2010 San Benito County
Traffic Model
HIGHWAY VALIDATION REPORT
Prepared for:
Council of
San Benito
County Governments
Prepared by:
Parsons
March 2013
Revised November 2013
2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Prepared for:
Council of San Benito County Governments
Prepared by:
PARSONS
March 2013
Revised November 2013
2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
1. INTRODUCTION
The San Benito County Traffic Model was developed in 1986 for use with establishing the first
traffic impact fee for the county (Resolution 86-113). It has been used since that time for
numerous traffic impact fee study updates, the Council of San Benito County Governments
regional transportation plans, traffic studies for numerous roadway improvement projects
(including the State Route 25 Hollister Bypass) and countless traffic impact studies for land
development projects, including the Santana Ranch and Fairview Corners Specific Plans (2010
and 2011, respectively).
The model has recently been updated to project future traffic associated with development growth
within San Benito County, up to the year 2035. As a basis for the 2035 traffic forecasts, the
model was validated to “existing conditions,” which represents the traffic volumes, roadway
network, and land use characteristics which exist for the model validation year (2010 and 2011).
The model validation indicated that the model was able to accurately replicate base year
conditions and respond in the appropriate direction and magnitude when changes were made to
input variables such as the roadway network. This document summarizes the results of this 2010
model validation update.
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
2. MODEL VALIDATION
Overview
Travel model validation should focus on the entire travel modeling sequence—trip generation,
trip distribution, mode choice, and trip assignment. In a typical model development process, the
individual model components (trip generation, trip distribution, mode choice (or mode split), and
time-of-day of travel) are calibrated using travel survey data and evaluated for reasonableness.
After all of the model components are calibrated, the model is run as a system, including trip
assignment. Assigned volumes are then compared to observed traffic counts for reasonability.
The comparison to traffic counts, in effect, forms a “super” validation point. If the assigned traffic
volumes do not reasonably match observed traffic counts, adjustments (such as those listed
below) are made to the various model components to improve the match.
The approach used for making model adjustments for validation purposes was to minimize the
number and magnitude of the adjustments. Assigned traffic volumes will never exactly match
observed traffic counts for several reasons. First, models are abstractions or simplifications of
regional travel that can never account for all of the nuances of daily travel throughout the region.
Second, traffic counts are not perfect. Traffic counts can easily vary by 10 percent or more
depending on the day of the count, the time of year the count is performed, or the method used to
perform the count. In addition, counts used for model validations are typically collected over
several years due to the costs of counting traffic. Thus, matching traffic volumes on count
locations within 10 to 15 percent is typically considered a success. Third, demographic
information is not precise.
Demographic Information
The demographic data for the households and population was obtained from the 2010 census.
Figure 1 illustrates the distribution of housing units in northern San Benito County as of 2010.
Housing unit counts at the block level were obtained from the 2010 census and accumulated to
larger “traffic analysis zones” or TAZ, which are used by the traffic model. Traffic analysis zones
provide the spatial unit (or geographic area) within which travel behavior and traffic generation
are estimated. The countywide model contains 413 traffic analysis zones and five cordon stations
(points of entry and exit along highways at the perimeter of the modeling area).
Figure 2 illustrates the distribution of non-farm employment (jobs) in northern San Benito County
as of 2010. Job location data was obtained from the 2002 and 2004 updates of the San Benito/
Hollister Traffic Forecast Model files, the AMBAG Regional Travel Demand Model base year
2005 TAZ files, and field verification conducted in 2012. The total number of non-farm jobs for
2010 was normalized to State of California Employment Development Department estimates for
the county.
Given these land use inputs (number of housing units, retail and non-retail employment), the
traffic model was run and the resulting traffic “forecasts” were compared with traffic count data
and Caltrans’ estimates of vehicle miles traveled (VMT) in the county.
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Figure 1. Northern San Benito County 2010 Distribution of Dwelling Units
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Figure 2. Northern San Benito County 2010 Distribution of Non-farm Employment
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Highway Network
The 2010 highway network was updated from the 2000 San Benito County Traffic Model. The
free flow speeds and capacities are reported in Table 1 and the updated highway network by
facility type is shown in Figure 3.
