Civil Engineering Research Institute for Cold Region Hirotaka Takechi, Masaru Matsuzawa, Yasuhiko Ito and Tetsuya Kokubu. Hokkaido.

Transcription

1 Influence of Roadside Environment and Road Structures on Blowing-Snow-Induced Visibility Hindrance on Winter Roads : Analysis using the results of weather observations by a visibility observation vehicle during blowing snow. Hokkaido Sapporo 2016 International Conference & Workshop on Winter Maintenance and Surface Transportation Weather Civil Engineering Research Institute for Cold Region Hirotaka Takechi, Masaru Matsuzawa, Yasuhiko Ito and Tetsuya Kokubu Tokyo

2 Outcomes To clarify the influence of following items on blowing-snow-induced visibility hindrance Road structures Length of windward flat land Width of roadside tree belt Width of roadside rows of houses Presence/absence of guardrails

3 Outline Background and objectives Method of moving weather observation Method of multivariate analysis Results of analysis Conclusions

4 Background Winter Road Problems in Hokkaido Hokkaido Tokyo Poor visibility and snowdrift caused by snowstorms Traffic hazards

5 It is important to accurately determine which locations are at risk of blowing snow. Background Installation of blowing-snow control facilities to mitigate traffic hazards caused by snowstorms Snow fences Snowbreak Woods

6 Objective It is necessary to develop the technology for risk assessment of snowstorms along entire routes for appropriate installation. Present technology for risk assessment of snowstorms Risk assessment of snowstorms (Image) The Highway Snowstorm Countermeasure Manual The Degree of Snowstorm Danger

7 Objective On The Highway Snowstorm Countermeasure Manual The degree of Snowstorm Danger Items and scores used to assess the degree of snowstorm danger were determined empirically To clarify the influence of the road environment and structures on blowing-snowinduced visibility hindrance Snowdrift factor Volume of snow settled at snowdrifts Roadside trees and houses Poor visibility factor Snowfall(snow depth) Frequent occurrence of blowing snow Snowfall(snow depth) Roadside trees and houses Windward flat land Road structure To survey by moving weather observation on winter road during blowing snow Degree of snowstorm danger ランク総合評点判定 A 44 点以上吹雪による障害の危険性が極めて高い B 吹雪による障害の危険性がある C 1-20 吹雪による障害に対して注意を要する D 0 以下吹雪対策の必要なし

8 Method of observation Moving weather observations were conducted during blowing snow by a visibility observation vehicles. Visibility, Wind velocity, Wind direction, Air temperature, Latitude and Longitude data ( Sampling interval was 0.1 sec. ) Sonic wind sensor (CLIMATEC,Inc CYG-85004) Installation height of 2.8m Forward scattering visibility meter (Meisei. TZF-31A) Installation height of 1.75m Visibility observation vehicle

9 Method of observation Locations of observation R232 Enbetsu city, Haboro city R238 Hamatonbetus city, Sarufutsu city R238 Saroma city, Monbetsu city R231 Iishikari city

10 Observation period : Three winters periods of 2012 to 2013, 2013 to 2014, 2014 to 2015 Method of observation Date of observations Route Route231 in Ishikari city (KP ) Route 232 from Enbetsu to Haboro city (KP ) Date of observations KP Maximum section 2012/12/26 10:49-16: /3/10 15:15-18: /1/13 12:48-16: /1/28 18:26-22: /1/31 14:44-17: /3/6 14:51-17: /2/2 15:13-20: /2/15 10:22-18: /12/27 8:52-16: /2/2 19:49-20: /2/3 8:32-9: /2/5 14:58-15: /2/20 6:32-12: /1/11 11:25-15: /1/28 16:00-21: /1/29 8:50-14: /1/31 17:33-18: /2/3 9:54-12: /3/7 15:44-16: /1/7 15:40-21: /1/8 11:35-11: /3/11 17:20-19: Number of observations Number of total observation times 43 48

11 Method of observation Observation period : Three winters periods of 2012 to 2013, 2013 to 2014, 2014 to 2015 Date of observations Route Route 238 from Saroma to Mombetsu city (KP ) Route 238 from Hamatonbetsu to Sarufutsu city (KP ) Date of observations KP Maximum section 2013/2/8 9:54-16: /3/2 15:05-17: /2/9 17:41-23: /2/17 8:07-10: /1/26 11:40-16: /2/3 12:40-15: /12/27 18:17-22: /1/26 16:10-16: /2/5 5:31-5: /2/10 14:44-18: /2/18 7:50-14: /2/27 8:27-20: /4/15 21:53-0: Number of observations Number of total observation times 10 36

