Road Safety Measures for Fog Visibility: Warning and Dispersal Systems

CONTENTS

1. INTRODUCTION

1.1 Background

1.2 Visibility Conditions of the Road

2. LITERATURE REVIEW

2.1 Data Needs for Transportation

2.2 Existing Systems

2.3 Other Services

3. METHODOLOGIES

3.1 Problem Identification and Proposed Solutions

3.2 Low Visibility Warning Systems

3.2.1 Components

3.2.2 Operating Procedure

3.2.3 Efficiency

3.3 Fog Dispersal Operations

3.3.1 Components

3.3.2 Operating Procedure

3.3.3 Outcome

3.3.4 Execution Issues

3.4 Implementation in Texas

3.4.1 Outline of Texas Climate

3.4.2 Strategies for Better Traffic Management

3.4.3 Other Fog Reduction Systems

3.4.4 Other systems for Enhanced Visibility

3.4.5 Cost

4. RESULTS

5. CONCLUSIONS & RECOMMENDATIONS

6. REFERENCES

1. INTRODUCTION

1.1 Background

Seeing and being seen are key requirements for the safety of all road users. Lacking perceivability is a vital variable that impacts the danger of a road crash among a wide range of road users.  In exceedingly mechanized nations, insufficient visibility assumes a vital part in most of the accidents like the vehicles that run into the back or sides of gradually moving or stationary vehicles, backside crashes that happen in poor climate conditions.

Fog discovery frameworks help recognize states of restricted visibility and admonish the drivers before they experience the fog. The warning framework may be basic signs warning motorists that the road area is helpless to substantial fog or progressed ITS framework, for example, Variable Message Signs (VMS) which give warning messages or counseling data on suggested rates. Dynamic frameworks, for example, fog recognition frameworks contained sensors to gather about climate, visibility, and movement conditions in blend with motorist warning frameworks. Furthermore, there are a few aloof which help caution and portray activity, for example, delineators, reflectors, striping and so forth.

The road accidents on the flat bends and vertical bends are a foundation for concern in all aspects of the world. A critical bit of accidents in rustic zones are on the bends just. One of the primary reasons of accident on bends is a result of the sight separation. While outlining the road, sight separation is situated up for halting in a safe configuration. On the other hand, the drivers will most likely be unable to judge the ceasing sight separate on the roadway and may slam into the first vehicle or some other articles. Forward perceivability is critical to ensure that drivers have important time to respond to an alteration in the road arrangement to explore the road securely. If not potential to give sufficient SSD in view of need in forward perceivability, the framework will help them to change their driving conduct inside the constrained time.

The road climate administration system of Federal Highway Administration expresses that 25 percent of all accidents gave an account of the nation are climate related. The climate related accidents can happen due to rain, hail or snow. On average, one year ago, 6,213 individuals are murdered on the road and more than 650,000 individuals are harmed somehow due to climate related accidents consistently. The enormous lion’s share of most climate related accidents happen on wet asphalt.

The Utah DOT has started two techniques to relieve fog issues. A low perceivability warning framework advises drivers on how fast they can go and supports more streamlined activity along a fragment of interstate roadway. In southern and eastern Utah’s mountain valleys, specialists use fluid carbon items to diffuse cool fog and advancement perceivability along parts of US interstates and other highways.

Another research by the University of Minnesota focused at sharpening the ability of drivers to maintain a strategic distance from accidents with snowplows and snow to surge the conspicuity of a snow.

1.2 Visibility Conditions of the Roads

The vast majority have known about the terrible chain response accidents which happen in fog. It is scarcely astonishing, given the impacts of fog on recognition. Fog clearly delivers accidents on the grounds that a driver can’t see as a long ways ahead. In any case, foggy conditions likewise advance accidents on the grounds that they influence perceptual judgments of pace and separation. The impacts are the aftereffect of diminished difference. We see objects, not in view of their outright splendor or dimness, yet on their distinction between the article shine and foundation. Fog brings down complexity considerably, creating items to wind up fainter and less particular.

