It is the busiest shipping lane in East Anglia carrying anything from cars to large amounts of cargo between the UK and Mainland Europe.

The A11 splits off again towards the North and the A14 continues through Bury St Edmunds, past Stowmarket then on to bypass Ipswich via the Orwell Bridge and finally comes to an end at the Port of Felixstowe fully connecting the Midlands to East Anglia.

Prior to the current A14, the main route from Birmingham to the Haven ports followed the M6, M1, A428 and A45 via Coventry, Rugby, Northampton, Bedford, St Neots and Cambridge, and then went through all the towns on the A14 to Felixstowe.

[7] Vehicles over 7.5 tonnes traveling east were banned from using the outside lane on a dual two-lane section on a 2-mile (3.2 km) steep climb to Welford summit close to Junction 1 (A5199) from spring 2007; a similar scheme covered 2 miles (3.2 km) of the westbound carriageway from Junction 2, including a particularly steep climb to Naseby summit.

The bans are active between 6am and 8pm, and are intended to reduce delays to other traffic from lorries attempting to pass on these climbs.

[8] Between 2007 and 2008 a new section of a two-lane dual carriageway was constructed at the Haughley Bends, one of Suffolk's most notorious accident blackspots,[9] to rationalise access using a new grade-separated junction.

[11] Variable Message Signs (VMS), traffic queue detection loops and closed circuit TV (CCTV) were installed at a cost of £50 million during 2009 to 2010[12][13][14] Both carriageways between Junction 52 (Claydon) and Junction 55 (Copdock) were refurbished during 2010 at a cost of £9 million.

Work was being carried out a year earlier than scheduled as part of a UK government's fiscal stimulus package.

[15] The Cambridgeshire Guided Busway connecting Cambridge, Huntingdon and St Ives, which opened in 2011, was intended to remove 5.6% of traffic using that section of the A14 (rising to 11.1% with the new Park & Ride sites), although as other traffic re-routes to the freed-up road space from other parts of the local road network, the net reduction is predicted to be 2.3%.

[20] After initially being shelved in 2010,[21] the Catthorpe Interchange at the road's Western terminus underwent a massive restructuring in 2014.

[25] The local Conservative MP David Renton had played a large part in choosing the route, which not everyone had liked.

The Godmanchester to Bar Hill section was built by Sir Alfred McAlpine (Southern), opening in April 1981 as the A604.

The original Fenstanton bypass had opened in early February 1965, as a single carriageway, built by Cementation Company.

[31] The contract for the Girton to Bar Hill section was awarded on Monday 16 February 1976 to Roadworks (1952) Ltd, of Ipswich.

At the end of June 1976 a £16m contract was given to Bovis Civil Engineering, for the Madingley to Stow cum Quy section.

[53] One of the WC French civil engineers working on the project, Richard Coult of Rushbrooke, West Suffolk, originally from Felixstowe, died on Turkish Airlines Flight 981 on 3 March 1974; he was one of the 17 players of Bury St Edmunds RUFC on the doomed flight.

[56] The 2.2-mile (3.5 km) A45 Woolpit to Haughley New Street section started in October 1975, built by Monk, costing £1.6 million.

The viaduct was reaching the end of its life and needed replacing, a task that would require closing the road for a long period of time and not improve congestion.

The contract was awarded to Costain Skanska Joint Venture on 28 January 2008,[58] which worked on detailed plans for the Highways Agency before publishing a draft order.

[60] In October 2009 the cost estimate had risen to £1.3 billion with work due to start in 2012 and being completed in winter 2015/2016.

[61] The Campaign for Better Transport was opposed to the plans, listing their reasons for objection as the carbon emissions the road would induce, the cost, and its negative impact on non-car travel.

In November 2012, it was reported that the scheme might be back on a fast track to implementation[67] and it was mentioned in the June 2013 spending review.

[70][71] In September 2018, Highways England said it was to ask the Planning Inspectorate to consider giving the upgraded section of A14 motorway status, to be known as the A14(M).

[72] However, shortly after the amendment of the Development Consent Order, the announcement came that the new Huntingdon southern bypass, between Brampton and the A1 to Swavesey, was ready a year ahead of schedule.

[73][74] A smart motorway in all but name, the new road has variable message signs and gantries, emergency SOS lay-bys and virtually all non-motorway traffic is prohibited from using the new road (this includes pedestrians, cyclists, horse riders, horses & carriages, motorcycles under 50cc and agricultural vehicles).

[75] The new route is also to be supplied with variable speed limits to reduce congestion when legislation is passed to allow this technology to be used on primary roads.

The construction works of the section between Huntingdon and Godmanchester, specifically where the River Great Ouse is crossed, was painted by Michael Murfin, a local artist.

The artist's work records various stages of the build, depicting workers on the site and the heavy machinery used in the construction of the viaduct.

Until the opening in 2019 of the Huntingdon bypass, there was some confusion as to the identity of the section of road between the A141 junction at Stukeley (Spittals Interchange) and the A1(M).

Therefore, the "Alconbury spur" of the former A14 trunk route finally carries a unique road number again, in the form of the A1307.