Table 1: Year 2010 Highway Network Speed and Capacity Table
FACILITY
TYPE
URBAN
RURAL
EXTERAL
SPECIAL
SPEEDS
CAPACITY
SPEEDS
CAPACITY
SPEEDS
CAPACITY
SPEEDS
CAPACITY
Freeways
55
1,500
60
1,500
65
1,500
60
1,500
Expressways
45
950
55
950
55
1,100
55
950
Major arterials
35
800
45
800
50
800
45
800
Minor arterials
30
600
40
600
45
600
40
600
Collector
25
500
35
500
45
500
35
500
Ramps
25
1,000
30
1,000
30
1,000
30
1,000
Centroids
15
9,999
15
9,999
15
9,999
15
9,999
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Figure 3. 2010 Highway Network Showing Facility Types
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Trip Generation
Table 2 shows the weekday daily person trips and the proportions of trips by purpose made by
San Benito County and external county residents.
Table 2: Year 2010 Validation Trip Generation Summary
2010 MODEL
TRIP PURPOSE
TRIPS
PERCENT
49,384
18%
162,260
60%
52,911
19%
Home-Based Work
2,850
1%
Home-based Non Work
2,880
1%
Non Home Based
1,440
1%
52,234
19%
165,140
61%
54,351
20%
Internal
Home-Based Work
Home-based Non Work
Non Home Based
External
Total
Home-Based Work
Home-based Non Work
Non Home Based
Total Trips
271,725
Traffic Assignment Validation
Model validation refers to comparing the model outputs (traffic volumes) to observed conditions
(traffic counts and vehicle miles of travel estimates). During validation, adjustments are made
primarily to model inputs, such as the road network and base year land uses, rather than calibrated
parameters such as trip generation rates or peak factors. Once validated, the model can be used to
predict future travel patterns with a high degree of confidence.
The 2010 highway base year model results were validated using traffic counts collected in
May 2011 for the SR 152 Trade Corridor Study and traffic counts collected during 2009 to 2011
for the 2035 San Benito County General Plan Draft Program EIR.
The 2010 model validation targets are based on several criteria which are as follows:
x Comparison of modeled traffic volumes to observed traffic counts across facility types by
percent volume deviation, with the maximum desirable deviation being 10 percent.
x Comparison of modeled VMT to estimates obtained from the Caltrans Highway
Performance Monitoring System (HPMS), with the maximum deviation being three
percent.
x Total volume and percent root mean square error (RMSE) by facility type and volume
group should be less than 40 percent for appropriate aggregate group of links.
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
x The percentage of links falling within the FHWA validation curve. The FHWA suggested
link-specific validation criteria is that 75 percent of freeway and principal arterials
(expressways), and 65 percent of all links should fall below the validation curve shown in
Figure 4.
x Use the Federal Highway Administration and Caltrans recommended error limits for total
error by functional classification (type of road) as a region-wide validation:
— Freeways less than 7 percent error
— Expressways less than 10 percent error
— Arterials less than 15 percent error
— Collectors less than 25 percent error
— Frontage roads less than 25 percent error
Figure 4. Maximum Desirable Error for Links
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
All the above targets are specified for comparisons to the daily traffic volumes. The AM and PM
peak periods were also compared, and in most cases, are well within the desired criteria.
Traffic Counts
The existing count data for the year 2010 model validation was counts collected from 2009 to
2011 as noted above. In all there were about 140 daily count locations by direction.
Caltrans HPMS
Caltrans prepares estimates of VMT for all roads in each California county for the HPMS. The
VMT estimates are based on an extensive traffic counting program on a large sample of roads
throughout the state. Local jurisdictions provide Caltrans with updates on the number of lanemiles of road within each classification type. Caltrans statistically extrapolates the traffic counts
to provide estimates of total traffic volume on all lane-miles of each functional classification, and
VMT. The HPMS based VMT trend for San Benito County for various years in shown in Table 3.
This table indicates that the HPMS estimate of VMT for San Benito County in 2010 was
1,839,140. A detailed table showing 2010 HPMS based VMT by jurisdiction for San Benito
County is shown in Table 4.
