Police said the 61-year-old man had left his own vehicle when he was struck by the lorry shortly after 13:00. He was pronounced dead at the scene.
The eastbound carriageway was closed at Junction 3 while emergency services attended, but has since reopened.
Police said they were attempting to establish the full circumstances of the incident.

Alcohol Concern said many young people recognised more alcohol brands than those of ice cream or cake products.
It is calling for new rules on what alcohol adverts can mention and it also wants them banned in film trailers.
Advertising body Isba said there was no strong evidence to suggest advertising influenced young people to drink.
Alcohol Concern's report was based on research by its Youth Alcohol Advertising Council (YAAC) - a group of young people in England and Wales who review alcohol advertising and issue complaints to the Advertising Standards Authority (ASA) when they discover content deemed to be irresponsible.
Three of their 13 complaints so far have been upheld.
In its report, Alcohol Concern said it had found "numerous" examples of inappropriate advertising and high levels of alcohol brand recognition among the young.
It called for new rules restricting what adverts could mention about an alcohol product, arguing that only characteristics such as strength, origin, composition and means of production should be described.
The charity also demanded a ban on alcohol advertising in the trailers of films shown in cinemas with less than an 18 certificate.
It urged the ASA to operate in a "more proactive way", instead of "depending on complaints from the public" before looking into advertising code breaches.
The ASA should be able to levy "meaningful" sanctions including fines for serious non-compliance, it added.
In a statement, the ASA said it was "not unheard of for an anti-alcohol lobby group to call for further restrictions on advertising".
"The ASA will continue to take a proportionate approach, regulating effectively alcohol ads across media, including online, against strict rules that are designed to protect young people," it said.
"The Department of Health's own figures show, encouragingly, that fewer young people are drinking."
The Alcohol Concern report called for statutory and independent regulation of the alcohol and advertising industries and a review of the way digital and online content is regulated.
In May, figures released by the broadcasting regulator Ofcom suggested children saw an average of 3.2 alcohol adverts per week in 2011 - compared with 2.7 in 2007.
It called for the UK's advertising regulators to reassess the rules that limit children from being exposed to alcohol advertising on TV.
Ian Twinn, from Isba, which represents advertisers, told BBC Radio 5 live there was a lack of well-researched evidence to show that advertising influenced young people to drink alcohol.
"What the advertisers are doing is trying to influence adults to drink their brand, not young people," he said.
"Underage drinking is declining in this country, where we have alcohol advertising, and in France it is going up, where they've banned it."
Without alcohol sponsorship of sport and music, parents and children would find it much more difficult to afford events, he added.
Alcohol Concern chief executive Eric Appleby said: "Children and young people are seeing more alcohol advertising than in the past and are better able to recognise alcohol brands than those of cakes or ice cream.
"This has to be a wake-up call to the fact that the way we regulate alcohol advertising isn't working."
He went on: "Young people tell us that they think alcohol advertising sends a message that it's cool and normal to drink, often to excess.
"It's time we reset the balance between commercial and public interest."
Stuart O'Reilly, a 19-year-old member of YAAC, said: "The code is clearly unfit for purpose. Young people are bombarded with adverts that may not explicitly state, but often heavily imply, messages about alcohol that are inappropriate or misleading.
"This can be extremely damaging to young people who use these messages to form their relationship with alcohol."
A man has died after being hit by a lorry on the M8 at Livingston in West Lothian.
[NEXT_CONCEPT]
Alcohol advertising should be banned at music and sports events to protect young people from excessive exposure, a charity says.