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CHAPTER 3
Existing Multimodal Corridors--
What Can We Learn From Them?
This chapter presents three types of new paradigm multi- so that both the capacities of the freeway and transit line are
modal corridors, discusses the evolution of corridors from one maximized.
type to another, and compares the old and new paradigms for The transit line's stations are designed to favor nonauto-
multimodal corridors. mobile access. Trip origin stations are placed as far as possible
from the freeway and its off-ramps to reduce both the amount
of automobile traffic in the station-area neighborhoods and
Types of New Paradigm
the negative externalities of the freeway facility. With the
Multimodal Corridors
possible exception of end-of-the-line (terminal) stations,
The new paradigm focuses on helping transit to compete stations have few, if any, park-and-ride spaces, and bus bay
effectively with and complement a neighboring freeway facility or other bus connection facilities are sited to maximize bus
by establishing one of the following types of multimodal access to the stations without disrupting pedestrian and bicycle
corridors: access. Corridor land uses and station area access are transit-
oriented, with higher density, mixed-use, and pedestrian-
· Transit-oriented: an operating environment conducive to friendly development.
transit, bicycle, and pedestrian access to the transit facility
· Park-and-ride access: an operating environment conducive
Where it Works
to automobile access to the transit facility
· Transit-optimized/freeway constrained: an environment There are no multimodal corridors that are consistently
where transit is given an operational advantage over the transit-oriented over their entire lengths. However, there are
freeway by constraining the capacity of the freeway cases where segments of multimodal corridors meet the transit-
oriented criteria. Examples include
Transit-Oriented Multimodal Corridors
· Washington D.C. Orange Line/I-66: from Ballston MU
Transit-oriented new paradigm corridors are designed to Station to Rosslyn Station
provide high levels of transit access within the corridor and · Chicago Blue Line/Kennedy Expressway (I-90): from
high automobile speeds with low local (i.e., infrequent) access Bellmont-Blue Station to Clinton Green Station
on the freeway. High levels of transit access are achieved by · San Francisco East Bay (BART) Pittsburg/Bay Point Line/
providing relatively short station spacings (between 0.50 and S.R. 24: Rockridge Station to 19th Street Station
0.75 mile); high automobile speeds and low local freeway access
comes from relatively long interchange spacings (more than Since these corridors are also transit-optimized/freeway
1 mile) on the freeway. This allows the transit line to serve constrained cases, further discussion is provided in the Transit-
short- and medium-length trips, while the freeway facility is Optimized/Freeway Constrained Corridors section below.
oriented toward long-haul and through trips.
Urban form in these corridors typically has high levels of
Park-and-Ride-Access Multimodal Corridors
residential and employment densities and a grid street network
that encourages nonautomobile travel in station areas. Ideally, Park-and-ride-access new paradigm corridors are designed
travel flows through the corridor will be relatively balanced, to provide high levels of automobile access and high transit
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speeds. This is achieved by designing the corridor's transpor- longer than the average interchange spacing for the Dan Ryan
tation facilities in an automobile-oriented complementary Expressway (0.50 mile) suggesting an automobile-oriented
fashion, taking advantage of the already-existing freeway's rela- complementary corridor. This difference divides the travel
tively short interchange spacings (between 0.25 and 0.50 mile) market within the corridor into roughly two segments--
and designing the transit line to have relatively long station long-haul, high-speed transit riders and freeway-accessible,
spacings (more than 0.75 mile). Urban form in these corridors more dispersed travel locations. It seems likely that this de-
is distinguished by sign helps the Red Line compete with and complement the
freeway to attract transit riders despite the corridor's sta-
· One (or more) highly concentrated employment cen- tion access characteristics and its lack of clear automobile-
ters (i.e., single or multiple business districts) versus transit-orientation in terms of urban form.
· Relatively low residential densities (at least, within a mile Perhaps the most notable transit-oriented characteristic for
or so of the transit line) the Red Line is the lack of park-and-ride spaces at its stations.
