How avoidance of detailed ground study resulted in failure of road infrastructures

As usual, I always begin by thinking whenever I see failure in road infrastructures; road construction in Bhutan has already passed half a century after its inception in the early 1960s. Exactly, at this time, mule tracks and footways are mere history to track back. Roads replaced all those detour tracks for transportation that touches high mountains and deep valleys. Slope failures on those tracks were out of the question since these don’t have one except the natural slope. But the road construction comes with designs that require cut and fill that develop another slope in addition to the natural slope, which is called the "cut and fill slope." The failure mechanism of these slopes must be addressed and learned. Despite engaging in road construction and maintenance for decades, are we enough with the trend? We have many questions to ask and things to do. Let the custodian of the road not bounce from one agency to another.

The Department of Roads, in the 11^th five-year plan and in the beginning of the current plan, Geog Connectivity roads with the department. Planning and budgeting works were mandated for the department. Finally, those roads were handed over to Local Government. Inconsistency in the decision of springing the custodian has left those improved roads further deteriorated and damaged.

We are adequate with road coverage. Every nook and corner of the country is connected. We are done with the length. The length of roads has outnumbered the technology involved. Now, what we need is advancement of technologies with the change.

 

Bailey Bridge subsided under the catastrophic slope failure.

Construction techniques of the road, starting from formation cutting to pavement strengthening, have improved with the advancement and introduction of new machinery and methods. An environment-friendly road construction technique was started in the late years of the 9th five-year plan, and now the time has triggered and reminded us to start preparations to integrate the construction of climate-resilient road infrastructures.  

Indeed, the monsoon has taught us valuable lessons. The change, we see, is through more destruction and damages in road infrastructures than before. We feel the change through roadblocks.

How is it possible to overcome the change, especially the climate change? What are differences in failure we observe between then and now? Are those failures due to climate change or something else?

Pavement or the road fails because of the failure of permanent structures—walls, drains, cross drainages, slopes, etc. Bridges usually fail because of overloading and slope failure. Otherwise, bridge failure due to other reasons is the least that we usually counteract immediately.

Let me explain one simple example—provision of both sides camber on pavement in any category of roads. Our Primary National Highways are wide enough to provide camber on both sides, and so are likely the Secondary National Highways. But is it really possible on Dzongkhag and farm roads? And our standards say that the camber should be on both sides. The standard carriageway width is only 3.5 meters. From my personal experience, there is a constructability issue. Even if there is no constructability issue like in the aforementioned category of highways, providing camber on both sides is unnecessary considering the different nature of soil conditions on downhill slopes. We must avoid infiltration of runoff from the pavement, prevent saturation of the slope, and let the slope fail grossly.

And why do our walls repeatedly fail in the same location?

 

Pavement failure due to excessive infiltration.

Likewise, are our standard design road drainages or cross-drainages adequate? Or do we need to revise?

The evidence of aggravating damages year after year on road infrastructures and restoration works that cost us dearly must be felt by every individual responsible and, indeed, must be felt by the end user as well. Or else we wait for the catastrophe that is looming large before us.

Therefore, road infrastructures designed and constructed decades ago may not suffice for the change now. We may need to revise the design criteria and focus more on slope stability studies. Much more information and awareness about slope engineering are indeed felt necessary in addition to the training provided for construction quality and more effective road asset management.

Tunnel Roads – the next phase of transport system in Bhutan

Department of Roads as parent agency for highways in Bhutan under Ministry of Works and Human Settlement has galloped a long journey since the start of first highway construction in early 1960s. Beyond highways, in the 11^th fifth year plan, department was ushered responsibilities for construction and maintenance of whooping networks of Geog Connectivity (GC) roads. At the inception of 12^th fifth year plan and thus far, almost all surface roads construction and improvement were completed; overall the adequacy of road networks have been accomplished under the dynamic farsighted leadership of the department. After successful completion of blacktopping of 182 GC roads out of 205, those roads were handed over to Local Government (LG), leaving the department mandated to focus only on highways.

