High PSV on Auckland Motorways. Bruce Chappell, AMA Glynn Holleran, AMA. Central Motorway area 200,000 vpd Areas of ramps and mainline require PSV >65 Mainline requires high texture surfacing for spray suppression and skid resistance - OGPA
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Bruce Chappell, AMA
Glynn Holleran, AMA
Areas of ramps and mainline require PSV >65
Mainline requires high texture surfacing for spray suppression and skid resistance - OGPA
Default in the past has been to use PSV65 Motouhora aggregate
Now AMA uses slag in OGPA on mainline
Slag does not provide PSV to old or new T/10The Problem
But for long term performance HSRS’s rely on a compatible pavement underneath, i.e.
no cracking or differential thermal movement
Many sites failed to provide long term valueThe Problem continued
For ramps and low speed areas check crash history to determine whether slag is an option
Consider the pavement structure, is it suitable for HSRS?
Compare whole of life costs for two options:
HSRS surfacing with structural fix if required
Slag aggregates in asphalt and replace more oftenThe Solution
Slag option is less than half calcined bauxite cost (without a structural pavement repair).
Does HSRS give twice or better the life?
Not without a compatible pavement (risk)
Not if poorly constructed (risk)
AMA proposes to implement best whole of life option that meets safety requirements.The Solution continued
Slag aggregate over 5 years similar performance to calcined bauxite
Asphalt Base Line
Now 2 years old- no accidents due to surface- formerly black spot
Courtesy New Zealand Steel