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HUMAN FACTORS PLANNING & DESIGN OF A CONTROL ROOM
THE CHANGING FACE OF CONSOLE DESIGN The emergence o new technologies, technologies, new ergonomic standards, standards, and increased public awareness o workplace health issues have combined to inspire a dramatic shit in console design. Today’s control workstations are smaller, more unctional, and more aesthetically appealing than earlier generations. The ergonomic approach approach to designing designing consoles into the layout layout o a control room should contribute to achieving the perormance objectives established or the space in question, while ensuring that every aspect o interaction between human, machine, machine, and the environment - rom raised ooring to acoustical concerns, rom indirect lighting to the overall well-being, health, health, and saety o each operator - is taken into account.
Top-Down Approach A top-down approach provides a ramework or ensuring that decisions on such matters as equipment selection, operating practices, working environments, and urniture choices all derive rom operating demands. No matter how well designed a workstation might be, the overall system will ail i operators are overloaded, overloaded, undertaking tasks or which they are poorly trained, or straining to read displays that are illegible. With a top-down approach, the limitations limitations o the operator are automatically included and potential mismatches between operator capabilities and system demands are minimized. The international international standard known as as ISO 11064 is the backbone backbone o ergonomic design o control rooms. The essence o this approach can be defned within a single term: user-centered user-centered design. The top-down approach approach requires that you frst frst spell out the the goals o the control center in various situations, including normal, o-normal, emergenc y, outage, and startup conditio ns. Determine D etermine what systems are required to accommodate these conditions, then list the unctions best undertaken by machines (e.g. repetitive calculations), ollowed by those unctions at which human operators are superior (e.g. coping with unexpected situations). The The result will defne system specifcations or computers as well as those tasks to be conducted by human operators. In addition to orcing an evolution in console design, revolu revolutionary tionary changes in technologies are also nurturing improved console aesthetics. The arrival o digital digital technologies, technologies, system system integration, integration, and at-panel displays have enabled console manuacturers to design a wider variety o consoles with smaller ootprints. Simultaneously, console manuacturers are also discovering more and more about the way people use control rooms. Sharing that knowledge with architects ensures that ergonomic actors will be designed into the larger control environment as well as into the consoles themselves.
Well-designed control rooms balance efciency with ergonomics. Winsted’s corporate mission is to create, develop, and market new products or new applications in the video production, broadcast, security, power power utilities, military, SCADA and transportation industries throughout the world. Since its ounding in 1963, The Winsted Corporation has consistently been the pioneer in the design and development o ergonomic consoles and control room urnishings, and over the years, its modular design systems have become the industry standard. In recent years, the company has broadened and expanded its product line with the development o specialized products or multiple industries. Winsted began expansion into overseas markets in 1975, primarily into the UK, and a year later, the company began establishing distribution in the Far East. Today, Winsted is a world leader in its industry.
Ater reading the content, one should be able to: 1. UNDERSTAND BASIC CONCEPTS OF CONTROL ROOM DESIGN AND CONSOLE PLACEMENT. 2. UNDERSTAND BASIC CRITERIA FOR FOR VISUAL ERGONOMICS. 3. BE FAMILIAR FAMILIAR WITH THE CRITERIA FOR ENSURING BOTH EFFICIENT WORKFLOW AND OPERATOR COMFORT IN ARCHITECTURAL SPACES DESIGNED FOR SYSTEM CONTROL OPERATIONS.
Ergonomics Ergonomics is the study o the human actors relationship between workers and their environment. Most original console standards were set back in the 19 60s, and have since been revised to accommodate both new technologies and new understandings o how our head, neck, and eyes operate. Past ergonomic stud ies were done with a person in the “sitting tall position ,” with his or her hips, shoulders, and ears in a straight, vertical line. Realistically, Realistica lly, no one would sit in such an uncomortable position, position, especially especially or the duration o an eight-hou r shit. Because we now understand underst and more about how the neck, head, and eyes operate, today’s ergonomic ergonomi c standards are based on more realistic assessm ents o how operators actuall y work at consoles. The latest ergonomic studies o people sitting in a relaxed position show that our heads tilt orward approximately approximately 8 to 15 degrees at a viewing angle o minus 30 to 35 degrees, and we preer an average
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HUMAN FACTORS PLANNING & DESIGN OF A CONTROL ROOM
Ergonomics Cont.
Figure 1
viewing distance dist ance o 30” to 35” rom the scree n, based on screen size. With that in mind, newer consoles are lowering the target angle o the primar y viewing displays. 8-15°
” 5 3
The average minimum viewing distance distance is largely determined by three actors: 30-35°
• • •
Eyesight accommodation is the distance at which our eyes focus when there is no object on which to focus. The eye muscles that focus the lens must work 2 1/2 times ha rder to focus at 12 ” than at 30”, which contributes to ey e strain.
