Thousands stranded in traffic over Kenya Covid rules
Videos and pictures posted on social media showed ambulances struggling to manoeuvre through the snarl-up.
Many people have criticised the authorities for imposing the measure.
Last month President Uhuru Kenyatta introduced a 20:00-04:00 curfew to deal with a third Covid-19 wave.
He also ordered the closure of bars, schools and restriction of movement in five counties including Nairobi.
"Whereas the foregoing measures will have a negative impact on the economy, these measures are temporary... the cost of not acting now will be much greater," Mr Kenyatta said.
The doctors union said at the time that there were no free intensive-care beds because of an increase in hospitalised Covid-19 patients.
Kenya has confirmed more than 151,000 cases of the virus and just over 2,400 deaths.
The UK and US have issued travel bans to the country because of Covid-19 and other security concerns.
media captionCoronavirus in Kenya: What it's like learning under lockdown
Kenyans voiced their displeasure online.
"Compliance with necessary public health measures is not about torture as happening on Thika road but about national dialogue and community engagement on protecting lives," tweeted Dr Githinji Gitahi, Global CEO of Amref Health Africa.
Frustrated drivers hooted continuously while some passengers decided to complete their journeys by walking.
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The Standard news site spoke to a couple who were taking their sick baby to hospital and had been stuck in traffic for two hours.
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It's unclear who gave the order but three hours after the gridlock began the police barricades were removed and traffic began flowing again.
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