ADVERSE WEATHER DRIVING

Wind 

Intense winds pose significant challenges to the handling of a school bus. Steering becomes more difficult, and staying within the travel lane is a struggle during high winds. Wind gusts can exert pressure on the side of the bus, leading to sideways thrust. In extreme cases, roof hatches have been known to pop open and tear off, highlighting the severity of the situation. Overcompensated steering can cause the bus to tip over or leave the travel lane. Wind may blow around debris that can hit the bus, causing damage or injuries. High winds increase just before and at the beginning of a change in the weather. Visibility can be severely impaired during thunderstorms, dust storms, and blizzards. Operators should be cautious when crossing bridges and overpasses, driving between hills, exiting tunnels, on open straightaways, and passing high-profile vehicles. 

Tips for driving in strong winds: 

• Grip 
  • Keep a strong grip on the steering wheel
  • Anticipate wind gusts. 
• Speed Reduction
  • Reduce speed to lessen the effect of the wind.
  • Pull off the road and wait. 
• Pull Over
  • Pull onto a solid shoulder, side road, or parking lot. 
• Call
  • Contact Dispatch to convey the situation and ask for instructions. 
• Observe Surroundings
  • Watch for blowing debris, falling trees or power lines. 
  • Reduced visibility may occur from blowing dust, sand, or snow.
• Prepare 
  • Always be prepared for the unexpected.

Tornadoes 

A tornado is a violently rotating column of air. In the northern hemisphere, tornadoes rotate counterclockwise. They develop in warm, moist air before an eastward-moving cold front. Most tornadoes move southwest to northeast. The average forward speed of a tornado is 30 mph, but it can be up to 70 mph. When the temperature is between 65 and 84 degrees, and the dew point is above 50, the dangers of a tornado are at their highest. Tornadoes often accompany severe thunderstorms. Tornadoes are common in eastern Colorado. Though rare, tornadoes are possible in the mountains, foothills, and western valleys.

Tornado Signs 

• Green-colored Sky 
• Hail
• Wall Cloud 
• Funnel Cloud

Many say a tornado sounds like a freight train approaching. If it does not appear to be moving, a tornado may be coming toward you. If you are on the bus and see a tornado, evacuate to a safe location, preferably a building. When in a building, go to an interior room or basement, away from windows, and have all passengers sit and cover their heads with their hands. When in the direct path of a sighted tornado and shelter in a building is unavailable and an evacuation is ordered, escort passengers to a nearby ditch, culvert, or depression. Direct all passengers to lie face down on the ground with their hands covering their heads. They should be far enough away so the bus cannot topple on them. Avoid areas subject to flash floods. Never go under a bridge or overpass, which can become the equivalent of a wind tunnel.

Downbursts - Microbursts and Macro bursts 

Downbursts

These are also known as straight-line winds, are intense winds formed by air that falls quickly to the ground and then disperses outward from the point of impact. The term downburst encompasses both macro and microbursts. The key distinction between microbursts and macrobursts is their size and duration. However, both types can unleash winds surpassing 100 mph, resulting in significant damage. 

Microbursts

A microburst is a small, focused downburst that releases a sudden burst of intense winds at or near the ground. Microbursts are compact, measuring less than 2.5 miles across, and typically last only five to ten minutes. There are two types of microbursts: wet and dry. A wet microburst occurs alongside heavy rainfall at the surface, whereas dry microbursts, often found in areas like the high plains and the intermountain west, happen with minimal to no precipitation reaching the ground.  

Macrobursts 

A macroburst is a sudden outflow of intense winds at or near the ground, spanning horizontal distances greater than 2.5 miles, which occurs when a powerful downdraft hits the surface. Initially, macroburst winds can start in a smaller region and then expand to a broader area, sometimes causing damage similar to a tornado. While they are typically linked to thunderstorms, macrobursts can also happen with light showers that lack sufficient strength to generate thunder. They are hard to detect, so be careful when thunderstorms and high winds are in the area. 

Other types of High Wind Weather 

Gust Front 

A gust front refers to the leading edge of cool air generated by rain, which collides with the inflowing warmer air of a thunderstorm. These gust fronts are distinguished by changes in wind direction, a drop in temperature, and gusty winds that precede a thunderstorm. Occasionally, these winds can elevate air above them, resulting in the formation of a shelf cloud or a detached roll cloud. 

