Context: the Governor’s Climate Context: the Governor’s Climate RoadmapRoadmap

Overall goalsOverall goals– quantify the relationship between land use and quantify the relationship between land use and

transportation sector greenhouse gas (GHG) emissions transportation sector greenhouse gas (GHG) emissions – evaluate a range of strategies including incentives, evaluate a range of strategies including incentives,

regulations and other forms of land use control to regulations and other forms of land use control to reduce GHG reduce GHG

Purpose of this meeting Purpose of this meeting – introduce new datasets combining population, land use introduce new datasets combining population, land use

and business locations and using grid approachand business locations and using grid approach– review MassGIS model for trips with residential originreview MassGIS model for trips with residential origin– discuss a cooperative approach - can MassGIS work discuss a cooperative approach - can MassGIS work

provide input into existing tranportation models in provide input into existing tranportation models in modeling GHG ? modeling GHG ?

Automated approach using GISAutomated approach using GIS• Create statewide grid of 250 meter cellsCreate statewide grid of 250 meter cells

• Allocate block level Census household and population Allocate block level Census household and population data to grid cells based on residential land use data to grid cells based on residential land use

• Map locations of all common destinations such as Map locations of all common destinations such as schools, grocery stores, libraries, restaurants etc. schools, grocery stores, libraries, restaurants etc. and assign to grid cellsand assign to grid cells

• Calculate distance from every cell to nearest (or Calculate distance from every cell to nearest (or several nearest) destinationseveral nearest) destination

• Using a set of trip weights from National Household Using a set of trip weights from National Household Travel Survey, estimate VMT for household origin tripsTravel Survey, estimate VMT for household origin trips

• Calibrate model using published VMT figuresCalibrate model using published VMT figures

First question:First question:

Where do people live? Where do people live?

Basemap – SE Mass.Basemap – SE Mass.

Census geography – no. Census geography – no. householdshouseholds

Census geography plus land useCensus geography plus land use

Allocation of population to res. Allocation of population to res. areasareas

Why use a grid cell approach?Why use a grid cell approach?

• Many operations can be performed on grids with Many operations can be performed on grids with little computational expense including addition, little computational expense including addition, multiplication, logical tests, spatial means, multiplication, logical tests, spatial means, distance to nearest feature etc. distance to nearest feature etc.

• Small grid cell size supports modeling at a very Small grid cell size supports modeling at a very local scalelocal scale

• Model can be easilty calibrated to published Model can be easilty calibrated to published results and can be run iteratively with different results and can be run iteratively with different scenarios scenarios

Grid cell representationGrid cell representation

Zoom out ...Zoom out ...

Household density (no. / 250 m Household density (no. / 250 m cell)cell)

Second question:Second question:

Where do people go?Where do people go?

Residential areas plus business Residential areas plus business locationslocations

Highlight a single kind of Highlight a single kind of destinationdestination

grocerystore

4 cells

6 cells

For each type of destination,create a grid that records the distanceto the nearest location in every cell –this is called a “euclidean distance grid”

4

grocerystore

2

Euclidean distance grid

For each type of destination, count the number of destinations at various distances from each cell - this is called a “focal sum grid”

Focalsum grid

2

4 cells

Trip Weights (partial listing)Trip Weights (partial listing)

need a surrogate for this item

don’t use closest destination, usefocal sum distance instead for 3-5 destinations

Trip type % of trips

Commute 13.13%

Friends/family 11.76%

Restaurants 10.15%

Groceries 7.26%

Malls 7.26%

School 6.52%

Dentists 4.96%

Church 3.79%

Hardware Stores 3.63%

Gyms 3.00%

Parks 2.90%

Gas Stations 2.90%

Doctors 2.49%

Convenience Stores 2.39%

Pharmacy 2.39%

Grid cell computationsGrid cell computations

Summing up grid cell values for each household, using just Summing up grid cell values for each household, using just euclidian distance examples: euclidian distance examples:

distance to groceries x % of trips = total distance traveled to groceries / total tripsdistance to groceries x % of trips = total distance traveled to groceries / total trips

distance to hardware x % of trips = total distance traveled to hardware / total trips distance to hardware x % of trips = total distance traveled to hardware / total trips

distance to church x % of trips = total distance traveled to church / total trips distance to church x % of trips = total distance traveled to church / total trips

etc. for 30 different destinationsetc. for 30 different destinations

SUM of grid cell values x total number of trips = total distance traveledSUM of grid cell values x total number of trips = total distance traveled

For each grid cell, we estimate the total distance travelled per For each grid cell, we estimate the total distance travelled per household and we know the number of households, so we household and we know the number of households, so we can estimate the total VMT for all householdscan estimate the total VMT for all households

Use of grid to estimate household Use of grid to estimate household tripstrips

WWii = T = Ti i / T/ Ttotal total WWii = 1 = 1weight = trips to destination i divided by total tripsweight = trips to destination i divided by total trips

VVtotal total = = (W(Wii * D * Dii) =) =

cell value = sum of weights multiplied by distances for all cell value = sum of weights multiplied by distances for all destinations = total travel over total number of trips for destinations = total travel over total number of trips for each household each household

VMTVMThouseholdshouseholds = H * = H * (T(Tii * D * Dii) = H * V) = H * Vtotaltotal * T * Ttotaltotal

total vehicle miles = number of households times total travel total vehicle miles = number of households times total travel for each household = number of households times cell for each household = number of households times cell value times total number of trips per household value times total number of trips per household

(T(Tii * D * Dii) ) T Ttotaltotal

All businesses with EDG for grocery All businesses with EDG for grocery storesstores

EDG for restaurants on the South EDG for restaurants on the South ShoreShore

Weighted average household VMT / Weighted average household VMT / trip trip

(all non-work destinations)(all non-work destinations)

Aggregate non-work VMTAggregate non-work VMT

Aggregate commuter miles (gross estimate)Aggregate commuter miles (gross estimate)

Aggregate all res. origin milesAggregate all res. origin miles

Grid model resultsGrid model results

Assuming.... Assuming.... – 30% correction for “as the crow flies” based on limited sampling 30% correction for “as the crow flies” based on limited sampling

– 4.2 trips / household / day4.2 trips / household / day

– 2000 Census and 2007 DNB 2000 Census and 2007 DNB

model computes 145 million residential origin DVMT model computes 145 million residential origin DVMT

Point of the model is NOT to estimate VMT, however, but to Point of the model is NOT to estimate VMT, however, but to understand variation in VMT based on geographic location understand variation in VMT based on geographic location

Major gaps and problems:Major gaps and problems:– JTW was based on census plus gross assumptions on average speedJTW was based on census plus gross assumptions on average speed

– social trips – not sure how to measure social trips – not sure how to measure

– weightings – is there a better surveyweightings – is there a better survey

Next stepsNext steps

– – correlate with land use, population density, business densitycorrelate with land use, population density, business density