8th Road Pavements Forum 17 Nov 2004

SABITA PROJECT:

Warrants for upgrading

SuperSurf

J Lea and P Paige-Green

BACKGROUNDBACKGROUND

• Transportek has made use of a simple spreadsheet for assessing the economics of upgrading for some time

• Sabita requested us to improve and formalise it

• To include various other components• Sort of “grandson” of SURF +

WHAT IS SUPERSURF?WHAT IS SUPERSURF?

• Does detailed economic analyses of various strategies for upgrading unsealed roads

• Tool to assist in making decisions regarding upgrading

• Economic justification for these decisions• Formalised structure

WHAT IS SUPERSURF NOT?WHAT IS SUPERSURF NOT?

• Not a forecasting tool• Does not identify options• Is not a substitute for HDM4 or CB Roads

STRUCTURESTRUCTURE

• Setup of standard inputs (discount rate, analysis period, etc)

• Standard base case – existing gravel road• Various options for upgrading

• Stage construction• Dust palliative• Bituminous surfacing

PROCESSPROCESS

Determine financial and economic costs of base case – maintenance, rehabilitation, VOC, accident, social and environmental

Can make use of shadow costs for maintenance and rehabilitation inputs

Add options – same inputs– Defaults built in – better to use actual

INNOVATIONSINNOVATIONS Vehicle operating costs – DBSA models

and average inflation rate Shadow cost facility for construction,

maintenance and rehabilitation Environmental costs Social benefits Paved road performance

SHADOW COSTSSHADOW COSTS

Default in road user costs Optional in construction, maintenance & rehab costs

SHADOW COSTSSHADOW COSTS

ENVIRONMENTAL COSTSENVIRONMENTAL COSTS Can “estimate” costs for different options related

to various operations/activities

SOCIAL BENEFITSSOCIAL BENEFITS Similar to environmental costs

PAVED ROAD STRATEGIESPAVED ROAD STRATEGIES Simple exponential deterioration model Similar to those in most PMS’s, but

based entirely on roughness

Rou

ghne

ss

Initial

Failure

ESALsDesign Life Overlay Life

Initial Performance

No reseal 1 reseal 2 reseals

Overlay

OUTPUTOUTPUT

Pseudo agency and economic costs Internal Rate of Return of various options

compared with base (existing) case