The physical reason is the same as the dissipating impact in downpour – light hits dampness droplets and disseminates. As droplet size reductions, be that as it may, both the sort and mount of dissipating change. Littler droplets cause more scramble and particularly more backscatter. Fog is delivered by suspension of fine droplets noticeable all around, so the measure of diffusing is significantly bigger and there is more loss of differentiation and more backscatter from headlights. This is the reason that you ought not to utilize high bars as a part of fog. It may appear to be characteristic to change to high pillars so you can see more distant. Indeed, the principle impact is to scramble all the more light back to the eye and really diminish visibility.

The measure of differentiation lost relies on upon the separation of the article and the coefficient of disperse of light in the medium. This thusly relies on upon the size and thickness of the dampness droplets suspended in the environment. These qualities differ with area of the fog, as droplets in urban territories are generally littler because of the dust particles noticeable all around.

The summed up idea is to give the ceasing sight separation data to the accompanying or the contradicting vehicles through presentation or lights about alternate vehicles in the path through discovery advances consequently staying away from any potential accidents. The ceasing sight separation may be given either on the separation or on the number rating high to okay.

The warning framework for the restricting vehicle meets expectations totally in an inverse to the accompanying vehicle. The framework for contradicting vehicle can be utilized for the vehicle overwhelming the former vehicle and not having the capacity to see the vehicle approaching structure the other path. The configuration, framework segments, work force included in the operation of this framework are all subject to change as per need or interest.

Fog additionally advances accidents by method for “flying viewpoint,” a visual impact which causes individuals to misinterpret separation. Individuals naturally see objects which are low differentiate and unclear as being more distant away. We realize this in view of an ecological normality: light from inaccessible items, for example, mountains that are far away, must go through more air atoms and gets to be more scattered. Removed items are then less vague and fainter. The driver approaching the halted auto will judge it to be more distant away than it truly is and accordingly think little of the time and separation expected to stop.

2. LITERATURE REVIEW

2.1 Data Need for Transportation

Road transportation in the U.S. is continually undermined by the whimsical character of climate, as climate “acts through perceivability disabilities, precipitation, high winds, temperature extremes, vehicle mobility, asphalt rubbing, and roadway framework”. Antagonistic climate improves the probability of car crashes, which may bring about wounds and fatalities.

In 2001, there were more than 1.4 million climate related accidents, bringing about 425,000 injuries and more than 6,900 fatalities (Federal Highway Administration). The evaluated financial expense from climate related crashes in the U.S. alone adds up to about $42 billion yearly (from the Office of Federal Coordination and Meteorological Services). Moreover, unfriendly climate reasons movement deferrals, evaluated at almost one billion man hours every year, which corrupt the profit, unwavering quality and client experience of the surface transportation framework.

Enhancing the quality and openness of street and climate data may advantage a wide range of climate information clients, including: state and metropolitan bureaus of transportations, open climate “estimating” organizations, open climate “purchaser” offices, private climate data suppliers, electronic and print media, street clients, in-vehicle route framework suppliers, the overall population, mass travel, and rail (Murphy, 2005).

For the State of Utah, a Road Weather Information Systems explorer data assessment finished in 2000 demonstrates that drivers favor street condition data when the conditions adjust driving execution (e.g., collecting snow, ice, high wind for truckers, street terminations). Also, conditions by particular area and passageway are favored over a more general depiction of zone climate.

Figure: Weather Impact on Transportation and Traffic

2.2 Existing Systems

Unfavorable climate is unavoidable, however it is conceivable to relieve the dangers it postures at first glance transportation framework, through auspicious, exact, dependable, and easy to use street and climate data that backings surface transportation. Notwithstanding guaranteeing the security, versatility, productivity and benefit of the transportation framework, climate data for surface transportation will assume an inexorably vital part in crisis readiness at all levels of government, state, and nearby arranging and reaction (OFCM, 2003).

While there is a plenitude of data from climate stations worked by different offices, challenges for transportation office clients remain. First and foremost, such data is regularly not accessible in an auspicious manner. Second, such data may not be dependable regarding information quality and accessibility. Third, such data is typically excessively general, making it impossible to determine the pattern of street temperature in a particular territory or on a particular course. At last, such data is not effortlessly available in an easy to understand way. In this way, evaluating the street and climate conditions in the locale is generally a period expending and wasteful undertaking, as the vast majority of the accessible climate information are not intended with the end goal of supporting surface transportation.

