Eastern Bypass:
Thika Road to the airport.

What it is actually for

The Eastern Bypass runs from Thika Road at Ruiru in the north, down the eastern side of the city through Kamakis, Njiru and Utawala, to Mombasa Road near the airport in the south. It crosses Kangundo Road on the way and meets Outer Ring Road and the airport approaches at its southern end.

Its purpose is simple and it is very good at it: it connects the two busiest radial corridors in Nairobi, Thika Road and Mombasa Road, without going near the CBD. Before it existed, getting from Ruiru to the airport meant coming down Thika Road into town and back out again, through the two worst peaks in the city.

Like the Southern Bypass, it has also become a commuter road in its own right. Kamakis in particular has grown into a genuine destination rather than just a junction, and the settlements along the route have expanded fast. That growth is where its congestion now comes from.

When it slows

Because it runs across the radials rather than along one, the Eastern Bypass is busy in both directions in both peaks, roughly 6:00 to 8:30am and 4:30 to 8:00pm. Some of that traffic is heading for Thika Road and town, some for the airport and the industrial areas, so the flows do not neatly reverse the way they do on a radial.

Two things make it worse than a normal day. Heavy goods traffic uses it constantly, since it is part of the route between the port road and the Thika corridor, and a truck incident here closes lanes for a long time. And weekends bring their own pattern around Kamakis, which is busy socially in the evenings in a way that has nothing to do with commuting.

If you are catching a flight from the Thika Road side, the honest advice is to treat the bypass as reliable but not fast at peak, and to leave a bigger margin than the distance suggests.

Where it slows

• Kamakis: the best-known point on the road and the busiest. Local traffic, roadside businesses and a major junction in one place. If the bypass is slow, start by assuming it is slow here.
• The Ruiru junction with Thika Road: the northern anchor. It inherits whatever Thika Road is doing, so a bad morning on the A2 arrives here too.
• The Kangundo Road crossing: a major turning movement, with matatu activity serving Ruai and Komarock.
• Njiru and Utawala: estate traffic joining and leaving, with heavy pedestrian movement across the road in places.
• The airport and Mombasa Road end: the southern anchor, shared with airport traffic, Outer Ring traffic and freight. This end is the one most likely to cost you a flight margin.

Using it well, and when Outer Ring is better

The Eastern Bypass and Outer Ring Road do a similar job, and drivers often pick the wrong one. The difference is how far out your trip sits:

• Take the Eastern Bypass when both ends of your trip are towards the outside of the city: Ruiru, Juja or Thika at one end, the airport or Athi River at the other. It is longer in distance and usually shorter in time.
• Take Outer Ring when your trip involves Eastlands itself: Kariobangi, Umoja, Donholm or Buruburu. The bypass passes too far out to serve those, and you would spend the saving getting back in.
• Pair it with the Southern Bypass to cross the whole city, north to west, without entering the centre at any point.
• For Kangundo Road destinations, join at that crossing rather than running the full length of either road.
• Check the far end before committing. Both anchors hand you into a busy road. A clear bypass that delivers you into a stopped Mombasa Road has not saved you anything.

How Eastern Bypass closures get announced

Planned works and diversions come from KeNHA, with Nairobi County and KURA involved on the local roads at its junctions. NTSA and the traffic police report incidents, and anything affecting the airport approaches may also come from the airport authority.

This road has had long-running construction and upgrade works along parts of its length, which means lane layouts change and a route that worked last month may not this month. That is exactly the sort of thing that never reaches a notice in time, and exactly what the driver a few hundred metres ahead of you already knows.