Approaching Curves

And Hill Crests

Vermont Driver & Traffic Safety Education Association Driver Risk Prevention Curriculum

Vermont Department of Education�Driver Education Programs

Click to play movie Hyperlink 7.02 Car in a Circle.wmv

A Curve is a High Risk Location!

The most frequent location of single car crash for young drivers is the CURVE!

So what’s the problem?

A curve isn’t straight

A hill isn’t flat

Roadways have different compositions and conditions

The laws of physics come into play in a big way

They challenge the natural path of the vehicle

They block the drivers view

They challenge the drivers expectancies

Curve Types

Constant Radius

Every curve follows part of the circumference of one or more circles (an arc), A curve that follows the circumference of just one circle is called a constant-radius curve.

Deceasing Radius

This type of corner is very deceptive and dangerous. The further the car goes into the curve, the sharper the curve becomes and more steering is needed.

Increasing Radius

This type of curve is sharper as you enter it and requires a reduction in the amount of steering input as you exit.

Up &/or Down Hill

In these type of curves, the car will naturally try to lose

or pick up speed.

Entry Decreasing Radius Curve

Exit Increasing Radius Curve

More Complications

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• Short sharp curves have a smaller radius and require slower speeds
• Longer curves have a larger radius, are easier to negotiate and require less reduction of speed

Roadway Camber

Positive Camber or Bank: Left curve, the outside edge of lane is higher than the inside edge of lane – like the inside of the bowl – help to counteract the natural roll forces to the right as the vehicle curves left.

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Negative Camber or Bank: Left curve, the outside edge of lane is lower than the inside edge of lane – like the outside of the bowl – increases the rolls force to the right as the vehicle curves left. A further reduction of speed is required!

How Many Curves Do You See?

2 Down Hill Grades

1 Left Curve, 1 Right Curve

1 Positive Camber – in Left Curve

You will make a right turn at the intersection. �Will the camber have a positive or negative effect on your vehicle? What actions will you take?

Different Roadway Surfaces

Each Surface Demands a Different Level of

Tire Adhesion or Traction and Contributes a Unique and Dangerous Layer of Risk!

Flat

Concrete

Blacktop

Polished

Banked + or -

Gravel

Sand

Leaves

Water

Snow

Ice

Oil

Vehicle Contributes to Risk

Height

Width

Length

Weight

Center of Gravity

Type of Tires

Tire Inflation

Condition of Tread

Load Distribution

And More!

Demonstration� Traction for Action

Traction & Vehicle Control:

Roadway Surface and Tire Grip

Curves, Speed and Vehicle Load

Don’t be misled by the “The Okay Expectancy.”

• Drivers don’t set out to crash their cars
• Negative behaviors don’t always have a consequence.
• The lack of a consequence misleads drivers to the belief that they are not engaging in negative high risk driving behavior.
• That can result in “The Okay Expectancy”
• But knowing what to do, for example in the use of lane positioning or speed reduction can give the driver the sensitivity to detect a small error before it becomes a devastating crash.

Watch Those Speed Signs

They are determined by engineers who’ve calculated the safest speed for the configuration of the roadway and are designed to help drivers maintain vehicle balance while negotiating a given curve.

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You are traveling at 50mp on a clear sunny day when you first see this sign.

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What speed should you travel before you enter this curve and why?

Walking Car Performance

Volunteer?

Approaching Curves

• See Curve in Target Area
• Check Rear Zone
• When Roads Are Wet Test Tire-Road Grip
• See a Left or Right Curve – Prepare for Effective Driveline

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Click to play Movie Clip Hyperlink

Evaluate Driveline.mpg

Approaching Curves

• See Radius of Curve Helps to Determine Speed Selection
• Get Best Speed Control See 4 Seconds of Visible Road

If you can’t see 4 seconds your going too fast!

• Check the Left and Right Front Zones for traffic and LOS-POT’s Determine Best Lane Position for Approach

Entering the Curve

• See LOS-POT at Apex.
• Look into the curve- turn your head. Exit in LP-1
• Evaluate your new target area
• Evaluate targeting path for changing zone conditions

Approaching Hills

• When approaching a hill take LP-1
• At the hillcrest evaluate your path of travel. Search over the hill for open or closed POT
• Get best lane position for POT

What zone change do you see?�What is the best lane position?

Curves and hills are…

• High Multiple Risk Locations
• Risk Factors Are Contributed by:
• Roadway
• Vehicle
• Drivers
• Zone Changes

Use the Best Habits

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Get the best information

Get the best speed

Get the best lane position

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