45” 30-35°
Convergence is when the eyes turn inward to focus on a near item. This actually contributes more to eye strain than accommodation.
22.75” 578mm
Depth of focus is the range of distances that do not require the eyes to refocus, which most frequently affects the over-40 op erator, erator, those of us requiring reading glasses.
The solution solutionss to problems problems arising arising rom rom all three three actors actors are similar: similar: Lower the the monitor monitor height, keep items and screens to be viewed at similar distances, position displays at the proper angle to line o sight, increase task lighting on printed material, increase text size, and change tasks periodically. Accommodation Accommodat ion and convergence are both shortened when the gaze is lowered. The average resting point o convergence convergence is 35” at 30 degrees down angle, an gle, 45” at horizontal, horizontal , and 53” at 30 degrees up angl e. This data oers a signifcant justifcation or lowering monitor height. The other beneft o lower monitor height is a reduction in dry eye syndrome caused by eyelids opening wider when looking up.
42” 1067mm
3 5 ”
49.13” 1248mm
24.37” 619mm 23.50” 597mm
28.5” 723mm
21” 533mm
Figure 2
The vertical and horizontal horizontal eye and and head movement diagrams in Figure 1 & Figure 2 demonstrate demonstr ate best viewing angles or an operator. Ideally, there is no head movement and minimal eye movement or the most important and most common tasks. In the design o a console it is necessary to determine i the workstation will be used as an isolated unit or in conjunction conjuncti on with overview displays or other workstations. The height o the console should be calculated so the smallest operator can see over the top o any mounted electronics to remote monitor walls or displays, and the clearance beneath the worksurace should allow or the tallest operator to sit comortably. The max imum eye height o the shortest 5 percent o operators may be as little as 42”, 42”, depending on the range o chai r adjustment. adjustme nt. Physical layouts should accommodate the use o non-electronic equipment and documents, such as operations manuals, log books, maps, and clipboards. An element o exibility should also be allowed or positioning such items as telephones, keyboards, keyboard s, mice, controllers controller s radio/intercom and writing areas. Th is will enable operators to change posture during their shit and minimize the eects o atigue.
15° - Ideal Eye Movement 35° - Maximum Eye Movement 60° - Maximum Head Movement (Ideal Movement Movement is 0°) 95° - Maximum Eye and Head Movement
Displays/Monitors When using the top-down approach to designing display layouts, start with management objectives rather than attempting to see how many monitors can surround an operator. operator. Keep in mind that the amount o inormation that an individual can handle is limited. Maximizing operator perormance requires that the designer knows the amount o activity associated with each monitor image and the size o detail, both o which aect the detection o signifcant events. Even with as ew as our monitors, accurate accurate activity detection in a busy environment decreases to 83 percent . Displays that are used or close image inspect ion should be positioned directly dir ectly in ront o the operator, with sizes typically ranging rom 19 ” to 24”. Displays outside the workstation and positioned at a greater distance or behind the console should range in sizes rom 24” to 42” and larger. The introductions o at-panel displays displays and touch-screen touch-screen technologies technologies have have had a signifcant signifcant impact on console console design. Large cathode ray tube tube (CRT) monitors have been replaced with at-panel screens that take up considerably considerab ly less space, reduce power consumption, and require less cooling within the console. Every year the resolution, reresh rate, and size o LCD screens increas e on a per-dollar per-dol lar basis. Today, it is difcult to fnd displays with native mode resolut ion as low as the long-standing VGA standard o 640 x 480 pixels. More commonly, commonly, today’s displays range rom 800 x 600 (SVGA) to 1280 x 1 024 (SXGA), 1600 x 1200 (UXGA), or even greater.
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HUMAN FACTORS PLANNING & DESIGN OF A CONTROL ROOM
Displays/Monitors cont. When screen resolution increases, it means the operator can get closer to the display and still not be able to detect the individual pixels. Still, it is important to keep in mind that there are practical limits to the size o displays. A quick rule o thumb or viewing video images is that the operator should be at least twice the distance rom the screen as the height o the largest image displayed (not the display itsel ), but not more than eight times. The sweet spot is our to six times, depending on text (closer) or video (arther) images. A more precise set o guidelines, based based on screen diagonal size and image resolution, is explained in Figure 3. To 3. To calculate calculate display display width, remember that today’ today’s displays displays oten employ employ a 16:9 aspect ratio. Using a 9:16:18 ratio (height: width: diagonal), diagonal), the width o a 20” diagonal scre en will be 18” and the height will be 10”. Moderate to high-r esolution monitors ranging rom 19” to 24” diagonal measurements are typically appropriate or primary d isplays.