Derecho 

A derecho is a common, long-lasting windstorm linked to a swiftly advancing band of showers or thunderstorms. Typically, a derecho includes many microbursts, downbursts, and clusters of downbursts. According to the definition, an event can be categorized as a derecho if the damage path extends over 240 miles and features wind gusts of 58 mph or higher for most of its length. 

Rain

When it starts to rain, the water mixes with oil and other road grime making the road very slippery. Standing water on the roadway may lead to additional challenges such as hydroplaning.

Thunderstorms

A thunderstorm is a rain event accompanied by thunder. As thunder results from lightning, every thunderstorm features lightning. A thunderstorm is deemed "severe” if it includes one or more of the following elements: 

• Hail one inch or greater,  
• Winds gusting in excess of 57.5 mph, or 
• A tornado 

Thunderstorms typically occur in spring and summer, primarily in the afternoon and evening, though they can happen at any time of year. They are often linked to various hazardous weather events. When conditions are favorable, the rainfall from thunderstorms can lead to flash flooding.  

Severe Thunderstorm Watch: The NOAA Storm Prediction Center meteorologists issue a severe thunderstorm WATCH when weather conditions are favorable for severe thunderstorms. A watch can cover parts of a state or several states.  

Severe Thunderstorm Warning: A Severe Thunderstorm WARNING is issued by the NOAA National Weather Service Forecast Office meteorologists when severe weather is reported by spotters or detected by radar. Warnings indicate a serious threat to life and property for those in the storm's path. A warning may encompass parts of one or more counties that are in danger. 

Lightning

Sudden storms can produce lightning. If a severe storm produces lightning, the safest place is in the vehicle, roll the windows up, and avoid contact with any conducting paths leading to the outside of the vehicle (e.g., radios, CBs, ignition, etc.). Avoid touching metal objects or pulling over in high-risk areas (canyons, near power lines, or tall trees). If a vehicle is struck by lightning, the metal shell acts as a Faraday cage, protecting passengers inside and making the vehicle relatively safe during a lightning storm. The electrical current from the lightning mainly travels through the metal frame and tires, avoiding the passengers. Despite this protection, the vehicle may still sustain damage, particularly to the antenna, electrical system, rear windshield, and tires.  After a lightning strike, it's recommended to remain inside the car for at least 30 minutes after the last sound of thunder before exiting. 

Water on Roadways 

Water on brake drums will reduce braking efficiency. A light application of the brakes can prevent excessive water between the drum and brake pads. During excessively wet conditions or after passing through standing water, it may be necessary to apply the brakes slightly for a short distance to dry them out and restore normal braking.

Hydroplaning

Hydroplaning can occur on any wet road surface. The first 10 minutes of a light rain can be the most dangerous. When a tire encounters more water than it can scatter, water pressure in the front of the wheel pushes water under the tire, thus separating the tire from the road surface with a thin film of water. The result is loss of traction, steering, braking, and power control.

How to avoid hydroplaning 

• Slow down when roads are wet. 
  • The faster the speed, the harder it is for tires to scatter water properly.
• Stay away from puddles and standing water.
• Do not use cruise control, if equipped.
• Drive in a lower gear.
• Avoid hard braking. 
• Try to avoid making sharp or quick turns.

Never attempt to drive in flowing water, as the depth and force of the current are unknown. Dangers may not be visible. There may be debris, downed power lines, or washed-out portions of the road.

Slippery Surfaces

Bus braking or steering cannot occur unless there is traction. Road conditions may reduce traction and require slower speeds. When slick road conditions exist, it will take longer to stop and be harder to steer the bus without skidding. Slippery surfaces can more than double stopping distances.

