Color Vision and the Railways: Part 3. Comparison of FaLant, OPTEC 900, and Railway LED Lantern Tests

The Farnsworth Lantern (FaLant) and the OPTEC 900 are nominated in the Commission Internationale de l'Éclairage (CIE) Color Vision Standard 2. Neither test uses the railway signal color code of red, yellow, and green, and only the OPTEC 900 is commercially available. The Railway LED Lantern Test (RLLT) is based on railway signaling practices in New South Wales, Australia, and is nominated in the Australian railway medical standard. The objective of this study is to compare the performance of the three lantern tests.

The RLLT, FaLant, and OPTEC 900 were administered to 46 color vision-normal and 37 color vision-deficient (CVD) subjects.

The pattern of errors on the RLLT was different from that of the FaLant and OPTEC 900. This may be accounted for, at least in part, by the different colors and the use of blank presentations in the RLLT. The three lanterns showed agreement in failing 21 and passing 6 of the CVD subjects (72.9%). The lanterns gave different results for 10 CVD subjects (27.9%): n = 5 passed only the RLLT and n = 3 passed only the FaLant; n = 1 failed only the FaLant and n = 1 failed only the RLLT. The overall failure rate by CVD for each lantern was 67.6% (RLLT), 73.0% (FaLant), and 78.4% (OPTEC 900).

Despite the different construction principles, the pass/fail levels of the RLLT, FaLant, and OPTEC 900 are comparable and consistent with the performance of other lanterns listed by the CIE for Color Vision Standard 2. The RLLT may be a little easier to pass and is based on the signal color code used and actual signaling practice. We propose that the RLLT is also an appropriate lantern for CIE Color Vision Standard 2.