2016 EUnited ME Conference 1st June 2016, IFAT Munich

Transcription

1 1st June 2016, Municipal and road operation services - New experiences & trends 1

2 Pre-wetting with increased brine percentages Experiences and strategies in Lower Austria 2

3 Road network in Austria highways, express roads rural roads B rural roads L urban roads Total road network: NL-km NL-km NL-km NL-km NL-km Note: NL-km (km road network length) 3

4 Road network in Austria Classification according to salt and grit routes Salt spreading routes: motorways and expressways: 100% rural roads B and L: 75% Gritting routes: rural roads B and L: 25% 4

5 Theoretical thawing capacity VS remaining salt on the road surface over time Theoretical thawing capacity of NaCl Salt losses and remaining salt over time (NaCl) Precipitation [mm] Snow [cm] 4,0 3,5 3,0 2,5 2,0 1,5 1,0 0,5 Theoretical thawing capacity of NaCl Application rate: 40 g/m² 30 g/m² 20 g/m² 10 g/m² max. theoretical thawing capacity of 1 cm snow with an application rate of 40 g/m2 and no losses at a road surface temp. of -3 C (TU VIENNA) Remainning amount of salt [%] Salt 100% losses and remaining salt over time (NaCl) 90% 80% 70% 60% 50% 40% 30% 20% 10% 0,0 0,0-2,0-4,0-6,0-8,0-10,0 0% Road surface temperature [ C] Time since last salting [min] 5

6 Residual amount of salt = spread rate losses initial losses traffic losses Salzmenge nach Anfangsverlust [%] 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 21% 48% 37% 42% 5 g/m² 10 g/m² 20 g/m² 30 g/m² Gemesene Salzmenge auf Fahrbahn (100% = Salzmenge bei Messbeginn) 110% 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% y = -5E-05x + 0,935 R² = 0,2718 y = -0,0003x + 0,8009 R² = 0,2048 trocken feucht nass Linear dry road (trocken) Linear moist (feucht) Linear wet (nass) y = -9E-05x + 0,8171 R² = 0, Verkehr nach dem Streuvorgang [KFZ] Residual salt measurements after 150 Cars after salt spreading (Source: Final Report "optimization prewetted salt", TU Vienna) 6

7 Application rates How to maintain a snow and icefree road during snowing Precipitation 0,0 mm to 0,25 mm - Snow depth 0,0 mm to 2,5 mm or hoarfrost application Road surface temperature [ C] application Road surface temperature [ C] rate [g/m²] rate [g/m²] Cars in treatment interval Cars in treatment interval Precipitation 0,25 mm to 0,5 mm - Snow depth 0,5 mm to 5 mm Precipitation 0,5 mm to 0,75 mm - Snow depth 5 mm to 7,5 mm Precipitation 0,75 mm to 1 mm - Snow depth 7,5 mm to 10 mm application Road surface temperature [ C] application Road surface temperature [ C] rate [g/m²] rate [g/m²] Cars in treatment interval Cars in treatment interval 7

8 Maintenance strategy Snowing with/out snow covered road 8

9 Preventive treatment The most effective salting strategy (release coating) 1. Preventive treatment before snowfall event e.g. 10 g/m 2 on the eve of a snowfall event of 1 cm/h road surface temperature = - 5 C mit treatment intervall = 3 h resulting in 3 cm snow depth per treatment interval 2. Dilution and formation of 2 phases 1. Phase snow/ice above (about 0% salt) density 0,1-0,9 g/cm 3 2. Phase brine below (8% salt) density 1,1 g/cm 3. The applied salt is dissolved gradually, until an equilibrium concentration is reached at 8% and -5 C 3. Snowploughing and salt application The brine film prevents adhesion of the snow on the road surface and relieves further snowploughing. For salt application applies: remaining snow + applied salt = brine 8%> (salt consumption depends on quality of ploughing and road condition) 4. Thaw residual snow (continue with 2) Thaw of the remaining snow and brine formation > 8%; ongoing development according to 2 until end of snowfalls (discharge loss due to traffic and mixing not considered) 9

