Attachment 37FEHR 1" PEERS
MEMORANDUM
Date: December 3, 2014
To: Trang TuNguyen, Town of Los Gatos
From: Katy Cole and Sarah Peters, Fehr & Peers
Subject: North 40 Specific Plan: Trip Generation Rate Comparison
5109 -1130
INTRODUCTION
The purpose of this memorandum is to review alternatives to ITE trip generation rates, such as
rates developed for the EPA MXD and National Cooperative Highway Research Program (NCHRP)
Report 684. These methodologies address trip generation for mixed -use developments. Mixed -
use development trip generation methodologies are appropriate for the North 40 Specific Plan
Area, where a variety of land uses, including housing, retail, hotel and offices, is proposed.
Trip generation refers to the number of inbound and outbound vehicle trips generated by a
project over a given period of time. Trip generation is estimated for proposed development
projects in order to understand how much traffic will be added to the surrounding transportation
network. This memorandum describes the difference between typical trip generation
methodologies for single use sites and for mixed use sites, and evaluates the effect on trip
generation forecasts for the North 40 project if trip generation were estimated using rates
developed for mixed -use development projects. We also note whether, in our professional
opinion, significant impacts would be reduced if trip generation were estimated using a mixed -
use methodology.
SUMMARY OF FINDINGS
We prepared trip generation estimates for the two North 40 Specific Plan project alternatives
using MXD +, a tool that combines two mixed -use trip generation methodologies (NCHRP 684
and EPA MXD) and provides greater overall accuracy than either method alone. These estimates
were then compared to trip generation estimates used in the North 40 Specific Plan TIA, which
were developed using rates published by the Institute of Transportation Engineers (ITE), with
modest reductions to account for pass -by trips to retail uses on the site and to account for the
site's mixed -use character.
Trip generation for North 40 prepared using the MXD+ methodology was slightly lower than ITE
rates during the AM peak hour and substantially lower in the PM peak hour. Reductions for each
project alternative are as follows:
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• Project Alternative A: AM peak hour reduction of 7% (49 trips) and PM peak hour
reduction of 23% (356 trips)
• Project Alternative B: AM peak hour reduction of 3% (49 trips) and PM peak hour
reduction of 24% (352 trips)
Based on this analysis, in our professional opinion using a mixed -use methodology to estimate
trip generation could reduce the level of significant impacts identified in the North 40 Specific
Plan TIA.
TRIP GENERATION METHODOLOGIES
Trip generation refers to the number of inbound and outbound vehicle trips generated by a
project over a given period of time. Trip Generation for a project can be developed using a variety
of mythologies.
The Institute of Transportation Engineers (ITE) publishes national trip generation rates and
methodology in the Trip Generation Manual and Trip Generation Handbook. ITE trip generation
data and analysis methods primarily apply to single -use, free - standing sites, limiting their
applicability to compact, mixed -use developments. In Santa Clara County, trip generation
estimates for new development are typically based on rates published by ITE and then reductions
are taken to account for mixed -use per the VTA Transportation Impact Study Guidelines.
Trip generation for the North 40 Specific Plan TIA was estimated using ITE rates, with reductions
taken to account for the project's mix of housing and retail and to account for retail customers
who would stop at the project on their way to another destination.
Mixed -use sites typically have several features that reduce auto trips compared to single -use
development, including:
• Complementary land uses, which allow residents and workers to access goods and
services within the development.
• Diverse land uses, which enable visitors to run several errands with a single auto trip.
• Walkable urban design and well- connected streets, which make walking and bicycling
more comfortable and convenient.
Several methodologies have been developed to account for the unique trip generation
characteristics of mixed -use sites. The two methodologies identified by the Los Gatos Town
Council, NCHRP 684 and EPA MXD, are among the best - researched mixed -use methodologies
currently in use. In its revised TIA Guidelines (October 2014), the Santa Clara Valley Transportation
Authority (VTA) identified both of these trip generation methodologies as appropriate for mixed -
use development in Santa Clara County.
The National Cooperative Highway Research Program ( NCHRP) Report 684, Enhancing Internal
Trip Capture Estimation for Mixed -Use Developments, analyzed three mixed -use developments in
Georgia and Texas to understand travel interactions between six types of land uses: office, retail,
restaurant, residential, cinema, and hotel. To test the accuracy of this analysis, researchers
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compared their results to trip generation studies conducted at seven mixed -use sites in Florida.
The resulting methodology yields reductions for ITE trip generation rates based on the
interactions between land uses.
