M4 Spur

You are here: Home » Bad Junctions » M4 Spur

Where is it?

Junction diagramM4 junction 4, where the main road west from London throws off a spur to Heathrow, the third-largest airport in the world.

What's wrong with it?

This isn't just a spur to Heathrow, since the road to the north is an important link to the suburbs nearby. The problem, as ever, is that a little roundabout isn't enough as a starting point for a spur by any means. The amount of traffic using this road is phenomenal and yet the best solution the Highways Agency have yet proposed is maybe adding an extra lane around the roundabout or closing off one side of it.

Why is it wrong?

When it was built in the 1960s, Heathrow wasn't such a big airport. As Heathrow grew and grew — today you need to go as far as New York to find one bigger — so did traffic demand, but the M4 didn't and neither did its paltry spur.

What would be better?

Shut off the access road to the north — build a new junction, 3A, to the east if necessary. Then, make it free flowing — a three-level junction would be possible on the site (local residents wouldn't like it, but they have far greater problems with Heathrow itself) — since it pretends to be urban but is really mostly countryside around the interchange. Once that's done the cars should move again.

Right to reply

Hate this junction? Or do you think it hasn't had a fair trial? Make yourself heard! Post a comment.

These are all the comments that have been made about this junction.

September 2005

Owain narrowly avoided disaster:

Although I am only an occasional user of this junction, I'll second that! I've never had any delays there, but I nearly had an accident on this roundabout several years ago, in the manner Dan describes. I was turning right off the M4 to enter the airport - and following the lane markings carefully! - when something in the corner of my eye made me swerve instinctively away. Had I not done so, the nose of a black car to my right would have shoved me to the left. At the time I blamed the incident on the fact its driver turned out to be devoting more attention to his mobile phone than to his driving, but Dan's comments now make me wonder if his lane ended and he simply decided to occupy mine.

Dan W :

I've used the M4 from Reading to Heathrow for nearly 2 years and I've never got stuck on either the spur road or the roundabout that feeds it from the M4! ...It deserves to be in your hall of shame for another reason - the horrendous road markings on the roundabout that result in 3 lanes merging into 2 as you travel around it towards Heathrow. I get cut up from the right hand side almost every single morning on that roundabout. The problem is that most people who use the airport and drive that route dont know it very well and the poor markings are an accident waiting to happen.

With thanks to Jim N. for information on this page.