Modeling Mobile Emissions with the FME

• Problem– BC Ministry of the Environment Need to

determine emissions from mobile sources– Exact quantity and location unknown – derive

surrogate emissions from model– Surrogate emissions estimated from spatially

distributed data that should be good indicators of emissions activities

– Population– Traffic Volumes– Fuel Sales

Modeling Mobile Emissions with the FME

• Problem• Here is the kicker

– Population» Census Tract Information» In BC an area can have a concentrated population with a large

area of low or no population density– Traffic Volumes

» Ministry of Transportation collects data at busy intersections around the province

» Large areas of the road network unmonitored– Fuel Sales– Point based – tied to postal areas– You may buy your fuel in Vancouver – and then drive to Kamloops – so

can be misleading• And finally

– Map the surrogate emissions onto the road network for BC– Each segment will the have a contribution from each of the surrogate

emissions sources

\

A) Data Preparation

B) Grid Preparation

Standardized Contributing Data Source

(SCD)

Coarse Grid (CG)

Fine Grid for Specific

Coarse Grid Cell (FG)

C) Grid Interpolation

Coarse

Contributing Data Source

(CDS)

SCD Subset for Coarse Grid Cell(SCG)

F) Grid Interpolation Fine

SCD Subset for Fine Grid

(SFG)

Target Road Network (TRN)

G) Grid Value Transfer

TRN with Transferred

Values (TTV)

E) Target Preparation and

Coarse Grid

TRN Subset for Coast Grid

Cell (TFG)

H) Grid UnionTRN Union (RNU)

User Defined Coarse Grid

D) Fine Grid FilterFiltered Fine Grid

Under-allocation

Census block with Popluation

value of 90Pop’n = 10 Pop’n = 10 Pop’n = 10

Pop’n = 10Pop’n = 10Pop’n = 10

Pop’n = 10 Pop’n = 10 Pop’n = 10

Pop’n = 18

Pop’n = 18Pop’n = 18Pop’n = 18

Pop’n = 18

Modeling Mobile Emissions with the FME

• Solution• Map Area, Point and Line Based Surrogates onto a

Single Uniform Grid• Look after under-allocation

– Road Lengths– Unused Grid Cells– Flood back into road network

• Accept that we are only making an estimate– Note all assumptions and simplifications– Document how to remove or improve on them in the

future