A sign says it's the "gateway to East and Central Africa" but at Busia, on Kenya's border with Uganda, a queue of lorries snakes back as far as the eye can see.

The road here has become a lorry park where drivers wait for days to cross - a sign of how increased health checks, including testing, are putting the brakes on trade.

And that's even as a pan-African free trade zone is due to be launched on January 1.

That date was put back by six months amid lockdown restrictions but at Busia, and with 2021 approaching, and Kenyan driver Joseph Kimani says a crossing that used to involve a five-hour wait can now take five days.

"Today is the third day we have been here in this queue. The queue moves at night a bit but during the day it stops completely. It stops, the vehicles are like this and where we are here as you can see there is no sanitary equipment."

He and other drivers say the line of lorries can stretch back more than 35 miles.

To cross the border, they need to show a negative test taken in the previous 14 days. Failing that, they must submit to testing at the border and wait two days for the result.

That's created big delays on a transport corridor that extends from Kenya's port Mombasa into landlocked nations such as Rwanda, South Sudan and the Democratic Republic of Congo.

Those four, along with 50 other countries, have signed up for the African Continental Free Trade Area, which aims to bring 1.3 billion people together in a $3.4 trillion economic bloc.

Its secretary general said last week that "innovative" arrangements will be required as not all the customs infrastructure will be ready in time.

Kenya's government says delays will be reduced once an approach road to Busia is turned into a dual carriageway - a project due for completion in 2022.

Until then, life on the road for the drivers at Busia has become exactly that.