The Effects of Commercial Electronic Variable Message Signs ...
The Effects of Commercial Electronic Variable Message Signs ...
The Effects of Commercial Electronic Variable Message Signs ...
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A.2 KEY MEASURES (DEPENDENT VARIABLES)<br />
Table 2. Expanded key measures (dependent variables).<br />
<strong>Variable</strong> Ref. # Advantages Disadvantages<br />
1.0 Vehicle Behavior 48<br />
1.1 Speed 125, 50<br />
1.1.1 Continuous More accurate pr<strong>of</strong>ile. Large amounts <strong>of</strong> data.<br />
Expensive.<br />
1.1.2 Discrete locations Less data. Cheaper.<br />
1.1.3 Speed exceedances:<br />
high; low<br />
Distraction indicator.<br />
1.1.4 Speed variance Distraction indicator. Best with continuous data.<br />
1.2 Lane position 161, 48,<br />
54<br />
1.2.1 Continuous More accurate pr<strong>of</strong>ile. Large amounts <strong>of</strong> data.<br />
Expensive.<br />
1.2.2 Discrete locations Less data. Cheaper.<br />
1.2.3 Lane excursions:<br />
right; left<br />
23 Distraction indicator. More difficult to measure.<br />
1.2.4 Lane variance Distraction indicator. Best with continuous data.<br />
1.3 Acceleration 48, 54<br />
1.3.1 Longitudinal: hard<br />
braking; delayed<br />
acceleration; braking<br />
without cause<br />
Excellent surrogate for<br />
distraction.<br />
1.3.2 Lateral: swerves 39 Good surrogate for<br />
distraction.<br />
1.3.3 Heave: bumps 125, 48 Not important.<br />
1.4 Other vehicle<br />
interactions<br />
39<br />
47
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