12 Method of analysis Multivariate analysis Mathematical quantification theory class I ( Hayashi's quantification method I ) Data were gathered for each 50-m section of road. Average of observed visibility values Data on road structure, roadside environmental conditions from road inventories, maps, and aerial photographs

13 Method of analysis 1. Response variable Visibility hindrance occurrence rate (%) Number of occurrences of avg visibility < 200m Number of total observation times 100%

14 Method of analysis 2. Independent variable Road structure Length of windward flat land Width of roadside tree belt Width of roadside rows of houses Presence/absence of guardrails A road section without blowing-snow control facilities were studied. Road structure (Height of cut and fill ) Windward Independent variable Item Length of flat land windward Width of tree belt Width of rows of houses Presence/absence guardrails Category 0 Cut of higher than 5.0m 1 Cut of 0-5.0m 2 Fill of 0-1.0m 3 Fill of m 4 Fill of m 5 Fill of higher than 5.0m 0 N/A m m 3 More than 300m 0 N/A 1 Scarce 2 10~30m 3 30~50m 4 50~100m 5 100~200m 6 200~300m 7 More than 300m 0 N/A 1 Scarce 2 10~30m 3 30~50m 4 50~100m 5 100~200m 6 200~300m 7 More than 300m 0 Absent 1 Present

15 Results of analysis Response variable Visibility hindrance occurrence rate (%) Road structure (Height of cut and fill ) Width of windward tree belt Width of windward rows of houses Presence/absence of guardrails Independent variable ( Item and category ) Category score Item range Partial correlation coefficient p-value 0: Cut of higher than 5.0m ^-7 1: Cut of 0-5.0m : Fill of 0-1.0m : Fill of m The rate (%)= 4: Fill of m Number of occurrences of avg visibilty < 200m 100% Length of Number of total observation times windward flat land 5: Fill of higher than 5.0m : N/A ^-8 1: m : m : More than 300m : N/A ^-3 1: Scarce : 10~30m : 30~50m : 50~100m : 100~200m : 200~300m : More than 300m : N/A ^-14 1: Scarce : 10~30m : 30~50m : 50~100m : 100~200m : 200~300m : More than 300m : Absent ^-8 1: Present Constant 2.761

16 Results of analysis Category score of each item 5 Category Score Cut of higher than 5.0m Cut of 0-5.0m Fill of 0-1.0m Fill of m Fill of m Fill of higher than 5.0m Road structure (Height of cut and fill ) N/A m m More than 300m Length of windward flat land N/A Scarce 10~30m 30~50m 50~100m 100~200m 200~300m Width of windward tree belt More than 300m N/A Scarce Category for each item 10~30m 30~50m 50~100m 100~200m 200~300m Width of windward rows of houses More than 300m Absent Present Guardrails G Constant C

17 Results of analysis Category score of each item 5 Category Score X -2 Cut of higher than 5.0m Cut of 0-5.0m Fill of 0-1.0m Fill of m Fill of m Fill of higher than 5.0m Road structure (Height of cut and fill ) N/A m m More than 300m Length of windward flat land N/A Scarce 10~30m 30~50m 50~100m 100~200m 200~300m Width of windward tree belt More than 300m N/A Scarce Category for each item 10~30m 30~50m 50~100m 100~200m 200~300m Width of windward rows of houses More than 300m Absent Present Guardrails G Constant C

18 Results of analysis Range of category score of each item Item range Height of cut and fill Length of windward flat land Width of windward tree belt Item Width of windward rows of houses Presence/absence of guardrails

19 Conclusions The visibility hindrance occurrence rate during blowing snow tended to be high for roads with long windward flat land. With flat land of 100 m or longer, the rate tended to be high. On roads with a windward tree belt of 100 m or wider or with rows of houses of 300 m or wider, the rate tended to be remarkably low. The visibility tended to be good at such locations. The rate tended to be high at fills of about 3 m or higher and at cuts of lower than 5 m. At sections with guardrails, the rate tended to be higher than at road sections without guardrails.

20 Thank you for your kind attention For more information, question Snow and Ice Research Team Civil Eng. Res. Institute for Cold Region