IT has been another frustrating morning for commuters after a crash caused 90 minute delays on the M6. 

A long stretch of the motorway currently has a 50mph speed limit while work takes place between junction 16 (Crewe) and junction 19 (Knutsford) to convert the section of road into a 'smart motorway'. 

But what is a smart motorway and why do we need it?

Here's the answers to some of the many questions you have probably been asking yourself while stuck in an M6 traffic jam.

Why do we need a 50mph speed limit during the work?

Highways England says this section of the M6 currently suffers from excessive congestion and unreliable journey times.

Narrow lanes, a 50mph speed restriction, CCTV coverage and average speed cameras have been installed for the 'safety of the travelling public and Highways England workforce'.

Why do we need a smart motorway?

The 20 mile stretch of the M6 motorway is being converted into an 'All Lane Running' Smart Motorway.

This is a motorway where all four lanes are open to traffic, with regular refuge areas available for emergency use in place of a hard shoulder.

The latest technology is used to monitor the traffic flow and set speed limits to maintain a constant traffic flow.

During these works the hard shoulder will be converted permanently in to a traffic lane.

How will this help?

Highways England says the work should reduce congestion and smooth the flow of traffic to improve travel times and make journeys more reliable. 

They also say it will provide much needed capacity on the motorway, reducing the cost of delays to commuters and business traffic. 

What will it be like driving on the M6 when it's finished?

In 2014 eight miles of the M25 became England's first All Lane Smart Motorway. 

But if you don't fancy the trip to see it, the RAC says under all lane running schemes, lane one (formerly used solely as the hard shoulder) is only closed to traffic via overhead and verge mounted cantilever signs, in the event of an incident.

Overhead gantry signs display the mandatory speed limit which varies depending on the traffic conditions and speed cameras are used to enforce these.

Signs can also be used to close lanes should that be required.

If an incident occurs in lane one – formerly the hard shoulder – a red cross (X) symbol is displayed to let motorists know the lane has been closed to traffic.

Driving in a lane under which the red X symbol is being shown is illegal and could lead to you being prosecuted.

CCTV is used extensively to monitor traffic for any incidents. Should drivers break down or be involved in an accident there are emergency refuge areas at the side of the carriageway for them to use with an average spacing of 1.5 miles apart.

What are they doing at the moment?

Highways England has completed the installation of the new concrete safety barrier in the central reserve between junction 19 and junction 16 and have switched the traffic management to the motorway verges.

Lane 4 between junctions 16 to 17 has now been resurfaced and teams are currently working in the motorway verge along the whole length of the works.

The verge work activities involve:

  • carrying out an extensive upgrade of the existing drainage system
  • replace and renew existing manholes and associated drainage
  • constructing 18 new emergency areas (EA) between junctions’ 18 and 19
  • installing a new cable ducting system for power and fibre cables
  • strengthening protection works to the over bridge structure’s that span the motorway
  • construct foundations for the new gantries
  • install overhead gantries and 258 electronic signs
  • install 70 CCTV cameras to provide full CCTV coverage

When is it expected to be completed?

Work started in December 2015 and is expected to be completed in March 2019 at an estimated cost of  £192 to £274 million.