Incidents of drivers crossing red traffic lights at the site of works on the A46 has prompted the Highways Agency to issue a warning.
Construction on the long-awaited widening of the road through Nottinghamshire began in June.
Traffic light-controlled crossings have been set up on local roads to allow safe access for construction traffic.
But in the past two weeks there have been a growing numbers of incidents where drivers have ignored the signals.
Work to make the 17-mile (28km) stretch between Newark and Widmerpool a dual carriageway will provide a new, fast link between the A1 and M1.
Colin Chadwick, Highways Agency senior construction manager, said: "There have been more than 30 instances of vehicles running red lights.
"It is quite unbelievable that people are willing to put themselves and others at risk of serious or fatal injury.
"Those delivering construction materials are driving dump trucks weighing 40 tonnes when empty and 80 tonnes when carrying a full load.
"The last thing we want is a tragedy because drivers cannot wait the few seconds it takes for the lorries to pass and the lights to change back to green."
The agency said the improvement work was due to be completed in 2012.