Driver visibility
Encyclopedia
In transport
, driver visibility is the maximum distance at which the driver of a vehicle
can see and identify prominent objects around the vehicle. Visibility is primarily determined by weather
conditions (see visibility
) and by a vehicle's design
. The parts of a vehicle that influence visibility include the windshield
, the dashboard
and the pillars
. Good driver visibility is essential to safe road traffic
.
Blind spots may occur in the front of the driver when the A-pillar (also called the windshield pillar), side-view mirror, and interior rear-view mirror
block a driver's view of the road. Behind the driver, there are additional pillars
, headrests, passengers, and cargo, that may reduce visibility. Blind spots are affected directed by vehicular speed, since they increase substantially the faster one goes.
situations, such as in roundabouts, intersections
, and road crossings. Front-end blind spots are influenced by the following design criteria:
are curved, which makes it possible to design vertical A-pillars that give the driver maximum forward visibility. However, it is impossible to design an aerodynamic small car with a vertical A-pillar because the more vertical the A-pillar is, the less space the door opening has, and the greater frontal area and coefficient of drag the vehicle will have.
Examples of cars with an almost vertical A-pillar:
and Chevrolet Camaro
from 1993-2002 had a windshield angle of 68° with the vertical, which equals just 22° with the horizon.
A flatter A-pillar's advantages include reducing the overall drag coefficient
and making the car body stronger in a frontal collision, at the expense of reducing driver visibility in a 180° field of view from left to right.
An A-pillar that is split up and haves a small triangle window (Front Quarter glass
) 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 sometimes the A-pillar can block the driver from seeing motorcyclists.
Also the B-pillar (car)
can block the vision of a tall driver in small 4 door cars.
A driver may reduce the size of a blind spot or eliminate it completely by turning their head in the direction of the obstruction. This allows the driver to see better around the obstruction and allows the driver better depth perception.
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.
A small dashboard gives some reflection on the lower part of the windshield.
A big dashboard can give reflection on eye height.
If the side of the window is curved there is less A-pillar reflection.
. Sometimes the sunlight
through the roof lights up the dashboard and gives a reflection
in the windshield.
Transport
Transport or transportation is the movement of people, cattle, animals and goods from one location to another. Modes of transport include air, rail, road, water, cable, pipeline, and space. The field can be divided into infrastructure, vehicles, and operations...
, driver visibility is the maximum distance at which the driver of a vehicle
Vehicle
A vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured, such as bicycles, cars, motorcycles, trains, ships, boats, and aircraft....
can see and identify prominent objects around the vehicle. Visibility is primarily determined by weather
Weather
Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...
conditions (see visibility
Visibility
In meteorology, visibility is a measure of the distance at which an object or light can be clearly discerned. It is reported within surface weather observations and METAR code either in meters or statute miles, depending upon the country. Visibility affects all forms of traffic: roads, sailing...
) and by a vehicle's design
Automotive design
Automotive design is the profession involved in the development of the appearance, and to some extent the ergonomics, of motor vehicles or more specifically road vehicles. This most commonly refers to automobiles but also refers to motorcycles, trucks, buses, coaches, and vans...
. The parts of a vehicle that influence visibility include the windshield
Windshield
The windshield or windscreen of an aircraft, car, bus, motorbike or tram is the front window. Modern windshields are generally made of laminated safety glass, a type of treated glass, which consists of two curved sheets of glass with a plastic layer laminated between them for safety, and are glued...
, the dashboard
Dashboard
A dashboard is a control panel placed in front of the driver of an automobile, housing instrumentation and controls for operation of the vehicle....
and the pillars
Pillar (car)
Pillars are the vertical supports of the greenhouse of an automobile — known respectively as the A, B, C or D-pillar moving in profile view from the front to rear....
. Good driver visibility is essential to safe road traffic
Road-traffic safety
The term road traffic safety is about the risk of a person being killed or seriously injured while using the road network as a pedestrian, cyclist, motorist or user of on road public transport...
.
Blind spots may occur in the front of the driver when the A-pillar (also called the windshield pillar), side-view mirror, and interior rear-view mirror
Rear-view mirror
A rear-view mirror is a mirror in automobiles and other vehicles, designed to allow the driver to see rearward through the vehicle's backlight ....
block a driver's view of the road. Behind the driver, there are additional pillars
Pillar (car)
Pillars are the vertical supports of the greenhouse of an automobile — known respectively as the A, B, C or D-pillar moving in profile view from the front to rear....
, headrests, passengers, and cargo, that may reduce visibility. Blind spots are affected directed by vehicular speed, since they increase substantially the faster one goes.
