Publication statistics
Pub. period:1987-1995
Pub. count:8
Number of co-authors:19
Co-authors
Number of publications with 3 favourite co-authors:
Daryle Jean Gardner..:2Xiaohong Hu:1John W. Rice:1 Productive colleagues
Helmut T. Zwahlen's 3 most productive colleagues in number of publications:
Colin G. Drury:32Stephan Konz:15Qi Li:13
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Helmut T. Zwahlen
Publications by Helmut T. Zwahlen (bibliography)
Zwahlen, Helmut T. (1995): Driver Nighttime Visual Detection of Diffuse or Retroreflective Objects within the Context of Traffic Safety. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. .
Zwahlen, Helmut T., Kim, Dae Sig and Gerth, Richard J. (1995): An Evaluation of Mounting Step Dimensions and Handhold/Handrail Dimensions on Semi-Trucks, Agricultural, and Industrial Vehicles. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. pp. 1028-1032.
“This study reviews the literature with regard to falls and slips occurring when operators are mounting or dismounting high profile vehicles (HPV's) and discusses the major applicable design standards and guidelines for mounting steps and handhold/handrails. A checklist for the evaluation of mounting steps and handholds/handrails on HPV's is designed (3 major categories: step dimensions, handhold/handrail dimensions, and step surface factors). A sample of 31 HPV's consisting of 12 semi-trucks, 9 agricultural vehicles, and 10 industrial vehicles were selected, and their mounting steps, handhold/handrail, and step surface dimensions were measured. The checklist results show that primarily due to the lack of a 3 point system, none of the semi-trucks conformed well to the standards and guidelines and must be considered as inadequate from a compliance and safety point of view! Similar conclusions were drawn for the other HPV's.”
© All rights reserved Zwahlen et al. and/or Human Factors Society
Zwahlen, Helmut T. (1993): Evaluation of Pushbutton Arrangements in Automobiles. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 969-973.
“The need for more fingertip operated pushbuttons on automobile dashboards, consoles and steering wheels has increased over recent years with the emergence of new, sophisticated entertainment systems, driver aids, and communication devices. The space to place these controls within a driver's reach envelope has remained fairly constant, or has actually shrunk due to the down sizing of cars and the addition of crash protection devices. For this reason designers are forced to design smaller pushbuttons and to place these pushbuttons closer together in order to fit them into the allotted space along with the accompanying displays. With designers reducing the pushbutton sizes and putting them closer and closer together, the driver is forced to devote more time, more and/or longer foveal eye fixations, and more concentration to push the correct pushbutton. This could impose safety problems if too much time and concentration are diverted from the driving task. An exploratory study was conducted in the field, during daytime under fairly realistic conditions to examine the push location distributions when required to push exactly at a certain coordinate point in a car as a function of coordinate point location, car speed, driving task and road surface condition. This study resulted in a database of 5400 coordinate points of push locations. A model was developed to allow a designer to determine the size and spacing of round, square and rectangular pushbuttons based on a desired probability level of pushing the correct button. This model also takes into consideration the desired probability level of pushing any adjacent incorrect buttons. A computer program was developed based on the model and the experimentally collected data. The designer is required to enter information about the pushbutton shape, size, in car location, speed, road surface condition, driving task and the population percentile value of the fingertip width. The model uses a fingertip width concept which requires the user to input the distance expressed as a percentage of the fingertip width by which the fingertip center lies outside the button border and will still result in the activation of the pushbutton. The software then outputs the probabilities of pushing the correct, any adjacent incorrect, and none of the buttons. Correctly designed pushbutton arrangements (adequate size and spacing) should minimize activation time, foveal eye fixations, fixation times and errors resulting in fewer repeated pushes, which in turn, should improve safety while driving and operating pushbuttons in the modern automobile.”
© All rights reserved Zwahlen and/or Human Factors Society
Zwahlen, Helmut T., Hu, Xiaohong, Sunkara, Murali and Duffus, LuAnn M. (1991): Recognition of Traffic Sign Symbols in the Field during Daytime and Nighttime. In: Proceedings of the Human Factors Society 35th Annual Meeting 1991. pp. 1058-1062.
Zwahlen, Helmut T., Yu, Jing, Xiong, Shaolin, Li, Qi and Rice, John W. (1989): Night Time Shape Recognition of Reflectorized Warning Plates as a Function of Full Reflectorization, Borders Only Reflectorization and Target Brightness. In: Proceedings of the Human Factors Society 33rd Annual Meeting 1989. pp. 970-974.
