International Journal of Industrial Ergonomics 35 (2005) 665–673 A method for assessment of degradation of task visibility from operator cabins of field machines Patrick J. Barron a,Ã , Philip M.O. Owende b , Kevin P. McDonnell a , Shane M. Ward a a Biosystems Engineering Department, University College Dublin, Earlsfort Terrace, Dublin 2, Ireland b Institute of Technology Blanchardstown, Blanchardstown Road North, Dublin 15, Ireland Received 30 September 2004; received in revised form 28 January 2005; accepted 1 February 2005 Available online 23 March 2005 Abstract Operator field of view is of primary importance for ergonomic, efficient and safe operation of field machines such as tractors, forest harvesting machines, and earthmoving equipment. This paper describes a technique that could be used for an objective assessment of operator cabin features that degrade the field of view. r 2005 Elsevier B.V. All rights reserved. Keywords: Visibility; Cabin ergonomics; Field of view evaluation 1. Introduction Clarity of the field of view is of primary importance for efficient and safe operation of field machines as 90% of the operator’s perception is visual (Drury and Clement, 1978). The field of view depends on the normal line of sight, and it covers the frontal area of the operator, which is estimated at 1801 on the horizontal plane and 1501 on the vertical plane. However, visual perception is not allocated equally over this entire area (Jung et al., 2000); hence, the visual field may be demarcated into (Sanders, 1970) the stationary field, where peripheral viewing is sufficient for detailed perception; the eye field, where supple- mentary use of the eye movements is required, and; the head field, where head movement is required. Ergonomic design of field machines with respect to operator visual perception considers factors such as optimal location of machine displays and appropriate sized window space for the viewing of respective machine operations (Mattila, 1996). Operator posture required to enhance task visibi- lity while in a working position must also be considered. For example, it has been suggested that warning displays should be within 301 of the normal line of sight or 451 for a ‘sit–stand’ ARTICLE IN PRESS www.elsevier.com/locate/ergon 0169-8141/$-see front matter r 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ergon.2005.02.001 Ã Corresponding author. Tel.: +35317167418; fax: +35314752119. E-mail address: pjbarron@ucd.ie (P.J. Barron).