Driver visibility

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[edit] Introduction

In transport, driver visibility is the maximum distance at which the driver of a vehicle can see and identify prominent objects around the vehicle.[1] Visibility is primarily determined by weather conditions (see visibility) and by a vehicle's design.[2] The parts of a vehicle that influence visibility include the windshield, the dashboard and the pillars. High driver visibility is essential to safe road traffic.

Visibility in a vertical plane is important to see the road-edges and traffic-light and traffic-signs.

Visibility in a horizontal plane is important to see the traffic and the road.

Logicality, the 180 degree in front of the driver is more important than the 180 degree behind the driver

In front of the driver the Windshield-Pillar, side-mirror interior-mirror eliminate the most of the Visibility.

Another name for Windshield Pillar is A-Pillar

Behind the driver there are more Pillars and head support that eliminate the visibility. Necessary passenger(s) or/and cargo also eliminate the visibility.

A-pillar blind spot
A-pillar blind spot

[edit] Windshield Pillar design

This diagram shows the blocked view on eye-height in a horizontal-plane in front of the driver This can give problems in Traffic situations


An A-Pillar always eliminate the Visibility in a horizontal-plane plane.

A percentage of the 180 degree in front of the driver are two spots.

These spots are called "Front-end-blind-spots"

These specifications influence the size of these two angles

  • Distance between the driver and the pillar
  • Thickness of the pillar
  • The angle of the pillar in a vertical plane side view
  • The angle of the pillar in a vertical plane front view
  • the form of the pillar straight or arc-form

[edit] Types of A-pillar design

40° angle A-pillar bar blind spots
40° angle A-pillar bar blind spots

[edit] Most common A-pillar design

Most passenger cars have a diagonal pillar in the side view.

  • The angle between the horizon and A-pillar is approximately 40 degrees
  • Straight pillar
  • Not too thick

This gives the car a strong, aerodynamic body with an adequately-sized front door.

vertical A-pillar having small blind spots
vertical A-pillar having small blind spots

[edit] Panoramic vertical A-pillars

The sides of a panoramic windshield are curved.

This design make it possible to design vertical A-pillars.

The visibility for the driver is better if the A-pillar is as vertical as possible.

It is difficult to design an aerodynamic small car with a vertical A-pillar; it takes too much space from the door opening.

Examples of cars with an almost vertical A-pillar:

Old big cars:

Modern cars:


A-pillar bars reduce driver visibility
A-pillar bars reduce driver visibility

[edit] Flat A-pillar design

Some modern car designs have an extremely flat A-pillar angle in the side view plane.

This does have some advantages in reducing the overall drag coefficient and, this makes makes the car body stronger in a frontal collision.


A flatter windshield reduces more driver visibility in a horizontal plane.


Visibility of short and tall drivers
Visibility of short and tall drivers

[edit] Height of the driver

Driver height can also affect visibility.

An A-pillar that is split up and haves a small triangle window can give a short driver visibility problems.

Some cars the windshield is fillet with the roof-line with a big radius. A fillet round A-pillar can give a tall driver visibility problems.

Also the B-pillar (car) can block the vision of a tall driver in small 4 door cars.

Turn your head to reduces blind spot
Turn your head to reduces blind spot


[edit] Corners of the eyes

It is best to turn the drivers head to the view direction. The driver can estimate better distances.

Because the distance between both eyes is more, the eyes can look better round the A-pillar, And reduces the size of front-end blind spot.

[edit] Visibility in a cabrio

Because there is no roof connection between the A- and B- pillar The A-pillars of a convertible automobile have to be stronger and even thicker,

However, with the top down there are no B or C pillars, improving driver visibility behind the driver.

[edit] Reflection in the windshield

Sunlight dashboard reflection
Sunlight dashboard reflection

[edit] Dashboard reflection

It is best if the dashboard has a non-reflecting dark colored surface.[3]

A small dashboard gives some reflection on the lower part of the windshield.

A big dashboard can give reflection on eye height.

[edit] A-pillar reflection

It is best if the inside of the A-pillar has a non-reflecting dark colored surface.[4]

If the side of the window is curved there is less A-pillar reflection. [5]

[edit] Light through roof reflection

Some new model cars have a very big roof-window. Sometimes the sunlight through the roof lights up the dashboard and gives a reflection in the windshield.


[edit] Other disadvantages of flat windshield angle

  • Other traffic can not see the driver through the reflection if the driver can see them.
  • The heater needs more time to heat the bigger window surface.
  • The flat windshield angle does not let snow slide off easily.
  • The driver cannot reach the whole flat window to clean it easily.

[edit] See also

[edit] References

  1. ^ Fasimod
  2. ^ Wide-angle driver visibility and safety innovations distinguish Volvo BeeVan Truck Concept
  3. ^ http://esvc000873.wic017u.server-web.com/iPublish/archives/1/080.010.020/83/fs_nx_general_pack_8.pdf
  4. ^ http://esvc000873.wic017u.server-web.com/iPublish/archives/1/080.010.020/83/fs_nx_general_pack_8.pdf
  5. ^ Blind spot offenders named | Auto Express News | News | Auto Express

[edit] External links