Showing posts with label MC70. Show all posts
Showing posts with label MC70. Show all posts

October 5, 2017

Road Topping Tender

Brace yourself for more chaos on the roads

Biggest white topping project to date set to begin in second week of October

In tune with the State government's move towards white topping roads, the Bruhat Bengaluru Mahanagara Palike (BBMP) has approved tenders for white topping 29 roads and six major junctions totalling to a length of 93.47 km at a cost of ₹723.71 crore. For motorists, this will be mean smooth roads, but citizens remain sceptical given the deteriorating condition of roads every monsoon.
Work is expected to begin in the second week of October simultaneously on multiple roads, and add to the traffic chaos across the city.
 
“BBMP has set a one-year deadline for completion of works on the 29 roads. We have split the work and given tenders to two firms so that the project starts simultaneously and is finished on time,” said K.T. Nagaraj, Chief Engineer, Projects, BBMP.
All roads will be provided with service ducts on either side for optic fibre cables and power cables. However, sewage and water lines will not be shifted, sources said.
White-topping is an overlay of Portland cement concrete layer over the existing asphalt layer on the road. Chief Minister Siddaramaiah and City Development Minister K.J. George are passionate votaries of the technology. Recently, Mr. Siddaramaiah had said that he would like to see roads in the city to be white-topped.
For now, however, sections on major roads like Outer Ring Road, Mysuru Road, Brigade Road, Hosur Road, Bannerghatta Road, Sarjapur Road and Tumakuru Road will be revamped.
This will be the biggest white-topping project in the city to date.
Bengaluru City Traffic Police, who have given their go-ahead for the works, said that though the project will disrupt traffic in the short run, white topping of roads is better since it provides a pothole-free ride, once completed. “We cannot block the roads. Work will be taken up on one lane while traffic will be allowed on the opposite lane,” said R. Hitendra, Additional Commissioner of Police (Traffic). He added that they would like the BBMP to press more paver machines into action to speed up the process.

October 2, 2017

Nothing world class about TenderSURE roads

By Ashwini M Sripad  |  Express News Service  |   Published: 02nd October 2017 04:38 AM  |  
Last Updated: 02nd October 2017 07:21 AM  |   A+A-   |  
Cunningham Road, developed under the TenderSURE project, gets invariably flooded every time it rains; (below) potholes have also surfaced on some of these roads
BENGALURU: When conceptualised, TenderSURE roads were termed as world class. The recent heavy rains have, however, exposed their poor quality as well as the tall claims of the officials concerned. Sunday night’s rain left the TenderSURE roads waterlogged in the city yet again, with people wondering if the crores of rupees spent on them literally went down the drain!“It was difficult to commute on the water-logged Cunningham Road on Sunday night. Water was gushing on to the street through manholes and drains, and an unbearable stink made matters worse,” said Arun Jha, a resident of R T Nagar.
According to traffic expert Prof M N Sreehari, TenderSURE roads are world class only in terms of the money spent. The quality of the roads is as bad as normal asphalted roads. “On all TenderSURE roads, footpaths have been made wider without conducting any pedestrian user survey. The paver blocks on the footpath have been laid unscientifically. These are laid on the top layer of the footpath. The ground below them is not properly layered, which results in an uneven top layer and gaps in between the blocks. Whenever it rains, water percolates through them, leading to water stagnation and damaged road surface,’’ he said.
Many of the TenderSURE roads built in the first phase have sewer lines beneath them, including Richmond Road, Residency Road and Cunningham Road. “At times, if there are clogged drains, we end up digging the roads to clear the blockage,’’ said an official.
BBMP Commissioner Manjunath Prasad agreed. “Ideally for TenderSURE roads, all the utility should be shifted to one side of the road. But in the first phase, BWSSB did not shift sewer lines on some of the roads. This is one of the reasons for flooding,’’ he said. However, he was quick to add that the problem has been rectified in the works undertaken during subsequent phases.
Another reason for water clogging is the sweeping practices. “Pourakarmikas often push dust and waste towards gratings on the road surface that have been put to let rainwater into the drain. This results in clogging,’’ an official said.
However, K T Nagaraj, BBMP Chief (Projects), maintained there is no problem with TenderSURE roads and they are indeed world class. Flooding, Nagaraj claimed, is because of heavy rains. The gratings have small outlets for the rainwater to enter the drains. “If there is more water and smaller outlets, water will obviously flow slowly. On TenderSURE roads, water does not clog for more than three hours,’’ he added.  
Of the proposed 45 TenderSURE roads, nine are complete. Works on another three will be finished soon. Tenders will be called for 13 more roads under  phase II. The cost of these roads was around `7.5 crore per km, including shifting of utilities, wider footpath and bitumen-mixed black-topping. BBMP officials boast of 25 to 30 years durability of these roads.

