11. Data Entry And Touch Screen Usability, Continued

Also a feature of both navigation devices is an auto-zoom that changes the scale of distances automatically. Depending on the traveling speed, the map shown on the screen covers a radius from about 500 ft to more than five miles with both units. This feature can be switched off and the user can choose between several scaling steps. We found this feature, however, not to be extensive enough. On several occasions we would have appreciated an overview of our location in a larger area, such as within a county or even a state. The screen resolution of the tested devices (320x240 pixels) is arguably not high enough, but the simple absence of such a capability is a substantial drawback, if compared to a plain old road atlas.

The use of both touch screens takes some time to get used to - especially to determine the right pressure needed to activate keys. After a few hours of usage, every user who tested our units felt comfortable with both devices. A downside of both touch screens, however, is the fact that fingerprints become quickly visible, even after just one route. As a result, we learned to always have a paper towel available before we used the devices.

The Magellan's screen received complaints from our staff due to reflection issues and lack of appropriate brightness and contrast settings. In direct sunlight, the screen is virtually unreadable and drivers will have to rely on the audio narration. The iWay has a clear advantage here with four preset brightness/contrast settings. Readability in bright sunlight deteriorates but can be considered acceptable in any light condition.

Readability of the screens deteriorates quickly in direct sunlight, shown here in a less extreme example. The Lowrance device has a clear advantage in making the content readable in any light condition.

Screen readability of course was not an issue during night driving. However, we discovered significant differences in the backlighting of the physical navigation buttons. While the orange illumination of the Roadmate 700's buttons can hardly be better, the iWay's blue LED buttons are too bright and unreadable in dark conditions. The Roadmate's buttons are made from hard plastic, are more pleasant to touch and last longer. The iWay has rubber-based buttons that simply get stuck when pressed often.

The Roadmate's buttons are illuminated perfectly.

The iWay's illumination is too bright and causes the button description to be unreadable in poor light conditions.