route_color_contrast: route text hard to read on its colour Warning

The contrast between route_color and route_text_color in routes.txt is below 4.5:1. A line badge some riders cannot read, and how to correct it in the feed.

Updated on 21 October 2026

What this rule means

In routes.txt, route_color gives a route's background colour and route_text_color the colour of the text drawn on it, both as six-character hexadecimal values. The validator computes the contrast ratio between them with the WCAG formula (relative luminance of sRGB colours). When the ratio is below 4.5:1, the WCAG threshold for normal-size text, it raises this notice. Severity: warning.

Only routes where both colours are filled in are checked.

Why it matters

A warning does not block a delivery in GTFS Express. But apps show the line's number (route_short_name) in a badge of the route's colour, with the text colour the feed provides. With poor contrast the number is hard to read in sunlight, on a dim screen, and for people with low vision or colour vision deficiency.

Common causes

• White text on a light colour (yellow, light green, pale orange) taken from the brand guidelines.
• route_text_color left at an old value after route_color changed.
• A route colour copied from a printed map designed for black text.

How to fix it

Change route_text_color to whichever colour contrasts best, usually 000000 on a light colour and FFFFFF on a dark one. If the brand fixes the text colour, darken or lighten route_color until the ratio exceeds 4.5:1.

In GTFS Express, the validation report lists the routes involved. "Fix one by one" opens each routes.txt row in the editor with the field flagged; the change is a retouch in the draft, and "Re-validate" confirms the new contrast.

Example

route_id,route_short_name,route_color,route_text_color
L12,12,FFD700,FFFFFF
L5,5,0055A4,000000

White on yellow gives about 1.4:1, black on blue about 2.8:1. Corrected:

route_id,route_short_name,route_color,route_text_color
L12,12,FFD700,000000
L5,5,0055A4,FFFFFF

See also the guide Validate a GTFS feed and the list of rules.