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NCTC /Grass Valley Travel Demand Model Update

Nevada County Transportation Commission

September 2020

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Study GoalsTJKM was hired to update the travel model to the latest base year and develop forecasts

Review the existing Model, identify areas for improvement

Update the model from 2012 to 2018 Base year

Calibrate and Validate the 2018 Model

Develop Future Year 2040 Data and Traffic Forecasts

Documentation

N

Travel ModelsA travel model is a statistical tool that uses existing demographic, land use and travel behavior data to forecast future traffic .

Forecasting Travel Demand is not simple. It involves many variables and complex relationships

Using rules of thumb and rapid assessment techniques is fine for short term, medium budget projects

For large scale investments, it is necessary to develop forecasts that have a proven technical basis.

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Modeling ProcessINPUTS

● Population ● Economy ● Land Use

OUTPUTS

Trip Generation (how many trips?)

Trip Distribution (Where do they go?)

Mode Choice (By what mode?)

Assignment (By what route?)

Traffic Flows on Network Links: Volumes and Speeds

N

Why do we need a travel demand model?

• A typical regional model is necessary to answer questions like: What happens in next 20 -30 years? How policies/investments affect our answers? How will economic, demographic or land-use changes

affect transportation system performance? Update Traffic Impact Fees Traffic studies for development projects

N

Roadway Networks and Zones

N

Land use Data – 2018 (Residential)

2178

7505

31712102 2818

793

18264

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Total Housing UnitsNevada City

6%

Grass Valley20%

Alta Sierra9%

Lake of the Pines6%Lake Wildwood

8%Penn Valley

2%

Unincorporated County

49%

Total Housing Units

Nevada City Grass Valley Alta Sierra

Lake of the Pines Lake Wildwood Penn Valley

Unincorporated County

N

Land use Data – 2018 (Employment)

0 1000 2000 3000 4000 5000 6000

Nevada City

Grass Valley

Alta Sierra

Lake of the Pines

Lake Wildwood

Penn Valley

Unincorporated County

Landuse by Category (Thousand SQFT)

Office Medical Office Light Industrial

Warehouse Church Public/Quasi-Public

Retail Restaurant Fast Food Restaurant

Office 16% Medical Office

4%

Light Industrial 22%

Warehouse 5%

Church 5%

Public/Quasi-Public 5%

Retail 40%

Restaurant 2%

Fast Food Restaurant 1%Landuse by Category

Office Medical Office Light Industrial

Warehouse Church Public/Quasi-Public

Retail Restaurant Fast Food Restaurant

N

Trip Data

HBW17%

HBO43%

NHB32%

SCHOOL6%

SIERRA2%

Trips by Purpose

HBW HBO NHB SCHOOL SIERRA

-

10.00

20.00

30.00

40.00

50.00

60.00

HBW HBO NHB SCH SIE HBWIE HBOIE NHBIE HBWEI HBOEI NHBEI XX

Average Travel Time (Minutes)

N

Daily Highway Validation – Facility Type

Facility Type Observed Traffic Counts

2018 Estimated Volumes Daily Validation Targets

Sum of Counts Sum of Model Volumes % RMSE % Error % RMSE % Error

Freeways 323,834 348,700 17% 8% ~40% +/-15%

Principal Arterials 240,892 256,969 13% 7% +/-20%

Minor Arterials 546,199 551,949 36% 1% +/-25%

Major Collectors 342,817 348,034 45% 2% +/-25%

Minor Collectors 163,425 145,808 93% -11% +/-30%

Local 113,964 90,092 57% -21% +/-40%

All 1,731,132 1,741,552 42% 1% ~40% +/-15%

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Daily Highway Validation – JurisdictionFacility Type Observed Traffic Counts 2018 Estimated Volumes Daily Validation

Sum of Counts Sum of Model Volumes % Error

Grass Valley 794,476 792,538 0%

Nevada City 144,778 139,561 -2%

Alta Sierra 43,638 41,549 -5%

Lake Wildwood 2,804 2,261 -19%

Penn Valley 32,436 27,992 -14%

Unincorporated County 481,954 513,423 7%

Grass Valley SOI 107,581 103,381 -2%

Total 1,607,666 1,620,705 -7%

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2040 FORECASTS• Developed based on California Department of Finance, Caltrans Economic

Forecasts, inputs from NCTC staff and staff from cities• Annual growth of 0.32% per annum for Population and 0.54% per annum

for employment

36,831

7,708

13,165

39,515

8,787

14,381

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

Dwelling units Employment sqft (000) School / College Enrollment

Growth - 2018-2040

Base Year 2018 Forecast Year 2040

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

HBW HBO NHB SCHOOL SIERRACOLLEGE

Trips by Model Year and Purpose

Base Year 2018 Forecast Year 2040

N

Growth in Volumes– Facility Type

Facility Type 2040 Estimated Volumes

2018 Estimated Volumes Difference Growth Rate

Freeways 366,208 348,700 17,508 0.22%

Principal Arterials 263,629 256,969 6,660 0.12%

Minor Arterials 605,342 551,949 53,393 0.42%

Major Collectors 379,750 348,034 31,716 0.40%

Minor Collectors 154,663 145,808 8,855 0.27%

Local 96,560 90,092 6,468 0.32%

N

PM Period Volumes and congestion 2018

N

PM Period Volumes and congestion 2040

N

QUESTIONS?