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CHAPTER 3
Performance Evaluation
3.1 Introduction
This chapter presents the results of the work conducted as part of Task 8 (Performance Eval-
uation) of the project. The primary objective of the performance evaluation task was to conduct
a comprehensive comparative assessment of the performance of different truck-only lane con-
cepts, as well as concepts without truck-only lanes.
The analysis is based on a detailed review of analytical/modeling studies of truck-only lane
projects and field data from real-world truck-auto separation concepts in the United States and
internationally, to the extent that data were available. The performance assessment effort did not
involve any new modeling work. Rather, we evaluated each truck-only lane concept against a
standard set of performance measures, which are discussed in the following sections:
· Performance Evaluation Approach describes the main types of truck-only lane concepts
(scenarios) included in the analysis, the types of system improvements (alternatives) consid-
ered for the relative performance assessment, the selected set of performance measures, the
data sources used for the evaluation, and the methodology used to compile, summarize, and
assess the results from the various data sources.
· Performance Evaluation Results provides a discussion of the performance analysis results
from each of the selected data sources, as well as a comparative summary and analysis of results
for each performance measure across data sources to arrive at a consistent assessment of the
relative performance of truck-only lane concepts compared to other types of system improve-
ments (alternatives).
3.2 Performance Evaluation Approach
The study team's performance evaluation was based on a procedure that pulled together data
reported in other studies in a way that allowed the team to compare the results of, and develop
consistent performance metrics for, a variety of different truck-only lane concepts. This approach,
shown in Figure 3.1 relied on existing data and information available from evaluations of truck-
only lane concepts--the study team did not define new alternatives to be evaluated, develop new
data, or conduct new modeling or other detailed analyses. A description of each of the steps shown
in Figure 3.1 is presented in this section.
Although this approach presents certain limitations in terms of the types of alternatives that
can be compared, the types of performance measures that can be evaluated reliably, and the abil-
ity to validate the results of the analysis, it does provide a consistent basis by which different truck-
only lane concepts can be compared. This kind of apples-to-apples comparison allowed the
researchers to identify the most promising concepts and scenarios for further evaluation in a more
24
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Performance Evaluation 25
Step 1. Identification of Corridor
Scenarios
Step 2. Selection of Alternatives
Step 3. Selection of Performance
Measures and Metrics (within Each
Measure) for Performance
Evaluation
Step 4. Identification and Review of
Data Sources (Modeling/Analytical
Studies) for Performance Evaluation
within Each Corridor Scenario
Step 5. Post-Processing of
Performance Results for
Consistency in Comparisons
Figure 3.1. Steps involved
in truck-only lane
performance evaluation.
controlled setting. In addition, this approach clearly defines some of the most critical research and
data gaps and helps frame ideas for future research as discussed in the final chapter of this report.
Step 1. Identification of Corridor Scenarios
The first step in the performance evaluation approach involved the identification of key corri-
dor scenarios for the performance evaluation of truck-only lanes. Two main generic scenarios were
identified for the analysis, which included: (1.) long-haul intercity corridors and (2.) urban corri-
dors. These two types of corridor scenarios are broadly representative of the major types of corri-
dors for which truck-only lanes have been proposed in the past.
· Long-haul corridors include intercity corridors that serve long-haul truck and auto traffic
demand. Truck traffic along these corridors is predominantly composed of large (five or more
axle) combination trucks moving long-haul freight. Some examples of key long-haul corridors
in the U.S. carrying high truck volumes include I-15 between Barstow and Las Vegas, I-94
between Chicago and Detroit, I-5 between Bakersfield and Sacramento, and I-90 between
Cleveland and Buffalo. Some of the characteristics of long-haul corridors that would make
them particularly good candidates to consider for potential implementation of CMV-only lanes
include travel demand (auto and truck traffic volumes), congestion, and LCV network connec-
tivity. Additional discussion of these issues is presented in a later section.
· Urban corridors include short-haul corridors in urban areas serving as primary access routes
to major freight facilities (such as seaports) or major auto and truck travel corridors in major
metropolitan areas. Examples of such corridors include the I-710, SR 60, and I-15 freeways in
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26 Separation of Vehicles--CMV-Only Lanes
Southern California; the I-395, I-95, SR 112, and SR 836 corridors serving the Port of Miami,
Florida; and the I-75, I-85, and I-285 freeways in metropolitan Atlanta.
Step 2. Selection of Alternatives
The second step was to select the range of operational and infrastructure investment alternatives
against which to evaluate the performance of different truck-only lane scenarios. It is important to
note that because our truck-only lane performance evaluation relied on existing feasibility studies
and analyses, the range of potential investment alternatives to consider was limited to those eval-
uated as part of these existing efforts.
Table 3.1 describes the types of alternatives that the study team assessed for both of the truck-
only lane scenarios. Since the applicability and viability of various system improvement options is
a function of corridor characteristics, the set of alternatives selected for the performance evalua-
tion was specific to each of the two scenarios. To understand the relative performance benefits of
truck-only lanes, a no-build alternative was included in all of the analyses in order to compare the
performance of truck-only lanes with an alternative without truck-only lanes. Additional alter-
natives were included in the evaluation process, depending on the availability of performance data.
