Dhaka-Sylhet highway to be made four-lane with $2.0b ADB funding

[Black_cats]

Dhaka-Sylhet highway to be made four-lane with $2.0b ADB funding

FHM HUMAYAN KABIR | Published: November 19, 2020 10:08:34 | Updated: November 19, 2020 11:00:18

File photo used for representational purpose only

The Asian Development Bank (ADB) is likely to provide US$ 2.0 billion worth of loan for widening Dhaka-Sylhet highway into four-lane, aimed at making the road suitable for regional connectivity as well as cross-border and regional trade, officials said on Wednesday.

The Roads and Highways Department (RHD) is working on preparing a project proposal for the highways based on the latest detailed design of the corridor, they said.

The project would require an estimated investment of nearly $ 2.88 billion, a senior RHD official said. "The ADB has agreed to provide the lion's share of the total cost in four trances during the entire project implementation period," he told the FE.


"We have already discussed with the ADB about confirmation of the loan," said a senior official at the Ministry of Road Transport and Bridges (MoRT&B).

After a setback with a Chinese funding proposal, the RHD has finally decided to take support from the Manila-based lender for the development project. Earlier, China had committed financing the project under a government-to-government (G2G) arrangement.

The Dhaka-Sylhet-Tamabil highway is one of the most important routes for the regional connectivity and trade. The transport corridor is now in bad shape due to lack of proper maintenance of the narrow road, which is not suitable for heavy vehicles.

Another senior RHD official said they had almost completed a detailed design of the road bringing some changes in the previous design prepared in 2015. In the latest design, there will be separate lanes for the slow-moving vehicles on both sides of the four-lane road, he added.

Besides, the intersection design is also being changed, and the authorities were planning to use polymer modified bitumen (PMB) for the wearing course of the road, he added.

Meanwhile, the land acquisition work for the Dhaka-Sylhet-Tamabil highway is going on under a separate project, the RHD official said.

The Executive Committee of the National Economic Council (ECNEC) approved the "Land Acquisition and Utility Transfer Project: Support to Improvement of Dhaka (Kanchpur)-Sylhet-Tamabil Highway into Four-lane and Construction of Separate Service Lanes on Both Sides of the Project" of Tk 38.86 billion in October 2018.

The RHD is also working on widening the Sylhet-Tamabil section of the corridor into four-lane one under another project.

The ECNEC in September last approved the project for upgrading the 56-km Sylhet-Tamabil corridor at Tk 35.86 billion.

The Asian Infrastructure Investment Bank (AIIB) is providing Tk 29.70 billion as project assistance while the rest of the fund would come from the internal resources.

The RHD official said they were preparing the project proposal for the Dhaka-Sylhet corridor for getting approval of the ECNEC. Soon after getting the approval, they would appoint contractor for rebuilding the road, he added.

When asked, a senior official at the Economic Relations Division (ERD) said the negotiations on the $ 2.0 billion loan with the ADB would complete shortly.

Insiders said the project would further facilitate trade with India's seven-sister states, including Assam.

Also, it will establish sub-regional road communication, and cross-border connectivity between China, Myanmar, and Bhutan.

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Dhaka-Sylhet highway to be made four-lane with $2.0b ADB funding

The Asian Development Bank (ADB) is likely to provide US$ 2.0 billion worth of loan for widening Dhaka-Sylhet highway into four-lane, aimed at making the road suitable for regional connectivity as well as cross-border and regional trade, officials said on Wednesday. The Roads and Highways Departme

www.thefinancialexpress.com.bd

 

[bluesky]

Besides, the intersection design is also being changed, and the authorities were planning to use polymer modified bitumen (PMB) for the wearing course of the road, he added.

"PMB polymer modified bitumen is blend of bitumen 60/70 with specific grade of SBS Styrene butadiene styrene in very special temperature and pressure. ... PMB polymer modified bitumen has high straight on fatigue and also high viscosity so will stick to aggregate and it will not segregate".

However, whatever may be the grade of wearing course, compaction of soil under it is a prime factor for a good and stable road surface. Good quality compacted soil is needed for that. Sometimes, soil needs to be replaced with select/suitable soil (about 1m depth) and compacted to get the required bearing capacity.

 

[Uguduwa]

What’s the big deal?

 

[mb444]

What’s the big deal?

Its a big deal because BD suffers from sub optimal infastructure. This will go some way to rectify the current scenario and accelerate economic activity and growth.

 

[Chhatrapati]

What’s the big deal?

Don't have many four-lane roads.

 

[Landmine]

"PMB polymer modified bitumen is blend of bitumen 60/70 with specific grade of SBS Styrene butadiene styrene in very special temperature and pressure. ... PMB polymer modified bitumen has high straight on fatigue and also high viscosity so will stick to aggregate and it will not segregate".

However, whatever may be the grade of wearing course, compaction of soil under it is a prime factor for a good and stable road surface. Good quality compacted soil is needed for that. Sometimes, soil needs to be replaced with select/suitable soil (about 1m depth) and compacted to get the required bearing capacity.

Yes, you are absolutely right! However, the subgrade soil condition is not uniform in our country. Which makes it difficult to come up with a uniform roadway structure. I am wondering why they are not considering the rigid pavement structure for such high profile projects. Yes, it looks expensive during the construction phase. However. such a roadway structure needs little to no maintenance over the lifecycle. Needless to say, the rain is the archenemy of the bituminous surface along with the overloaded trucks. There is no way we can deny these two significant factors. As such, selecting the rigid pavement structure for the future roadway project would be the best strategy TMO.

