Cost-benefit and risk assessment tools are readily available in RSAPv3. Slide 8

9 Slide 9 Image source: gurl=https%3a%2f%2fupload.wik imedia.org%2fwikipedia%2fcom mons%2fthumb%2f1%2f12%2f Dice_Distribution_%2528bar%252 9.svg%2F250px- Dice_Distribution_%2528bar%252 9.svg.png&imgrefurl=https%3A%2 F%2Fen.wikipedia.org%2Fwiki%2 FProbability_distribution&docid=Dl K1zbnmD2cMHM&tbnid=OOUB0B v408twcm%3a&vet=10ahukewj 8rumbiYnUAhVHzoMKHXp2DCU4 ZBAzCAcoBTAF..i&w=250&h=188 &bih=638&biw=1360&q=probabilit y&ved=0ahukewj8rumbiynuahv HzoMKHXp2DCU4ZBAzCAcoBTA F&iact=mrc&uact=8

10 Enc/Mi/Year/EDGE For a roadside, the probability of observing a crash can be found using RSAPv3. The number of trials is equal to the number of encroachments Bi-directional AADT (vpd) Slide 10

11 An undivided roadway with a posted speed limit of 45 mph and 10% heavy vehicles was considered. The design alternatives considered were as follows: Slide 11

12 Slide 12

13 Slide 13

14 274 Slide

15 Enc./Edge-mile/Year A+K Risk Slide 15 Offsets: 11' 20' 30' 137' 137' 137' 200' 200' 200' 274' 274' 274'

16 Slide 16

17 Dead on Arrival Dead at Scene Died in Hospital Serious Injury Total A+K City County State Misc. way Total Crashes/yr Slide 17

18 Evident Injury Possible Injury No Injury Unk Total BCO City ,124 County ,306 State ,423 Misc. way Total ,911 Crashes/yr , Slide 18

19 Centerline Miles Jurisdiction One-way Miles Divided Miles Undivided Miles Edge Miles State Highway , , , County Highway , , City Highway , , Slide 19

20 K+A Crash Risk/year/edge mile (1/256) (1/500) (1/1000) City County State Jurisdiction Slide 20

21 Enc./Edge-mile/Year 5 State County City A+K Risk Slide 21 Offsets: 11' 20' 30' 137' 137' 137' 200' 200' 200' 274' 274' 274'

22 Two utility pole crashes per year per mile? One? Zero? Maybe we can agree to reduce the existing risk by, for example, by half? Slide 22

23 Enc./Edge-mile/Year 5 State County City A+K Risk Slide 23 Offsets: 11' 20' 30' 137' 137' 137' 200' 200' 200' 274' 274' 274'

24 Enc./Edge-mile/Year 5 State County City A+K Risk Slide 24 Offsets: 11' 20' 30' 137' 137' 137' 200' 200' 200' 274' 274' 274'

25 Does a pole at a location create more than what is considered acceptable? Yes locate elsewhere No consider next pole. Slide 25

26 Example Application 6-degree horizontal curve. 5% downgrade 200 SR 1 Slide 26 11

27 Enc/Mi/Year/EDGE encroachments/edge-mile/yr Bi-directional AADT (vpd) Slide 27

28 Modification f HC = Slide 28 Degree of Curve in Primary Direction of Travel

29 Modification Let s say %G=-5 f VC_PRIM = Percent Grade in the Primary Direction of Travel Slide 29

30 = On average 1.53 vehicles/edge-mile/year will leave the travelled way on this particular road with its 6 degree horizontal curve and 5% downgrade. Slide 30

31 Enc./Edge-mile/Year 50% State Risk A+K Risk Slide 31 Offsets: 11' 20' 30' 137' 137' 137' 200' 200' 200' 274' 274' 274'

32 This example shows that the existing utility pole risk can be quickly compared to the jurisdictional risk goal or site-specific goals. This method also allows the engineer to quickly assess if changing the offset or spacing would reduce the risk to an acceptable level. The primary advantage to this approach is that it allows for utility companies and transportation agencies to target improvements to the neediest areas. Slide 32

33 Christine E. Carrigan, P.E., PhD Phone: Malcolm H. Ray, P.E., PhD Phone: Slide 33