Forward visibility
This diagram shows the blocked view in a horizontal-plane in front of the driver. The front-end blind spots caused by this can create problems in trafficTraffic
Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel...
situations, such as in roundabouts, intersections
Intersection (road)
An intersection is a road junction where two or more roads either meet or cross at grade . An intersection may be 3-way - a T junction or fork, 4-way - a crossroads, or 5-way or more...
, and road crossings. Front-end blind spots are influenced by the following design criteria:
- 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
- Angle of the windshield
- Height of the driver in relation to the dashboard
- Speed of the opposite car
Effects of A-pillar angle on visibility
Most passenger cars have a diagonal pillar as shown in this side view. The angle between the horizon and A-pillar is approximately 40 degrees with a straight pillar that is not too thick. This gives the car a strong, aerodynamic body with an adequately-sized front door.Panoramic windshield
The sides of a panoramic windshieldWindshield
The windshield or windscreen of an aircraft, car, bus, motorbike or tram is the front window. Modern windshields are generally made of laminated safety glass, a type of treated glass, which consists of two curved sheets of glass with a plastic layer laminated between them for safety, and are glued...
are curved, which makes it possible to design vertical A-pillars that give the driver maximum forward visibility. However, it is impossible to design an aerodynamic small car with a vertical A-pillar because the more vertical the A-pillar is, the less space the door opening has, and the greater frontal area and coefficient of drag the vehicle will have.
Examples of cars with an almost vertical A-pillar:
- HondaHondais a Japanese public multinational corporation primarily known as a manufacturer of automobiles and motorcycles.Honda has been the world's largest motorcycle manufacturer since 1959, as well as the world's largest manufacturer of internal combustion engines measured by volume, producing more than...
Step Bus Concept - Saab 900Saab 900The Saab 900 was a car produced by Saab Automobile from 1978 until 1998 in two generations. The first generation from 1978 to 1993 is known as the "classic"; the generation from 1994 to 1998 is known as the "new generation" ....
- School busSchool busA school bus is a type of bus designed and manufactured for student transport: carrying children and teenagers to and from school and school events...
- Almost all CadillacCadillacCadillac is an American luxury vehicle marque owned by General Motors . Cadillac vehicles are sold in over 50 countries and territories, but mostly in North America. Cadillac is currently the second oldest American automobile manufacturer behind fellow GM marque Buick and is among the oldest...
s from 1954–1959
Flat windshields
Some modern car designs have an extremely flat A-pillar angle with the horizon. For example, the Pontiac FirebirdPontiac Firebird
The Pontiac Firebird was built by the Pontiac division of General Motors between 1967 and 2002. The Firebird was introduced the same year as the automaker's platform-sharing model, the Chevrolet Camaro...
and Chevrolet Camaro
Chevrolet Camaro
The Chevrolet Camaro is an automobile manufactured by General Motors under the Chevrolet brand, classified as a pony car and some versions also as a muscle car. It went on sale on September 29, 1966, for the 1967 model year and was designed as a competing model to the Ford Mustang...
from 1993-2002 had a windshield angle of 68° with the vertical, which equals just 22° with the horizon.
A flatter A-pillar's advantages include reducing the overall drag coefficient
Drag coefficient
In fluid dynamics, the drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment such as air or water. It is used in the drag equation, where a lower drag coefficient indicates the object will have less aerodynamic or...
and making the car body stronger in a frontal collision, at the expense of reducing driver visibility in a 180° field of view from left to right.
Other disadvantages of a 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.
Height of the driver
Driver height can also affect visibility.An A-pillar that is split up and haves a small triangle window (Front Quarter glass
Quarter glass
Quarter glass on automobiles and closed carriages may be a side window in the front door or located on each side of the car just forward of the rear window of the vehicle. Only some cars have them. In some cases the fixed quarter glass may set in the corner or "C-pillar" of the vehicle...
) can give a short driver
Driving
Driving is the controlled operation and movement of a land vehicle, such as a car, truck or bus.Although direct operation of a bicycle and a mounted animal are commonly referred to as riding, such operators are legally considered drivers and are required to obey the rules of the road...
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 sometimes the A-pillar can block the driver from seeing motorcyclists.
Also the B-pillar (car)
Pillar (car)
Pillars are the vertical supports of the greenhouse of an automobile — known respectively as the A, B, C or D-pillar moving in profile view from the front to rear....
can block the vision of a tall driver in small 4 door cars.
Visibility in a convertible
Because there is no roof connection between the A- and B- pillarThe A-pillars of a convertible
Convertible
A convertible is a type of automobile in which the roof can retract and fold away having windows which wind-down inside the doors, converting it from an enclosed to an open-air vehicle...
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.
Windshield reflections
Dashboard reflection
It is best if the dashboard has a non-reflecting dark colored surface.A small dashboard gives some reflection on the lower part of the windshield.
