Ministers should do more to justify plans to build a £250 million lorry park for use when cross-Channel services go into meltdown, MPs said.
The Government "has not demonstrated clearly enough what options have been evaluated", according to the Commons Transport Select Committee.
A report published by the committee found that the decision to proceed with the project in Kent was taken "hastily" in reaction to the events of last summer when Operation Stack was used for longer than ever before.
Sections of the M20 were turned into a HGV park for up to 5,000 lorries when services at the Channel Tunnel or Dover port were hit by the Calais migrant crisis and striking French ferry workers.
Nearby roads were also gridlocked as a result of Operation Stack, leaving many local businesses out of pocket and hauliers stuck in tailbacks having to dump their cargoes.
Kent County Council estimated that the county's economy lost around £1.5 million a day when Operation Stack was enforced, prompting widespread calls for a long-term solution to be found.
Two potential sites are being considered for a major new lorry park, both near Junction 11 of the M20 near Stanford, in Kent.
But the Transport Select Committee has called for ministers to demonstrate the necessity of the development, including whether the benefits merit the quarter of a billion pounds in cost, the environmental and social impacts on the local area and the long-term cost of operating and maintaining the site.
It listed possible alternatives such as upgrading the M20 and/or the A2/M2, increasing the capacity of cross-Channel services, building a network of smaller lorry parks or introducing a "virtual queuing" system.
Labour MP Louise Ellman, chair of the committee, said the solution proposed by the Government is "on a vast scale".
She went on: "Ministers need to do more in order to justify this spending and it should do more to demonstrate why a lorry park roughly the size of Disneyland in California is better than the alternatives we heard about during our inquiry.
"We are not saying that the Government should not press ahead with its proposal, only that it has more work to do to persuade us of the business case for this investment."
A Department for Transport spokesman said: "We are acutely aware of the impact Operation Stack has on residents and businesses. It is right that we find a permanent solution and we're determined to keep Kent moving.
"That is why up to £250 million was made available to build a lorry park which could take lorries off the county's roads in the event of disruption."
Operation Stack began as a temporary measure in 1988 but there has been strong criticism that a workable solution has not been implemented in the intervening years.
The Federation of Small Businesses was among organisations which wrote to the Government calling on ministers to address, once and for all, the travel chaos caused by Operation Stack following the gridlock in the summer.
The location of the proposed sites would mean that they could potentially be used to help manage any disruption affecting either the Port of Dover or Eurotunnel services.