 

[Homo Sapiens]

What’s the big deal?

Because a lot of drama is happening for the finance of this project in the last 7-8 years. At first, Bangladesh govt. tasked a Chinese company to construct this road, but they demanded exorbitant cost, which government refused. One time it was revealed that the above mentioned Chinese company was engaged in bribing attempt to the minister for this work. Then govt. cancelled Chinese contract and decided to build entirely with it's own money. But after 2-3 years of attempt they realized that they can't spare such a big money for it. So again search began for financiers. Now it seems ADB is finally found.

 

[bluesky]

Yes, you are absolutely right! However, the subgrade soil condition is not uniform in our country. Which makes it difficult to come up with a uniform roadway structure. I am wondering why they are not considering the rigid pavement structure for such high profile projects. Yes, it looks expensive during the construction phase. However. such a roadway structure needs little to no maintenance over the lifecycle. Needless to say, the rain is the archenemy of the bituminous surface along with the overloaded trucks. There is no way we can deny these two significant factors. As such, selecting the rigid pavement structure for the future roadway project would be the best strategy TMO.

The first inter-district long roads built in BD during 1960s were all made of concrete with a thickness perhaps about 125 mm (5 inches) with one layer of steel mesh reinforcement.

Finally, most broke down because of weak soil with low CBR (California Bearing Ratio) values, insufficient thickness and reinforcement, and heavy traffics. The concrete roads were subsequently demolished, widened and replaced with flexible (asphalt) pavement.

You are right about the bad effects of rainwater on the asphalt pavements. Asphalt starts breaking and float. However, this can be fixed

- by raising the road surface elevation to a level that is good for drainage. At present, most road surfaces lie little below the non-paved grass areas at the left and right that causes rainwater to accumulate over the roads.

- by providing correct transverse slopes (2% each side of the road center line) on the road surface. Note that 2% transverse slope is the international norm supported by AASHTO (American Association of State Highway and Transport Officials) as well as BS codes.

- by arranging longitudinal drains at both sides of a road along with collection pits @30m pitches and transverse ditches to discharges the water below to the farmlands.

There are many other facets that must be taken care of by the authorities during the design and construction stages. I know, American roads are built with concrete, but here in Japan all are asphalt paving except that concrete is used where there are steep slopes.

 

[Landmine]

The first inter-district long roads built in BD during 1960s were all made of concrete with a thickness perhaps about 125 mm (5 inches) with one layer of steel mesh reinforcement.

Finally, most broke down because of weak soil with low CBR (California Bearing Ratio) values, insufficient thickness and reinforcement, and heavy traffics. The concrete roads were subsequently demolished, widened and replaced with flexible (asphalt) pavement.

You are right about the bad effects of rainwater on the asphalt pavements. Asphalt starts breaking and float. However, this can be fixed

- by raising the road surface elevation to a level that is good for drainage. At present, most road surfaces lie little below the non-paved grass areas at the left and right that causes rainwater to accumulate over the roads.

- by providing correct transverse slopes (2% each side of the road center line) on the road surface, Note that 2% transverse slope is the international norm supported by AASHTO (American Association of State Highway and Transport Officials) as well as BS codes.

- by arranging longitudinal drains at both sides of a road along with collection pits @30m pitches and transverse ditches to discharges the water below to the farmlands.

There are many other facets that must be taken care of by the authorities during the design and construction stages. I know, American roads are built with concrete, but here in Japan all are asphalt paving except that concrete is used where there are steep slopes.

[Disclosure: I am not a pavement engineer, my major is traffic engineering. Whatever I am saying is based on my limited civil engineering knowledge and work experience. If any technical gap or discrepancies is found, please point it out. I would be more than happy to correct me and learn from my mistake]

Thanks for the valuable comment. I like the way you put emphasis on developing a comprehensive drainage system for the roadway. Yes, it is Vital to have a proper drainage system as well as the transverse slope (2-3% depending on storm return period).

I am not aware of the pavement related incident of 1960 you talked about. However, while I was working with foreign pavement engineers (mostly Japanese) in different big projects, most of the time they recommend the government to implement rigid pavement. The main reasons for such a recommendation could be simplified as follows:

1. Water clogging (You already discussed the possible solutions)
2. Overloaded traffic (Traffic loaded beyond the design limit impacts exponentially the flexible pavement. Where the impact of such traffic on the rigid pavement is linear (Source: Mechanistic empirical pavement design guide 2015). We cannot simply solve the overloaded traffic situation in Bangladesh)
3. Stagnant traffic (Standing traffic does more harm to the flexible pavement as compared to that of the rigid pavement. One most common scenario in Bangladesh is the lateral and transverse shifting of the bituminous layer. Stagnant traffic is one of the major reasons for occurring such shifting).
4. Roadside unplanned market.

For example, I want to draw the reader's attention to the implementation of rigid pavement in some places of the newly constructed Dhaka-CTG highway. I am not sure about the design specification, however, they did a pretty good job there. Since they are adopting rigid pavement structure for the limited scope, why they are not expanding their horizon?

To my understanding, the reason behind the 1960s failure of the rigid pavement system is a complete design issue, not a methodological issue. In the USA, they are gradually replacing flexible pavements with composite pavements (base structure: rigid, surface: bituminous). We should adopt the same strategy TMO since the drainage, overloaded and stagnant traffic, roadside market issues of our country could not be solved overnight (I am not sure whether it would ever be solved )

Thanks, @bluesky for your valuable information. I would encourage you to give more such information.