A fire at a scrapyard that led to the closure of a section of the M1 has prompted ministers to ask for a review of roads and railways that may be at risk of a similar accident.
The stretch of the M1 between junctions one and four was closed following the fire under an elevated motorway section on Friday, causing traffic disruptions.
On Monday afternoon, two lanes on both carriageways along the seven-mile affected section were opened.
However, drivers have been warned they could face more delays over Easter if a contraflow with three lanes is not implemented in time.
They have been advised to consider alternative routes.
Transport secretary Philip Hammond saidHighways Agency staff had "worked tirelessly around the clock to reopen the motorway".
Mr Hammond said: "It is crucial that we learn the lessons from this hugely disruptive event and ensure that we minimise the risk of something similar happening again.
"I have, therefore, asked the chief executives of the Highways Agency and Network Rail in the first instance to provide me with a report on potential sources of risk to the strategic transport networks from activities below roads and railways, or on adjacent sites.
"As well as identifying sources and categories of risk, the report will detail the options currently available for managing those risks, identify any gaps and make recommendations about how these should be filled.
"I have asked for the initial report to be produced within the next six weeks as it is vital that we quickly identify any action that needs to be taken to protect our critical transport infrastructure."
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