Building Climate Resilience into Timor Leste’s Roads

The only thing worse than taking 5 hours to drive 106 km along  winding and often damaged mountainous roads, is the realization that having reached your destination you have to turn around and repeat the trip to get home. R0013423That was in the forefront of my mind as I sat in the very quiet town of Ainaro, south of the capital in Dili. The second thing I thought about was that we had to do a lot of work to help Timor Leste make their roads more resilient to the effects of climate: or more particular, water.

Timor‐Leste is a small and mountainous island country, with a population of about one million surrounded by Indonesia. It has a dramatic topography dominated by the Ramelau Mountains stretching across the middle of the island from the east to the west. About 44 percent of the Timor‐Leste’s total land area lies between 100 and 500 meters in elevation, and 35 percent above 1,000 meters. My trip took me across this mountainous spine towards the south of the country.

Now I don’t want to get into to the climate change debate. I know one of my readers (hi Ron!) is in the strongly sceptical group, and I must say that I have quite a few reservations about what is being put forward by the media and elements of the scientific community. Anyone who reads the objective ‘Climate Debate Daily’ web site would. However, what we do know is that the roads today are suffering from the effects of the climate, and there are changes happening in Timor Leste, no matter what is causing it.

For example, an assessment of the likely impact of climate change on Timor Leste in 2009 by the consultant Cardno Acil forecasted that rainfall would increase in the future. This may bring fewer extreme rainfall events but their intensity would be more important. I’m sure Ron with his mathematics background will have lots of comments on the graph below 🙂


Water and roads do not mix, particularly in mountainous areas such as in Timor Leste. This was obvious during my field trip where there was ample evidence of erosion, slope failures, and pavement damage from water. The photos below given a idea of the type of the types of issues encountered. It is clear that irrespective of what is predicted in the future, it is necessary to take steps to build some climate resilience into Timor Leste’s roads now.










Traditionally, the responses to hazards such as flooding and landslides was designing and providing additional or reinforced engineering structures such as more/better drainage, culverts, higher bridges and re-aligned road sections. However, it is now recognized that re-vegetation and bioengineering measures for water courses and road slopes are a key to implementing a lasting solution.

Bio-engineering improves slope stability, controls storm water and sediments, and helps adsorb pollutants through natural processes. There are a variety of measures that can be taken including tree and shrub planting on unstable slopes, and the use of vegetated erosion control blankets which are natural fibres able to retain soil and sediments while providing a medium for planting shrubs. The goal is to increase water retention capacity and slow infiltration through natural or bioengineered systems.

There is still a place for civil engineering measures—such as providing sufficient capacity longitudinal and transverse drainage, as well as improved retaining walls, gabions (i.e. stone filled nettings)—but without bio-engineering they are only partial solutions.

The Timor Leste government is already taking steps to address the issues, and there were quite a few locations where civil engineering works were going on. There were many good examples of well constructed gabions, as well as other examples where they had not been so effective.




There were workers constructing excellent quality retaining walls from local stone, one thing which there is an abundance of. It was impressive to see a crew quarrying stone from the side of the mountains, attacking large rocks with sledge hammers and then moving the stone around as if it weighed very little.




A major benefit from constructing stone retaining walls, gabions and stone drainage is that it creates work for local communities. This can provide much needed stimulus and support to the local economy. The team building the gabion below were all recruited from the local village. They estimated that it would take them a month to gather the necessary stone and construct the gabion, and said they were very grateful to have the opportunity to work. The ILO has been working on labour based methods for road construction in Timor Leste, and it is clear that there are a number of areas of success.


We plan on exploring how we can assist the government of Timor Leste with building resilience into their road network to better cope with rainfall. Relatively modest investments will yield major benefits not only in keeping roads open, but in saving on potentially large future maintenance or rehabilitation investments. It will also help to create employment which is sorely needed. It’s great to be able to work on such worthwhile projects.


6 Responses to Building Climate Resilience into Timor Leste’s Roads

  1. Ron Allan says:

    Ron will have a comment on the graph? Yes indeed

    But first I’ll take the bait on global warming. Earth has always been warming….. or cooling. I don’t know whether anthropogenic warming exists or not. But I am very sceptical of those who claim to know. (Scientists turned politicians.) Study the science of chaos.

    Now the graph… of precipitation in mm/day, so it says. Hmmm, negative precipitation. The rain falls upwards over Timor?

    On the topic, I am a fan of gabions for the reasons given, and more. They are permeable (no water pressure build up behind them) and flexible (if the ground fails beneath them they may just sag and distort but continue to do their job).

    On another point, the water that damages roads need not be deluges. In the 90s I noticed a localised section of failed pavement on a section of hill road outside Kathmandu. Water trucks filled at that spot. In went the hose. Out it came when the water overflowed. Not a lot of water, but the road was always wet. I assume the constant damp meant water penetrated pavement layers beneath the seal… resulting in failure.

    So, what is more important? The amount of rain, or its frequency?

  2. Scott Wilkinson says:

    Great blog Chris.
    Ron, to answer your last question, the answer really is both! Like roads failing due to drainage issues, so too do slopes. As you say, it’s all about the pore water pressure buildup, which can happen either through prolonged or intense periods of rainfall.
    Looking forward to getting over there and having a look for myself!

  3. Ramsey says:

    Enjoyed reading the blog.

    Comments on drainage and slopes are interesting. Increase in intensity whilst not having an increase in extreme events I guess would cancel itelf out, to a certain extent. And presumably in certain areas where terrain is flatter and the time of concentration is longer it won’t make much difference (or may even be beneficial from a drainage design point of view). However mountainous areas will presumably be at a disadvantage.
    In UK, good practice is to apply a “climate change” percentage of up to 20% to allow for increased rainfall over the next 20-30 years. I think it is also the case for slopes/retaing solutions etc..
    I was wondering if there was similar good practice guidance for developing countries?


    • triduffer says:

      Thanks for your observation. To my knowledge developing countries are not applying such an approach. Indeed, many that I have worked in either do not have any design standards or are using ones which are very out of date (I’ve seen 20+ year old Soviet standards used in the Caucasus – which of course never considered the economic implications of investments). On our projects we usually have international design consultants who *should* use appropriate standards, but too many use what they know and is convenient, leaving it to the International Financing Agencies to help persuade the government and them to use something more appropriate.

  4. Ramsey says:

    I’m not sure how much effort went in to studies in the UK that resulted in a climate change of 20% (environment agency stipulation). I think the idea is that by 2030 the rainfall will increase by 50mm which correlates to 20%. There is buy-in by the agencies (highways agency, local authority etc..) and it therefore has to be implemented. It is not driven by the design consultant as it effectively gets included in a TOR

    It makes the asset more future proof and less susceptible to increased maintenance costs resulting from the lack of capacity. And the level of service is less compromised.

    20+ year old design standards – must have been well written! Although aspects of highway geometry have remained unchanged for decades.




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