Antagonistic climate is unavoidable, yet it is conceivable to moderate the dangers it postures at first glance transportation framework, through opportune, precise, solid, and easy to understand street and climate data that backings surface transportation. Notwithstanding guaranteeing the security, versatility, productivity and gainfulness of the transportation framework, climate data for surface transportation will assume an inexorably critical part in crisis readiness at all levels of government, state, and nearby arranging and reaction.

2.3 Other Services

Few of the organizations are frequently in contract with free climate administration suppliers to get definite gauges. Case in point, Meridian ecological Technology is one climate administration supplier that supplies support organizations with nitty-gritty conjecture data. Meridian has expanded the proficiency of estimate era and scattering, which permits meteorologists of a chance time to break down climate examples, delivering gauges with higher exactness (Block et al, 2003). It has been accounted for that advances in meteorology, information transfers and computational projects “have made a circumstance in which forecasters have more to offer transportation administrators and clients than any time in recent memory” (Davies et al, 1998).

The climate emotionally supportive network that was produced as a component of the push to get ready Salt Lake City and Utah for the 2002 Winter Olympics is an extraordinary illustration of such new headways at work. This framework helped UDOT with the upkeep of winter roadways, averting postponements to venues by both competitors and onlookers. NorthWest Weathernet Inc. was the essential supplier of street and asphalt condition figures for UDOT amid the Olympics, and since the Olympics, this supplier has kept giving climate estimates to UDOT.

3. METHODOLOGIES

3.1 Problem Identification and Proposed Solutions

While advancement has been made to support offices with climate data, the data is regularly lacking for operations. This is to some degree on the grounds that numerous teams depend on the National Weather Service (NWS) or private administrations that re-bundle information from NWS. NWS gauges are regularly excessively ambiguous for support staff as far as timing, tempest power and area. In 2003, FORETELL, a multi-state system concentrated on coordinating Intelligent Transportation System and astute climate frameworks (IWS) to give climate data to surface transportation, performed a business sector examination. From this investigation, the insufficiencies with current climate information were highlighted, including:

• Lack of data and geographic scope;
• Inaccuracies that outcome in absence of trust in deciding;
• Lack of essential point of interest,
• Difficulties in gaining data, and
• High cost for getting data.

In Utah, the Department of Transportation has developed 2 effective methods to reduce the fog related crashes.

1. Low Visibility Warning System.
2. Fog Dispersal Operations.

3.2 Low Visibility Warning System

Because of high movement volumes and neighborhood conditions helpful for thick fog development, the Utah Department of Transportation conveyed a low visibility cautioning framework on Interstate 215 to inform drivers of safe travel speeds and to advance more uniform activity stream. The notice framework was introduced on a 2 miles road over the Jordan River in SLC where more accidents happened which involved multiple vehicles due to fog and poor visibility conditions.

3.2.1 Components

1. Forward Diffuse Visibility Sensors: These Sensors are responsible for detecting the visibility conditions of the road by transmitting the light into atmosphere and at the same time reading the scattered light due to fog.
2. Loop Detectors: Vehicle detection loops, called inductive-loop traffic detectors, can detect vehicles passing or arriving at a certain point. An insulated, electrically conducting loop is installed in the pavement. The electronics unit transmits energy into the wire loops at frequencies between 10 kHz to 200 kHz, depending on the model.
3. Ultra High Frequency Radio Modems: Used to transfer the data from the Sensors (on-field) to the Traffic Manage Center where the data is processed to generate appropriate warning messages.
4. Central Computer: This computer will be used for calculation of the output to DMS systems based on the input which was provided by the sensors by applying certain pre-defined set of algorithms.
5. Dynamic Message Signs: These are also called Variable Message Signs, which are the huge, electronic signs which overhang or show up along major thruways in numerous urban areas. The signs are normally used to show data about movement conditions, go times, development, and road occurrences. The signs are utilized for development, road occurrences, or other relative data. The signs can also be utilized for open notices, climate data, or whatever other sort messages.

3.2.2 Operations

Four forward-diffuse visibility sensors and six vehicle location locales are introduced on the expressway to gather information on winning conditions. Visibility separation is measured progressively and inductive circle identifiers record the pace, length, and path of every vehicle. Through Ultra-High Frequency radio modems these information are transmitted to a focal PC framework that records field information in a database, methods field information, and posts advisories on two roadside Dynamic Message Signs (DMS).

