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Pages 45-70

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From page 45...
... 45 Over 70 percent of the nation's roads are located in snowy regions, which receive more than five inches (or 13 cm) average snowfall annually.
From page 46...
... 46 • Sand has poor performance characteristics and produces particulate matter which leads to low LOS (low mobility and safety) and causes health problems; and • Plowing slows traffic (low mobility)
From page 47...
... 47 The widespread use of rock salt (sodium chloride) to remove snow and ice and facilitate a ‘bare pavement' LOS has provided for the increased safety of motorists for some time.
From page 48...
... 48 Category I Ranking by Frequency Specific Technology Plow Configuration 1 (53/54) Front plows 2 (29/54)
From page 49...
... 49 and inexpensive while performing relatively well. CaCl2 and MgCl2 perform better than NaCl in colder conditions, but they lead to higher cost and possibly greater impacts on infrastructure.
From page 50...
... 50 • Surface overlay (Rochelle, 2010) -- Special bonded surface overlays set anti-icing chemicals in place and gradually release them onto the surface.
From page 51...
... 51 maturity and then the introduction of alternative technology to the re-discovery of technology. Figure B-2 provides two examples of anti-icers and corrosion- inhibiting chemicals.
From page 52...
... 52 In the Identify step, several new, advanced technologies were introduced. In particular, information technology and equipment have plentiful, heterogeneous sets of sub-technologies.
From page 53...
... 53 overlay can generate enough heat to prevent ice formation on a bridge deck when connected to a power source. The Nebraska Department of Roads (DOR)
From page 54...
... 54 the roadside and is able to provide a useful measurement of slipperiness (i.e., friction)
From page 55...
... 55 • Conservation of Momentum. When the lead states effort came to its conclusion, the SICOP61 (Snow and Ice Pooled Fund Cooperative Program)
From page 56...
... 56 technologies to be compared; (2) set up standards and create metrics to judge; (3)
From page 57...
... 57 tions (temperature/ice and pavement bond/frost or thin ice/ slush, loose snow, packed snow, thick ice) • Traffic conditions: traffic volume (very low/low/medium/ high/very high)
From page 58...
... 58 incorporate the following measures that might actually be available to a transportation agency (Maze, 2007) : • Measure: Degree of clear pavement – Approach: Manual observation – Approach: Camera-assisted observation • Measure: Traffic flow – Approach: Detectors providing information on speed, volume, and occupancy – Approach: Road closure • Measure: Crash risk – Approach: Friction (or slipperiness)
From page 59...
... 59 Road surface conditions (Friction coefficient) Safety: Relative risk Mobility: Relative speed Condition 1 All snow and ice is prevented from bonding and accumulating on the road surface.
From page 60...
... 60 • Terrestrial vegetation: potential damage by airborne contaminants • Streams: depletion of dissolved oxygen (DO) , water quality concern • Air quality: fine particulate material For the normative unit, the research team created metrics based on output or outcome of environmental and corrosive effects with four different scales for measurement in both corrosive and environmental terms: • Metric Value 1 – serious effect; • Metric Value 2 – moderate effect; • Metric Value 3 – small effect; • Metric Value 4 – no/little effect.
From page 61...
... 61 primarily de-icing and anti-icing. Based on that, the research team assumed that snow-belt states execute anti-icing practices while non-snowy region states employ de-icing practices.
From page 62...
... 62 – Number of car accidents: the number of crashes related to human and property damages dropped from 31 (during winter season of 1996-1997) to 9 (during 2000-2001)
From page 63...
... 63 0 0.5 1 1.5 2 2.5 3 3.5 4 Safety Mobility PreservationSustainability POSI CaCl2 (Vehicle) KAc (Vehicle)
From page 64...
... 64 using CaCl2 as the active chemical became starker. In the normative 1 to 4 scaling, by definition there cannot be a greater than four times difference.
From page 65...
... 65 less sensitive to modification or local agency circumstances, it is important to look beyond the total shown. The use of calcium chloride in combination with FAST has the lowest operational cost followed by the thermal method which has the highest net fixed cost.
From page 66...
... 66 Tradeoffs in Metrics There are complex tradeoffs between metrics for preservation, safety, mobility, and sustainability. Regarding environmental issues, for example, transportation agencies are continually challenged to provide a high LOS and improve safety and mobility in a cost-effective manner while minimizing corrosion and other adverse effects to the environment (Maze, 2007)
From page 67...
... 67 While chemical dispersal from vehicles is preferred to others in terms of initial cost (e.g., equipment and installation) , the thermal method dominates the others in terms of hard-to-quantify costs (e.g., benefits from reduced travel time and crash)
From page 68...
... 68 Figure B-10. Comparison of technology application bundles using natural units.
From page 69...
... 69 Figure B-12. Comparison of technology application bundles by integrating all summary metrics and POSI, using natural units.
From page 70...
... 70 Figure B-14. Comparison of technology application bundles by integrating all summary metrics and POSI, using natural units, and including notations on agency-specific net cost ($000s/bridge)

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