Table 3: HPMS Summary for San Benito County HPMS by Jurisdiction
DAILY VEHICLE MILES OF TRAVEL
YEAR
TOTAL
HOLLISTER
SAN
JUAN
BAUTISTA
COUNTY
ROADS
NATIONAL
PARK
SERVICE
STATE
HIGHWAYS
STATE
PARK
SERVICE
2005
1,445,080
105,780
5,640
259,070
560
1,046,450
27,580
2006
1,483,230
101,460
5,640
258,550
450
1,089,550
27,580
2007
1,394,030
101,460
5,640
258,550
450
1,000,350
27,580
2008
1,387,050
101,420
7,300
258,550
440
991,760
27,580
2009
1,375,770
142,410
7,300
259,330
670
938,480
27,580
2010
1,839,150
142,410
7,300
259,330
670
1,401,860
27,580
2011
1,346,160
168,710
6,700
276,800
670
865,700
27,580
Source: Caltrans
Table 4: 2010 San Benito County HPMS by Jurisdiction
COUNTY/
LOCATION
Cities
JURISDICTION
Hollister
San Juan Bautista
Other
DAILY VEHICLE MILES
OF TRAVEL
MAINTAINED MILES
County
National Park Service
State Highways
State Park Service
RURAL
URBAN
TOTAL
RURAL
URBAN
TOTAL
0.00
95.00
95.00
0
142,410
142,410
10.23
0.00
10.23
7,300
0
7,300
364.92
18.75
383.66
227,870
31,470
259,330
8.68
0.00
8.68
670
0
670
83.97
6.11
90.08
1,375,600
26,250
1,401,860
306.40
0.00
306.40
27,580
0
27,580
774.20
119.85
894.05
1,639,020
200,130
1,839,150
Source: Caltrans 2010 Highway Performance Monitoring System
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
The daily vehicle miles of travel reported in Tables 3 and 4 appear to contain a computational
error under the “State Highway” entry for 2010 based on trend line data reported in Table 3.
Table 3, which reports HPMS data published by Caltrans for year 2005 through 2011, indicates
that annual average daily VMT, as computed by Caltrans, is typically in the ±1.4 million range
for San Benito County.
Independent estimates of annual average daily VMT on state highways (prepared by Parsons)
places the 2010 total miles of travel at 949,824. This estimate is based on Caltrans published
annual average daily traffic (AADT) volumes and highway link lengths for 2010. This calculation
is confirmed by 2009–2011 traffic counts and link segment lengths assembled for the 2035 San
Benito County General Plan Draft Program Environmental Impact Report, as updated by Parsons
for the Highway 25 Widening Draft EIS/EIR Re-evaluation Traffic Study. This calculation
produced a VMT estimate of 951,300 for state highways in San Benito County.
Based on the above, Table 5 shows the updated HPMS VMT estimates for 2010. A more detailed
table showing 2010 HPMS based VMT by jurisdiction for San Benito County is shown in Table 6.
Table 5: Updated HPMS Summary Based on Count Data
DAILY VEHICLE MILES OF TRAVEL
YEAR
TOTAL
HOLLISTER
SAN
JUAN
BAUTISTA
2010
1,387,114
142,410
7,300
COUNTY
ROADS
NATIONAL
PARK
SERVICE
STATE
HIGHWAYS
STATE
PARK
SERVICE
259,330
670
949,824
27,580
Source: Parsons
Table 6: 2010 San Benito County HPMS by Jurisdiction (Updated)
COUNTY/
LOCATION
Cities
Other
MAINTAINED MILES
JURISDICTION
RURAL
URBAN
TOTAL
Hollister
San Juan Bautista
County
National Park Service
State Highways
State Park Service
0
10.23
364.92
8.68
83.97
306.40
95.00
0
18.75
0
6.11
0
95.00
10.23
383.66
8.68
90.08
306.40
774.20
119.85
894.05
DAILY VEHICLE MILES
OF TRAVEL
RURAL
URBAN
TOTAL
0
7,300
227,870
670
889,674
27,580
142,410
0
31,470
0
60,150
0
142,410
7,300
259,330
670
949,824
27,580
1,153,094
234,030
1,387,114
Source: Parsons
Vehicle Miles of Travel
Vehicle miles of travel are calculated as the number of vehicles on a road segment multiplied by
the length of the segment, summed over all road segments in a certain geographic area. The
Caltrans HPMS estimates annual average daily vehicle miles of travel for each county in
California based on a sample of traffic counts on various road types. A comparison of modelestimated VMT with VMT from the HPMS can indicate if the model is generating the correct
magnitude of travel, even if there are inaccuracies in the specific road segment traffic volumes.
Average weekday (Tuesday through Thursday) vehicle miles of travel are calculated from the San
Benito County traffic model by multiplying link volumes times link distances. These modelgenerated estimates of average weekday VMT can then be compared to the HPMS AADT VMT
estimates reported in Table 5. The model validation goal is that the VMT calculated from the
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
model should be within three percent of the HPMS estimate. The 2010 model base year estimated
1,582,974 miles of vehicle travel for all highway links in the network (excluding centroid
connectors) within San Benito County. The 2010 model VMT estimate, 1,582,974, is higher than
the updated Caltrans HPMS estimate of 1,387,114 for San Benito County. A comparison of the
two estimates is provided in Table 7. The modeled daily VMT estimates are over the acceptable
range of plus or minus three percent. One possible reason for this increase is the larger highway
network that is reflected in the travel forecast model. In other words, the number of roadway
miles is significantly higher that the Caltrans estimates of roadway miles in the county.