Figure 3 Minimum Recommended Viewing Distance for Display 60” Screen 50” Screen 40” Screen
QSXGA 2560 X 2048 QXGA 2048 X 1512 UXGA 1600 X 1200
30” Screen
HDTV 1920 X 1080
21” Screen
SXGA 1280 X 1024
17” Screen
XGA 1024 X 768 SVGA 800 X 600
12” Screen
VGA 640 X 480
Touch-screen Touch-screen technology technology is also aecting aecting the ergonomics ergonomics o new console console designs, designs, 9” Screen especially in high-security or high-attention environments. environments. While touch screens 0 100 200 300 are not used in many applications, new studies show that when some operators Viewing Distance (inches) get extremely nervous or come under high stress, they have trouble fnding and clicking on an icon using a mouse. But typically they have less trouble pointing with their fnger to an element on a touch screen. As a result, touch screens are becoming more and mor e prevalent in high-stress, control room applications. However, However, consoles incorporating incorporating touch-screen technology must oer a shorter distance between the operator and the screen - typically less than 28” rom the edge o the console worksurace - so that the screen can comortably be touched rom a relaxed sitting position.
Whatever the hardware interace, the the ideal is a design in which operator attention is ocused on a single source o vital inormation relevant to each situation. To minimize head and and extreme extreme eye movement, movement, the primary primary images images to be viewed, viewed, whether whether displayed displayed locally locally or on a distant distant video video wall, wall, should be centered centered within a 30 degree cone. To calculate the minim um distance, multiply the width o the display times 1.8 7. Thus, using our previous 9:16:1 8 example, a 20” diagonal display will have a width o 18 ”, meaning that the minimum distance d istance rom the di splay should be 34”, 34”, which is slightly less than the sweet spot calcu lation o our times the th e image height hei ght o 10”. 10”.
Control Room Layout Issues to consider when designing console placement in the control room include the room’s dimensions, the number o stations, the dimensions o each station, the dimensions o any video wall, and the width o the aisles. The distance rom rom which to view view a large-screen large-screen display or group group o displays should not be less than twice the display’s largest image height or greater than 6 times its height or normal norma l video. However, However, i this is a primary monitor or the operator, where it should ft into the 30 degree cone o viewing, then the longer-range ormula o screen width x 1.87, should take precedence. As an example, consider a console that is 42” deep, and aisles that are also 42” wide between rows o consoles, or a total o 84”. 84”. I the plan is to use one 80” diagonal display with 4:3 aspect ratio, here is how you would calculate the room layout: The frst row o o operators will will be 10’0” rom the ront (1.87 times the 64” width o a 80” diagonal screen). The back row will be no more than 31’0” rom the ront (6 times times the 64” width o a 80” diagonal screen). Be sure to add the last 42” aisle or a total depth o 34’ 6”. This will permit a maximum o our rows rows o consoles consoles and three aisles, aisles, to keep within within the maximum distance. To calculate calculate the maximum width o each row with adequate viewing angles rom each position, the frst row at 120” deep may be up to 14’8” wide wide (2 x (distance rom ront - hal the width o one screen) or 2 x (12 0 - 32)). The second row at 204” (102 + 84) may be up to 28’8” wide. The third row at 28 8” (120 + 84 + 84) may be up to 42’8” wide. wide. The ourth row at 372” ( 120 + 84 + 84 + 84) may be up to 56’8” wide. Alternatively, Alternati vely, you might be asked to determine the proper siz e or a large screen display, given certain room di mensions. The same ormulas apply. A command control room should be designed or more than just day-to-day operations. You need to consider every situation in the initial design and or uture upgrades. upgrades. Enough space should be maintained in and around the console so that multiple groups o personnel, rom supervisors to security proessionals, emergency service personnel, or even government ofcials, ofcials, can view and analyze inormation quickly and efciently. Design or crisis - hope or routine.
