Southern Bypass to close this weekend for Nairobi Marathon

Motorists travelling between Ole Sereni and Kikuyu have days to plan alternative routes before Sunday’s disruption.

By Collins Kibet

The Kenya National Highways Authority has announced a temporary closure of a section of Nairobi’s Southern Bypass this weekend to accommodate the 2026 Standard Chartered Nairobi Marathon, with significant traffic disruptions expected between Ole Sereni Interchange and Kikuyu Town.

The closure takes effect at midnight on Saturday, October 25, and lifts at 2:00 p.m. on Sunday, October 26. Motorists who regularly use the bypass are advised to identify alternative routes before departure, confirm the specific sections affected through official KeNHA announcements, and allow considerably more travel time than usual. The window to prepare is narrow. It closes at midnight on Saturday.

KeNHA has designated Mombasa Road, through Uhuru Highway, as the principal diversion for affected drivers. Motorists heading from Dagoretti towards Mombasa Road may be redirected through Waiyaki Way or Ngong Road via Mbagathi Way, while those travelling from Lang’ata towards Kikuyu are likely to be routed through Karen. Drivers should follow official traffic signs and instructions from police officers and marshals deployed along the corridor, as the appropriate diversion will vary depending on destination. Attempting to navigate informally or relying on unverified directions risks compounding delays and, more seriously, endangering marathon participants whose safety depends on controlled road conditions throughout the event.

The closure will affect a wide cross-section of road users. Commuters who depend on the Southern Bypass for daily movement between Nairobi’s western and southern corridors face the most immediate disruption. Public transport operators running matatu routes through Ole Sereni, Kikuyu and surrounding areas will need to adjust their stops and schedules, potentially affecting thousands of passengers who rely on those services for work, medical appointments and essential travel. Operators who fail to communicate changes to their passengers early enough risk contributing to the congestion that the diversion arrangements are designed to prevent.

Commercial freight companies and businesses dependent on timely deliveries face their own set of pressures. Sunday morning is not a low-traffic window in Nairobi. Wholesale traders, logistics operators and suppliers moving goods across the city will find key corridors under strain. Transport companies are advised to notify customers of potential delays in advance, adjust delivery windows where operationally possible, and brief drivers thoroughly on the approved alternative routes before Saturday. A failure to plan at the company level will translate directly into missed deliveries, frustrated clients and vehicles stalled on roads already carrying diverted traffic from the bypass.

The broader challenge the closure exposes is one Nairobi confronts repeatedly during major public events: how to manage a city with a constrained road network when significant sections of that network are temporarily removed from use. Nairobi’s arterial roads — Mombasa Road, Uhuru Highway, Ngong Road and Waiyaki Way — already carry volumes of traffic that regularly exceed their designed capacity during ordinary weekday conditions. Redirecting bypass traffic onto those same roads on a Sunday morning, when the marathon itself will be drawing spectators and participants across the city, concentrates pressure onto corridors that have limited room to absorb it.

Authorities must therefore ensure that the logistical arrangements match the scale of the disruption. Diversion signage must be clearly displayed and positioned well in advance of the closure points, not erected hastily on Saturday evening. Traffic personnel must be stationed at critical intersections along all designated alternative routes, not only at the closure barriers themselves. Emergency vehicle access to Nairobi’s hospitals, including Kenyatta National Hospital, MP Shah and the various facilities along Ngong Road and Mombasa Road, must remain unobstructed throughout the closure period. A marathon that saves seconds for elite runners while blocking an ambulance for critical minutes is an event that has failed in its most basic duty of care to the city it runs through.

Public communication is equally non-negotiable. KeNHA should ensure that closure notices reach motorists through every available channel — radio bulletins, social media updates, SMS alerts and public address systems — in the days remaining before Saturday midnight. Information posted only on official websites or circulated exclusively through formal government channels will not reach the matatu driver, the night-shift worker or the family planning a Sunday outing. Broad, accessible, repeated communication is not a courtesy. In a city the size of Nairobi, it is the difference between a manageable disruption and a chaotic one.

Kenya’s marathon tradition is a source of genuine national pride. Nairobi consistently stages a world-class event that draws elite athletes and recreational runners from across the globe and showcases the country’s unmatched distance-running heritage. That tradition deserves to be celebrated and protected. But a great race and a well-managed city are not competing ambitions. With adequate preparation, clear communication and disciplined traffic management, Nairobi can deliver both.

Plan your route now. The marathon starts Sunday. The disruption starts Saturday night.

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