Table 7: 2010 Daily VMT/VHT by Facility Type
MODEL
ROAD TYPE
VMT
HPMS
ROAD
MILES
VMT
ROAD
MILES
PERCENT
DIFFERENCE
VMT
ROAD
MILES
MODEL
VHT
MODEL
AVERAGE
SPEED
Freeways
442,493
21.49
10,331
58.83
Expressways
479,820
52.79
9,575
50.11
Major arterials
448,055
142.83
11,695
38.31
Minor arterials
70,347
69.26
2,033
34.60
138,528
351.92
4,492
30.84
3,731
1.72
124
29.98
96,756
433.08
6,450
15.00
Total—all roads 1,582,974
640.02
35,441
40.45
Collectors
Diamond ramps
Centroids*
1,387,114
578.97**
+14.12%
+10.54%
Source: Parsons, San Benito County Traffic Model
**Centroids not included in totals
**Park roads not included
The comparisons presented in Table 7 indicate that the model generated estimates of VMT are
14.12 percent higher than the revised estimate of VMT reported for HPMS purposes. Excluding
mileage associated with state and national park service roads, the mileage included in the travel
forecast model is 10.54 percent greater than the road segment mileage reflected in the HPMS
estimates of VMT. Thus, the two estimates of VMT may be closer to one another than they
appear.
In addition to the above comparison, Parsons investigated potential adjustments to the model
estimates of average weekday (ADT) VMT versus the HPMS estimates of annual average daily
traffic (AADT). For this exercise, a comparison was made of seven-day average daily traffic
volumes versus Tuesday through Thursday average traffic volumes, based on 24-hour, 7-day
traffic counts collected for the SR 152 Trade Corridor Project throughout northern San Benito
County. The results of this investigation are presented in Table 8, and indicate that no adjustment
in model generated VMT is warranted. In other words, for San Benito County, AADT estimates
of VMT are equivalent to ADT estimates of VMT.
By way of comparison, the AMBAG Regional Travel Demand Model was calibrated for a base
year of 2005. The Caltrans-reported HPMS VMT for that year was 1,445,080. Runs of the 2005
AMBAG Base Year Model by Hexagon Transportation Consultants for the 2035 San Benito
County General Plan Draft PEIR produced estimates of 1,772,012 of VMT for San Benito
County. This estimate of VMT is 22.62 percent higher than the Caltrans-reported HPMS estimate.
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Table 8: 2010 San Benito County AADT versus ADT Comparison
FACILITY TYPE
HPMS VMT (AADT)
State Roads
U.S. 101
1
SR 156
2
SR 156
3
SR 25
4
SR 25
SR 146
SR 129
TUESDAY–THURSDAY:
7-DAY RATIO
EQUIVALENT
WEEKDAY VMT (ADT)
Total
390,821
80,083
224,885
187,887
39,766
1,264
25,118
949,824
0.9347
1.0297
0.9421
1.0777
0.9636
NA
1.0068
0.9760
365,301
82,461
211,864
202,486
38,319
1,264
25,289
926,984
Total
259,330
1.0454
5
271,102
Total
149,710
1.0454
5
156,507
Total
28,250
NA
County Roads
City Roads
Other
TOTAL
1,387,114
28,250
0.9969
1,382,843
1
U.S. 101 to Alameda
2
Alameda to County Line
3
Hollister to County Line
4
South of Hollister
5
Volume weighted average of 4th Street, Union Avenue, San Felipe Road, and Fairview Road.
The daily, AM peak and PM peak period VMT by facility type are shown in Table 9.
Table 9: AM Peak and PM Peak VMT/VHT by Facility Type
AM PEAK HOUR
PM PEAK HOUR
ROAD TYPE
VMT
VHT
AVERAGE
SPEED
VMT
VHT
AVERAGE
SPEED
Freeways
Expressways
Major arterials
Minor arterials
Collectors
Diamond ramps
Centroids*
Total—All Roads
29,909
33,006
27,646
4,844
7,497
278
4,723
103,180
505
777
701
136
239
9
315
2,367
59.26
42.50
39.42
35.54
31.34
29.97
15.00
39.67
35,803
35,939
31,833
5,166
9,457
307
6,277
118,505
612
792
822
147
303
10
418
2,686
58.51
45.37
38.71
35.15
31.17
29.96
15.00
39.81
Source: Parsons, San Benito County Traffic Model (*centroids not included)
Traffic Assignment Validation
The traffic assignment validation is conducted for daily, AM peak and PM peak period traffic
conditions and is based on several criteria, including total volume by road type, percent of links
within acceptable limits and VMT.
