||Main Contractor (Joint Venture)|
||June 2013 to July 2014|
Scope of Works:
Birmingham Airport is one of the UK’s busiest airports, handling over 9 million passengers a year. The airport offers both domestic flights within the UK and international flights to Europe, North America and the Middle East.
In 2012, a Colas joint venture (JV) began works to extend the airport’s runway. Colas’ airports team extended the runway pavement by 450m, including 405m of operational runway. This took the runways operational length to 3,003m. The extra runway allows aircraft to take off from Birmingham Airport with more fuel and fly directly to destinations previously out of reach, such as China, South America, South Africa and the west coast of the USA.
As a prelude to the airport runway project, one of the most significant economic developments ever undertaken in the Birmingham area, Colas created a 2km section of dual carriageway to divert the A45. The A45 is the airport’s main access road which is located south of the runway, outside of the airport boundary. The diversion of the A45 created the space needed to extend the runway. Operations on the 4 lane carriageway were launched in August 2012 and were completed in the autumn of 2013. This included major earthworks, the diversion of water courses, building demolition and resurfacing works. In addition, the Colas carried out landscaping and installed street lighting, safety barriers and a surface water drainage system.
A new perimeter road and a Centro road were also constructed.
The A45 works and the runway extension project were run as one construction contract to generate savings that made both projects more cost efficient. For example, the road construction generated surplus material which was used to develop the airfield and the airfield site.
Colas dug out 300,000m3 of clay from the road, of which 60,000m3 was used as structural fill for the runway. The clay was also used as bunds on the site. In addition to the costs savings, as the road diversion created the land for the runway extension, undertaking the work simultaneously was key.
The early stages of the airside works involved the provision of drainage and a culvert beneath the planned runway extension. Construction of the airside culvert required four deliveries of metal to allow the first 250m to be constructed. Built to facilitate the drainage of excess water, the culvert was situated across the airfield and underneath the new runway extension where it connects to an existing watercourse.
In the summer of 2013, with the works to divert the A45 nearing completion and traffic now using the new carriageway, Colas began operations to extend the runway. The extension was constructed from concrete and consisted of a keel section on the runway, the main area of trafficking being central to the runway. The pavement design enabled Colas to reduce the width of the full strength pavement to the central area and linearly reduce the structural thickness to 300mm. The vertical bays were linked by dowels and varied in depth from 300–400mm within the extension and 195-210mm within the shoulders to the extension.
A no fines concrete mix was used for the delethalisation of the taxiways and vertical facing edges where required. The voids formed in the no fines mix produced a suitable surface for the topsoil to integrate with and a passage for the standing water to seep through, whilst maintaining the structural function.
The whole runway was then resurfaced with Marshall Asphalt.
The Colas team designed and constructed new runway pavement, resurfaced taxiways, replaced AGL and provided all associated drainage. Our ability to lay concrete and grooved Marshall Asphalt was also demonstrated.
The runway extension and resurfacing works began in November 2013 which saw Colas’ airports team work during restricted night time closures where all flights were halted. It was essential that the runway was handed back over to the client at the end of each shift so that normal flying operations could commence.
The 450m runway extension was constructed from concrete overlaid with HDM base course and Marshall Asphalt binder and surface courses. The concrete mix design produced by Colas yielded a compressive strength in excess of 55MPa at seven days.
Colas setup a concrete batching plant on-site which provided sufficient amounts of concrete to create the 450m extension. The plant also enabled the concrete needed as part of the taxiway and perimeter road works to be batched locally.
The use of the concrete batching plant provided the following advantages:
- The availability of a constant supply of bespoke mixes of high quality concrete, with a reduced risk of traffic delays.
- A steady supply of concrete and enhanced productivity, particularly during night works where the working window was limited to 5-6 hours.
- Minimisation of disruption on local roads and disturbance to local residents as a result of reduced vehicle deliveries.
In addition to the concrete works for the extension, Colas also resurfaced the entire runway using grooved Marshall Asphalt. Marshall Asphalt was selected as Birmingham has a cross wind runway and the grooving of the asphalt facilitates drainage. An alternative surfacing material, BBA (Beton Bitumeux Aeronautique), was also used to resurface the runway shoulders and taxiways.
When carrying out the resurfacing, Colas had to consider the weather as Marshall Asphalt has a large amount of fines and rain has a tendency to adversely affect them. Furthermore, cold conditions cause the surface to go off too quickly. However, Colas was able to work through the winter weather and carry out resurfacing operations on the runway which spans 60m in width (46m for operational use plus two 7m wide shoulders).
The resurfacing works were facilitated through the establishment of a Colas mobile asphalt plant on site. Within the Colas Group, we operate a fleet of mobile asphalt plants which support the efficient production of large quantities of asphalt throughout the duration of a contract. For the Birmingham Airport runway resurfacing works, Colas supplied our highly mobile Intrame UM280 asphalt plant which produced the Marshall Asphalt and BBA surfacing materials.
The mobile asphalt plant was a great asset to the project as it provided a reliable and uninterrupted supply of asphalt, producing 300 tonnes per hour. A specialist team of Colas operatives were responsible for the management of the mobile asphalt plant and the production of asphalt for the works.
Colas supported the manufacturing of concrete and asphalt by providing a UKAS accredited on-site mobile laboratory. Colas technicians used the lab to undertake all of the necessary tests required by the contract. This included the inspection and testing of the concrete mix design to demonstrate compliance with the project specification and relevant standards. A calibrated weighbridge was also mobilised which was essential for accurate stock control, materials reconciliation and forecasting.
Prior to the laying of the concrete and asphalt, a runway trial area was constructed where Colas tested all of the materials planned for the runway extension and resurfacing works. This ensured that the materials performed as expected. To do this, our site team placed the materials in layers before compacting them with a roller. Compaction and moisture tests were then performed to guarantee that the materials could take the required loading.
Our team of technicians monitored and controlled the quality of all concrete and asphalt produced. The quality and testing regime undertaken for all materials was detailed in the project Proof of Compliance Plan. It was the responsibility of the Colas Technical Manager to implement and oversee the delivery of the plan. The plan allowed for initial assessment of aggregates immediately after award of contract, followed by a comprehensive test regime once the UKAS accredited lab was established on site, well in advance of mixing starting. Routine testing of aggregates, concrete and asphalt was undertaken during the works.
As part of the runway extension and resurfacing works at Birmingham Airport, Colas installed new AGL lighting. This involved the installation of new AGL cable and fittings to the following lighting systems:
- Hi Intensity Runway edge lighting.
- Low Intensity Runway edge lighting.
- Threshold lighting.
- Hi Intensity Approach lighting.
- Strobe lighting.
- PAPI lighting.
- MALMS Testing of new fittings.
All AGL cabling was installed including a new AGL circuit fitted through a new pit and duct system located on the runway verge. A substation was also constructed for the south pumping station and low voltage and communication cables fitted. In addition, a high voltage cable was fed from a new substation to TWC3 approximately 1000m.