1

Methods to Assess Land Use and Transportation Balance

By

Carlos A. Alba

May 2007

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Objective of the Study

Find levels of land use activity in a urban area so that traffic operates at volumes that balances design capacity of the streets.

Two questions:

• What are reasonable thresholds in terms of traffic volumes?

• How land use should be modified to get to those traffic volumes

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Traditional Four Step Process for Travel Demand Forecast

Trip Generation

Trip Distribution

Mode Split

Traffic Assignment

Traffic Flow

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Procedure

Capacity Analysis

Threshold Volumes

Traditional Forecasting Process

Trip Table Adjustment

O-D Factors

Land Use Activity Adjustment Display

Interpretation and Analysis

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Capacity Analysis

Enter the following information:

Determining Free-Flow Speed: Determining Demand Flow Rate: Calculating ATS and PTSF:

BFFS: (default=60) 60 mi/h V:(demand volume for the full peak hour) 1500 veh/h

no-passing zones (%):

(default=20-50) (0%-100%) 20

Lane Width: (default=12, min=9)

12 ft PHF: 0.90 Directional Split: (default=50/50) 50/50

Shoulder Width: (default=6 ft) 6 ft Type of Terrain: (Level=L / Rolling=R) L Acess Points/mi: (max=40) 15 ProportionTrucks: (0-1) (default=0) 0.1

Proportion RVs : (0-1) 0(Two Way Highway=T / Directional =D)

T

Calculations:

FFS: 56.25 Vp (speed): 1683 Vp (Time following):fLS 0 fG 1.00 fG 1.00fA 3.8 ET 1.10 ET 1.00

ER 1.00 ER 1.00fHV 0.99 fHV 1.00

ATS: 42.63 PTSF: 79.72 LOS: Dfnp: 0.56 fd/np: 2.8

BPTSF: 76.9

1667

Type of Analysis:

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Traffic Volume Vs Lane Width

1514 1514 1514 1514

1000

1100

1200

1300

1400

1500

1600

9 10 11 12

Lane Width (ft)

Dem

and

Vo

lum

e (v

eh/h

) .

Traffic Volume Vs Percentage of Trucks

1514 1514 1514 1514

1000

1100

1200

1300

1400

1500

1600

0 10 15 20

% of Trucks

Dem

and

Vo

lum

e (v

eh/h

) .

Capacity Analysis

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Traffic Volume Vs Directional Split

1514 1499 15191471

1397

1000

1100

1200

1300

1400

1500

1600

1700

1800

50/50 60/40 70/30 80/20 90/10

Directional Split

Dem

and

Vo

lum

e (v

eh/h

) .

Traffic Volume Vs Shoulder Width

1314

1503 1514 1514

1000

1100

1200

1300

1400

1500

1600

0 2 4 6

Shoulder Width (ft)

Dem

and

Vo

lum

e (v

eh/h

) .

Capacity Analysis

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Traffic Volume Vs Passing Zones

1646

1514

14031320

1000

1100

1200

1300

1400

1500

1600

1700

1800

0 20 50 100

Percentage of no-passing zones

Dem

and

Vo

lum

e (v

eh/h

) .

Traffic Volume Vs Access-Point Density

1514 1514 1514

1366

1044

1000

1100

1200

1300

1400

1500

1600

0 10 20 30 40

Access points per mile

Dem

and

Vo

lum

e (v

eh/h

) .

Capacity Analysis

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Traditional Forecasting Process

“Seed” Trip Table

Traffic Count Input

Trip Table Estimation Method Selection(Fratar Biproportional Static)

Adjusted Trip Table

Land Use Adjustment Factors

Trip Table Estimation

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Trip Table Estimation

• The Fratar Biproportional model is appropriate for peak period analysis

• The refined trip table do not deviate much from the seed table

• Only the links where the traffic volume is at 70% or more of the threshold volumes were included in the analysis

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Trip Table Estimation

2.3464419 x 0.9101944=2.1357183

Increase by 113.6%

0.3339485 x 0.9101944=0.3039581

Decrease by 69.6%

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Land Use Activity Adjustments(Origin Display)

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Land Use Activity Adjustments(Destination Display)

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Land Use Density

District 1

District 2

District 3

District 4

District 5

District 6

District 7

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Land Use Activity

2461

925

2718

4514

22452929

1138

5849

1347

1533

3611

2093

5725

1032

267

3110

995

2210

1456

1668

6794

0

2000

4000

6000

8000

10000

12000

District 1 District 2 District 3 District 4 District 5 District 6 District 7

HH

Nonretail

Retail

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29%17%

52%44% 39%

28%

13%

68%

25%

29%35%

36% 55%

12%

3%

58%

19% 21% 25%16%

76%

0%

20%

40%

60%

80%

100%

District 1 District 2 District 3 District 4 District 5 District 6 District 7

HH

Nonretail

Retail

Land Use Activity

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Conclusions

• Importance of understanding the implications of selecting the threshold traffic volumes.

• The number of access points and the percentage of no-passing zones are critical when calculating LOS and defining the threshold traffic volumes.

• Most of the land use activity is located in downtown and along principal arterials.

• This methodology is a tool for making planning decisions and not necessarily for changing land use distribution.

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Conclusions

• There are some policy implications of using this methodology.

• Growth should avoid areas with high levels of activity unless a transportation system is envisioned for such areas.

• No change implies the need of transportation facilities.

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Questions

?