The two most minimal visibility readings from the fours sensors are found the middle value of, and if this normal is beneath the limit, then the caution is stumbled and a sign is sent straightforwardly to the VMS’s to show the proper message. The framework additionally consolidates variable velocity limits. In the event that visibility is over 250 meters, then no message is shown. On the off chance that the visibility is somewhere around 200 and 250 meters, then the message “Fog Ahead” is shown. In the event that the visibility is somewhere around 150 and 200 meters, then “Thick Fog” is shown, substituting with “Exhort 50 mph.” If visibility is somewhere around 100 and 150 meters, “Thick Fog” is shown, rotating with “Prompt 40 mph.” If visibility is somewhere around 60 and 100 meters, “Thick Fog” is shown, exchanging with “Prompt 30 mph.” If visibility is under 60 meters, then “Thick Fog” is shown, exchanging with “Prompt 25 mph.” This is a bulletin framework, and the prescribed paces are not enforceable. Nonetheless, information have demonstrated that speed difference diminishes by 22% when the “Exhort” framework is actuated.

The central PC recognizes perils by using visibility partition, vehicle rate, and vehicle gathering data in a weighted ordinary computation to center when conditions warrant driver takes note. Right when visibility division falls underneath 820 feet (250 meters), the PC characteristically demonstrates a notification on DMS. In light of stopping sight partitions, safe travel speeds are posted on DMS when visibility is under 656 feet (200 meters). Messages indicated for distinctive visibility ranges are shown in the table underneath.

3.2.3 Efficiency

To study the adequacy of the framework Utah Traffic Lab (UTL) and UDOT introduced a framework known as Adverse Visibility Information System Evaluation (ADVISE) along the roadway to check for the visibility condition and effectiveness of the posted messages for the approaching drivers of the forthcoming fog ahead. The assessment of the framework was performed through consistent estimation of visibility condition and sending the bulletin rate to the drivers in view of the predefined edges of visibility levels. The study uncovered that decrease in pace variability among the vehicles driving in foggy condition was the significant result of the framework as the crevice between the rapid and the low speed of the drivers were diminished by just about 22% after the framework arrangement. Then again, the mean velocity was diminished by 15%.

3.3 Fog Dispersal Operations

There are three fundamental types of fog: warm mists, where droplets exist in air temperatures hotter than 0 degree C, super cooled hazes, where droplets exist in air temperatures colder than 0 degree C; and ice mists, where air temperatures are commonly colder than -30 degree C. Ice hazes are closely resembling thick cirrostratus mists, and have ice precious stone sizes somewhere around 2 and 50 μm at number densities somewhere around 30 and 700 cm-3. Pretty nearly 5% of all hazes in the United States are joined by sub-solidifying air temperatures.

Fog may be further arranged by physical procedures in charge of their development. A haze delivered by radiative cooling of the world’s surface is known as a radiation or ground mist. For instance, fog in the Central valley of California are by and large radiation mists. Shift in weather conditions hazes are delivered from the development of warm, soggy air (as in water vapor-loaded air) over a surface sufficiently chilly to prompt buildup above it. Fog along the U.S. west drift are by and large shift in weather conditions hazes. Shift in weather conditions mist that hence moves over generally colder ground, which keeps on cooling by radiation, is termed shift in weather conditions radiation haze. Haze that structures in damp air that streams up along a slope is called upslope mist. Haze that structures from the mixture of two distinctive air masses, whether these diverse air masses are immersed is ordinarily termed vanishing blending mist. Steam mist is a sample of vanishing blending haze and may be seen over the warm lakes at Yellowstone National Park, particularly amid the winter months (e.g. Dennis, 1980). Another illustration of dissipation blending mist could be one’s breath. Ice mist may be a radiation, shift in weather conditions, shift in weather conditions radiation, or an evaporation mixing sort haze

Utah has inquired about the utilization of aerial and ground seeding systems for the scattering of fog. These analyses have been fruitful in scattering fog to enhance road safety; nonetheless, the achievement relies on upon logistical arranging alongside meteorological and physical conditions that are inside the useful furthest reaches of the seeding idea.