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HUMAN FACTORS PLANNING & DESIGN OF A CONTROL ROOM
Environmental Environmental Design The provision provision o an appropriate appropriate working environment environment is essentia essentiall or control control rooms that must must accommoda accommodate te auditory auditory or or visual visual tasks. tasks. Where speech speech communicatio communication n is important, all auditory needs o the environment must be appropriately specifed. specifed. Ambient noise levels need to be controlled by considering such actors as room and console fnishes, noise output o equipment, and control o external sources o noise. Ceiling acoustics should strive to achieve an NRC (noise reduction coefcient, a measurement o sound absorption characteristics) o 0.65 to 0.75 or better and an AC (articulation class, a measurement o sound attenuation) o 40 to 44 or better. better. Air quality and air temperature can play an important part in keeping operators awake and alert. One o the most common criticisms o control room design is a lack o consistent ambient temperature. An example o how environmental design can contribute directly to operator perormance is an air-conditioning system that is automatically set to increase the ambient temperature to compensate or natural early-morning drops in body temperature. Room temperature should range rom 70 degrees to 72 degrees F, with relative relative humidity rom 40 percent to 65 percent and minimal air movement not exceeding 4” to 6” per second. To maintain maintain the most consis consistent tent operat operator or environme environment, nt, a separate separate equipment equipment room room should should be provide provided d to house house CPUs, servers, servers, and other other rack-mount rack-mount equipment. equipment. This will will remove remove the the biggest biggest sources sources o heat heat rom disk arrays arrays and and processo processors rs and noise rom cooling cooling ans rom rom the operators’ operators’ area. It also has has the beneft o locating locating the most sensitive equipment in a secure, limited access area that is designed or proper cooling. Wherever extensive arrays o displays are used, lighting within control control rooms should be sufcient and suitable or all visual tasks. A lighting scheme largely based on indirect ambient lighting, where the ceiling reects light down into the room, has been ound to oer an eective solution. In designing a lighting scheme, attention needs to be given to the range o tasks undertaken as well as the ages o the operators. operators. Low levels o lighting may be fne or image monitoring but can pose problems with paper-based tasks. Operators o all ages, but especially older workers, will require adjustable task lighting to conduct small-scale visual tasks.
OPERATOR CONSIDERATIONS When designing a control room, the ollowing steps should be taken to ensure operator comort and saety: • Testco estconso nsole lelay layout outwi with thuse users rsfor for“Hu “Human manT Task asks” s”in inclu cludin ding g sequential task simulations. If necessary, modify console console layouts based on trial feedback. • Deve Develo lop pwo work rkst stat atio ion nla layo yout uts sde desi sign gned eda aro roun und dac acce cept ptab able le reach zones and visual limitations. • Takein akeinto toacc accoun ountm tmain ainten tenanc ancer erequ equire iremen ments tsand andre remov moval al of equipment from both the rear and front of the workstation. • Provid Providee eergo rgonom nomic icfoo footr trest estsw swher herea eappr ppropr opriat iate. e. • Provid Provide2 e24/7 4/7ch chair airsw swith ithfu full lladj adjust ustmen mentc tcapa apabil biliti ities. es. • Redu Reduce cee exc xces ess she heat ata and ndn noi oise seb by ylo loca cati ting nge ele lect ctro roni nics csiin nan an equipment room.
• Inw Inwor orks ksta tati tion ond dim imen ensi sion ons, s,con consi side der rth the efu full llh hei eigh ght tra rang nge e and size range of the users, utilizing height adjustment work surfaces where appropriate.
Ceiling materials should oer moderate to high reectance o 0 .8 or more to improve light distribution throughout the room and reduce energy costs or lighting. Walls should be an o-white matte or at fnish with a reectance range o 0.5 to 0.6. Floor materials should have a lower lower reectance o 0.2 to 0.3 or carpet or 0.25 to 0.45 or oor tiles. Operators typically do not like working in windowless environments. environments. Unless prescribed or operational or security reasons, it is strongly recommended that north-acing windows be included in a control room, primarily primar ily or psychological reasons. However, such light sources also pose potential security challenges and can contribute to reections and glare. Windows and doors should be o the primary feld o view but visible rom a seated position. Allow circulation space around doors to minimize congestion. A rectangular room provides the most possible options or equipment, display, and console positioning. In general, rooms with sharply angled walls or with support columns should be avoided. avoided. Designing a control room o the right size and shape can go a long way toward achieving an efcient, comortable operating environment.
REFERENCES CCTV Control Room Ergonomics, E Wallace & C Diey, PSDB Publication No 14/98.
Taking Control, Control, J Wood, CCTV Today, Volume 4, Number 2.
The Ergonomics o Closed Circuit Television (CCTV) Systems, 1997, Proceedings International Ergonomics Association Congress.
The Changing Face o Console Design, Neal Linnihan 615 1st Avenue NE Minneapolis, MN 55413
ISO 11064 - Ergonomics Design o Control Centers.
We have addressed a ew ergonomic considerations, considerations, but or the complete resource, reer to: Ergonomic Design o Control Centers, which is the International Standard ISO 11064.
CCD Design & Ergonomics Ltd Bank House 81 St Judes Road Englefeld Green, Egham, Surrey, TW20 0DF
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