· A high-capacity street network that favors automobile In general, the Red Line relies on bus-to-rail transfers and
access to the transit stations pedestrian access. There are several bus transfer stations located
within the freeway right-of-way, and the 95th Street Terminal
Transit trip origin stations (i.e., the non-business district sta- station is one of the busiest in the system. Therefore, while its
tions) are close to the freeway off-ramps, have ample park-and- surrounding corridor land uses and its multimodal coordi-
ride capacity, and have a high-capacity street network nearby nation represents an auto-orientation, its lack of park-and-
to handle the peak-period demand at stations from park-and- ride facilities suggests that the Red Line should be considered
riders and pick-up/drop-off activities. By contrast, transit as a transitional example from its transit-oriented cross-
trip destination stations (i.e., the business district stations) are town neighbors (the Eastern Kennedy and Eisenhower Blue
placed far from the freeway to promote pedestrian activities Lines) to the more automobile-oriented, park-and-ride ac-
within employment centers. In these multimodal corridors, cess examples that followed it.
transit provides a long-haul travel alternative to the freeway.
Los Angeles Green Line/Century Freeway. Los Ange-
les's Green Line/Century Freeway is a more recent example of
Where it Works a park-and-ride access corridor. While light rail generally has
· Chicago Red Line/Dan Ryan Expressway (a transitional lower operating speeds and carrying capacities than commuter
case--see discussion below) or heavy rail, the Green Line attracts roughly 42,000 average
· Los Angeles Green Line/Century Freeway weekday boardings, making it one of the top performers in
· Denver T-REX/I-25 Corridor this study.
Furthermore, and perhaps most striking, the Green Line
Chicago Red Line/Dan Ryan Expressway. The Chicago does not directly serve a concentrated activity center or central
Red Line/Dan Ryan Expressway is an excellent example of a business district. All the other case study corridors have a
multimodal facility. It serves various residential uses within radial alignment, running like a spoke on a wheel from a central
the city. This includes a number of neighborhoods with du- business district, but the Green Line is circumferential and
plexes and single-family homes. Although the freeway was runs from east to west, well south of downtown Los Angeles.
built first, the Red Line was an important complement to Adding further challenges to the success of the Green Line,
the original south side elevated line. The Red Line extends the Los Angeles region is the prototypical automobile-oriented
to the north side of the city and connects with other Chicago metropolitan area. Although downtown Los Angeles is large
Transit Authority (CTA) rapid transit lines in downtown enough to support a light rail line, with roughly 40 million
Chicago. All stations are served by bus lines on intersecting square feet of office space, most of Los Angeles's trip attrac-
streets. Sections of the freeway consist of 14 lanes of through tors are dispersed throughout the region in a polycentric
traffic. Many of the freeway sections have continuous service fashion.
roads. Finally, like all multimodal corridors, the Green Line com-
The corridor shares one important element with other petes for ridership with its freeway neighbor. The more capacity
Chicago multimodal corridors--the size of Chicago's cen- the freeway has, the more difficult it is for transit to compete.
tral business district (CBD). As discussed earlier, the CBD The Century Freeway is a ten-lane facility, the largest freeway in
provides a regional concentration of destinations, which our study. Nevertheless, the Green Line is relatively successful
encourages people to use transit. when compared to other multimodal corridor transit lines.
In terms of multimodal coordination, the average station Part of the Green Line's success may be its role as a transfer
spacing for the Red Line (1.11 miles) is more than a half-mile facility, feeding the Blue Line, a radial alignment light rail line
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that serves downtown Los Angeles. Ridership data supports This study employed a proxy indicator of urban design that
this interpretation, since a substantial number of Green Line measured the average density of four-legged intersections in
riders transfer at the Imperial/Wilmington station on to the the travel corridor (see the discussion of Land Use and Urban
Blue Line. Design characteristics in Chapter 5). With an average density
The Green Line also serves non-CBD employment and of 0.4 four-legged intersections per acre compared to the
activity centers, such as the nearby Los Angeles International study average of 0.9, this corridor has a street grid pattern that
Airport (LAX). This would appear at first glance to be a sub- is decidedly suburban and automobile-oriented.
stantial trip attractor that would mitigate the lack of direct However, the size of Denver's CBD (roughly 23 million
service to a CBD, but the Green Line's nearest station to LAX square feet) and the fact that the line also serves the Denver
(Aviation/LAX) is roughly a mile from the airport and riders Tech Center--an office park concentration south of the CBD--
have to transfer to a shuttle to reach the airport. Nevertheless, seems to help overcome these automobile-oriented corridor
there is a fair amount of employment in the Green Line cor- challenges, providing a relatively strong anchor on which to
ridor, if dispersed. It has an employment density of roughly build the transit line's ridership.