In northern Utah area, super-cooled fog (i.e., under 32 degrees F) can endure in mountain valleys for a considerable length of time. Utah Department of Transportation (DOT) upkeep staff use fluid carbon dioxide to scatter fog and enhance visibility along sections of Interstates 15, 70, 80, and 84; US Highways 40, 89, and 91; and also auxiliary roads in Cache Valley and Bear Lake Valley. This treatment methodology incorporates the use of anti-icing chemicals as fog is scattered to keep dampness from solidifying on the roadside.

3.3.1 Components

1. Gas Barrel
2. Mounting Sections
3. Copper Funnel
4. Carbon Dioxide
5. Vehicle to hold the equipment.

Fog dispersal hardware, contained monetarily accessible items are introduced on about 70 support vehicles or 15 percent of the armada. Every truck is outfitted with a packed gas barrel, a manual valve get together, mounting sections, copper funnel, and an administering spout. Every barrel holds fluid carbon dioxide at a weight of 2,000 pounds every square creep (psi).

Liquid Carbon-Dioxide Release System

3.3.2 Operations

Before vehicles leave the support yard for typical watch obligations, the barrel and valve gathering are appended. Gadgets are turned on when support vehicles leave the yard and killed when they return. As the vehicles go through super cooled fog, little measures of fluid carbon dioxide are showered into the slipstream of the truck. The carbon dioxide rapidly vanishes expelling warmth from water droplets in the fog. The droplets structure ice precious stones and hasten as fine snow or ice. To keep the acceleration, from solidifying on the road surface, against icing chemicals are at the same time connected. In the event that the air temperature is beneath 20 degrees F (-6.7 degrees C), regular road salt is pre-wetted with fluid magnesium chloride and connected to asphalts. Road salt or sodium chloride saline solution is spread when the air temperature is over 20 degrees F.

Nozzle Size	Orifice (inches)	Release Rate (lb/hr)
1	0.020	20.80
2	0.028	34.40
3	0.034	52.80
4	0.041	70.00
5	0.044	94.80

Figure: 15-min test results on Carbon Dioxide Nozzles

This data joined with the way that fluid CO2 weighs roughly 8.5 pounds every gallon can be utilized to gauge the period of time that two chambers manifold together can be utilized persistently until the CO2 is exhausted. Case in point, with a number 3 spout, two full barrels ought to last pretty nearly 1.9 hours (100/52.8 pounds every hour = 1.9 hours).

3.3.3 Outcome

The fog dispersal treatment method enhances roadway versatility and security. This technique can expand visibility separate behind the upkeep vehicle from 33 feet (10 meters) to 1,640 feet (500 meters) in under 30 minutes. The treatment stays powerful for 30 minutes to 4 hours, contingent on air temperature and wind speed. Enhanced visibility has fundamentally diminished backside collides with support vehicles, upgrading the wellbeing of DOT staff and people in general.

3.3.4 Execution Issues

In 1990 the DOT’s Research Division supported a University of Utah examination award to examine fog control at an extension area. Amid the study college specialists perceived that a passage of clear visibility shaped in the fog as carbon dioxide was administered. In 1992 DOT and college analysts added to a model with tweaked equipment segments and started the field testing of versatile fog dispersal systems. The Research Division distributed field trial results in 1993. Based upon suggestions in the field trial report and lessons gained from against icing operations close Salt Lake International Airport, upkeep staff arranged a truck with fog dispersal hardware made out of business off-the-rack items. This design was more practical than the altered arrangement grew by the University, which was restrictively costly.

Before fog dispersal hardware was sent in 2000, the DOT built up a two-hour instructional class to guarantee representative security when working with packed fluid carbon dioxide. Instructional class themes included oxygen-relocation properties of the concoction, compound taking care of procedures, and operation of the high-weight allocator.

3.4 IMPLEMENTATION IN TEXAS

3.4.1 Outline of Texas Climate

Texas’ atmosphere is firmly affected by three substantial geological highlights. The main is the Rocky Mountains, or all the more broadly, the North American Cordillera. This arrangement of mountain reaches and levels, reaching out from Alaska through western Canada and the United States to Mexico and Central America, presents an impressive obstruction to air setting out from west to east or from east to west.

