Work to ease traffic flows around a congestion hotspot at a Cumbria motorway junction was due to be completed on Monday.
The £2.3m project around junction 40 of the M6 at Penrith, where the M6 meets the A66 and A592 started in September.
About 44,000 vehicles use the junction every day and work included widening entry roads and the roundabout.
Flexible signal posts have also been used, which are designed to bend or break when hit, as a safety measure.
Other measures have included installing full-time traffic signal controls, improving the cycleway and footpath on the A66 and introducing an on-demand traffic signal crossing on the M6 northbound entry slip road.
The bendy signal posts come after safety tests at high and low speeds showed they cause less damage to vehicles and help protect passengers from serious injury.
Highways Agency project manager Phil Davies said: "This junction has been highlighted as one of 92 priority action sites by the Department for Transport to tackle congestion.
"These improvements will bring long-term benefits to motorists by increasing the capacity of the junction, reducing congestion and improving safety."