Finding Permanent Solutions with Temporary Roads

Whether they are used to solve access problems for workers so materials, equipment and vehicles can be easily transported or to create routes for the public, temporary roads are vital for a number of industries.

But how do you make something cost effective and fast while ensuring it is also safe and environmentally friendly? Here we list some projects that have employed efficient temporary road construction techniques.

Rok on with portable tracks

Rok was contracted to improve site access to a wind farm in Kilbraur, Scotland, so a multi-million pound extension could be built. To do this the company had to lay more than 3km of temporary roadway in a cost-effective way that was also sensitive to the environment.

The company decided to use a portable roadway system from TPA, one of the largest providers of portable access equipment in Europe. TPA uses two styles of track: the more traditional Traxpanels and MD40 (named because of its medium-duty 40t capacity).

Both were installed using HIAB cranes and lowered or rolled into position using a two-man crew. The 3m × 3.5m Traxpanels were made from nine aluminium planks that slotted together in a tongue-and-groove style to create sturdy panels. Aluminium was chosen because of its strength and the fact it is environmentally friendly, as damaged planks are melted down to make new ones.

Despite the environmental demands of the remote location, the trackway system met Rok’s requirements. “The ground conditions were particularly challenging and included areas of peat bog where the membrane was very delicate and vegetation could not be disturbed,” says Amanda Cruxton-Chance, TPA’s business development director.

The track was laid and recovered in a short space of time, meaning the impact on the ground below was minimal. The trackway proved to be environmentally acceptable and economically sound.

Not only was it less expensive than laying a permanent roadway but, according to Rok’s construction manager, the project ran “five weeks ahead of programme”.

Traxpanels come into their own when there is an emergency situation, as the roadways can be implemented so quickly. When a remotely located viaduct needed repairing in Appleby, Cumbria, Birse Rail needed to transport 4,000t of gravel and raw materials to the site, meaning the access road needed to support the weight of heavy vehicles, including eight-wheeler tipper lorries.

“Laying a semi-permanent roadway using the more traditional stone method would have been slow, but within 48h TPA specialist equipment and crews had installed 0.5km of temporary roadway with passing points, enabling Birse Rail to deliver vital materials to the site,” says Chance.

Asphaltic surface solutions

A recyclable, cost-effective, durable temporary road was required as part of Beloit’s Gateway Boulevard extension in Wisconsin, US. The route is used by cars and light vehicles. Work to extend Gateway Boulevard from Eagles Ridge Drive to Hart Road started in June 2009.

There was also great pressure to produce problem-free access. “The biggest issue was that failure of the temporary road was not an option,” says Lance H Wagner, the principal of RH Batterman, which manages the project for the Wisconsin Department of Transportation. “While temporary, it is the only route to a large business at its far end.”

The temporary roadway was constructed with 4in of asphaltic surface on 8in of crushed aggregate dense base course. Once complete the asphalt will be recycled and the base course reused.

“These materials were chosen because they are constructed relatively quickly, are the most cost-effective and are recyclable,” says Wagner. So far there have not been any problems with the temporary road and the project is on schedule for completion in June 2010.

3D software optimises road design

As temporary road constructions become more demanding, 2D engineering solutions are no longer adequate. The industry has come to depend more on AutoCAD Civil 3D, so much so that industry staple Eagle Point is now focusing on Civil 3D as its development platform.

China State Construction Engineering (CSCE) needed to build a temporary road for a construction site it was working on in Hong Kong, which required a three-year closure of a public road. It used AutoCAD Civil 3D to optimise the process.

The new road was to angle down a steep, uneven slope, yet its gradient was required to be no more than one to ten, and in certain places concrete blocks would need to support the outer edge. These would range from 1m to 10m in height.

To complicate matters overhead cables needed to be avoided by trucks travelling to and from a local quarry.

CSCE chief surveyor Bruce Pang decided such a complicated design would be “difficult and time consuming” using traditional software. “We needed software that would help with the design process so we could input data about the existing slope and determine how much we would need to excavate and how many concrete blocks would be required for a given design,” Pang says.

It was important to find the optimum route for the road and calculate the correct amount of fill for precise scheduling and purchasing. “We wanted accurate numbers of blocks so we could place orders as the work progressed,” says Pang.

On the 3D model the team carried out many “what if” scenarios and reduced the length of road from 310m to 250m. They also made several changes to the road alignment. As each item was quantified for sections every 2.5m, the site engineer could plan and manage the schedule and materials more easily. “This proved a big help for quantity surveyors and payment schedules,” says Pang.

The software enabled the team to optimise construction despite the difficult constraints, and its efficiency brought a significant cost saving. “About 22% less material was excavated and the road was shortened by 19%,” says Pang.