September 28, 2017

Another Tender War


Work on white-topping of roads is set to begin and around 30 roads stretching 93.47 km will be white-topped in two phases. The tender process for the project, which has been divided into two packages, has been completed.

The first package has been handed over to NCC which involves six roads and six circles. The second package involves 24 roads and the contract has been handed over to Madhukan. The companies have been given 11 months to complete the project.

“Roads will be white-topped on the lines of Nrupathunga Road. Work will start by October,” said Bruhat Bengaluru Mahanagara Palike (BBMP) commissioner N Manjunath Prasad.

He also said the stretch along Mysuru Road-Sumanahalli Junction-Goraguntepalya-BEL Circle-Hebbal-KR Puram will be taken up soon since the traffic here is heavy. “We are trying to reduce the inconvenience caused to motorists as much as possible and hence we have instructed the contractors to complete the project within six months,” said Prasad.

“We need to completely bar vehicular movement during the project. We will create alternative routes during this period in consultation with the traffic police,” said K T Nagaraj, BBMP chief engineer, (projects).

He also said work will 
be taken up according to the availability of the paver machines which are used for white-topping.

Around six circles are being white-topped in the project. The circle near Ramakrishna Ashram, Lalbagh West, North and East gates, near Siddapura Teacher’s College and Bhashyam Circle will be white-topped. A total of Rs 21.24 crore is being spent on this. “These works come under Package 1,” said Nagaraj.

White-topping, or concretisation, gives roads a life of up to 25 years and results in fuel savings of 14%. The Centre for Smart Cities (CSC) Research had recommended that white-topping helps in reducing traffic and increasing the lifespan of the road. The state government has allotted Rs 2,000-3,000 crore under the Nagarothana scheme for this project.

Source- Deccan Herald

September 27, 2017

Mombasa to Nairobi- The Political Road

In another three years, a Kenyan travelling from Mombasa to Nairobi will have at least four major options Kenya has chosen to build a brand new road between Mombasa and Nairobi instead of expanding the existing highway in what will leave consumers spoilt for choice Transport CS James Macharia said the deal had not been signed and that several other companies could be allowed to bid Kenya has chosen to build a brand new road between Mombasa and Nairobi instead of expanding the existing highway in what will leave consumers spoilt for choice.

The Sunday Standard has established that instead of turning the current road into an expressway, the government decided to construct a completely new road to run side by side with the existing one. ALSO READ: Kenya Railways threatens top managers of RVR This means that in another three years, a Kenyan travelling from Mombasa to Nairobi will have at least four major options. One may choose the Standard Gauge Railway (SGR) passenger train that takes about five hours or take a flight and land in the coastal town in an hour. If he wants to travel by road, he will have two roads to pick from. If in a hurry, and would like to drive at speeds of 120 kilometers per hour, he will take the expressway whose contract was handed to an American firm, Bechtel, three days to the General Election in a deal described as a ‘thank you gift’ to the Americans.

