Completion of this work would be much more costly if the general or prime contractor was not allowed some flexibility to get the various types of work done. The general contractor has numerous subcontractors like construction signing, concrete slabjacking (lifting) or replacement, joint sealing, asphalt milling, trucking companies, chip sealing. The typical process is described below:
• City marks curb for lifting or replacement.
• Contractor or subcontractor install No Parking signs a minimum of 24 hours before construction starts. No Parking signs may be removed or left in place for any of the subsequent construction activities.
• Slabjacking (lifting) subcontractor moves in and lifts marked curbs and driveways.
• Concrete subcontractor removes and replaces marked concrete curb and driveway and replaces storm inlet castings as required. Intersection ramps and street valley gutter crossings replacements are coordinated with the paving crew and may be replaced either at this stage or later. Detours may be needed for valley gutters. Homeowner may request more work be done at same time such as a driveway widening.
• Paving contractor either places gravel or asphalt patches at the front of the curb replacement sites. After new concrete cures for at least 4 to 7 days, black dirt is placed behind the curb. Seeding and mulching usually take place much later in the process when many sites can be done at once.
• City marks streets for patching or milling (grinding off about 1 to 2 inches of old asphalt).
• Paving contractor completes the asphalt patching and crack seals open joints.
• Paving contractor places thin leveling course on patched or non-milled streets where dips, humps or other pavement irregularities are pronounced.
• Paving contractor mills pavements, sweeps loose material, and may come back later to remove pavement around manholes or valve box covers.
• Paving contractor adjusts tops of manhole and valve box castings to match the new pavement surface.
• Paving contractor places new pavement on milled streets.
• Paving contractor or subcontractor places seal oil and chips on pavements when temperatures are expected to be 70° F or warmer for several consecutive days.
• Chip seal is allowed about one week of cure time before loose chips are swept off street.
Coordinating all these different types of construction activities would be difficult to maintain workforce efficiencies. Scheduling and moving each specialized work crew from one project to another can be impacted by unforeseen circumstances like, weather, poor soil conditions or added work. Delays related to weather or construction difficulties may cause the time interval between any of these tasks to be considerable.