10 employees per acre, just below the average of 11.5 for all Station access indices used in this study also suggest a
study corridors. This is particularly impressive since some corridor that has been designed to maximize automobile-to-
of the study corridors have downtown stations, raising the station transfers. On average, there are roughly three freeway
study average substantially. ramps touching down within a quarter-mile of each station
Residential corridor densities are low in this corridor, with (higher than the 2.75 study average), suggesting that the T-REX
an average (gross) housing density of 3.4 dwelling units per light rail line was designed to offload traffic from the freeway
acre (compared to an average of 5 dwelling units per acre onto transit. The average distance between stations and the free-
for all study corridors). This pattern is ideal for maximizing way is roughly 0.05 mile, well below the study average of 0.13.
automobile mobility, but is difficult to serve effectively with While the number of park-and-ride spaces per station in this
high-capacity transit. corridor (513) is below average compared to the study group
In terms of multimodal coordination, the average station (620), it is well above the average for study corridors that have
spacing for the Green Line (1.68 miles) is more than a mile
light rail transit (324), suggesting that for a light rail line, this
longer than the average interchange spacing (0.65 mile) sug-
corridor's stations are highly automobile-oriented.
gesting an automobile-oriented complementary corridor. This
substantial difference divides the travel market within the
corridor into two segments: long-haul, high-speed transit Transit-Optimized/Freeway Constrained
riders and freeway-accessible local travelers. This complemen- Multimodal Corridors
tary coordination works synergistically with the predominantly
The distinguishing feature of these corridors is the restricted
automobile-oriented land uses and stations to overcome the
capacity of the freeway facility. Constraining freeway capacity
Green Line's challenges in this corridor.
gives the corridor's transit line a performance advantage over
Denver T-REX/I-25. Denver's Southeast Transportation its freeway neighbor. Ideally, these corridors will combine the
Expansion Project (T-REX) line extends along the west side constrained freeway facility with either transit-oriented or
of reconstructed Interstate 25 to Lincoln. LRT lines to Union park-and-ride access features to take full advantage of transit's
Station and to 16th Street in the eastern part of the CBD link performance advantage. More specifically,
both trunk lines with the City Center (see Figure 3-1). The
T-REX/I-25 corridor, which was built and opened in 2006 has · In the "upstream" (non-CBD) section of the corridor before
been very successful at attracting transit riders. That this the freeway capacity constraint, the corridor is typically
corridor has attracted a substantial transit ridership, despite designed in a park-and-ride-access fashion where transit
the increased capacity brought by the T-REX project's free- services are oriented toward long-haul commuter travel.
way widening, suggests there is a great deal to be learned from Land uses and station access characteristics are generally
this case. automobile-oriented. Interchange spacings on the freeway
Urban form in the corridor before the project's opening are shorter than the transit station spacings, providing
suggests an extremely automobile-oriented pattern. Housing access to local corridor land uses by automobile.
densities were among the lowest found in the study group, with · In the "downstream" or CBD segment, the corridor is
less than 1 unit per acre (gross), substantially less than the designed in a transit-oriented fashion, with the transit line
study average of roughly 5. Employment is also low, with an oriented toward short-haul travel. Land uses and station
average density of roughly 5 employees per acre (gross), less access in this downstream segment are generally transit-
than half the study average of nearly 12. In terms of urban oriented as is the multimodal coordination, with long inter-
design, this corridor is decidedly automobile-oriented, as well. change spacings and short station spacings.
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Source: Colorado Department of Transportation, T-REX Fact Book.
