Calculating the Cost of Road Wear on Local Roads

Mark BondiettiRiaan Burger

October 2013

Contents

• Background• Methods• Marginal Costs• Catalogue Method• Case Study• FAMLIT• Future Work

Background

• Local Governments seek mechanisms to quantify cost of road wear

• Impact of road wear much higher on local roads• Various methods have been tried – too

expensive, specialised skills.• Seek simple method

Methods for Evaluating the Cost of Road Wear

• Routine Maintenance Determination• Evidence Based Reporting• Pavement Design Approach• Single Marginal Cost• Catalogue of Marginal Costs

MRWA Policy

• For vehicles operating 23.5 t triaxles the charge will be 0.4 cents per tonne per kilometre of payload (over and above the initial 300,000 tonne per annum).

• For alternative mass limits the charge will be determined on the basis of 5.5c per additional ESA.km

• Is this sufficient for Local Roads?

Pri

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PortFarmJourney from Farm or Mine to Port

Major Main Road

State Rural Highway

Minor Main Road

Regional Local Road

Minor Local Road

Price Charged

Road Wear Cost – Farm or Mine to Port

Urban Highway or Freeway

Determine Vehicle type and

loading

Calculate Equivalent

Standard Axles for Transport Task

Determine road type and distance of transport route

• Road pavement structure would preferably be required however this can be inferred from the road classification

Determine appropriate

marginal cost for road type

Calculate cost of road wear

• Cost of road wear = ESA x Marginal Cost x Distance

Calculating the Cost of Road Wear on Local Roads

Calculation Example: Yalgoo – Ningham Road

• ESA / payload tonne = 0.18

Therefore 1.4 m tonne = 252 000 ESA

• For rural collector 30c / SAR km

For Arterial = 5c / SARkm(Austroads)

Using 7c:

Therefore cost = 252000 x 58.1 x 0.07

= $1 024 884 per annum

Quad Road TrainConcessional Load – 23.5t per triaxle

58.1 km task1 400 000 tonne/ annum

Sealed Rural Collector / Arterial Road

FAMLIT

• Quick description– Background– Model description

• Results of pilot study for WALGA

FAMLIT Background

• FAMLIT is a sealed pavement life-cycle costing analysis tool (Austroads project AT1165)

• Other similar tools are:– HDM-4– PLATO

• FAMLIT was used in Austroads project AT 1394 due to its relatively simple input data requirements

“Preliminary methodology for estimating cost implications of incremental loads on road pavements”

FAMLIT Description

• Life cycle costs are calculated over a 50-year analysis period

• Routine and periodic maintenance costs are combined in a constant annual value for a given traffic load

• Structural works are triggered based on condition• FAMLIT implementation used two models for triggering

structural works:– Rutting/roughness model– Pavement strength model

• Model parameters/coefficients are similar to those used in the ROMAN II dTIMS set-up

FAMLIT Results

• Traffic is applied to pavement and condition modelled over time

• Routine and periodic treatments are constant costs over analysis period

• When condition triggers, structural work costs are calculated and condition reset to pre-determined levels

• Total cost for each loading scenario is converted to Equivalent Annual Uniform Cost (EAUC)

• For each pavement/climate scenario the EAUCs for the different load scenarios are plotted and a straight line fitted

• Marginal Cost is the slope of the line

y = 71938.011x + 1144.000 R² = 0.995

y = 18437.304x + 1528.658 R² = 0.976

y = 16942.635x + 2778.694 R² = 0.986

0

2000

4000

6000

8000

10000

12000

14000

16000

0 0.05 0.1 0.15 0.2 Annual million equivalent axles (MESA)

Thornthwaite = 10 CBR = 12

Rural Access

Rural Collector

Rural Arterial

Linear (Rural Access)

Linear (Rural Collector)

Linear (Rural Arterial)

EUAC

($)

Future Work

• Refine input data– Divide state into regions– Obtain unit rates applicable to regions– Refine pavement strength model– Refine pavement types and composition for

regions• Produce simple to use tool for Local

Governments– Form baseline of discussion regarding

compensation with industry operators

Questions