The essential climatic examples in Texas are genuinely basic: yearly mean temperature increments from north to south, and yearly mean precipitation increments from west to east

Extreme and High-Impact Weather:

Texas atmosphere, and the effect of changes in Texas atmosphere, is characterized by changes in normal conditions as well as changes in weather extremes. One could contend that the condition of Texas is the overall pioneer in the consolidated recurrence and mixture of extreme and high effect weather. Extreme weather incorporates tornadoes, hail and harming rainstorm winds. The pervasiveness of each of the three sorts of extreme weather by and large increments in Texas from south to north and from west to east (Figure 2.13). In South Texas and Far West Texas, critical tornadoes (those delivering F2 harm or more noteworthy) come surprisingly close to any given point not exactly once at regular intervals.

Winter weather is a threat to Texas to some extent on the grounds that it is so uncommon. Aside from the Panhandle and Plains and the mountains of Far West Texas, critical snowstorms or ice tempests are surprising. Thus, they ordinarily convey movement to a stop. Ice storms, specifically, cause harm to trees and electrical cables and can deliver force blackouts that keep going for quite a long time or weeks, especially in East Texas. The recurrence of winter weather abatements as one goes southward, however snow has been recorded in all sides of the state.

Figure: Texas Fog Advisory in winter

Driving in foggy weather on Texas roads:

It is not unprecedented for Texas drivers to be confronted with hazardous weather conditions on the road, including thick fog. This huge heap up was abnormal in size, on the other hand. As indicated by the Texas Department of Transportation, there were 1,610 engine vehicle mishaps brought about by fog in Texas in 2011. Of those, 19 mischances brought about fatalities and 273 prompted serious individual wounds.

At the point when conceivable, it is best to stay off the roads when a Dense Fog Advisory has been issued. In such circumstances, thick fog prompts visibility of just a quarter mile or less. Obviously, there are times when drivers must go amid such hazardous conditions. The Texas DOT suggests that those going in thick fog drive gradually and leave additional room in the middle of them and the auto before them. Drivers ought to never utilize their high pillar headlights, and ought to utilize fog lights on the off chance that they have them. Furthermore, drivers ought to abstain from switching to another lane at whatever point conceivable.

Accidents Due to Fog:

On November 22, 2012, two individuals were killed and scores of individuals were harmed Thursday when up to 140 vehicles crashed in thick fog Southeast Texas in an accident that left trucks wound on top of one another and powers hurrying to force survivors from the destruction.

The chain-response impact happened in to a great degree foggy conditions at around 8:45 a.m. Thanksgiving Day on Interstate 10 southwest of Beaumont, a Gulf Coast city around 80 miles east of Houston.

3.4.2 Strategies for Better Traffic Management

Just like the 2 systems (Variable Message Displaying Signs and Fog Dispersion Methods) implemented in Utah, we can implement those as the Climatic conditions in winter will be almost similar in Texas for past couple of years.

Fog Dispersion Method: Impact dry ice grains (strong carbon dioxide, temperature of -78.5 °C, estimate between 50 µm and 2 mm) with high-pressurized air at just about sonic pace into the fog. The dry ice grains slam into the fog droplets, gathering them and subsequently developing in size. Chilling off the fog prompts buildup development and thermodynamic shakiness of the fog. This instrument, called nucleation impact, has not been utilized so far by whatever other fog dissemination technique. The methodology is accelerated by constrained convection because of the plane. Hence, fog dissemination happens even past the direct dry ice plane.

By impacting 1 kg of become ice scarce to 50 m into the fog, it is scattered inside 3 minutes, passing a circle of 200 m in width. Utilizing portable frameworks, a passageway 200 m wide and 15 up to 25 km long can be dispersed inside 60 minutes.

3.4.3 Other Fog Reduction Systems

A few fog reduction frameworks utilized at airplane terminals may be changed for expressway utilization.