This will not just be the most comfortable drive given how smooth the road would be, it will just take him three and-a-half hours. But this will not be without a cost. He will have to part with some unspecified amount of money in toll fees to enjoy the road. If he does not want to pay or is not in a hurry, he will still have the current road at his disposal, which will be available but only for smaller vehicles. The current road will also have been downgraded to stop trucks and big buses from using it. Shelved proposal It will also mean that the government will buy land afresh, in a similar fashion as it did before it build the SGR, in what could provide land cartels with another round of minting millions from government projects. The initial proposal, which was shelved in favour of the current deal, involved expansion of the existing highway to four lanes between the Machakos Turnoff to Mariakani.  ALSO READ: Kenya Railways threatens top managers of RVR It has also emerged that the contractor building the controversial expressway will be allowed to ‘sell’ it to another private contractor, who will charge users toll fees to recoup the billions sunk in the project.

“Under the Exim Bank financing model, the government has the opportunity to privatise or securitise the individual sections of the expressway that could reduce the total borrowing requirements,” Engineer Peter Mundinia, the director general of the Kenya National Highways Authority (Kenha) said in a statement. The authority, however, refused to comment on the cost of the project. A source familiar with the project says the government will pass the road to private investors, who have the experience to monetise the road. “Private investors will buy the road and charge toll fees in line with the initial Public Private Partnership (PPP) model after it is constructed.

This must not wait until it is fully built but it can start with the sections as they get completed,” a source said in an interview. This will make the multi-billion road the first ‘private road’ in the region. Kenha has contradicted the Ministry of Transport which had denied claims that the contract had been signed. In a press release this week, Kenha said the commercial contract for the project was signed on August 5. Reacting to an earlier story by the Standard, Transport CS James Macharia said the deal had not been signed and that several other companies could be allowed to bid. ALSO READ: Kenya’s Sh300b ‘thank you gift’ road project to US sparks tender wars But Kenha, which handed the project to the American firm without a competitive process, says the development is under its mandate. Available estimates show that the project will cost about Sh300 billion, before the cost of buying the land is factored in.

Kenha says its economic projections show that there is an infrastructural symbiotic relationship between the SGR and the new road as it offers connectivity for people, business and communities along the road. “Once completed, the expressway will play a critical role in improving Kenya’s transportation logistics and trade competitiveness while supporting the spatial and industrial development along the corridor,” Mundinia said. Kenha has defended the decision to opt for the construction of a new road on grounds that it is distinct from the PPP alternative given that it offers a new alignment designed as a high speed six-lane expressway of higher capacity and safety standards.

“The expressway project will include highway capacity through construction of the greater Nairobi-Southern Bypass which has been planned for several years, thereby contributing to decongestion of the fast-growing Nairobi Metropolitan Area,” Mundinia said. But as details of the deal become available, it is emerging that the mega project has stark similarities to the SGR contract handed to a Chinese company in the run-up to the 2013 General Election. Both the contracts of the SGR and the expressway project were signed shortly before the elections. The firms constructing them are the ones tasked with determining the costs of the projects. Worse, both have been single-sourced and were entered in the cover of government-to-government contracts, in deals that reduce the level of public disclosure and scrutiny that open tenders go through. The biggest concern for sources familiar with government financing is that both of these projects are now going to be financed largely from borrowing at a time when the government is exhausting its headroom to stock up any additional debt.

Kenya Railways set to operate old line It has emerged that top officials of the PPP directorate were caught unawares after the government made an about turn on the project and decided to build a new road instead. A working paper from insiders at the Treasury and the Ministry of Transport seen by this paper raised sharp questions on why the project had to be announced in a rush, three days before the elections, and why it was not competitively done. The deal has also brought back the American government on the front row seat of firms that have bagged big infrastructure projects after being elbowed out by Chinese companies.