A big dashboard can give reflection on eye height.
A-pillar reflection
It is best if the inside of the A-pillar has a non-reflecting dark colored surface.If the side of the window is curved there is less A-pillar reflection.
Light through roof reflection
Some new model cars have a very big sunroofSunroof
An automotive sunroof is a fixed or operable opening in an automobile roof which allows light and/or fresh air to enter the passenger compartment. Sunroofs may be manually operated or motor driven, and are available in many shapes, sizes and styles...
. Sometimes the sunlight
Sunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
through the roof lights up the dashboard and gives a reflection
Reflection (physics)
Reflection is the change in direction of a wavefront at an interface between two differentmedia so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves...
in the windshield.
Other automobile design factors
Other design factors may prevent a manufacturer from maximizing visibility. These include safety, as narrower pillars cannot be made strong as easily as thicker pillars, and size restraints pertaining to aerodynamics, as taller, more vertical windshields create additional drag and reduce fuel efficiency.Rear-view mirror blind spots
A vehicular blind spot is the area of the road that while driving cannot be seen when looking forward or through either the rear-view or side mirrors. Blind spots can be checked by turning one's head briefly, eliminated by reducing overlap between side and rear-view mirrors, or reduced by adding other mirrors with larger fields-of-view. Detection of vehicles or other objects in blind spots may also be aided by systems such as video cameras or distance sensors, though these are uncommon or expensive options in automobiles generally sold to the public.See also
- Experimental Safety VehicleExperimental Safety VehicleExperimental Safety Vehicle is the designation for experimental concept cars which are used to test car safety ideas.In 1970 the U.S. DOT announced its ESV project, the aim of which was to obtain safer vehicles by 1980. : A car produced by this effort was known as the Minicar RSV.In 1991, the ESV...
(ESV) - PininfarinaPininfarinaPininfarina S.p.A. is an Italian car design firm and coachbuilder in Cambiano, Italy.Founded as Società anonima Carrozzeria Pinin Farina in 1930 by automobile designer and builder Battista "Pinin" Farina, Pininfarina has been employed by a wide variety of high-end automobile manufacturers,...
vertical A-pillar Ferrari P4/5 - Volvo SCCVolvo SCCThe Volvo Safety Concept Car is an ESV concept car which was first shown at the 2001 North American International Auto Show in Detroit, Michigan.The car was the first and, to date, the only car to have an experimental criss-cross seatbelt...
- Blind spot (automobile)Blind spot (automobile)A blind spot in a vehicle is an area around the vehicle that cannot be directly observed by the driver while at the controls, under existing circumstances...
- AutomobileAutomobileAn automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
- Automobile design
- CrashCar accidentA traffic collision, also known as a traffic accident, motor vehicle collision, motor vehicle accident, car accident, automobile accident, Road Traffic Collision or car crash, occurs when a vehicle collides with another vehicle, pedestrian, animal, road debris, or other stationary obstruction,...
- Car handlingCar handlingAutomobile handling and vehicle handling are descriptions of the way wheeled vehicles perform transverse to their direction of motion, particularly during cornering and swerving. It also includes their stability when moving at rest. Handling and braking are the major components of a vehicle's...
- Car accidentCar accidentA traffic collision, also known as a traffic accident, motor vehicle collision, motor vehicle accident, car accident, automobile accident, Road Traffic Collision or car crash, occurs when a vehicle collides with another vehicle, pedestrian, animal, road debris, or other stationary obstruction,...
- Rear-view mirrorRear-view mirrorA rear-view mirror is a mirror in automobiles and other vehicles, designed to allow the driver to see rearward through the vehicle's backlight ....
- :Category:Automotive safety technologies
External links
- Volvo SCC (Safety Concept Car)
- Driver visibility in a School-bus
- http://www.autospies.com/news/Mercedes-Uses-Virtual-Reality-to-Study-Driver-s-Worldview-16700/Mercedes Uses Virtual Reality to Study Driver's worldview and visibility problems with the pillarsPillar (car)Pillars are the vertical supports of the greenhouse of an automobile — known respectively as the A, B, C or D-pillar moving in profile view from the front to rear....
. (22 jun 2007)] - "No vehicle may be equipped with more than two 'A' pillars..." (.DOCDOC (computing)In computing, DOC or doc is a filename extension for word processing documents; most commonly for Microsoft Word. Historically, the extension was used for documentation in plain-text format, particularly of programs or computer hardware, on a wide range of operating systems...
) - Vehicle Safety Site
- European safety ratings
- European vs US roof strength
- 2003 visibility test popular European car models
- American safety ratings
- There is no regulation for minimum driver visibility jet
- National Transportation Safety Board (USA)
- NRMA Insurance rating of driver vision for Australian vehicles
- CAR design