10 Thaw performance tests FS30 and FS100 Result after 1 hour after snow removal and spreading temperatures around freezing point brine - half amount 10

11 grip measurements brine 30 g/m² (6,0 g/m² NaCl) grip Time after the measurement run quicker initial thawing effect of brine and the same achieved grip despite lower amount of salt in brine (total sufficient) 11

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13 Knowledge from the brine spreading project Salt consumption can be significantly reduced due to salt spreading at temperatures around the freezing point and in preventive spreading a more favorable course of grip despite lower thawing quantity (better distribution effect of spreading brine opposite FS30) the application was made only to -5 C; at low temperatures has not been tested -> new research project 13

14 control of spreading pattern Visual control through Driving behind the spreader 14

15 control of spreading pattern Spreading pattern control by video recording on spreader 15

16 Analyse of the spreading pattern by measuring the salt amount 7m³-spreader on a rural road 10 min after spreading: 15 g/m² - 6m spreading width Spreading pattern for FS30 Spreading pattern for FS30 16

17 Analyse of the spreading pattern by measuring the salt amount 7m³-spreader on a rural road 10 min after spreading, after new setting by company; 15 g/m² - 6 m spreading width Spreading pattern for FS30 Spreading pattern for FS30 17

18 Residual salt measurements before and after the adjusting the spreaders with FS30 before adjusting after adjusting Spreading test with 15 g / m at 6.0 m and 3.5 m width Before adjusting too few salt was applied 18

19 Residual salt measurements Measuring device SOBO 20 and logging of results Alle 1,0 m < 0,5 m 5x Messung SOBO20 arrangement of measuring field 19

20 Residual salt measurements for FS30 Spreading pattern for FS30 Spreading pattern for FS30 FS30 - spreading quantity 15g/m² - width 3,5m the average measured residual amount of salt was 8,2 g/m² 20

21 Residual salt measurements for FS50 Spreading pattern for FS50 Spreading pattern for FS50 FS50 - spreading quantity 15g/m² - widht 3,5m the average measured residual amount of salt was 10,5 g/m² 21

22 Residual salt measurements for FS70 Spreading pattern for FS70 Spreading pattern for FS70 FS70 - spreading quantity 15g/m² - width 3,5m the average measured residual amount of salt was 4,0 g/m² 22

23 Knowledge from the FS50, FS70 and FS100-applications better distribution effect of the applied wet salt towards FS30 (uniform distribution pattern) faster thawing effect at higher brine shares a more favorable course of the grip in spite of less sodium chloride lower spreading losses at higher brine shares Salt consumption can be significantly reduced at higher brine percentages 23

24 FS0, FS30, FS50, FS70, FS100 in comparison spreading quantity, amount sodium chloride, amount residual salt FS 0 (dry spreading) FS 30 (wet salt classic) FS 50 (wet salt increased) FS 70 (wet salt more increased) FS 100 (pure brine spreading) 20 g/m 2 20,0 20 g/m 2 20,0 20 g/m 2 20,0 20 g/m 2 20,0 20 g/m 2 20,0 15,2 12,0 8,8 5,0 5,7 6,0 4,9 4,0 2,4 residual salt after 10 min 25% residual salt after 10 min 37,5% residual salt after 10 min 50% residual salt after 10 min 55% residual salt after 10 min 60% Legend: Adjusted (salt + water) [g/m 2 ] spreaded salt [g/m 2 ] Residual salt [g/m 2 ] with 20% brine concentration 24

25 Modification of existing FS30-spreader for FS50 Modification must economically and technically justified (brine pump) rd. 2/3 existing FS30 salt spreaders could be modifiend Spread rate adjustment for FS50 as before with FS30 for the same applications 25

26 Modification of existing FS30-spreader for FS50 additionally brine tank Second brine hose for an additional incidence point of brine 26

27 Prewetted with encreased Brine shares FS 50 and FS70 additional brine tanks iter tank for 5 m³ dry salt altogether liter brine 5 m³ sodium chloride prewetted salt spreader with an additional brine tank for FS50- and FS70 27

28 THANK YOU FOR YOUR ATTENTION 28