Mombasa Road: the roadworks, the Expressway above it, and the plan for a four-lane highway to the coast
Mombasa Road is Kenya's busiest artery: the road to JKIA, the Nairobi Expressway above it, and the route to the port. Here is what the recent works were for, and the plan to widen the whole road to Mombasa.
If you use Mombasa Road, you have seen the cones and diversions. Here is what is going on, from the drains at Cabanas to a plan to widen the road all the way to the coast.
Three roads in one corridor
| Road | What it is |
|---|---|
| Mombasa Road (A8) | The main highway from Nairobi to Mombasa, about 460km. Outside Nairobi it is mostly two lanes, and it carries much of the freight from the port of Mombasa. |
| Nairobi Expressway | The tolled, mostly elevated road from JKIA to Westlands, built above Mombasa Road and Uhuru Highway and opened in 2022. |
| Eastern Bypass | Links Mombasa Road at Cabanas to Thika Road and the east of the city, so trucks can avoid the CBD. |
The recent works
- Cabanas box drain. The Kenya National Highways Authority (KeNHA) partly closed the JKIA-bound section at the Cabanas–Eastern Bypass off-ramp from 17 September to 22 October 2026 to build a large box drain. Motorists to JKIA were sent through a diversion lane.
- Why drains matter. Box drains carry storm water under and away from the road. With a strong El Niño expected this season, flooded roads are a real risk (see our El Niño explainer).
- Wider maintenance. The closures are part of KeNHA's wider maintenance and rehabilitation of major roads in and around Nairobi, covering lighting, drainage and resurfacing.
- Expressway works. The Expressway's operator has also carried out maintenance, including night closures on Waiyaki Way after the Westlands exit in September.
The big plan: four lanes to Mombasa
The National Treasury says it has begun evaluating bids for a transaction adviser to prepare the expansion of the Nairobi–Mombasa highway.
- What: widen the existing highway, about 460km, from two lanes to at least four.
- Tolled: it will be a toll road with controlled entry and exit points.
- How it is paid for: a public–private partnership (PPP), in which a private investor builds and is repaid from tolls.
- Where it stands: very early. The adviser will first study traffic, engineering, environmental and social impacts and costs to test whether the project works.
A rival plan: in 2024, Everstrong Capital proposed a new 440km, six-lane expressway estimated at KSh365 billion. The PPP Committee rejected it and asked for a plan to expand the existing road instead. The firm said in April 2026 that it would challenge the decision in the High Court.
What it means for you
- Short term: expect more night and weekend closures. Check KeNHA's notices before travelling to JKIA, and allow extra time.
- Long term: a wider highway could cut travel time and accidents on one of Kenya's busiest roads, and lower the cost of moving goods from the port. The trade-off is tolls.
- Watch for: who is chosen as adviser, the estimated cost, and proposed toll rates.
Related: the new JKIA terminal and the planned Thika expressway.
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