A brief by the State Department of Infrastructure as it sought concurrence to proceed with the project says Kenya will borrow funds from American lenders (US Exim Bank and OPIC) and then sign an Engineering, Procurement and Construction (EPC) contract to build the road on a single source basis. The brief queries why a previous model financed by the World Bank was abandoned and how it was determined that the single sourcing approach would offer taxpayers better value for money and would be faster than a PPP.  “Although the proposal is being referred to as ‘alternative project concept’ or ‘highway development concept,’ it is simply a non-competitive, single source procurement of an EPC contractor who is able to bring financing with it,” the brief notes. Engineer George Kiiru, the head of PPP at Kenha, told the Sunday Standard that the government changed its focus from a PPP to EPC because it will be delivered faster as compared to PPP. Shorter period


 “Achieving commercial and financial close for PPP contracts can take two to three years thereby delaying the start of construction and completion of the project,” Kiiru said. “A comparative analysis between a PPP model for a 20-30 year concession shows cumulative repayments under the PPP approach would be higher compared to the alternative approach with ECA (US Exim/OPIC) support,” Kiiru said. The brief from the State Department of Infrastructure, however, intimates that there is no reason to suggest that the construction will take longer under the PPP arrangement. “Indeed, there are strong arguments that overall construction period may be shorter under the PPP project as it splits construction between three different EPC contractors. In any event, the constraining factor is always likely to be land acquisition, so it would be a mistake to assume that the Betchel proposal can deliver construction completion more quickly,” the brief notes.   Kenha says the government is yet to determine the exact cost of the project and is waiting for a complete detailed design, which is yet to be undertaken, before it can determine the actual cost. Kenha also refused to give a cost range that the project is expected to fall in on grounds that it did not want to speculate despite the fact that costs are the first considerations in deciding if a project is viable or not. Costs per kilometre “This project is a government to government initiative. The US Government nominated Betchel International to work with the implementing Agencies in Kenya to develop the project,” Kiiru said. In 2015, Kenha says, the governments of Kenya and the US signed a memorandum of understanding for development of priority infrastructure projects supporting Kenya’s Vision 2030. Kenya later held discussions with the US government for development of the highway. The US, through the US Exim Bank, has provided a letter of support to Betchel for the Nairobi–Mombasa Expressway under a proposed government to government agreement.

“The US Exim Bank has shown interest to finance the project together with other US Export Credit Agencies such as the Overseas Private Investment Corporation (OPIC),” Kenha said in its response. The brief says Betchel’s construction costs per kilometer are higher than estimates presented to the ministry by PricewaterhouseCoopers (PwC) on construction costs for the PPP approach of Sh600 million per kilometre versus Sh500 million per kilometre ($6 million Vs $5 million). “The per kilometre costs under the PPP proposal includes all taxes and duties while Betchel’s proposal assumes complete tax exemption for the project (corporate tax, income tax and import duties) which could reasonably be assumed to cost the government an additional Sh100 million per kilometre,” the brief notes. It goes on to argue that as part of the American firm’s proposal, an advance payment of Sh30 billion and also a payment of Sh10 billion as ‘establishment fee’ will be required. “So Betchel will be Sh40 billion in funds and highly cash positive before the start of the project whereby the government will be paying interest on this sum from day one as this will be drawn immediately by Betchel at contract signing,” the brief notes. There is also a further Sh6 billion of design management fees. The proposal from the American firm excluded all relevant taxes.

Read more at: https://www.standardmedia.co.ke/article/2001255435/billion-shilling-u-turn-that-will-cruise-you-to-coast-in-three-hours

Road Upgrade

Council to spend $1m on road upgrade


Last week, official manager Mark Blackburn voted to hire Palmerston-based contractor JLM Civil Works for the job.
“I think this is a straightforward contract,” he said.
A report by Melissa Moss, Environment and Strategic Support Officer, recommended awarding the tender — worth $1,058,389.64 — to the company.
Also vying for the contract was local company Ciarla Constructions, who tendered $1,413,054.80; and BMD Urban which has its head office in Queensland.
Ms Moss said each contract was weighted on local industry; past performance experience; resources and methodology knowledge and skills. “All Contractors assessed by the tender evaluation committee were identified as being capable of performing the works to the standard described in the tender documents,” she said.
“After evaluating all tenders against both the price and non-price criteria, the tender submitted by JLM Civil Works Pty Ltd, was considered to offer best value for money.”
Ms Moss said three tenders were submitted, though nine were downloaded.
Former chief executive Ricky Bruhn, who quit last week, said it was the second time the project had come before council.
“We got a better response this time round,” he said. 
“We’re hoping to start this project as soon as possible — before the rain starts.”
In July, Palmerston Council voted not to accept any tender for the Yarrawonga and Wallaby Holtze Road upgrade, as none were deemed suitable.
At the time, Mr Blackburn voted to tender the project again, as the only tender recieved exceeded the current budget allocation.
The revised tender included outcomes from a flood mitigation/drainage study carried out by the NT Government.

