Which characteristic is vital for passenger awareness in the Blue Stripe program's signage at night?

The use of reflective materials and illumination in the Blue Stripe program's signage is crucial for passenger awareness at night because it ensures that the signs are visible and legible in low-light conditions. Effective signage in such settings must not only catch the eye but also convey important information quickly and clearly. Reflective materials enhance visibility by reflecting ambient light, which is particularly beneficial in dark environments, such as airport terminals or parking lots. This visibility is essential for guiding passengers safely and efficiently, especially during nighttime travel when visibility is compromised. Therefore, the characteristic of signage that focuses on ensuring that it can be easily seen and understood at night is critical for maintaining safety and enhancing the passenger experience.