Virginia may not be the biggest of American States, ranking a lowly 35th, but it has a lot going for it. At 'only' 430 miles long by 200 miles wide, the state is shaped by the Blue Ridge Mountains and the Atlantic Ocean. The birthplace to eight past presidents, the east coast state is now home to the Pentagon, the world's largest naval base and a bustling technology sector. Despite it relatively small size, Virginia has the third largest state highway system in the US, with the total road network stretching an incredible 68,429 miles (110,126 km). With both tourism and computer chips fuelling the local economy, its eight million inhabitants also contribute to traffic congestion in the cities. According to the American Automobile Association, Virginia is home to one of the top 10 busiest commuter hot spots' in the US.
The traffic problems are not solely due to commuters: truck traffic has also increased with the growth of large distribution centers along the major interstate I-81, which lies in the western mountain region of the state. This route enables passage from the southwest and Mexico northwards to New England and Canada.
To improve safety and to help keep traffic flowing, the Virginia Department of Transportation (VDOT) is insisting that contractors begin milling (or resurfacing) operations at night after rush hour traffic has dwindled. Paving usually begins between 9-11pm and must be stopped - with all equipment off the road - by at most 6am. That doesn't leave much time for laying asphalt, especially with the added pressures of financial penalties imposed on the contractor for going past the morning deadline. Fines vary by location, but can be as much as $2,500 for each 15 minute period, adding up to $10,000 an hour.
Bright team member
The Blaw-Knox 6000 series pavers from Volvo Construction Equipment are doing their share to meet the challenge. Using the Omni 318 Blaw-Knox 3m (10ft.) screed with a flexible track or rubber-tired tractor and paver mounted lighting system, one machine can resurface highway or interstate roads at night - and still be able to lay a smooth parking lot during the day. Technological improvements incorporated into the machine's digital control systems provide the service technician with useful diagnostic information to simplify repairs, speed up troubleshooting and reduce downtime.
Volvo Construction Equipment is represented in Virginia by local dealer Richmond Machinery & Equipment Company (RM&E). Established in 1919, the family-run company has been promoting Volvo's Blaw-Knox pavers since the mid 1950s. These have more recently been joined by Volvo's ABG pavers, with their double-tamping bar screed that can accommodate special asphalt mixes like SMA (stone matrix asphalt).
Contractors are seeing the added benefits of using Volvo. For example its pavers' Tier 3 engines and large 30 kW on-board generators can handle the latest gas vapor lighting systems - ideal for night projects. Other updated technology improvements include electrically-heated screed bars (compared to diesel burners), hydraulic valves with manual override buttons for easy troubleshooting and automatic speed control which assists the operator in ensuring mat quality by adjusting and maintaining a constant paving speed.
Getting its kicks on the road
Branscome Paving Co. of Manassas, Virginia is paving on I-66 in Manassas for 24 miles (39km), along with several ramps, on a mill and overlay maintenance project. It is using a 76-22 polymer modified liquid asphalt mix. A 38-50mm (1½-2in.) compacted layer is placed with the PF-6110 and a MC-30 MTV. The time constraints after milling are to start paving between 10 and 11pm and stop by 3:30am. All construction equipment has to be off the road by 5am, allowing a clear route for Washington, D.C. commuter traffic. Even with that short time period, Branscome is able to put down over 1,300 tonnes each night.
"We have been able to easily meet our density requirements of 98 to 99%," says David Branscome, head of the company. "A lot of the thanks for that go to the paver. What comes out from behind the paver is crucial to meeting all those objectives. The vibrators on the screed help us achieve our required density. Then there is less compactive effort required of the rollers."
Fellow Virginian contractor Adams Construction Co. is using a Volvo Blaw-Knox PF-6170 paver at night in downtown Roanoke. The firm has to lay the complex SMA mix to resurface and inlay I-581 for 6.4 miles (10km) in both directions. The $7 million project consists of three lanes with a 1.2 m (4ft) inside shoulder and 3 m (10ft) outside shoulder. Paving is at night only, from Sunday night to Thursday night. Traffic cones are positioned after the rush hour, at about 9 pm with milling operations starting up immediately thereafter, followed by paving commencing several hours later. Inlay is 37.5mm (1½in.) compacted SMA mix, one lane at a time until about 4:45 am. The next part of the project is an additional 37.5 mm (1½in.) compacted overlay, using the same SMA mix. The paver speed is programmed for 9 m (30ft) per minute or less, depending upon truck flow to the mobile transfer vehicle (MTV).
Paul Jones, foreman with the Volvo paving crew, said that it is one of the easiest pavers to use. "It lays a good mat and is just a great paver. The lighting system is far brighter than the balloons we used to use - and the speed control is helpful. Punch in the number you want for speed on the LCD screen and you can worry about all the other things an operator needs to watch - not how fast you are going."
B&S Contracting's I-81 project involves 10,000 tonnes of surface mix, laid on two 3.7m (12ft.) wide lanes that are 6km (3.7 miles) long. It is being milled first and immediately filled with a layer of 50mm (2in.) compacted 12.5 mix. The PF-6170 paver is used in conjunction with the company's MC-330 MTV for a better surface ride. The operator programs the paver to run 6m (20ft.) per minute, so the rollers can keep pace and compact the material correctly.
These teams of pavers are once again proving that they are up to the task, paving all kinds of roads in the state of Virginia - from interstates to highways to city streets. Volvo is also lighting the way - all around the paver - for ease of operation and for traffic and work crew safety.