Thursday, February 6, 2003

Nonergonomic! City Bus Door Controls

Nonergonomic! City Bus Door Controls
[人因工程 ]

City Bus Door Controls

The author/editor works in Taipei and takes the bus to work every day. One feature of the buses that has caught his attention is the design and layout of the bus door opening and closing controls. The controls consist of two levers which move up and down that are mounted side-by-side on the dashboard, slightly to the right of the steering column.

The general location of the two levers, though not ideal, is acceptable, and within reach of the driver's right hand. The problem is not with the general location, but with the size of the levers, their orientation, and their direction of travel.

Design Recommendations:

The levers are far too short. I am guessing here, but they appear to be about 2 inches or 5 centimeters in length. However long they actually are, they should be much longer -- two or three times as long. How do I know this? Because every bus driver in Taipei, without exception, has jerry-rigged his own custom remedy. Most have cut 4 to 6 inch lengths of rubber hose and slipped them over the black plastic switch extensions. The rubber hose extensions work suprisingly well. Not only do they allow the driver to flick the lever more easily, they provide a friendlier Man Machine Interface, cushioning the impact on the driver's fingertips. Some drivers have deliberately cut one hose shorter than the other to distinguish the front door switch from the rear door switch. These ingenious bus drivers who used their heads ought to change places with the product designers. Others have removed the black plastic switch extensions altogether and replaced them with what I swear are plastic ballpoint pen housings. They look like Bics.

The levers are oriented incorrectly. They should not be oriented one beside the other, but rather one in front of the other. Why? Because the doors to the bus are oriented in one in front of the other, therefore the door controls should naturally map this "one in front of the other" arrangement.

The levers move in the wrong direction. The levers should move left to right, not front to back. Why? Because when the doors open they open left to right (toward the curb), and when they close, they close right to left (toward the bus body shell). Therefore the movement of the levers should naturally map this "left to right, followed by right to left" movement. With switches arranged in this fashion, the driver who wishes to close both doors need only open his palm and sweep the two levers inward toward his own body. This movement does not require pausing to recall some artificial, consciously memorized "mental rule" before executing. Being completely natural, it feels right and is easily performed spontaneously, without the need to second guess oneself. That is what good design is all about.

The levers should not be the same length. The top or front door lever should be made longer than the bottom or rear door lever. The driver can then close either door or both doors in a single motion, merely by positioning his hand higher or lower before he flicks the levers left or right.

The bus manufacturers should pay attention to what end users, i.e., bus drivers, are telling them, indirectly. Bus drivers on Taiwan have been making these spontaneous modifications for at least ten years -- I first witnessed this Do It Yourself modification back in 1992. So why hasn't anyone with the bus manufacturing companies done anything about it in all this time? As is often the case, problems such as this persist not as a result of scientific and technological limitations, but as a result of defects in human institutions.

Explanation: City Bus Door Controls
Illustration: City Bus Door Controls (to be added when available)
Author: Bevin Chu
Affiliation: CETRA Design Information Section
Source: Bevin Chu
Publication Date: 2003
Original Language: English
Editor: Bevin Chu, Registered Architect

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