“A study, using 11 subjects sitting in a stationary car on an unused airport runway with low beams on, was conducted to determine the distance at which a shape coded, white, reflectorized warning plate can be recognized at night as a function of the amount of reflectorization (either fully reflectorized or borders only reflectorized) and as a function of target brightness. Recognition distances were recorded for a balanced and randomized combination of 30 experimental conditions consisting of 3 different specific intensity levels of target brightness (high, prismatic sheeting material, 1080 cd/fc/sq ft at .2 degree observation angle and -4 degrees entrance angle; medium, encapsulated lens, 305 cd/fc/sq ft; and low, embedded or enclosed lens, 105 cd/fc/sq ft), 5 different target shapes of equal area (18 square inches, rectangle, square, triangle, circle and octagon), and two different types of reflectorization (targets that were fully reflectorized and targets that had only 4.25 square inches along their borders reflectorized). A car heading of -3 degrees to the left was used for the experiment to maximize target illumination. The results indicate that increasing target brightness had either no effect or only a small detrimental effect on correct target recognition distances for both the full reflectorization and borders only reflectorization, and that the triangle (the object with the fewest and longest sides) was recognized at the largest distance and with the fewest errors for both the full reflectorization and borders only reflectorization. The embedded or enclosed lens sheeting material transmitted the most information and produced the highest percentage of correct responses. Targets with the borders only reflectorized were also recognized further away than the fully reflectorized targets (15% further for 23.6% reflectorization). Implications of these results for the design of shape coded reflectorized warning plates for night use for both traffic and industrial settings are discussed.”
© All rights reserved Zwahlen et al. and/or Human Factors Society
Zwahlen, Helmut T., Aghazadeh, Fereydoun, Drury, Colin G., Gardner-Bonneau, Daryle Jean, Johnson, Steven, Konz, Stephan, Mital, Anil and Sanders, Mark S. (1988): Undergraduate and Graduate Courses in Industrial Ergonomics, Industrial Human Factors and Industrial Safety -- Where are We Today and Where Do We Need to Be in the Future?. In: Proceedings of the Human Factors Society 32nd Annual Meeting 1988. p. 495.
“The field of human factors, ergonomics, and safety has grown and expanded rapidly over the last two decades. The area of industrial ergonomics, industrial human factors, and industrial safety is becoming a smaller and smaller subset among the new emerging areas within the general human factors field and efforts of the Human Factors Society. The Human Factors Society has started an accreditation program for human factors education at the graduate level. At this point in time the accreditation document of the Human Factors Society is rather non-specific when it comes to the descriptions, teaching strategies, and experiences of industrial ergonomics, industrial human factors, and industrial safety courses.”
© All rights reserved Zwahlen et al. and/or Human Factors Society
Zwahlen, Helmut T., Gardner-Bonneau, Daryle Jean, Adams, Charles C. and Miller, Michael E. (1988): Night Time Recognition of Reflectorized Warning Plates as a Function of Shape and Target Brightness. In: Proceedings of the Human Factors Society 32nd Annual Meeting 1988. pp. 971-975.
“Two independent studies, each employing 12 subjects sitting in a stationary car on an unused airport runway with low beams on, were conducted to determine the distance at which a shape coded, reflectorized warning plate can be recognized at night as a function of target brightness. Recognition distances were recorded for a balanced combination of 15 experimental conditions consisting of 3 different specific intensity levels of target brightness (high 1080 cd/fc/sq ft at .2 degrees observation angle an -4 degrees entrance angle; medium 305 cd/fc/sq ft and low 105 cd/fc/sq ft) and 5 different shapes of equal area (18 square inches) targets (rectangle, circle, square, triangle, octagon). Study 1 used a car heading angle of 10 degrees to the right while Study 2 used a car heading angle of -3 degrees to the left. Results of these studies indicated that increasing target brightness had either no effect or only a small effect on target recognition distance, and the triangle (the object with the longest sides) was recognized at the largest distance and with the fewest errors. Targets were also recognized further away at the 10 degree car heading angle (less beam illumination) than at the -3 degree car heading angle (near maximum beam illumination). Implications of these results for the design and display of shape coded reflectorized warning plates in both traffic and industrial settings are discussed.”
© All rights reserved Zwahlen et al. and/or Human Factors Society
Zwahlen, Helmut T. and Jr., Charles C. Adams (1987): Development of a Work-Rest Schedule for VDT Work. In: Salvendy, Gavriel, Sauter, Steven L. and Jr., Joseph J. Hurrell (eds.) Social, Ergonomic and Stress Aspects of Work with Computers, Proceedings of the Second International Conference on Human-Computer Interaction - Volume 1 August 10-14, 1987, Honolulu, Hawaii. pp. 157-164.
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