September 21, 2017

Tender Sytesm Vs Cops




Systemic delay in repairing roads.Systemic delay in repairing roads.


HYDERABAD: The long-drawn tender process followed by the Greater Hyderabad Municipal Corporation (GHMC) for relaying dug-up roads should either be done away with completely or streamlined to put the city's road infrastructure back on track, feel traffic cops.

Pointing out that currently it takes at least six months to complete just the tender process for restoration of dug up roads, which the city just cannot afford, traffic cops said there are several instances of road stretches being dug up repeatedly and not being re-surfaced, leaving behind un-motorable roads as the civic body's tender process takes its own sweet time.

As per the current system, when an agency seeks permission from GHMC for road digging, cost of required restoration work has to be submitted by the agency to the civic body before taking up the work. However, the tender process for restoring roads starts only after digging is completed.

"While it not possible to refuse permission for any development work, in most cases the contractor just dumps mud or loose gravel on the stretches. It is the gap between the completion of work and the actual filling of the road that results in traffic woes. We have suggested that the procedural fulfilling of tender be done away with and the road be filled immediately after the work is done," said AV Ranganath, deputy commissioner of police, traffic (Hyderabad II).


In fact, Malkajgiri, Anandbagh, Banjara Hills (Road No 5), Ayyappa Society , Secunderabad, LB Nagar, Bowenpally , Madhavpuri Hills, Chandanagar, PJR Enclave, KPHB and Sultan bazaar are examples of areas where such dug up road stretches have become a never-ending nightmare.


"The Maharani Jhansi Road from Putlibowli Chowrasta to Afzalganj has been in a poor condition for the past two ye ars. Only surgical repair work by pouring bitumen is done after the frequent digging work," complained resident Balasubramanyam Perugu.

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Chandramohan Singh, a resident of Marredpally , said, "The road from Reliance Fresh super market to the check post in West Marredpally was repaired about six months back but is back to its potholed self. Even the road near Lions Hospital, which was dug up for laying drainage pipes, has not been restored."


While GHMC authorities admitted the tender process takes at least two months, they said that in the case of Malkajgiri the delays stretched to nearly a year because the payment was completed only recently by Water Board, which has taken up pipeline laying work. "Once the work is completed, estimates are drawn up and sent for sanction. Then a tender is called for and a contractor is decided. The process requires at least two months.While dealing with other departments we can't press for payment beforehand," said M Shanker, deputy chief engineer, maintenance, GHMC.

Source- Times of India

September 6, 2017

Road Projects

Contractors finalised for a number of road projects in FS 
MARK STEENBOK 
15:22 (GMT+2) Tue, 05 Sep 2017
Contractors finalised for a number of road projects in FS  | News Article
The Free State Department of Police, Roads, and Transport says there are a number of roads in the province that still need to be fixed.

MEC Sam Mashinini today said that these roads, including the one between Odendaalsrus and Wesselsbron, are not covered in the current financial year and needs attention. He added that since the end of July the department has finalised tenders for successful contractors for a number of road projects in the province. The handover site meetings for, among others, the Kroonstad-Steynsrus, Vredefort-Hoopstad, Vredefort-Viljoenskroon and Bothaville-Viljoenskroon roads commenced yesterday. He says the department needs to maintain these roads once it is completed.
“One of the problems that I am currently giving attention to, is how best do we make sure that the roads in the province are maintained over the long term. I have deliberately asked the different stakeholders to say how,  once the road between Bothaville and Viljoenskroon is completed, we can maintain it. That road is economically viable in terms of the farms there. That road is mostly used and that’s why we are targeting it,” says Mashinini.
He adds that the department’s objective is to build capacity by investing in human resources through skills development. He says the department wants to create a sustainable economic climate in the province and to deliver public infrastructure by using labour intensive technology.
He says from 2008 until last year they have had an intake of 173 contractors of which 83 graduated. In total 78 is still active and engaged in projects in the province.