Step 3. Selection of Performance Measures and Metrics
Because different truck-only lane scenarios may have different performance objectives, appro-
priate performance measures and metrics must be evaluated for each truck-only lane scenario. It
is more critical to assess potential productivity gains along long-haul corridors, for instance, than
Table 3.1. Alternative types by corridor scenario.
Scenario Alternatives Description
Long-Haul No-build (without LCV Includes all committed improvement projects to be implemented
Corridors operations) along the study corridor in the future, without LCV operations
No-build (with LCV Includes all committed improvement projects to be implemented
operations) along the study corridor in the future, along with LCV operations
on general purpose lanes
CMV-only lanes without Includes implementation of truck-only lanes along the study
LCV operations corridor (in addition to the projects included in no-build), but
without LCV operations
CMV-only lanes with LCV Includes implementation of truck-only lanes along the study
operations corridor (in addition to the projects included in no-build), along
with LCV operations on truck-only lanes
Urban No build Includes all committed improvement projects to be implemented
Corridors along the study corridor in the future
Additional general purpose Includes implementation of additional general purpose lanes along
lanes the study corridor (in addition to the projects included in no-build
as well as Transportation Supply Management/Transportation
Demand Management (TSM/TDM*) strategies)
CMV-only lanes Includes implementation of truck-only lanes along the study
corridor (in addition to the projects included in no-build as well as
TSM/TDM strategies), without the application of tolls
Note:
*TSM strategies include projects that optimize transportation system supply in a region to handle demand. For
example, managed lanes optimize capacity of a roadway network by varying bidirectional lane capacities of a
roadway for the morning and evening peak periods to account for varying commute travel demand in these time
periods. TDM strategies include projects that optimize the demand on the transportation system, to encourage
optimal system capacity utilization. An example of a TDM strategy is congestion pricing, which manages
demand during congested time periods through the use of user fees.
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Performance Evaluation 27
along urban corridors. Conversely, congestion relief or travel time reliability benefits might be
more relevant for urban corridors. It is important to note that this section is solely dedicated to
analyzing the relative performance of truck-only lanes (based on consideration of a key set of per-
formance measures) against other alternatives, without consideration of costs. Chapter 4 looks
specifically at the net performance benefits of truck-only lanes compared to other alternatives
based on an estimation of benefit-cost (B-C) ratios.
The performance measures/metrics considered to guide the study team's evaluation process
are as follow:
· Travel Time. This measure is used to quantify the mobility benefits of truck-only lanes com-
pared to other alternatives. The benefits are quantified in terms of percent savings in travel time
for the build alternatives (including the truck-only lane alternative) compared to the no-build
alternative. For the truck-only lane alternative, travel time savings are estimated primarily for
autos (and trucks) on general-purpose lanes (and for trucks on truck-only lanes to the extent to
which these savings were quantified in the reviewed studies).
· Travel Time Reliability. Travel time reliability is measured by the percent change in incident-
related (nonrecurrent) delay for the build alternatives (including the truck-only lane alternative)
compared to the no-build alternative. The following key aspects of truck-only lanes expected to
contribute to reliability improvements along a corridor include:
Reduction in accidents due to mobility improvements on the general purpose lanes (due to
diversion of trucks to truck-only lanes),
Accident reduction due to truck-auto separation and improvements in general flow condi-
tions due to less weaving of trucks and autos, and
Increased capacity on the general purpose lanes resulting in improved processing of bottle-
necks during incidents (increased capacity will result in increased efficiency in alleviating the
traffic impacts of incidents).
· Productivity. This measure is used to quantify the productivity enhancements realized by the
private sector (shippers and carriers) due to operations on truck-only lanes. The parameter used
to quantify productivity benefits is the increase in net earnings (revenue less cost) per ton mile29
for carriers. This parameter is computed based on (1.) the contribution of speed improvements
on truck-only lanes to increased productivity of trucking operations (i.e., increased trucking
industry earnings per ton mile from improvements in truck operating speeds); and (2.) contri-
bution of LCV operations to productivity enhancements (increased net earnings per ton mile
due to increase in truck payloads).
· Safety. Safety benefits are quantified in terms of reduction in the number of accidents on gen-
eral purpose lanes for the build alternatives (including the truck-only lane alternative) relative
to the no-build alternative. Truck-only lanes also contribute to safety improvements along a cor-
ridor by improving mobility on the general purpose lanes, and by reducing interactions between
autos and trucks by diverting trucks to truck-only lanes.
Step 4. Identification and Review of Data Sources
As described earlier, the study team's evaluation approach relied on data and information
from existing planning and analytical/modeling studies of truck-only lane projects conducted in
the United States. Although there have been a number of truck-only lane projects, studies, and
29
Earnings per ton mile is an appropriate parameter to quantify productivity benefits of truck-only lanes
because it can capture increased earnings for truckers due to improved speeds and an increase in payloads.
