PennDOT 408 Concerns. Dangerous and Expensive

Transcription

1 PennDOT 408 Concerns Dangerous and Expensive

2 PennDOT 408 Concerns Pennsylvania Department of Transportation prohibits the use of backhoe or excavator mounted hydraulic compaction equipment (ie plate compactors and sheepsfoot rollers) for compacting when working in any of their roadways. These attachments when properly used have been proven to work more effective and safer for over 25 years. These compacting methods have been allowed and have been used on township and county roads for over 25 years with proven results. No one has a more vested interest in compaction than the excavator who has posted up to two year maintenance bond to guarantee their work.

3 Compaction What is Compaction? Why is Compaction necessary? How is Compaction achieved?

4 What is Compaction Compaction is the process of mechanically increasing the density or unit weight (lb/ft3) of soil by packing the soil particles closer together to force out air.

5 Why is compaction necessary? When soil is disturbed by excavation, soil particles become separated by air pockets. The volume of soil increases greatly, thereby greatly reducing density. All disturbed soil will settle with time, however, mechanical compaction greatly reduces the time for this to occur. Soil must be as dense as possible to maximize its load carrying capability, provide stability, and minimize settling. Settling can result is cracking or displacement of supported structures, paved surfaces, pipelines, etc.

6 How is compaction achieved? Compaction is achieved through the application of mechanical force to layers or lifts of the disturbed soil. This force causes coil particles to become closer together and therefore increases density. Compaction falls into two categories. Dynamic Force Static Force

7 Static Compaction Static compaction is simply the application of extreme force to the disturbed material, causing it to compress until it is capable of supporting the applied force. Static forces include kneading and compression and are typically applied by nonvibratory rollers. Static compaction is typically limited to the soil/material near the surface and is most effective for thin layers of non granular materials and asphalt.

8 Dynamic Compaction Dynamic compaction introduces waves of motion in the soil that set the particles in motion, causing them to reorient and fill vacant spaces, thus making the soil denser. Dynamic forces include impact and vibration and are applied by a variety of hand-guided and machine-mounted devices that generate stress waves that are transferred to the soil. Vibration compaction generates higher frequency, smaller stroke motion which is transferred to the soil through direct contact. The stress wave causes the soil particles to move and vibrate, effectively liquefying the soil, which allows the soil particles to fill voids between them. The result is a denser, more compact soil.

9 Rammax

10 Rammax Dangerous In most cases, in order to properly use the Rammax machine an operator must be down in the trench following the machine. Even when operating the machine via remote control, the machine still needs to be hooked manually to be removed from the trench. With a trench shield in place, areas outside the trench shield can not be properly compacted without subjecting workers to unsafe conditions.

11 Rammax Utilizing a Rammax is significantly slower Required to compact stone in smaller lifts. (8 ) Must manually chain and lower machine into and out of trench. Must have an additional machine to level stone in order for Rammax not to get stuck or roll over in trench. Rise in production costs will mean higher bids on work involving State Roads. Higher bids means higher costs for projects.

12 Rammax in use

13 Hydraulic Mounted Plate Tamper

14 Hydraulic Mounted Plate Tamper Efficient Can quickly get machine into position to compact Can use one operator in a backhoe to push stone into trench, then spin machine around to compact with Plate Tamper mounted on back. Safety Box can be moved forward while compaction occurs behind. Can compact deeper stone/soil lifts. (30 +/-) Can effectively compact around and under existing utilities.

15 Hydraulic Mounted Plate Tamper Safer No operator in trench during compaction! No danger of failing trench edges with a person in the trench Loose rocks that may fall due to vibrations no longer risk injury. Machine can reach into deep trenches to compact safely. Can effectively compact trench areas outside the trench shield when the trench walls are not vertical (i.e. when excavating in rock or previously excavated trenches).

16 Hydraulic Mounted Plate Tamper Cost Effective Contractors can bid projects more aggressively. Daily production significantly increases. Increase in production allows for per foot pricing to be much lower. More aggressive bidding equals less expensive project. Less expensive projects equals lower cost to citizens and money to be used on other projects.

17 Hydraulic Mounted Plate Tamper- in use

18 Hydraulic Mounted Plate Tamper- in use

19 Hydraulic Sheepsfoot

20 Hydraulic Sheepsfoot Can quickly get machine into position to compact Can use one operator in a backhoe to push stone into trench, then spin machine around to compact with Sheep s Foot mounted on back. Safety Box can be moved forward while compaction occurs behind. Can compact deeper stone lifts.

21 Hydraulic Sheepsfoot Safer No operator in trench during compaction! No danger of failing trench edges with a person in the trench. Loose rocks that may fall due to vibrations no longer risk injury. Machine can reach into very deep trenches to compact safely. Can effectively compact trench areas outside the trench shield when the trench walls are not vertical (ie, when excavating in rock or previously excavated trenches).

22 Hydraulic Sheepsfoot Cost Effective Contractors can bid projects more aggressively. Daily production significantly increases. Increase in production allows for per foot pricing to be much lower. More aggressive bidding equals less expensive project. Less expensive projects equals lower cost to citizens and money to be used on other projects.

23 Hydraulic Sheepsfoot in use

24 Hydraulic Sheepsfoot compacting outside trench shield

25 Testing - Compaction Test #1 - used a Hydraulically Mounted Plate Compactor on Lancaster Ave (township road) in Schaefferstown, PA. Test #2 used Ram X in first half of Main Street crossing from Lancaster Ave to middle of road. Test #3 used Hydraulically Mounted Sheep s Wheel on second half of Main Street crossing from middle line to Lancaster Ave.

26 Testing Results

27 Testing Results

28 Testing Results All Three Methods used had 100%+ compaction. Per usual requirements sewer pipe was tested to ensure that no methods used crushed or cracked the pipe.

29 Conclusion If we can save money by increasing production while creating a safer work environment and neither the roadways or pipe integrity is being compromised there should be no reason not to allow the hydraulically mounted compaction equipment to be used on state roads. Together we can help increase work safety as well as save taxpayers/rate payers significant amounts of money on all public water and sewer work.

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