Two crashes caused severe midday disruption to motorists near St Albans and Watford.
A crash blocked the M1 southbound exit at junction 6 for the A406 (Watford and St Albans) today (May 20).
The M1 "incident" and road traffic collision blocked the entire exit slip-road.
The road reopened at around 3pm.
There was also a crash on the M25 clockwise between junction 16 (M40, Uxbridge), and junction 17 (A412, Maple Cross), approaching Watford.
The M25 crash blocked three out of four lanes.
It has since cleared.
Tailbacks began at the M3 near Chertsey in Surrey, and stretched past Heathrow Airports to the M40.
An earlier queue began at junction 22 (A1081, St Albans) and ran anti-clockwise to the M40 at Uxbridge.
For the most up-to-date information about the county's roads, visit our LIVE Hertfordshire traffic map.
Join our Hertfordshire Travel Information group on Facebook for all the latest traffic news in Hertfordshire.
Do you have a live or breaking news story from across Hertfordshire? Email: hertslivenews@archant.co.uk
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here