Plant, Machinery & Equipment, Products & Technology

Taking AIR excavation technology on rail

Manco Rail recently teamed up with Kiwi contractors Alliance Services to complete site-commissioning of an innovative piece of rail equipment.

The New Zealand specialist contracting company Alliance Services, in conjunction with Manco Rail, recently completed final site-commissioning of a combined piece of novel contracting and rail equipment. The unit incorporates two new ground-breaking technologies that offer a high degree of productivity and environmental benefits. Firstly, the utilisation of the recently developed European air excavation methodology, which uses a high-pressure air blast wand in conjunction with a 43,000 m3/h air flow vacuum excavation system, (“AirVac”) is a serious alternative option to the traditional use of a water jet and vacuum excavation, known as a HydroVac. Additionally, as material is kept dry when excavated, any contaminated waste (or spoil) can be re-used on site, eliminating expensive slurry disposal costs incurred by HydroVac units.

Secondly the interface of the AirVac unit is on a rapidly deployable, tunnel compliant, rail transport system. This 30-tonne GVM, 134kw Tier 4 self-drive diesel rail unit, features a 12metre low level deck, mounted on two fully oscillating, rotating tandem bogies, fitted with fail safe brakes on all wheels. With hydraulic loading ramps, vehicle loading can be quickly completed at any level, two-lane road crossing. Positioning of the unit on track is achieved using an articulated boom, truck-mounted crane of about 60 tonne/ metre capacity. The two deck sections of the rail bogie can be transported to the work site using either a clear six-metre deck or semi-trailer.

Once on-track, an infinitely variable 15 kph track speed is obtained by the rail operation trained AirVac operator, using the radio remote control console from his normal seating position when travelling forward and from a clip on rear mounted seat located on the rear of the AirVac when travelling in reverse. Engine status and reversing camera console is mounted on top of the power pack in full view of the operator.

A “cold, wet day” in South Auckland

Alliance Services general manager Scott Bainbridge describes the day that the technology was put into action.

“It was a cold, wet, late-autumn morning at the Glenbrook Vintage Railway Station site, five minutes from the small rural town of Waiuku, in South Auckland, where the commissioning and training took place. Even given the weather, it was hard to mask the excited enthusiasm of the day’s events,” Bainbridge said.

“As those in attendance eagerly looked on, twelve months of hard work was finally put to the test. Engineers from Manco and staff from the Glenbrook station joined senior managers and operators from Alliance Services as their bespoke, fit-for-purpose combined rail system was given the green light and testing and operator on the track took place.”

Bainbridge said much time and energy as well as money had gone into the new system.

“On the test and trial day we got to watch an idea come to reality,” he said.

“It was wonderful to see all those present embrace what we had been talking about for so many months.”

With New Zealand’s only fleet of Air Vacuum Excavators (or AirVacs), Alliance Services has steadily grown the demand for air excavation, nationwide, over the last four years. With a growing number of clients now preferring AirVac over hydrovac units, the company has had to continue to innovate in order to service a diversifying number of clients.

The benefits of using AirVac over hydrovac units are many, with environmental impact one of the leading factors in choosing the method. Because the AirVac excavates material in a dry state, the contents of the nine-cubic-metre bin can be tipped and reused on site if needed. As well as this, air is designed to ‘bounce around’ underground pipes or cables once it locates them, whereas high-powered water (i.e., hydrovac units) will still cut through services if used recklessly. Air also ensures that no chlorinated water or chemicals are added to the environment or excavation site, which is becoming an increasingly important factor, particularly when working around tree roots.

Demand “through the roof”

“The demand for our AirVac units for rail-based excavation work is now going through the roof,” Bainbridge said.

“It makes sense: when it comes to excavating underneath rail lines and ballast, the last thing you want is to introduce water like hydrovac units do. With AirVac, we only use air to disrupt the soil and vacuum it up. That way, the ground conditions stay dry and stable.

“To date, our rail customers – particularly KiwiRail directly – have understood that we are limited to work on parts of the network that can be accessed directly through access points, or locations we can drive to. The problem with that, though, is that it leaves around 70% of the rail network in New Zealand un-reachable.”

Hi-railing was simply not an option for AirVac because of the truck’s size and weight, as we are already operating to maximum permissible GVM and axle loads. Furthermore, there was no room within the chassis, for the two front and rear rail modules to be installed. The AirVac is ten metres long, almost four metres tall and up to 23 tonnes when full. Thus an innovative solution was required, with Alliance Services approaching the team at Manco Rail to explore possible options.

“We needed something that was essentially a bespoke solution, customised specifically for our AirVac trucks,” Bainbridge said.

Customers were screaming out for a solution to our access issues, and we really wanted to see if we could do something about it.”

After agreeing on the project, the team at Manco have spent the better part of twelve months designing, building and now testing the dolly system; working closely with Alliance Services and KiwiRail alike. The result: something of pure engineering beauty.

Now with testing completed, Alliance Services have two identical dolly systems up and running on existing projects since early June, and productivity and customer expectations are being fully met, with a considerable level of positive comments coming from all levels of the client’s operations.

An enjoyable experience

Manco managing director Bryan Black, with some 37-years in the rail equipment business, remarked that working with quality people such as Alliance Services had made all stages in the design and build an enjoyable experience for all his staff.

“These difficult custom builds require a great deal of customer confidence in what you are trying to accomplish and it’s important that what they have interpreted in our original quotation is reflected in the end product,” Black said.

“I believe that we have successfully achieved that objective and trust that we will have the opportunity to work with Alliance Services again on other projects in the future.”  

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