The significant issues included when attempting to apply airplane terminal strategies to expressways are the more noteworthy territories included, the expense, and the specific gear essential. In uneven regions, the fog covers a restricted territory and repeats in give or take the same area. This is not the situation in fiat territories where the fog may happen over wide regions or in patches. The most encouraging fog decrease frameworks have all the earmarks of being the accompanying:

a) Fog Seeding: The seeding idea includes the redistribution of drop sizes in regular fog with the need of changing fluid water content. It can be effectively shown that at whatever point the drop size appropriation in a fog is adjusted to cause the fluid water to be gathered in a couple large droplets, instead of the typical huge number of little droplets, visibility will be moved forward. Seeding common fog with a moderately couple of goliath hygroscopic cores can impact such a redistribution in drop size. Counts and examinations propose that for thruway application NaCl particles of around 4 microns span are best, albeit bigger particles are vital if fast clearing is craved.

Two sorts of seeding may be utilized ground seeding and airborne seeding. Ground seeding is proficient utilizing a vehicle that shoots the hygroscopic particles into the air. The primary disadvantage of the ground method is that just a moderately little zone of fog can be dealt with at once utilizing a solitary seeding unit. This recommends that a progression of littler seeding units would be ideal for expressway applications.

The best ethereal seeding technique includes flying opposite to the predominant wind and scattering the hygroscopic material in equally separated lines over the fog. The consequences of flying seeding trials have been empowering. Inside a couple of minutes in the wake of seeding, slender ways can be recognized in the fog, they increment in size until, after around 15 minutes, vast regions of fog are totally dispersed. In analyses in which quantitative information were gathered, the clearing held on for around 20 minutes prior unmodified fog started to lessen visibility in the seeded range.

b) Air Mixing with Helicopters: This procedure includes the utilization of vast helicopters to blend the immersed air with drier air from overtop. The framework obliges that the dampness of the drier air be close to 90% in light of the fact that blending almost soaked air with the fog can result in the cloud to end up denser.

c) Forest Stands and Vegetation Barriers: These hindrances hypothetically could be utilized to square the development of shallow fog from higher heights to low-lying encompassing territories. The writing doesn’t propose setups of planting to finish this.

3.4.4 Other Systems for enhancing visibility

No single system secured in the writing will deliver satisfactory visibility amid substantial fogs and no blends of techniques will restore visibility to the non-fog condition. The blend of techniques given underneath will expand visibility, will have a tendency to keep vehicles from running off the road (a real reason for mishaps amid fog) and will keep drivers from losing all sense of direction in fog.

a) Button lights introduced into asphalt edges at 20 foot dispersing: This method utilizes lineal direction got from light sources inset into asphalt surfaces. Low force light sources nearly divided have been discovered to be desirable over higher wattage units put on more extensive dividing. A purpose behind this is that the progression of the lineal example is enhanced and the glare every individual unit is enormously diminished, A quartz, iodine cycle, tungsten globule of from 5 to 8 watts gives off an impression of being suitable on the grounds that it can be worked in the open without harm by dampness, rain, snows or other weather conditions. The quartz globule is free from warm stun, and the general development of the unit is accounted for to be rough. It ought to be called attention to that slices will must be made in the asphalt for the establishment of the lights and resealed with epoxy around the establishments, and that the electrical wiring will be covered underneath the asphalt edges. One other potential issue is the likelihood of harm to the lights amid snow furrowing.

b) Low level lighting, mounted with the base of the luminaire 2.5 feet in stature: The cutoff plane is to be turned 4.15 ° underneath flat and the cone of enlightenment pivoted 110 ° to the middle line toward travel. Sharp cutoff and exact development of the reflectors are of awesome significance, as is precise conformity of the tilt of the cutoff plane. The lighting ought to be mounted at the edge of the cleared shoulder as per interstate road edge delineators. The establishment will be raised 2 feet past the external edge of the shoulder or the substance of un-mountable control or in the line of guardrail. A trial dispersing of 20 feet is recommended with enough versatility in the framework to take into account expanding or diminishing the dividing if fundamental. Exceptional consideration ought to be paid in configuration to prepare for vandalism and to guarantee that the stylish highlights of the road are not pulverized.

c) Pavement edge lines utilizing, reflectorized paints and a width of 6 creeps: The Highway Department may wish to consider three test areas. One for the lineal direction framework, one for the low level lighting framework, and one for a blend of the two frameworks. Every one of the three test areas would utilize a 6 inch edge line.

