Well, the big dig is on. And it is very impressive, particularly at night.
Last week was the tidy up, finish, clean up, and set up. The concreting of the beams at the top of the piles at Ormond was only just completed. The final section south of North Road, near Elster Creek, was poured on Thursday. The final section north of North Road, at the extremely northerly end, was poured on Friday. At other locations low key excavation continued - between McKinnon Rd and Elster Creek, around Bentleigh station, and south of Centre Rd. The final portion of the reconstruction of the Elster Creek drain under the western part of Murray Road was completed. Half of Nicholson St (between McKinnon and Bentleigh) was fenced off to give working space, and the remainder was made one way (southbound). Large numbers of lights were attached to the piles. Curiously, one reinforced column for the new Bentleigh station was erected.
Machinery really started to arrive in the second half of the week. A massive machinery dump was created on the EE Gunn reserve north of Ormond, with a smaller dump in the former western car park at Bentleigh. A huge mountain of crushed rock has been stockpiled in the EE Gunn reserve, while a smaller stockpile is situated in the northern carpark at Glenhuntly.
McKinnon Road and Centre Road level crossings were closed to road traffic at 8 pm. By 9 pm work had commenced to remove the boom barriers at Centre Rd. North Road level crossing was abolished with the last train about 12.30, but the road wasn't closed.
By mid Saturday morning all the level crossing equipment had been removed at all three level crossings - boom barriers, cantilevered flashing lights, pedestrian wickets, and relay cabinets. Work was underway removing the overhead. This commenced at the north end of the work site and progressed south. By midday, it had reached McKinnon Rd. At this stage the track was intact, but dismantling work was in progress at Ormond. McKinnon Rd was closed, but Centre Rd was reopened for road traffic during Saturday for the trading. A Metro work train had been parked north of Leila Rd, Ormond, on the Down line for recovery of the concrete sleepers and rail.
By midday Sunday the track had been dismantled and was being recovered. At the north end it was being loaded into the work train. At the southern end the sleepers and rails were being stacked south of Brewer Rd. At this time the signals had not been removed. The newer (temporary) overhead stanchions had been dismantled, but the older ones were still standing. Work was underway at McKinnon and Centre Roads to break up and remove the temporary road surface to reveal the bridge deck underneath. By that evening the bridge deck had been revealed, and both roads were reopened to road traffic on the bridge deck by Monday morning. Traffic is driving on the bare concrete - asphalt has not been laid. During Sunday work started on cleaning up the ballast and beginning to dig - particularly south of Centre Rd.
By Monday evening they were well stuck into digging along the entire worksite and large quantities of earth had already been removed.
The general method appears to be as follows. Large tracked excavators are used to actually dig the earth out. The earth is easily worked, and appears mostly sandy soil with clay patches. I've seen no rocks yet. The earth is loaded into large three axle articulated trucks (too large for street work) which haul the earth along the worksite, perhaps for less than 100 metres, to a transfer location. Here the earth is dumped, and the articulated truck goes back for another load. At the transfer location a bulldozer mounds the dumped earth, and further tracked excavators dig it up and load it into conventional road dump trucks and trailers which are used to take it offsite. Three bucket loads of earth load the dump truck, and another three the trailer. Variations exist at each site, depending on the lead the earth needs to be moved.
To give a specific example: the excavation on the north side of McKinnon Rd this evening. Three tracked excavators. One excavator is used to dig out the earth under the bridge deck. The earth is dumped within reach of the second excavator, which transfers it to a point that can be reached by the third excavator. This excavator loads it into the three axle articlulated trucks - at least two are in use, but no more than four. The articulated trucks take it underneath McKinnon Rd (yes, the bridge has been holed through, at least on the future Up line) to a transfer point about 100 metres south of McKinnon Rd. Here there are two excavators at a transfer station and at least one bulldozer. Each can load a dump truck/trailer in about 2 to 3 minutes.
There has been careful planning of the dump truck routes. At McKinnon, again, the dump trucks approach McKinnon from the east along McKinnon Rd, cross the new bridge, and turn south down Nicholson St. Here they are directed to one of the transfer loading points (there are at least 5) where they are loaded. They continue south along Nicholson St and turn east on Centre Rd. It appears that the intensity of loading is increased at night when road traffic is less. Presumably the earth is stockpiled during the day. To facilitate the dump truck traffic, the McKinnon Rd bridge has been closed each night to normal road traffic.
Other loading points are on Katandra Ave (earth from Ormond north of North Rd), Cadby Ave (earth from immediately south of North Rd), Murray Rd (earth from the approach cuttings north and south of Elster Creek), Bentleigh west car park (earth from north of Centre Rd). The Murray Rd loading point is interesting - the trucks approach from the west along Murray Rd, cross over the railway alignment (where the two loading points are situated), and then continue east along the other half of Murray Rd to Jasper Rd.
Interestingly, the temporary road surface and tracks haven't yet been removed from North Road.
Digging is scheduled to continue for another week.
For anyone interested in watching - and the locals certainly are - the best places are the three new bridges - North, McKinnon, and Centre Rds. During the day, it's interesting just how much earthmoving machinery can be seen. I reckon it's even more impressive at night.