tailbacks

/T EY1 L B AE0 K S/
noun
  1. 1

    A line of motor vehicles causing or the result of traffic congestion or a traffic jam; backup.

  2. 2

    A running back or halfback who lines up furthest to the rear in an I formation.

Source: https://en.wiktionary.org/wiki/tailback, https://en.wiktionary.org/wiki/tailbacks