There are three main types of smart motorway:
This type of smart motorway has mandatory speed limits with a hard shoulder available for emergencies only.
Hard Shoulder Running
The hard shoulder can be opened during busy, peak times on the motorway when needed, reducing congestion.
All lane running schemes
This type of smart motorway opens all lanes for traffic to use including a former hard shoulder and makes use of variable speed limits.
Only in the event of an incident is the hard shoulder lane closed to traffic.
A lane closure is indicated by a big red X on the gantry overhead. This means that, if you are already in lane 1 (the hard shoulder), you must exit it as soon as possible, as it indicates an obstruction in that lane. Ignoring the X sign can be extremely dangerous and will bag you a fine and points on your license.