Many are squashed inside and those without seats are packed into the aisle or hang from the doorway.
Nigeria's commercial capital, Lagos, one of Africa's biggest cities with 10 million inhabitants, is famous for three things:
There's the sprawling filth, the squalid congestion and its distinctive yellow commercial buses.
The big buses are called molues and the minibuses, which first appeared in the 1970s, are called danfos.
Journeys constantly stop-start, seating is uncomfortable, the horns are constant and loud and the buses accelerate aggressively.
But fares are cheap, even though they can increase drastically during petrol shortages, riots or even on the whim of a bus driver.
Hand up
At bus stops, the rule is: "Keep moving!"
And it is common for bus conductors, hanging out from the doors, to use one hand to lift a running passenger onto a moving molue. They always take on board more than the recommended 44 passengers.
Many are squashed inside and those without seats are packed into the aisle or hang from the doorway.
Passenger crowding into molues triggered the song, "Suffering and Smiling", from late Nigerian Afrobeat musician Fela Anikulapo Kuti.
"44 (passengers) sitting, 99 standing; suffering and smiling...", sang Fela, as he lambasted the Lagos authorities for the lack of a proper transport policy.
The danfos have seats for 12 passengers.
Death traps
Most buses, with the accelerator pedal at the mercy of alcohol-fuelled or madness-filled drivers, are not roadworthy.
The bodywork is battered; tyres are as bald as the pate of a 90-year old; plumes of thick, black smoke are emitted from silencers as the buses chug on with barely functioning brakes.
Layi Ojo, an officer with the Lagos state Vehicle Inspection Unit, says that bus drivers seldom obey traffic rules.
"You wonder how most of the buses secured roadworthiness certificates in the first place. And when you ban the buses from the roads, they still find a way of returning to the roads."
The regular involvement of the buses in accidents has made commuters label molues as moving morgues and danfos as flying coffins.
The local media is often full of horrific stories of bloody road crashes involving buses.
In November, Lagos papers carried a heart-rending story of a road accident involving a danfo. The papers said the danfo, with 14 passengers inside, was travelling to the city centre in the morning hours.
There was a traffic snarl-up in its lane and the danfo driver, in a fit of madness, defied the simplest of traffic rules, swinging the bus onto the opposing lane and facing on-coming vehicles. It ran headlong into an articulated truck, was flung into the Lagos lagoon and all the bus occupants drowned.
Blame
Drivers of molue and danfo buses blame the fast pace of life in Lagos for their driving style.
Kafaya Alafa, with 12 years experience as a molue driver, said: "Everyone is in a hurry. Some passengers are very impatient and hate the delays caused by the traffic jams, so we always move on to please them."
Ismaila Ojo, a danfo driver, said: "In Lagos, making money is the name of the game. If you don't hurry up, the money will leave you behind."
Petty thefts, pick-pocketing and occasional muggings are also common. But entertainment is usually also on the menu.
Selling
"Praise God... praise god! one passenger yells, a bible in one hand and Christian pamphlets in the other.
His fellow danfo commuters give an "Hallelujah" reply.
Household products are also sold and before the bus reaches its destination, a few passengers exchange their money for goods.
Lagos commuters have, however, come to accept their buses with a love-hate relationship.
"They may have their potential dangers but my day won't be complete if I don't travel in one," says lawyer Gabriel Odefe.
"Through them, I'm able to catch up with the latest gossips in town."
Despite the dangers and discomfort, the buses have one compensation - their entertainment value.