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. Author manuscript; available in PMC: 2021 Mar 1.
Published in final edited form as: Hum Factors. 2019 Jul 30;62(2):229–248. doi: 10.1177/0018720819864510

Table 3.

FCW System Parameters

Level Warning Characteristics TTC
1 Centered red rectangle taking up 6% x 3% of screen 4.0s-3.5s
2 Centered red rectangle taking up 8% x 4% of screen 3.5s-3.0s
3 Centered red rectangle taking up 10% x 5% of screen 3.0s-2.5s
4 Centered red rectangle taking up 12% x 6% of screen 2.5s-2.0s
5 Auditory warning & centered red rectangle taking up 12% x 6% of screen <2.0s

Note: TTC uses the relative speed of the lead and following vehicles to calculate the number of seconds until they would collide without intervention.