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2010 San Benito County Traffic Model
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The traffic counts and the model volumes are compared by facility type (Tables 10 through 12)
and by the volume range in which they are classified (Tables 13 through 15). The comparison is
made in terms of total model volume compared to total traffic counts and the root mean square
error (RMSE), which is also used as a validation criterion.
Table 10: Daily Highway Validation by Road Type
ROAD TYPE
NUMBER
OF LINKS
TRAFFIC
COUNTS
MODEL
VOLUME
DIFFERENCE
PERCENT
CRITERIA
10
14
60
34
12
225,040
112,522
268,795
56,678
13,360
226,637
115,835
262,591
49,150
14,914
0.71%
2.94%
–2.31%
–13.28%
11.63%
±7%
±10%
±15%
±25%
±25%
130
676,395
669,127
–1.07%
±5%
19.23%
CRITERIA
PERCENT
RMSE
Freeways
Expressways
Major Arterials
Minor Arterials
Collectors
Total—All Roads
PERCENT
RMSE
Table 11: AM Peak Highway Validation by Road Type
ROAD TYPE
Freeways
Expressways
Major Arterials
Minor Arterials
Collectors
Total—All Roads
NUMBER
OF LINKS
TRAFFIC
COUNTS
MODEL
VOLUME
DIFFERENCE
PERCENT
10
12
12
8
0
14,573
6,237
3,650
721
15,756
6,820
3,566
866
8.12%
9.35%
–2.30%
20.11%
±7%
±10%
±15%
±25%
±25%
42
25,181
27,008
7.26%
±5%
31.15%
CRITERIA
PERCENT
RMSE
Table 12: PM Peak Highway Validation by Road Type
ROAD TYPE
Freeways
Expressways
Major Arterials
Minor Arterials
Collectors
Total—All Roads
NUMBER
OF LINKS
TRAFFIC
COUNTS
MODEL
VOLUME
DIFFERENCE
PERCENT
10
12
12
8
0
16,764
7,193
3,957
890
18,281
7,183
3,964
717
9.05%
–0.14%
0.18%
–19.44%
±7%
±10%
±15%
±25%
±25%
42
28,804
30,145
4.66%
±5%
21.76%
PERCENT
RMSE
Table 13: Highway Validation by Volume Range—Daily
VOLUME RANGE
LINKS
COUNT
VOLUME
DIFFERENCE
PERCENT
CRITERIA
<4,999
>5,000 to <9,999
>10,000 to <14,999
>15,000 to <19,999
>20,000 to <24,999
>25,000 to <29,999
>30,000 to <34,999
93
23
6
0
4
2
2
237,570
166,462
67,259
0
84,560
56,050
64,494
219,946
176,360
66,972
0
86,215
52,958
66,676
–7.42%
5.95%
–0.43%
0.00%
1.96%
–-5.52%
3.38%
60%
41%
33%
29%
27%
25%
24%
130
676,395
669,127
–1.07%
Total—All
19.23%
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Table 14: Highway Validation by Volume Range—AM Peak
VOLUME RANGE
LINKS
COUNT
VOLUME
DIFFERENCE
PERCENT
CRITERIA
<500
>500 to <999
>1,000 to <1,499
>1500 to <1,999
>2,000 to <2,499
>2,500 to <2,999
28
2
8
2
1
1
6,074
1,409
9,762
3,172
2,110
2,654
6,682
967
11,196
3,133
1,767
3,263
10.01%
–31.37%
14.69%
–1.23%
–6.26%
22.95%
60%
41%
33%
29%
27%
25%
42
25,181
27,008
7.26%
Total—All
PERCENT
RMSE
31.15%
Table 15: Highway Validation by Volume Range—PM Peak
VOLUME RANGE
LINKS
COUNT
VOLUME
DIFFERENCE
PERCENT
CRITERIA
<500
>500 to <999
>1,000 to <1,499
>1,500 to <1,999
>2,000 to <2,499
>2,500 to <2,999
26
5
5
2
3
1
6,390
3,626
6,413
3,319
6,255
2,801
6,489
3,230
7,021
3,840
6,273
3,292
1.55%
–10.92%
9.48%
15.70%
0.29%
17.53%
60%
41%
33%
29%
27%
25%
42
28,804
30,145
4.66%
Total—All
PERCENT
RMSE
21.76%
The RMSE is a statistical indicator that is intended to represent the average percent error between
an estimated value (such as a model volume) and an observed value (such as a traffic count). The
RMSE is calculated as:
where:
n
Ci
Vi
i
= the total number of links
= the observed count for road i
= the model volume for road i
= represents a road link
The RMSE provides a measure of accuracy based on the statistical standard deviation. The
RMSE places a greater emphasis on larger errors that may cancel each other out in the
comparison of total model volumes and traffic counts. The overall RMSE target is 30 percent.
