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1
Methods to Assess Land Use and Transportation Balance
By
Carlos A. Alba
May 2007
2
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
3
Traditional Four Step Process for Travel Demand Forecast
Trip Generation
Trip Distribution
Mode Split
Traffic Assignment
Traffic Flow
4
Procedure
Capacity Analysis
Threshold Volumes
Traditional Forecasting Process
Trip Table Adjustment
O-D Factors
Land Use Activity Adjustment Display
Interpretation and Analysis
5
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:
6
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
7
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
8
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
9
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
10
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
11
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%
12
Land Use Activity Adjustments(Origin Display)
13
Land Use Activity Adjustments(Destination Display)
14
Land Use Density
District 1
District 2
District 3
District 4
District 5
District 6
District 7
15
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
16
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
17
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.
18
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.
19
Questions
?
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