July 11, 2017

ONLY 10 percent of the surfaced (tarred) national road network is in good condition, with 30 percent in poor condition while 57 percent is in fair condition, a senior Government official has said.

About 3 percent of the road network has been unclassified, 1 percent of gravel and earth roads were certified to be in good condition, 22 percent was in fair condition, 72 percent was said to be in poor condition while five percent was unclassified at this stage.

In response to this situation, Government has initiated a number of road rehabilitation projects, including building new ones. Some of the road rehabilitation projects initiated through the Ministry of Transport and Infrastructure Development include. . .

Tenders will be awarded on a Build Operate Transfer (BOT) basis for the Beitbridge-Bulawayo-Victoria Falls, Harare-Nyamapanda and Rutenga-Boli-Sango roads before the end of this year.

Currently, feasibility studies and detailed engineering designs are underway for the Beitbridge-Bulawayo road and should be completed by August this year, after which tenders will be floated.

Transport and Infrastructure Development Minister Dr Jorum Gumbo said Government had made significant investment into the road network and more funds would be channelled towards infrastructure. The minister said about $300 million had so far been channelled into infrastructure development, including road rehabilitation.

"Some $13,28 million was spent on rehabilitation and maintenance of road infrastructure in 2015 and $11,44 million in 2016. At the same time, rehabilitation of the Plumtree-Mutare road was done from 2012 to 2016 at a cost of $206 million," said Dr Gumbo.

"In the aviation sector, the major investment has been upgrading of Victoria Falls Airport in the last three years to December 2016, at a cost of about $150 million. There was also some money spent on rehabilitation of the runway at Harare International Airport," he said.


All the road works were funded by the Zimbabwe National Road Authority and the Ministry of Finance and Economic Development.

"There has been no private financing of transport infrastructure development since the New Limpopo Bridge in 1994 and Beitbridge-Bulawayo Railway (BBR) in 1998.

"The Plumtree-Mutare project was financed through a loan obtained by ZINARA from DBSA (of South Africa). Victoria Falls Airport was financed by a loan to Civil Aviation Authority of Zimbabwe from China," said Dr Gumbo.

Minister Gumbo said the National Railways of Zimbabwe also carried out some rehabilitation work on the national railway network.

The condition of the country's road network had deteriorated since the last condition survey in 2010. At that time, 20 percent of the national road network was assessed to be in good condition, 30 percent in fair condition and 50 percent in poor condition. Ongoing road projects include the dualisation of Beitbridge-Harare-Chirundu highway, including the Harare Ring Road.

"The construction team has started arriving from China, and construction is expected to start in September this year," he said.

"We are also going to construct Phase 2 of the Harare International Airport Road. The late commencement has been due to delays in carrying out the required feasibility study. Again this will be done and project implementation will commence before the end of the year." the Minister added.

More funds, especially foreign direct investment, could have been channelled towards road projects, among other infrastructure development projects, but lack of appropriate and adequate legislation governing Public Private Partnerships was a hindrance.

"However, we now have the Joint Venture Act, and we trust that from now on we will be able to attract significant levels of FDI in transport infrastructure development," the Minister added.

Source - Bulawayo

June 29, 2017

£165m roads project facing legal challenge


A long-awaited £165m roads project for Belfast is now facing a legal challenge, it has emerged.

Around eight years after it was first announced, cash was finally earmarked for the York Street Interchange development as part of the DUP's £1bn deal with the Tories.

But now, a legal challenge, which has been confirmed by the Department for Infrastructure, over the awarding of the main construction contract, could delay the scheme further.

