Gatwick M23 disruption and delays caused by viaduct repairs
Repairs to a corroded bridge have been causing traffic tailbacks of up to seven miles (11km) on the M23 in Surrey and Sussex.
The delays are affecting blood delivery service Serv, whose managers have complained about a lack of information.
Alan Rogers, Serv Surrey controller, said bikers had been affected by the roadworks on the Coopers Hill Viaduct.
The Highways Agency said drivers should allow an extra 40 minutes for journeys, especially if heading for Gatwick.
In peak times about 4,500 vehicles an hour use the section of the M23 between junctions eight, which joins the M25, and nine, for the airport.
Night-time closures and a variable contraflow system, which started last month and will last until the end of November, have been causing tailbacks on both carriageways.
'It's a challenge'
Mr Rogers said Serv's bikers collected blood at night from Tooting in south London for distribution to hospitals in Surrey.
They also meet riders on the A23 at Hooley to transfer blood for hospitals in Kent and Sussex.
"We don't know which parts of what roads are going to be closed on any particular night and that makes planning quite difficult," he said.
"The challenge is getting to the liaison with the Kent or Sussex guys for our pre-arranged rendezvous time."
Peter Phillips, Highways Agency manager for the M23, said: "If you are trying to get to Gatwick then please give yourself plenty of time or find yourself an alternative means of travel.
"There is a very good rail link but if you have got to come by car leave yourself plenty of time.
"Our website is the best source of information."
Separate roadworks to widen the A23 between Handcross and Warninglid in West Sussex are coming to an end.
The Highways Agency said a third lane would open to the public this week, with remaining resurfacing taking place at night.