A421 Marsh Leys Interchange

Layout and signage

Northampton
A428 (A6)
Bromham
Kempston
  B531

A428
(A6)
      Northampton
A428 (A6)
Bromham
Kempston

Lane configuration

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  • Lane 1 is gained from the entry sliproad.
  • Lane 2 continues, with option to exit.
  • Lane 3 continues ahead.

LanesLanesLanesLanesLanes

  • Lane 1 exits and does not return.
  • Lane 2 continues ahead.
  • Lane 3 continues ahead.

In this section

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The forever bottleneck, part 1

The M4 into London was one of the UK's earliest and most ambitious motorway projects. It was bold, pioneering... and almost instantly regretted.

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