Improved speeds (for truckers on truck-only lanes) would result in a reduction in operating costs per mile,
which would translate into increased net earnings per mile. An increase in payloads (from LCV operations on
truck-only lanes) would result in reduction in operating costs per ton, which would result in increased net
earnings per ton.
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28 Separation of Vehicles--CMV-Only Lanes
Table 3.2. Alternatives considered within long-haul corridor
truck-only lane studies.
General Purpose
Lanes Truck Lanes with Truck Lanes
Study No-Build with LCVs LCVs without LCVs
Reason Foundation Study
Western Uniformity Scenario
Analysis
I-35 Trade Corridor Study
Georgia Statewide Truck Lane
Needs Identification Study
initiatives in the United States, the study team only used those studies that analyzed long-haul
or urban corridors and provided performance analysis results that could be used, either directly
or after post-processing, for the performance evaluation process. The following data sources
were used for performance evaluation:
· Long-haul corridors
Reason Foundation study on long-haul truck corridors,30
Western Uniformity Scenario Analysis,31
I-35 Trade Corridor Study,32 and
Georgia Statewide Truck Lane Needs Identification Study.33
· Urban corridors
I-710 Major Corridor Study,34
I-15 Comprehensive Corridor Study,35
Georgia Statewide Truck Lane Needs Identification Study,36 and
PSRC FAST corridor study.37
Tables 3.2 through 3.5 describe the alternatives considered by each of these studies, and provide
information on which of the key performance metrics described in this section (travel time, travel
time reliability, productivity, and safety) are considered in these studies.
It is clear from this analysis that different truck-only lane scenarios have different performance
objectives. Long-haul corridor scenarios, for instance, are concerned with improving overall travel
time, productivity, and safety (in cases where corridor configurations and truck-auto interactions
are having safety impacts). As part of the performance analysis, these studies typically compared
truck-only lane concepts against a no-build alternative (and, in some cases, against the benefits
30
R. W. Poole, Jr. and P. Samuel, Toll Truckways: Increasing Productivity and Safety in Goods Movement, Reason
Foundation, http://www.fhwa.dot.gov/download/hep/freightplanning/talkingfreight3_16_05bp.ppt.
31
U.S.DOT, Western Uniformity Scenario Analysis: A Regional Truck Size and Weight Scenario Requested by the
Western Governors' Association, April 2004.
32
HNTB and Wilbur Smith Associates, I-35 Trade Corridor Study: Recommended Corridor Investment Strategies,
Texas Department of Transportation, September 1999.
33
Georgia Department of Transportation, Statewide Truck Lane Needs Identification Study, "Technical Memo-
randum 3: Truck-Only Lane Needs Analysis and Engineering Assessment," April 2008.
34
Los Angeles County Metro, I-710 Major Corridor Study: Final Report, March 2005.
35
Southern California Association of Governments, I-15 Comprehensive Corridor Study, December 2005.
36
Georgia Department of Transportation, Statewide Truck Lane Needs Identification Study, "Technical Memo-
randum 3: Truck-Only Lane Needs Analysis and Engineering Assessment," April 2008.
37
Kuppam, et al., Evaluating Freight Mobility on a Regionwide Basis Using EMME/2--Freight Action Strategy
(FAST) Truck Model for the Puget Sound Region, 16th International EMME/2 User's Group Conference,
Albuquerque, New Mexico, March 2002.
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Performance Evaluation 29
Table 3.3. Alternatives considered within urban corridor truck-only lane studies.
Mixed-Flow TSM/TDM
Study No-Build Lanes Truck-Only Lanes Strategies
I-710 Major Corridor Study
I-15 Comprehensive Corridor
Study
Georgia Statewide Truck Lane
Needs Identification Study
PSRC FAST Corridor Study
Table 3.4. Performance metrics described within long-haul corridor
truck-only lane studies.
Study Travel Time Productivity Safety
Reason Foundation Study
Western Uniformity Scenario Analysis
I-35 Trade Corridor Study
Georgia Statewide Truck Lane Needs
Identification Study
Table 3.5. Performance metrics described within urban corridor
truck-only lane studies.
Study Travel Time Reliability Safety
I-710 Major Corridor Study
I-15 Comprehensive Corridor Study
Georgia Statewide Truck Lane Needs
Identification Study
PSRC FAST Corridor Study
and impacts of LCV operations on truck-only lanes). Conversely, urban corridor scenarios are
more concerned with improving overall travel time, travel time reliability, and safety. Truck-only
lane concepts in these areas were compared with other congestion-reduction alternatives, such as
additional general purpose (GP) lanes and transportation system management strategies. As a
result, these different scenarios use different performance metrics--long-haul corridors use travel
time, productivity, and safety measures, while urban corridors calculate travel time, reliability, and
safety measures.
Recognizing these key differences, the study team structured their evaluation approach to nor-
malize only those performance metrics that are applicable to each corridor scenario, as shown
in Table 3.6.
Step 5. Post-Processing of Performance Results
In order to ensure consistent comparisons of performance results, the study team found it nec-
essary to normalize the results from studies in order to develop a common metric for comparisons.
The team used post-processing factors in cases where the desired performance metric was not esti-
