GPS machine control paves the way for Turkish canal

GPS machine control for earthworks and concrete paving is helping to fast track construction of an irrigation canal in Turkey - Claire Symes reports

The Turkish economy is expected to flourish as a result of construction of a new irrigation channel currently underway in the east of the country. This canal is benefiting from the latest concrete paving and earthmoving technology and will bring with it prosperity to a deprived area of the country. But the project is already taking the lead in terms of Turkish technology by taking the main contractor Eren Inşaat into aggregate processing and GPS machine control for the first time.

Although not a highway project as such, it is using sophisticated paving and earthmoving technology developed for the highway sector, as well as using new access roads to allow the construction work. Eren Inşşaat is working on a 63km section of a 221km long irrigation canal project will take water from Ataturk reservoir for irrigation of agricultural land in the summer months. Financing of the project to get the work completed quickly is a high priority for the Turkish government and Eren Inşaat has focused on fast delivery with investment in over 100 new machines for the work.

Eren Inşaat is in charge of the last section of the channel, which runs between Mardin and Ceylanpinar in Eastern Turkey, and started work on the project last June. This phase of the project is valued at US$100million but the whole scheme is estimated to be costing the Turkish government US$300million.

It is estimated that irrigation from the channel will help the region grow enough crops for export to feed Europe three times over. "We are very proud to be involved in this scheme," said Eren Inşaat chairman Yaşar Eren.

Work on the 221km channel started in 1997and the first 86km section has been complete and in use for some time. Construction work on two other sections is running concurrently with Eren Inşaat's work on the Mardin and Ceylanpinar phase.

Work on this section started in June last year and, according to Eren, will take two and a half years to complete. "The government scheduled the work to take four years but we are investing in technology to deliver it earlier, with excavation work expected to be completed in July next year," he said.

Eren Inşaat is blasting and excavating rock from the channel before carrying out fine grading of the slopes which are overlaid with a geotextile followed by slipformed concrete. The project also includes construction of underpasses, overpasses, waddi crossings, siphons and sluice gates. Around 90% of the work is being done in-house by Eren Inşaat, but the company has subcontracted culvert and small bridge construction to Çaba and siphon work to Kappasimal.

"The project is unusual in terms of funding as it has been given a high priority - many projects in Turkey experience funding issues that delay work," explained Eren. "The government has the desire to build this project as quickly as possible and the funds for this scheme are readily available if you deliver the work." The canal is 10m wide at the bottom with 12m slopes that will allow a 6m water depth in the main channel. It total the company will move 13million m3 of earth and use 2million m3 of fill to complete the profiling work. Productivity is essential as Eren Inşaat is aiming to have the excavation phase completed by July 2011. So far all of the siphons are built and 10km of the project is paved.
This need for production is partly what has led Eren Inşaat to invest in new equipment and technology for the work. "We have bought 102 new machines for this project," said Eren. "New machines help to bring down the overall costs because of the higher availability, lower operating costs and easier access to parts.

"Around 80 of the new machines are 178 Caterpillar ones because of the high reliability they offer. When I started the company in 1987, I invested in Cat from the beginning - all machines eventually fail but it is the logistics of repair that are key because time is money and Cat's local dealer understands this." This investment and focus on efficiency means that Eren now operates the largest fleet of equipment in Turkey fitted with Cat's Accugrade GPS machine control. At the time of WH's visit to the project site, Eren Inşaat's 218 Gomaco concrete paver was also being fitted with 265 Leica machine control to allow for stringless paving.

Eren Inşaat trialled Accugrade on a Cat 365 excavator for four months before investing in more units - the company now has it fitted to a Cat D6 dozer and six other excavators working on the project. According to local Cat dealer Borusan Makina, Eren Inşaat plans to have 17 machines on the projected fitted with the system in a bid to finish the excavation work ahead of schedule.

Drilling for the blasting operation is being carried out by two 161 Atlas Copco D7 rigs but the actually blast design varies depending on the geology and the depth of the excavation.

The route passes through both limestone - which only requires light blasting and can sometime be excavated by machine - and basalt which requires conventional drill and blast techniques. The profile also varies as in some areas to meet the geometry of the canal, Eren has to place fill and carry out less excavation, whereas in others the excavation is much greater than the canal profile. High level power cables also cross the site several times so blasting in these areas has to be carefully designed.

The limestone is taken away from the site or used as backfill but the basalt is being crushed and screened in order to be reused as concrete aggregates for the project.

This is Eren Inşaat's first venture into aggregate production - the nature of the project pushed the company into this area but Eren has said that they are likely to look to undertake similar operations on future projects. "Previously we have used locally-won river aggregates for our work but a legislation change in January this year has banned that practice," he said. "We needed to excavate the basalt to create the canal so it made sense logistically to use it for aggregates.

"Carrying out the crushing and screening in-house has been a big experience with a lot of learning in the process, but other aggregates projects are inevitable now with the new legislation so it has been a positive step for the company." The company has a locally manufactured stationary crushing plant on the same site as its office complex but the company also has two mobile 6934 Metso Lokotrack crushing and screening trains that are being moved as the project progresses. Similarly, concrete plants are co-located with the stationary and mobile crushing and screening operations with a fleet of 10 mixer trucks to deliver the material to the construction sites.

The plants produce three sizes of material - 0-4mm, 4-15mm and 15-22mm with around 25% of the aggregates being produced by the stationary plant.
Concrete paving is being carried out using a Gomaco GP260 for the sloping walls and a 6805 Massenza 2401 for the flat floor of the canal.

The concrete is being laid over a T-Grip geotextile because some of the soils along the route have the potential to absorb the water and swell. Concrete is being laid in a 150mm thick layer.

After laying, the concrete is covered with fabric and sprayed with water for four days to prevent surface cracking during curing. The mix design for the 20MPa concrete is fairly standard despite the challenging environmental conditions.

In the same way that Accugrade has helped Eren Inşaat to improve grading operations, the company hoped that stringless paving with the Leica system on the Gomaco paver will have similar benefits. This is particularly useful on this project where the paving is being carried out in low light conditions at night due to the high daytime temperatures on site.

The site employs 350 people - 60% recruited locally - who work two 10 hour shifts per day on the project with the focus during daylight on excavation and grading of the slopes in preparation for paving. "Previously the grading process was holding up the paving work but this is no longer the case now we are using Accugrade," said Eren. "The efficiency is about 400% greater with the GPS control - the men can work not only faster but also more accurately.

"It is also safer - we don't need to have surveyors out marking the site. The other added benefit is that it allows the machines to be used in a more fuel efficient manner - this is a critical consideration in Turkey as we have some of the highest diesel prices in the world here." The company is currently grading 500m per day, while the slipforming is achieving 250m per day, although this is likely to increase with full commissioning of the Leica system. Eren is confident that the machine investment means that his company will deliver the project ahead of schedule.