3.4.5 Cost

The expense of fog relief systems relies on the sort and measure of hardware introduced and the level of computerization included. Systems reaching out over long sections of highway or making serious utilization of sensors and signs have a tendency to cost more than shorter or easier systems. Those that utilization complex calculations to focus the activity that needs to be taken likewise have a tendency to cost all the more, as do systems obliging fiber optic or remote interchanges.

Among the current fog systems for which there were figures accessible, the expenses ran from $20,000 for individual segments to $4.5 million for a complete system. In Utah, 4 fog sensors with 2 Variable Message Signs (VMS) and 6 loop detectors cost almost half a million dollars.  (It ought to be noted that since these systems were introduced at distinctive times, the estimation of the dollar contrasts among systems.)

4. RESULTS

To assess the effects of the framework, in-asphalt circle finders were utilized to screen vehicle speed and grouping by path, course, and time of day amid foggy and clear conditions, prior and then afterward the framework was sent. Assessment information were gathered in three stages. Stage I information were gathered before arrangement to assess movement conditions when drivers settled on their own choices about travel speeds (benchmark condition). Stage II information were gathered to balance the framework, and Phase III information were gathered to gauge framework sways.

Between the Phase I and Phase III information gathering periods, I–215 was re-striped and transformed from a three-path to a four-path expressway to administration activity bypassing onto I-215 as an aftereffect of I-15 slope conclusion ventures. The vicinity of top stream activity conditions was accepted to change vehicle speeds as much as the vicinity of fog; hence, to help detach the impacts of the bulletin velocity messages, information gathered amid top periods were excluded in the examination.

The Phase I information gathered on 18 fog occasions, 594 minutes of antagonistic climate, and 38,522 individual vehicles going in off-crest periods. The Phase III information gathered on three fog occasions, 152 minutes of unfavorable climate, and 6,803 individual vehicles going in off-crest periods. In spite of the fact that the quantity of vehicles watched was impressively lower in the “after” condition, the study discoveries were demonstrated to be factually dependable.

5. CONCLUSION & FURTHER RESEARCH

The outcomes demonstrated the arrangement was fruitful at advancing more uniform activity stream amid fog occasions in Utah. As a surrogate measure of security, the enhanced uniform activity stream demonstrated there was less hazard for drivers going in repeating fog zones. The information demonstrated that when suggested travel rates were given, the quantity of too much moderate drivers diminished. The ADVISE innovation adequately lessened the normal standard deviation of rate between vehicles by 22 percent. Preceding the organization, the standard deviation was 9.5 mi/h. After the framework was conveyed and ADVISE messages were given, the standard deviation diminished to 7.4 mi/h.

The report likewise noticed that the normal vehicle velocity measured amid fog occasions expanded from 54 miles every hour (mi/h) to 62 mi/h after the framework was sent. The report inferred that the increment in normal pace was demonstrative of the general 6 mi/h increment in normal velocity saw amid non-fog days since 1996, and was incompletely attributable to the diminishment in exorbitantly moderate drivers amid fog occasions.

Based on the results from various state departments of transportations, given implementation methods suggest a better traffic management which will reduce the number of accidents thus by increasing the safety of the passengers in foggy road conditions and these methods can be implemented in various locations of Texas. Further research to include identifying the high probable accident prone locations on the interstate highways. Then based on the attributes of the location, more research needs to be done, on finding out the best implementation method.

6. REFERENCES

http://www.virginiadot.org/vtrc/primary/online_reports/pdf/72-r2

http://www.weather-tec.com/1334.html

http://www.nydailynews.com/news/national/35-injured-50-car-pileup-texas-article-1.1206412

http://www.texasclimate.org/Portals/6/Books/ImpactTX/Ch2Nielsen-Gammon.pdf

http://etd.fcla.edu/CF/CFE0003946/Hassan_Hany_M_201108_PhD.pdf

http://ops.fhwa.dot.gov/Weather/Publications/Case%20Studies/26.pdf

http://www.udot.utah.gov/download.php/tid=297/UT-02.12.pdf

http://www.udot.utah.gov/main/f?p=100:6:0::::V,T:,1

http://www.txdot.gov/inside-txdot/forms-publications/publications/txdot-reports.html