Barbco BMTA Used to Complete Runway Crossing
As 2023 has come into full swing in the underground construction world, many engineers and constructors are faced with a similar question: What trenchless method is best?
In today’s world, there is surely no lack of effort from trenchless equipment manufacturers in touting their latest models with the newest innovations. For new projects, this means even more choices than ever in determining what methods are specified and ultimately employed for a trenchless crossing. While new machines offer advanced features and unique capabilities, the downside is the cost of purchasing new equipment, especially in today’s market with escalating prices. As a result, many contractors are wondering: “Is there another way?”
The team consisting of Drake Barbera, Clay Gillilan, and Tyler Nestleroad, of BGN Trenchless Consulting, with John Barbera, of Barbco Inc., had set their sights on a project facing the same question. The project involved the installation of 84-in. casing to be built by guided jack-and-bore or conventional tunneling. The project, held by Archon Construction, of Addison Illinois, needed an answer. As the team reviewed the crossings on the project, 270 lf of 84-in. steel casing and 350 lf of 84-in. steel casing, the answer was clearly to tunnel the crossings.
In the past few years, new tunneling methods have been become increasingly popular for underground utility construction: Direct Pipe, microtunneling, large diameter TBMs – all of which are different methods to achieve similar results. As for the BGN team on site, none of these options were cost achievable, except for the Barbco BMTA.
The BMTA (boring machine tunneling attachment) is similar to traditional TBMs, except that it uses a common jack-and-bore machine and auger to remove cuttings from the cutting face. With the Barbco BMTA, and the team’s existing equipment provided a cost-effective solution for the O’Hare project.
On the project, the first crossing was 270 lf under a busy runway at the airport. Due to the airport restrictions, the team could only preform work from 10 p.m. to 6 a.m., creating a tight window for forward production. The team set up its Barbco 48-950 ABM, as any other jack-and-bore would be performed, and then moved on to the BMTA and accessories.
Following the complete setup in the jacking pit, it was time to launch. The team entered a face of swelling clay and maintained line and grade by utilizing the electric-over-hydraulic steering system in the BMTA. As the tunnel progressed, wet and running sugar sand was encountered roughly 30 ft in. Upon seeing the sand, a simple adjustment to the “spoil doors” from the inside of the BMTA’s cutting head mitigated risks of ground “hour glassing,” which could ultimately lead to voids above the tunnel’s path.
After about 10 ft of encountering running sand, the team was able to fully open the doors, and progress normally back into the clay. Throughout a span of 15 days under the tight restrictions of the airport and precise line and grade requirements of the crossing, the team entered the exit pit, perfectly in line with the preset structure for the casing to enter. Following a standard post survey, the team was able to simply remove the BMTA from the first piece of 84-in. pipe, pull augers like any normal jack-and-bore, and make way to celebrate the day.
In conclusion, an experienced contractor, such as Archon Construction, partnering with experienced teams, such as BGN Trenchless Consulting and Barbco Inc., can lead to successful results while utilizing more cost-effective, project-capable equipment, ultimately moving a project forward successfully, and under budget.
Article provided by Barbco.