"A single yellow line denotes a parking restriction. It is typically located on the side of the road and is painted yellow."
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White Lines vs Yellow Lines
White lines demarcate the roadway’s edge and separate opposing traffic flows. White lines, unlike yellow lines, do not indicate parking restrictions.
Parking on a single yellow line is not always permitted in the United Kingdom. It is essential to be aware of the parking restrictions in your area, including the times when parking is prohibited and any possible loading restrictions.
Check for nearby signs and road markings, and be aware of any possible exemptions, especially for disabled drivers and blue badge holders. If you are still determining the parking regulations in your place, you should always err on the side of caution to avoid receiving a PCN.