Nonetheless, journey of further enhancement and development of transportation system in the country must travel far to the world standards for enhancement of socio-economic development.

For that matter, as reflected in the current plan document, the next stage for the department to get engage is in tunneling and underground space engineering works. Best for the country like ours that is geologically challenging and mountainous, start of tunneling works shall gear the department in accomplishing the mission statement of reducing travel time.

The first ever underground/tunnel road (1.50 km) (Video published by Bhutan Tube)was constructed on Tsirang – Wangdue National Highway by Punatshangchu Hydro project II and successfully opened to traffic on 25^th June 2014.

Since the start of hydro-power plants construction to meet the target to harness 20000 MW by 2020, Bhutanese in general have seen tunnel construction in hydro sector only.

 

Highway tunnel on Tsirang - Wangdue National Highway. Photo from PHPA-II website

Tunneling roads will not only help in reducing travel time, it will also reduce the current setback triggered by unusual monsoon. Though the initial construction expenditure will be huge as compared to surface roads, operation and maintenance costs will be minimum; thereby, the best judgment to invest in the tunneling works considering the Life Cycle Costing and also the climate change effect on the roads such as now will be meager.

For that matter, it is time for the government and department in particular to start groundwork for the tunneling and underground space engineering knowledge. Ultimately, with tunnel roads that are best suited for country like ours, transportation system will be in the next level.

Therefore, as an introductory process to tunneling, short course on tunneling is scheduled on 24^th to 27^th September at Druk Hotel, Thimphu. Dr. Manoj Verman, Tunneling and Rock Engineering Expert, President, Indian National Group of ISRM (International Society for Rock Mechanics and Rock Engineering) is organizing the course. The course fee is Nu. 17,000.00 (Seventeen thousand only).

I aspire, interested engineers of the nation would participate in the short course to originate light in future tunnel roads and underground space engineering.

Blacktopping of Dakpai-Buli-Nimshong GC Road

Dakpai-Buli-Nimshong GC Road starts at Dakpai, 18.00 km on Tingtibi – Zhemgang SNH at an altitude of 1263 m. It traverses through forest touching many villages until Buli (36.60 km), 1698 m. The highest elevation, it passes between Dakpai & Buli is at Talila (18.00 km), 2014 m.

From Buli, the road inclines up through randomly dense forest till Gonglithang (5.10 km), 2154 m. The road further inclines up through the continuously dense forest & crosses Malaya top (10.50 km) at an altitude of 2626 m. The road, then declines down until Rongdigang (19.60 km), 1833 m and incline bit up with four short zigs. Further it traverses straight until Churmulung (25.50 km), 1937 m and then decline down till Nimshong (30.20 km), 1740 m.

The road, Dakpai-Buli was constructed in early years of ninth fifth year plan and Buli-Nimshong road was constructed in later years of 10^th fifth year plan.

 

Blacktopping work in progress at Nimshong

From the above alignment description of the road, it is clear that the road stretch from Dakpai to Buli (36.60 km) passes through uniform elevation variation. Whereas, the road stretch from Buli crosses the highest elevation variation. Due to high elevation and dense forest cover along Gonglithang until Rongdigang, the road corridor and the pavement in particular receive less sun, leaving the road stretch marshy and damp throughout the year.

Although major sections of the road have been blacktopped, it is observed deterioration of wearing coarse in the form of potholes; alligator cracks, depression distress, shoving etc. At certain stretch, the gross failures of pavement are observed.

Due to more damp and marshy locations, almost 2.40 km of road beyond Malaya towards Nimshong were left without blacktopping.

 

Road stretch through dense jungle beyond Malaya

To forgo the blacktopping of marshy sections, discussion were held in various meetings and even in Department’s Quarterly meeting and resolute the same.

That’s why, certain stretch along Buli to Nimshong GC (2.40 km out of 30.20 km target) road was not blacktopped. Nonetheless, estimates for the remaining pavement improvement works have been prepared inclusive of cross drainage and road drainage for the betterment of smooth road along the high elevation ranges. 

I generously regret the inconveniences caused to the public of Upper Kheng, UK.