Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 61
Benefit-Cost Analysis 61
· Assessing what the minimum level of diversion would need to be in the case of LCV opera-
tions to make truck-only lanes a viable investment option in comparison to additional mixed-
flow lanes;
· Assessing optimal diversion rates for truck-only lanes that provide the highest levels of cost-
effectiveness (for congested corridors with high truck volumes, very high diversion rates
would not necessarily maximize cost-effectiveness since congestion reduction on the general
purpose lanes due to truck diversion might be offset by high levels of congestion on the truck-
only lanes--this would be particularly relevant in the case where use of the truck-only lanes
is mandatory); and
· Assessing the differences in diversion rates required for truck lanes with and without LCV
operations to achieve similar levels of cost-effectiveness in the case of long-haul corridors.
4.2 Performance Metrics Considered
for Benefit-Cost Analysis
The performance metrics discussed in the remainder of the following subsections were con-
sidered for the B-C analysis of truck-only lanes.
4.2.1 Public Benefits
Public benefits could include the following:
· Travel time savings that accrue to autos on general purpose lanes as trucks divert from general
purpose lanes to truck-only lanes, thereby reducing congestion and improving travel speeds on
the general purpose lanes. This metric is typically evaluated in terms of percent savings in travel
times on the general purpose lanes due to the implementation of truck-only lanes.
· Reliability benefits that accrue to autos on general purpose lanes due to the implementation
of truck-only lanes. The diversion of trucks to truck-only lanes reduces congestion and truck-
auto interaction on the general purpose lanes, thereby improving safety and providing asso-
ciated reliability benefits (in terms of reduction in incident-related nonrecurrent delay). This
metric is typically evaluated in terms of percent savings in incident-related (nonrecurrent)
delay on general purpose lanes due to the implementation of truck-only lanes.
· Safety benefits that accrue to all users. As discussed previously, the implementation of truck-
only lanes can provide safety benefits on the general purpose lanes, since diversion of trucks to
truck-only lanes would reduce congestion and truck-auto interaction on the general purpose
lanes. This metric is typically evaluated in terms of percent reduction in total accidents (fatal acci-
dents, if total accidents were not reported) on the general purpose lanes.
Reduction in emissions due to improved travel speeds on the general purpose and truck-only
lanes would be another important public benefit of implementing truck-only lanes. The capac-
ity enhancement along a corridor due to the implementation of truck-only lanes would result in
improved travel speeds for autos and trucks on the general purpose lanes, as well as for trucks
using the truck-only lanes. This improvement in travel speeds is expected to directly contribute
to a net reduction in emissions along the corridor. However, the B-C analysis conducted in this
study did not include environmental benefits (reduced emissions) as a public benefit category,
primarily because of the lack of data required to accurately estimate travel speeds on general pur-
pose and truck-only lanes. Also, the capacity enhancement due to the implementation of truck-
only lanes is expected to result in some induced traffic along the corridor, as well as the
displacement of auto and truck traffic from other corridors. This resulting increase in total VMT
along the corridor would offset some of the emissions reduction from improved travel speeds.
However, without the availability of a travel demand model, the net impact of increased VMT
and improved travel speeds on emissions could not be assessed as part of the current study. Also,