DUP Tory deal new £1bn allocation breakdown - where will the money go in Northern Ireland?

The Department has said that “the tender process to appoint a contractor to bring the scheme to a construction ready stage has now been completed... however, tender award cannot occur at present due to a legal challenge. The legal process is ongoing.”

The interchange is intended to solve the Belfast's increasing traffic problems.

It aimed to transform traffic flow where the Westlink, M2 and M3 converge.

The bulk of the cash needed to build it, around 40%, was originally due to come from the EU.

The upgrade of the York Street Interchange aims to tackle the traffic gridlock which occurs daily.

As Northern Ireland's busiest junction, it carries 100,000 vehicles daily, mostly commuters to and from Belfast from around Co Antrim.

It was revealed this week that part of a £1bn fiscal package for Northern Ireland as part of the DUP deal with the Conservatives, will include £400m for infrastructure. And as part of that, money will be freed up for the York Street Interchange.

At the end of last year, former Infrastructure Minister Chris Hazzard accepted a recommendation from a public inquiry that the York Street Interchange scheme should progress in principle but reiterated warnings that Brexit had placed a question mark over funding.

Speaking about the project, Wesley Johnston, an expert on Northern Ireland's roads, has said that commuters can still expect delays at the York Street interchange even after work has been completed.

Belfast Telegraph Digital

February 17, 2017

Bitumen in Road Construction

Bitumen is used in road construction due to various properties and advantages it has over other pavement construction materials. Advantages of bitumen for road construction is discussed.

Why is Bitumen Used in Road Construction?

Bitumen gain certain unique properties that are inbuilt in it during its manufacture. The bitumen as a raw material in flexible road construction and bitumen as a mix (composing other materials i.e. aggregates/ pozzolans) serves certain advantages, that prompt to use bitumen widely in road construction.


Use of Bitumen in Flexible Road Construction

The reason behind the significant application of bitumen in flexible pavements are explained below:

1. Production of Bitumen is economical

Bitumen is a by-product of crude oil distillation process. Crude oil itself is a composition of hydrocarbons. The primary products that are available are the petrol, diesel, high octane fuels and gasoline.
When these fuels are refined from the crude oil, the bitumen is left behind. Further treatment of by-product, to make it free from impurities give pure bitumen.
As the primary product demand is of utmost importance to the society, the bitumen as a by product has survival for long. This by product is utilized as a new construction material, without going for any other new resource.

2. Physical and Rheological Properties of Bitumen bring Versatility

The physical and the chemical properties of Bitumen are found to be a function of load level, temperature and the duration of loading. It is a thermoplastic and viscoelastic material.
These dependencies make us to truly access the traffic on the road so that a bitumen mix properties can be varied based on the stress levels calculated. This versatility of bitumen results in a large variety of bitumen mix, based on the road application.

3. The Melting Point of Bitumen is low

It is highly appreciable about the fact that bitumen has a favorable melting point, that helps in both surface dressing and wearing resistance with ease.
The melting point of the bitumen should not be too high, that it can be melted easily during laying the pavement. At the same time, bitumen has a melting point, which would not let the already casted road pave to melt and deform under high temperatures.
In areas of high temperatures, along with this quality of bitumen, the aggregate composition helps to cover up the effect of large temperature.

4. Bitumen can undergo Recycling

As the melting point of bitumen is favorable, it can be melted back to its original state. This is called as asphalt recycling process.
The torn-up asphalt pieces are taken up to the recycling plant, instead of sending them to landfills. This recycled mix can be reused. If necessary, the old bitumen is mixed with new bitumen and new aggregates to make the mix live again.

5. Bitumen gain Adhesive Nature

As explained in the production of bitumen, it is free from hydrocarbon and hence not toxic. The by product is refined to maximum to get rid of organic materials and impurities.
The bitumen has a highly adhesive nature, which keeps the materials in the road mix bind together under strong bonds. These become stronger when the mix is set i.e. ready for vehicle movement.