The EPA MXD Model was developed from a sample of 239 mixed -use developments in six
metropolitan areas from across the United States. The methodology reflects how different aspects
of a site, including the density and type of development, affect vehicle trip generation by
providing nearby destinations and shifting trips to walking or transit. The resulting trip reduction
approach has been tested at 27 sites, primarily in California.
MXD+ is a trip generation methodology developed by Fehr & Peers as part of their internal
research and development efforts in collaboration with the EPA to combine the strengths of the
EPA MXD and NCHRP methodologies and data. The methodology was developed by combining
the results from both methods and comparing the results against trip generation recorded at 27
mixed -use sites. The resulting trip generation estimates were found to be more accurate than
either the EPA MXD or NCHRP 684 methodologies alone. In May 2013, the American Planning
Association published a memorandum outlining the MXD+ methodology through its Planning
Advisory Service. MXD+ has been used in several transportation impact analysis studies in Santa
Clara County, including the Apple Campus II EIR, the Lawrence Station Area Plan for the City of
Sunnyvale, as well as a number of transportation impact analysis projects in other Bay Area
counties.
Table A summarizes the research basis of these three methodologies.
TABLE A - MIXED -USE TRIP GENERATION METHODOLOGIES
Average Error Rate'
Methodology Data Source
Validation Professional Practice
AM PM Daily
27 ASCE peer review
sites
Household surveys
SANDAG
EPA MXD
(C UT, TX, GA, FL,
12% 8% 2/
at 239 sites
Environmental studies
NC
(CA,WA)
Traffic counts,
NCHRP 684 interviews at 3
3 sites NCHRP review panel
30% 18% N/A
sites (GA and TX)
Combined sources
Combined sources
MXD+ from EPA MXD
(27 sites used for APA Planners Advisory
12% 4% 2%
and NCHRP 684
EPA MXD and Service Memo
NCHRP 684)
Note:
1. Average error rate when
compared to vehicle trip counts at
27 validation sites.
Source:
Walters, J., B. Bochner, R. Ewing. Getting Trip Generation Right Eliminating the Bias Against
Mixed Use Development.
Planners Advisory Service, American Planning
Association. May 2013.
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TRIP GENERATION ANALYSIS
To understand how the application of a mixed - use - oriented trip generation methodology could
affect trip generation for the project, we developed trip generation estimates using the MXD+
tool and compared them to the trip estimates used in the North 40 Specific Plan TIA, which were
developed using ITE rates.
TIA Trip Generation
Trip generation for the North 40 Specific Plan TIA was estimated by using rates published by the
Institute of Transportation Engineers (ITE) in its Trip Generation report and Trip Generation
Handbook. Separate trip reductions were taken to account for pass -by trips to retail uses on the
site and to account for the site's mixed -use character. These reductions were based on guidance
published by the Santa Clara Valley Transportation Authority (VTA), as follows:
Pass -by reductions: VTA publishes guidance for diverted and pass -by trip reductions in
its Transportation Impact Analysis Guidelines (2009). Pass -by and diverted link trips are
intermediate stops made as a driver is going to their final destination. For example, a
driver may stop at a bank on their way home from work. This trip is not new to the
roadway network: therefore, it should not be included in the transportation impact
analysis. ITE studies report that pass -by and diverted linked trip reduction rates average
34 percent for retail uses (Trip Generation, 2004). VTA guidelines list slightly lower trip
reduction rates. To present a conservative analysis and comply with VTA guidelines, we
reduced retail trips by 25 percent. Project driveway analysis was adjusted to reflect
changes
Mixed -use reductions: The VTA Transportation Impact Analysis Guidelines (2009) provide
guidance for reducing ITE trip generation estimates at mixed -use developments. To
account for the mix of land uses proposed in the North 40 Specific Plan, a trip reduction
was applied to reflect a 15 percent reduction of residential trips plus an equal number of
matching trips generated by retail uses. This resulted in a total mixed -use reduction of
784 daily trips, 60 AM peak trips and 76 PM peak trips, or 30 percent of all residential
trips for both project alternatives.
Table B presents trip generation developed for the two project alternatives in the North 40
Specific Plan TIA.
Project Alternative A
• Retail: 269,000 square feet
• Hotel: 150 rooms
• Office: 125,000 square feet (62,500 square feet of medical /dental office and 62,500 square
feet of general office space)
• Residential: 364 units (73 cottage cluster units, 73 apartments and 218
condominium /townhouse units)
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Project Alternative B
• Retail: 400,000 square feet
• Hotel: 150 rooms
• Residential: 364 units (73 cottage cluster units, 73 apartments and 218
condominium /townhouse units)
MXD+ Trip Generation
To understand whether using a mixed -use trip generation methodology could change trip
generation estimates, we prepared trip generation estimates the two project alternatives in the
North 40 Specific Plan TIA using the MXD+ methodology.
