Letters

Take note of Nairobi expressway design gaps

Nairobi Expressway

Nairobi Expressway under construction. PHOTO | LUCY WANJIRU | NMG

Summary

  • The engineers should have worked on a design that allows for future improvements after the toll period lapses.
  • As designed, possible improvements to maximise existing road reserve will prove challenging unless the road is demolished or additional land is acquired.
  • Use of double piers as opposed to a cantilever in some sections would have brought in flexibility in the future without additional costs.


The Nairobi expressway is taking shape. It is a good progress. This week the Transport Cabinet Secretary indicated the project will be complete by next February.

The contractor and the Kenya National Highways Authority have done largely well with traffic management. The people who use Mombasa Road and Uhuru Highway may not agree with that statement as much.

However, we all know the slow pace of Kenyan contractors. Recently, I witnessed the construction of the stretch between the NHIF Building and KCB Towers, a 900-metre stretch.

One can only imagine if we had a Kenyan as the main contractor. I hope the local contractors are taking lessons from the building of the expressway.

It is constructed using the public-private partnership (PPP) and shows the possibilities such models can help improve our infrastructure.

However, I would like to point out the importance of public participation in such projects. The following design aspects of the projects limit future improvements.

Use of double piers as opposed to a cantilever in some sections would have brought in flexibility in the future without additional costs. Such a design would have left space for other express lanes below that could be used for BRT or other functions.

The section between University Way and Westlands is a good example.

The project, privately funded, will run a toll road until the investors recover the outlay and profit. The design had to ensure that the project is viable and allow the developers to recover their investment in the shortest period.

The toll will run for approximately 30 years. Having competing routes below will negate the business model. However, the engineers should have worked on a design that allows for future improvements after the toll period lapses.

We could, for example, create space and plant flowers for now and later convert them into traffic lanes. Alternatively, have non-motorised transport on the sections for now. Beyond the 30 years, the new generation would then improve the road on need.

As designed, possible improvements to maximise existing road reserve will prove challenging unless the road is demolished or additional land is acquired. Such acquisitions have been marred by controversies in the past.

I have not checked the design parameters but I also think the BRT along Mombasa Road will be slower. It is just to ensure the expressway business model works. It is a case of our engineers signing off on a bad design.

I hope the government will not delay implementing the two greater eastern bypasses to ensure the expressway is functioning as designed. In design, the two bypasses start from Lukenya bypass to join Nairobi-Nakuru highway and the other joining A2 past Thika.

The two bypasses effectively reduce traffic from Mombasa into town and traffic from Western Kenya and from Central Kenya going to the Coast.

The other aspect not considered is that the future modes of transport will change. Whereas traffic is a problem today, it may not be the case tomorrow.

It is also a well-known fact that extra lanes never sort traffic jams the world over. An efficient public transport system with provisions for non-motorised provisions is the solution. We do not have to look far; Thika Road is a good example. It is getting congested each day and soon will not function as designed. We also see the effects of designs that are not futuristic at all. Introducing BRT on Thika Road is a nightmare and costly.

Citizens now understand the importance of non-motorised transport, a majority of them preferring to walk or cycling to work.

Non-motorised transport will be made more desirable with the advent of hybrid electric bicycles. It means one can use battery energy in the morning to avoid sweat in the office and cycle back in the evening for exercise.

I know a few workspaces with provisions of bathrooms too, making life easier for riders. If provisions for non-motorised transport are in place, city roads it will attract more users and reduce traffic significantly.

Back to our expressway. It will not be surprising that one day the future generation will bring this huge infrastructure down and in its place plant trees.

Joffrey Cheruiyot, an engineer