Common Slippery Surfaces 

• Shaded areas 
  • Shaded parts of the road may remain icy and slippery long after open areas have melted and dried. 
• Bridges 
  • When the temperature drops, bridges freeze before the road surface.  
  • Be especially careful when the temperature is at or near freezing (32°F). 
• Snow 
  • Various types of snow offer different levels of traction. The most traction can be obtained from dry, granular snow or very cold snow. 
  • Occasionally, packed snow may give better traction than freshly fallen snow. 
  • When temperatures fluctuate around freezing, the danger of driving increases because the road surface may be covered with snow, camouflaging ice, or the snow may be ice-covered, thus reducing traction. 
  • The roads are most hazardous when the snow or ice begins to melt. 
  • It is important to exercise extra caution when driving on packed snow or icy roads when the temperature outside is close to freezing (32°F). 
• Black Ice 
  • When the temperature drops below freezing, but the road looks wet, it may be covered in black ice.  
  • This thin, transparent layer of ice can occur anywhere but is more common in high-traffic intersections and areas exposed to wind. 
  • It is most prevalent during the early morning hours, especially after snow melts on the roadways, and it can refreeze overnight when the temperature drops below freezing. 
  • This can also form when roadways are slick from rain, and temperatures drop below freezing overnight. 
• Hail
  • Like ice, hail provides a unique set of hazardous circumstances.
  • Hail on the roadways can produce an extraordinarily slippery and uneven road surface.  
  • Hail can also break windshields and windows. 
  • If you're facing hail, it's generally wise to look for a sheltered, low-risk parking spot if available. It’s better to wait it out than risk damaging your windows. 
• Mud and Mudslides 
  • Roads covered in excessive mud can become slippery and nearly impossible to navigate. 
• Heat 
  • High temperatures can lead to the tar in road pavement surfacing, resulting in a soft or slippery area. 
• Other 
  • Materials applied to roadways for anti-icing and de-icing, such as gravel, magnesium chloride, and salt, can initially enhance traction by melting the upper layer of snow or ice during daylight. However, as temperatures fall below freezing at night, they may lead to the formation of new ice, ultimately reducing traction. 

Skids 

A skid happens when a vehicle’s tires lose traction on the road. Some common ways this can happen are: 

• Over-braking 
  • Either braking too hard and locking up the wheels,
• Over-steering 
  • When the operator turns the wheels sharper than the bus can turn at a given moment.
• Over-acceleration
  • When the drive wheels’ spin due to too much power sent from the operator. 
• Driving too fast 
• Serious skids result from driving too fast for road conditions.

Operators who adjust their driving to the conditions do not over-accelerate and do not have to over-brake or over-steer from gaining too much speed. Learning to stay off the brake and react quickly during a skid takes a lot of practice. Avoid sudden movements, such as abruptly changing the steering, acceleration, or braking, which could worsen the skid. Keep your eyes up and look where you want to go, focus on your desired path, not where the car is currently sliding. The best place to practice this is on a large driving range or "skid pad.”

Drive-Wheel Skids 

This is the most common skid and happens when the rear wheels lose traction through excessive braking or acceleration. Rear wheel braking skids occur when the rear wheels (drive tires) lock. This usually happens on slippery surfaces. Because locked wheels have less traction than rolling wheels, the rear wheels usually slide sideways in an attempt to “catch up” with the front wheels (steer tires). In a bus, the vehicle will slide sideways into a “spin out.”

To correct a drive-wheel skid 

• Stop accelerating 
• Stop braking to allow the rear wheels to roll again 
• Steer into the direction the vehicle is sliding. This helps to counteract the sliding motion and regain control. 
• Once the vehicle regains traction, gently steer in the desired direction to continue moving forward. 

Important Considerations:

• Front-wheel drive (FWD) and all-wheel drive (AWD) vehicles 
  • Lifting off the accelerator and steering the direction of the slide will best help to correct the skid. 
• Rear-wheel drive (RWD) vehicles 
  • Steering to the skid is particularly important in RWD vehicles, as the rear wheels are the ones losing traction. 

Front-Wheel Skids 

Driving too fast and having inadequate tread depth on the front tires causes most front-wheel skids. In this type of skid, the front of the bus tends to go in a straight line regardless of how much the steering wheel is turned. This causes extreme difficulty (if not impossibility) when steering around a curve or turn. 

To correct a front-wheel skid 

• Release the accelerator 
• Do NOT brake. This will allow the front wheels to turn again and regain traction. 
• In a front-wheel skid, it is generally better to keep the steering wheel in the position it was in before the skid happened.