The 2010 model validation results meets the RMSE target for total volumes for daily, AM peak
and PM peak validation scenarios.
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2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Percent Error by Facility Type and Volume Range
The Federal Highway Administration and Caltrans recommended error limits for total error by
functional classification (type of road) are as follows:
x Freeways: less than 7 percent error
x Principal arterials: less than 10 percent error
x Arterials: less than 15 percent error
x Collectors: less than 25 percent error
x Frontage roads: less than 25 percent error
The daily 2010 traffic validation reported in Table 10 meets the criteria for all facilities. The
overall percent difference is one percent, which is well below the criteria of five percent.
The 2010 traffic validation for the AM peak period reported in Table 11 shows the all the
facilities except the freeways meet the allowable criteria listed above. The freeways are one
percent higher. The overall percent difference is 72 percent above the allowable criteria of
five percent.
The 2010 traffic validation for the PM peak period reported in Table 12 shows that the all
roadway facilities except the freeways meet the allowable criteria listed above. The freeways are
two percent higher the criteria. The overall percent difference is five percent and is within the
allowable criteria of five percent.
The FHWA and Caltrans travel forecasting guidelines include a graphic showing the maximum
desirable deviation between daily model volumes and traffic counts for individual link volumes
(Figure 4). The maximum desirable deviations in total volume from the FHWA graphic are
recommended for the validation by volume range and are included as criteria in the tables.
x
x
x
The suggested link-specific validation criteria are that 75 percent of the highway facilities
meet the maximum desirable deviation.
The 2010 model validation results show that 86 percent of links for daily, 75 percent for AM
peak and 83 percent for the PM peak hour meet the criteria for the maximum allowable
deviation of at least 75 percent of links within acceptable deviation allowance. The summary
results are shown in Table 16.
The 2010 model validation results indicate a 19 percent RMSE for daily and 22 percent
RMSE for the PM peak hour, which are below the allowable 30 percent RMSE. The AM
peak hour RMSE is 31 percent, which is just above the threshold by one percent.
x
The 2010 model validation results show a 0.97 correlation coefficient for daily, a
0.94 correlation coefficient for the AM peak hour and a 0.97 correlation coefficient for the
PM peak hour. They all meet the criteria for the maximum allowable correlation coefficient
of at least 0.88.
x
The 2010 model validation results reported in Table 13 for the daily meets all the FHWA
criteria for all of the volume ranges. The 2010 AM peak and PM peak model validations,
reported in Tables 14 and 15, respectively, meet the FHWA criteria for all of the volume
ranges.
15
2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Therefore, the 2010 San Benito Travel Demand Model adequately meets the highway validation
criteria for percent error.
Table 16: Highway Validation Summary
ONE-WAY LINK VALIDATION
CRITERIA FOR
ACCEPTANCE
DAILY
AM PEAK
HOUR
PM PEAK
HOUR
Percent of links within Caltrans deviation allowance
At least 75%
86%
75%
83%
Correlation coefficient
At least 0.88
0.97
0.94
0.97
Percent root mean squared error
Below 30%
19%
31%
22%
Traffic Assignment Results
Figures 5 through 10 illustrate various results from the traffic assignment validation effort.
16
2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Figure 5. 2010 Daily Differences Model minus Count
17
2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Figure 6. 2010 AM Peak Hour Differences Model minus Count
18
2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Figure 7. 2010 PM Peak Hour Differences Model minus Count
19
2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Figure 8. 2010 Daily Traffic Volumes — Bandwidth
20
2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Figure 9. 2010 AM Peak Hour Traffic Volumes — Bandwidth
21
2010 San Benito County Traffic Model
HIGHWAY VALIDATION REPORT
Figure 10. 2010 PM Peak Hour Traffic Volumes — Bandwidth
22