Since the Hammersmith flyover closed on 23 December 2011 the Ocean Outdoor and Clear Channel premium outdoor sites alongside the flyover have not carried any paid-for advertising.
Ocean Outdoor’s two sites, the Two Towers West, comprise two large format digital sites either side of the flyover. To place an ad in one of four 10-second slots over a two-week period can cost up to £60,000.
Clear Channel sells ads on a banner on the front of the HMV Hammersmith Apollo and a large format site on a tower next to the flyover. Combined, the ratecard price to advertise on the two sites is £120,000 for two weeks; although the usual price paid is believed to be a high five-figure sum.
Last week a statement from the London Mayor’s office said the engineers examining the flyover had confirmed it "will be repaired and fully available to traffic before the London 2012 Games" in July.
If the flyover is closed completely until the start of the London 2012 Olympics the combined ad revenue across the four sites could be worth more than £3m.
Engineers investigating the extent of the damage to the cables that give the flyover its strength are expected to decide whether it is strong enough to reopen to light traffic as early as today.
A spokesman for Transport for London said it hoped to at least partially open the flyover in the coming weeks.
It is understood that after initially turning off its digital sites Ocean Outdoor has turned the Two Towers back on and is offering advertisers who had booked onto the sites free ad space if they would like to use it.
Tim Bleakley, chief executive of Ocean Outdoor, said: "We are monitoring the situation and we are working very closely with the buying community to protect advertisers either via alternatives or compensation.
"It affects the number one outdoor location in the UK so clearly there are concerns but the closure of the main arterial route into London in 2012 goes way beyond the media industry and Ocean’s interests."
The Clear Channel sites are not carrying any advertising and are not expected to do so until the flyover reopens.
Matthew Dearden, chief executive of Clear Channel Outdoor UK, said: "We have been working closely with our clients and agency partners to place any affected campaigns at alternative locations. With a range of premium sites and products, we can readily accommodate our clients’ needs.
"The disruption from the Hammersmith flyover damage is a real shame, but safety has to come first; we look forward to the Mayor’s office and Transport for London announcing when it will re-open."
It is understood that Ocean Outdoor does not have to pay any rent for the sites to its landlord Hammersmith & Fulham Council if they are not sold to advertisers. When they are sold the council takes more than 50% of all ad revenue.
Clear Channel rents both its sites from private landlords. Clear Channel is believed to be paying rent on the two sites despite the flyover’s closure but it is understood the media owner will look to renegotiate terms if it is closed for an extended period.
It is understood that if the flyover reopens but only allows a limited amount of traffic or a limited number of lanes Ocean Outdoor and Clear Channel Outdoor will be willing to adjust their ad rates accordingly.
Both media owners have a number of other premium sites including Clear Channel’s Cromwell Road domination and Ocean Outdoor’s newly opened Two Towers East.