6. Bitumen has Color Variety

The traditional bitumen is black in color. This is because the dense organic material within bitumen is black in color. Now, when certain pigments are added to bitumen, the color of our choice can be obtained. These are colored bitumen.
It is costly than the normal colored bitumen. The disadvantage of colored bitumen is that it requires more chemical additives and materials.

Requirements of Bitumen Mixes for Road Construction

An overall bitumen mix is used in the construction of flexible pavement to serve the following needs.
  • Structural Strength
  • Surface Drainage
  • Surface Friction

Structural Strength of Bituminous Pavements

The figure below shows a typical cross section of flexible pavement, that was developed in the USA. The structural bitumen layer composes of:
  • Bituminous surface or wearing course
  • Bituminous binder course
  • Bituminous base course
The primary purpose of these bitumen mixes is structural strength provision. This involves even load dispersion throughout the layers of the pavement. The loads involved are dynamic or static loads, which is transferred to the base subgrade through the aggregate course.
A granular base with a bituminous surface course is only provided for roads of low traffic. It is just sufficient and economical.
The rebounding effect of bitumen upper layers helps in having resistance against high dynamic effect due to the heavy traffic. Rebounding property is reflected by the stiffness and the flexibility characteristics of the bitumen top layers. When looking from bottom to top, the flexibility characteristics should increase.
Studies have shown that the above mentioned characteristics of aggregates are attained using densely graded bitumen mixes. This mix should make use of nominal maximum size aggregate (NMAS), that must decrease from the base course- binder course – surface course.
The nominal maximum size aggregate (NMAS) = One sieve larger than first sieve-to retain more than 10% of combined aggregate.
There is a higher amount of bitumen content in the wearing course, that make the layer more flexible. This would help in increasing the durability.

Surface Drainage of Bituminous Pavements

Subsurface drainage can be facilitated using granular sub base in the construction of flexible pavement. Permeable asphalt treated base (PATB) can be used to provided positive surface drainage in major highways. This would behave as a separate course for facilitating subsurface drainage.

Surface Friction of Bituminous Roads

It is essential for the pavement layer to provide enough skid resistance and friction, during vehicle passage, especially in wet condition. This would ensure the safety of the passengers. The macro and the micro surface texture of the asphalt mix contributes towards the surface friction.

The mix gradation i.e. open graded or dense graded will contribute to macro surface texture. The open graded mix have higher macro surface than dense graded. The water is squeezed out from the bottom of vehicle tire when the high macro surface texture is implemented.
The micro surface texture is contributed by the aggregate surface, that is exposed when the above bitumen layer is torn.

Advantages of Bituminous Road Construction Over Concrete Pavements

1. A smooth Ride Surface

It does not make use of any joints; Hence provide a smooth surface to ride. It also gives less sound emission when compared with concrete pavements. The wear and tear are less in the bituminous pavement, thus maintaining the smoothness.

2. Gradual Failure

The deformation and the failure in the bituminous pavement is a gradual process. The concrete pavement shows brittle failures.

3. Quick Repair

They have an option to be repaired to be quick. They don’t consume time in reverting the path for traffic; as they set fast.

4. Staged Construction

This helps in carrying out staged construction in a situation when problems of fund constraint or traffic estimation problems are faced.

5. Life Cost is Less

The initial cost and overall maintenance cost of bituminous pavement are less compared to concrete pavement.

6. Temperature Resistant

They act resistant against high temperature from melting and are not affected by de-icing materials.

Disadvantages of Bituminous Pavement

  1. Bituminous pavements are less durable
  2. Low tensile strength compared to concrete pavement
  3. Extreme weather and improper weather conditions tend to make bituminous pavement slick and soft.
  4. Bitumen with impurities can cause pollution to soil, hence ground water by their melting. These may have hydrocarbons in small amounts.
  5. Clogging of pores and drainage path during construction and service life
  6. More salting- to prevent snow during winter season
  7. Cost of construction high during extreme conditions of temperature

Source - enggfeed