M6 Junction 20 (Lymm / Thelwall)
This is the busiest measured stretch of the entire M6. Junction 20 is where the M6 meets the M56 for Manchester Airport and North Wales, immediately south of the Thelwall Viaduct over the Manchester Ship Canal.
Live traffic speed flow: M6 Junctions 19 to 22
Untick all three to see just the speeds. We show the important overhead signs and the mandatory speed limits (red ring); see every overhead sign.
Go to our live M6 traffic speed flow map ›
NOTE: The speed flow, overhead sign messages or other information shown on our live traffic speed flow map is updated every few minutes. We cross check the data and aim to provide warnings if there could be a delay or an inaccurate speed reading. There can be occasions, beyond our control, and despite our best efforts where the speed flow could be inaccurate. We cannot therefore guarantee the speed you can expect on any stretch of the motorway is always accurately shown. However we hope you will find our live traffic speed flow map a useful tool in trying to plan your journey. Safe driving.
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How Busy Is the M6 at Junction 20?
The Department for Transport counts traffic on this stretch of the M6 — from Junction 20 to Junction 21 spur, a length of 2.5 miles. These are the 2025 figures.
| Measure | Per day |
|---|---|
| All motor vehicles | 187,521 |
| Cars and taxis | 129,006 |
| Lorries (HGVs) | 23,492 — 12.5% of all traffic |
| Length of this stretch | 2.5 miles |
© M6Traffic.co.uk · Statistics from the Department for Transport
That makes it the 1st busiest measured stretch by total traffic, and the 4th busiest for lorries. It is counted at 99 separate points along its length — see how busy the M6 is junction by junction.
What Our Own Speed Readings Show for Thelwall
Our readings for the stretch over Thelwall Viaduct come mostly from the evening and overnight hours, because National Highways' daytime readings here are patchy. In those hours, during Monday 12 to Friday 16 October 2026, traffic in both directions averaged well below what National Highways usually expects: around 42 to 44 mph in the evening and overnight, against a usual 58 to 61 mph. Our data does not say why. Overnight lane closures for roadworks are a common reason for slow night-time speeds, so it is worth checking M6 roadworks and M6 closures tonight before a late journey. National Highways reported no incidents on this stretch in the week we recorded.
| Time of day | Northbound | Southbound | Minutes of stop-start (north / south) |
|---|---|---|---|
| Overnight (00:00 to 06:00) | 43 mph (usual 59) | 42 mph (usual 58) | 0 / 0 |
| Morning peak (06:00 to 10:00) | Too few readings | Too few readings | 0 / 0 |
| Daytime (10:00 to 15:00) | 38 mph (usual 58) | Too few readings | 0 / 10 |
| Evening peak (15:00 to 19:00) | Too few readings | 39 mph (usual 52) | 0 / 0 |
| Evening (19:00 to midnight) | 44 mph (usual 61) | 43 mph (usual 60) | 0 / 0 |
© M6Traffic.co.uk · Our own record of National Highways’ live speed data (NTIS), Monday 12 to Friday 16 October 2026, averaged over the weekdays; “usual” is National Highways’ own expected speed for that hour. Stop-start means readings under 15 mph over at least 400 metres. One week of readings: we will add more weeks as they are collected.
Traffic count figures on this page are from the Department for Transport road traffic statistics, 2025.
Live traffic news at M6 Junctions 20 and 21
Incidents and roadworks between Junction 19 and Junction 22 that we are aware of.
M6 Northbound and Southbound mobile hardshoulder closure (MP 290/5 - 346/6)
05:42 (5:42am)23 Oct 2026reported 14 min ago
- Location
- M6 southbound between J23 and J22
- Direction
- Northbound
- Lanes closed
- Hard shoulder closed
- Reason
- Sweeping of road
- Schedule
- 20:35 (8:35pm) Sun 5 Apr 2026 → 23:59 (11:59pm) Fri 31 Mar 2028
+ 2 more near Junctions 20 and 21 - see all the M6 traffic news →
This is the news for Junctions 20 and 21 only, not the whole M6. For the rest of the motorway see all the latest M6 traffic news, the overhead signs and the speed limits in force now.
Updated 05:57 (5:57am) Fri 23 Oct 2026