As outlined above, the MXD+ methodology combines the NCHRP 684 and US EPA
methodologies and provides greater overall accuracy than either method alone. To be consistent
with the analysis presented in the TIA, a pass -by reduction of 25% was applied to retail trip
generation. Table B presents trip generation for two project alternatives developed using the
MXD+ tool.
TABLE B - COMPARISON OF ALTERNATIVE TRIP GENERATION ESTIMATES FOR THE
NORTH 40 SPECIFIC PLAN AREA
Method Daily AM Peak PM Peak
In Out Total In Out Total In Out Total
Project Attemative A
TIA' 7,880
7,877
15,757
422
263
685
690
836
1,526
MXD +2 7,080
7,077
14,157
392
244
636
529
641
1,170
Difference -800
-800
-1,600
-30
-19
-49
-161
-195
-356
% Change -10.2%
-7.2%
-23.3%
Project Attemative 8
TIA' 7,750
7,750
15,500
229
240
470
761
727
1,488
MXD +' -- 6,879
6,879
13,758
221
231
453
581
555
1,136
Difference -871
-871
-1,742
-8
-9
-17
-180
-172
-352
% Change -11.2%
-3.6%
-23.7%
Note:
1. Per VTA TIA Guidelines (2009), trip generation for retail uses was reduced by 25% to account for pass -by trips.
Trip generation for residential uses was reduced by 15% to account for "trip capture" by project retail. An equal
amount of retail trips were removed.
2. Trip generation for retail uses was reduced by 25% to account for pass -by trips.
Sources: North 40 Specific Plan TIA, March 2014; MXD+ 2.0 trip generation analysis tool, October 2014.
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Results
As shown in Table B, trip generation for North 40 prepared using the MXD+ methodology was
slightly lower than the TIA trip generation during the AM peak hour and substantially lower in the
PM peak hour. Reductions for each project alternative are as follows:
• Project Alternative A: AM peak hour reduction of 7% (49 trips) and PM peak hour
reduction of 23% (356 trips)
• Project Alternative B: AM peak hour reduction of 3% (49 trips) and PM peak hour
reduction of 24% (352 trips)
Based on this analysis, in our professional opinion using a mixed -use methodology to estimate
trip generation could reduce the level of significant impacts identified in the North 40 Specific
Plan TIA.
The TIA identified significant and unavoidable freeway impacts for both project alternatives. These
impacts could be eliminated if 46 or fewer project trips were assigned to mixed -flow lanes and 8
or fewer project trips assigned to HOV lanes. In the TIA, freeway impacts were identified as
follows:
Project Alternative A:
• Southbound SR 85 from Winchester Boulevard to SR 17: The PM peak hour impact
results from 52 project trips being added to mixed -flow freeway lanes. If a project has
46 trips or fewer in the mixed -flow lanes the impact is considered less -than-
significant. Therefore, if North 40 added 6 fewer trips to the freeway (or 12% fewer),
the impact may be eliminated. Based on our professional, since using a mixed -use
methodology could result in an overall PM peak hour trip reduction of 23.3% this
significant freeway impact may be eliminated.
• Southbound SR 85 from Bascom Avenue to Union Avenue: The PM peak hour impact
results from 71 project trips being added to mixed -flow freeway lanes. If a project has
46 trips or fewer in the mixed -flow lanes the impact is considered less -than-
significant. Therefore, if North 40 added 25 fewer trips to the freeway (or 35% fewer),
the impact may be eliminated. Based on our professional, since using a mixed -use
methodology may result in an overall PM peak hour trip reduction of 23.3% this
significant freeway impact would likely remain.
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Decembber er 3, 2014
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Project Alternative B:
• Southbound SR 85 from Bascom Avenue to Union Avenue: The PM peak hour impact
results from 48 project trips being added to mixed -flow freeway lanes. If a project has
46 trips or fewer in the mixed -flow lanes the impact is considered less -than-
significant. Therefore, if North 40 added 2 fewer trips to the freeway (or 4% fewer),
the impact may be eliminated. Based on our professional, since using a mixed -use
methodology could result in an overall PM peak hour trip reduction of 23.7% this
significant freeway impact may be eliminated.
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