Publication Detail

California Advanced Driver Information System II (CADIS II): Extended Tests of Audio and Visual Route Guidance Displays

UCD-ITS-RR-95-03

Research Report

Suggested Citation:
Srinivasan, Raghavan, Paul P. Jovanis, Francine H. Landau, M. Laur, Charles Lee, C. M. Hein (1995) California Advanced Driver Information System II (CADIS II): Extended Tests of Audio and Visual Route Guidance Displays. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-95-03

The current study supplements the analyses conducted during CADIS-I to resolve other human factors and technical issues relating to the development of in-vehicle route guidance systems. The CADIS II workplan proposes to explore more interface designs as well as test the performance of interfaces in isolation (not with the electronic map as a common technology). As a result, a two-phased approach is implemented in CADIS II: first, individual interfaces are tested in the high fidelity Hughes Simulator; then a broader set of map, guidance screens and voice systems are tested on a moderate fidelity table top simulator developed for the project and located at UC Davis.

The experiments in the Hughes driving simulator are a direct extension of the CADIS I experiments and are conducted to address the following issues regarding the design of route guidance systems that arose as a result of findings from CADIS I:
  • 1. Will audio-guidance alone perform as well and be perceived as favorably as the audio-guidance electronic map combination?
  • 2. Is a heads up guidance display superior to a heads down guidance display, given the same display format?
  • 3. Will a modified guidance display (compared to the one used in experiment 1) perform better and be perceived more favorably that in experiment I?
To address these issues, five route guidance systems are tested: (1) Paper map, (2) Heads down electronic map, (3) Heads up guidance display alone, (4) Heads down guidance display alone, and, (5) Voice guidance alone. The study used the same simulated roadway network as in CADIS I, however, some changes are made to the driving scenarios. All lead vehicles in front of the subject are eliminated as subjects had responded inconsistently to the vehicles. Two secondary tasks (roadside scanning task and a monitoring task for vehicles that start to move into intersections) are added to increase and more uniformly distribute subject workload and increase the sample size of subject reaction times so that the distraction attributable to the interfaces could be identified with greater precision. Dependent variables included response times to the scanning and monitoring tasks, number of navigation errors and collisions, subjective workload and user perceptions.