Figure 3-1. Denver's I-25/T-REX corridor alignment.
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Where it Works downstream--create an effective hybrid corridor that matches
the design of the freeway and transit line to local urban form
· Washington DC Orange Line/I-66
patterns. The result is a highly successful transit line--the
· Chicago Blue Line/Kennedy Expressway (I-90)
only case in this study where the transit line's average daily
· San Francisco East Bay (BART) Pittsburgh/Bay Point Line/
boardings (139,000) exceed the estimated person trips of the
S.R. 24 freeway (127,000).
Washington DC Orange Line/I-66. Washington DC's
Chicago Blue Line/Kennedy Expressway (I-90). The
Orange Line runs into the District of Columbia from the
Kennedy Corridor is unique in several respects. Built in 1962,
Virginia suburbs to the west along Interstate 66. The rapid
its southern section was placed adjacent to the already existing
growth seen in this area over the past 30 years is an important
Union Pacific Northwest Line; as a result, the neighborhood
part of the story behind this corridor's success. Interstate 66
impacts of this portion of the Blue Line and the Expressway
is a unique case in that it was purposely built as a capacity-
were minimized. Land uses in this corner of Chicago were
restricted facility. Its four to six lanes could have easily been
established early and are distinctly transit-oriented in its
built as eight or more to handle the rapid growth in the
downstream segment and automobile-oriented in its upstream
corridor. However, as a part of the financing package from
segment.
Congress to fund the construction of the Orange Line, the
There are several reasons for this corridor's success. First,
Interstate was restricted to six lanes.1 While the section between
it has a heavy rail line that provides fast, high-capacity transit
Washington DC and the Theodore Roosevelt Bridge is
service directly to downtown Chicago. This transit advantage
designated as an HOV-2-only facility during peak periods,
is complemented by the freeway's design, which has a relatively
the capacity restriction still serves to effectively discourage
modest six lanes in its western portion, giving the rail line
automobile traffic on the inner section of this corridor. As such,
an advantage during peak congestion hours on the freeway.
this case sets an example of how freeway capacity restrictions
However, once I-90 merges with I-94 in the southern section,
can substantially boost parallel transit line ridership and
the freeway facility widens to include eight general-purpose
may also restrict total corridor throughput. The Orange Line's
lanes and two center-median reversible lanes, providing higher
separation from the freeway as it travels through the Rosslyn
freeway capacity to handle the added traffic from I-94. This
neighborhood of Arlington, Virginia, helps to make this one
freeway merge (and the reduction in total lanes from the
of America's best example of off-lining an HRT alignment to
two upstream feeder freeways) helps make the transit share
leverage TOD.
of total person-trips in the corridor 16 percent and placing its
Since the corridor has developed from largely rural
ranking at fifth-highest among the study corridors.
countryside to low-density suburban with large "edge city"
This corridor's success is also due in part to the way the
concentrations, urban form is decidedly automobile-oriented
transit line and the freeway were designed to match the vari-
in its non-CBD, upstream, segment and largely transit ori-
ations in the corridor's land uses and urban designs. Overall,
ented in its downstream segment. Housing densities in the
housing densities in the corridor are a respectable 10 units per
corridor--about 2.4 units per acre--are well below the study
acre (gross) but with significant variations within it. The up-
average of roughly 5 units per acre. In suburban fashion, the
stream segment generally has lower densities and the down-
street network in this corridor is largely automobile-oriented
stream segment higher. Employment densities show a similar
(largely curvilinear as opposed to a grid design) as suggested
variation, with the downstream segment providing direct
by the relatively low density of four-legged intersections
(0.7 for the corridor compared to 0.9 for the study cases). access to the CBD. Downtown Chicago has one of the largest
However, this corridor is rich with transit-oriented employ- concentrations of non-commercial floorspace in the United
ment in its downstream segment. The Orange Line runs States and is the second-largest of the study corridors. This
through several suburban "edge cities." As a result, the employ- provides a large anchor at the end of the corridor that attracts
ment density for this corridor is estimated to be roughly commuters to use the transit and highway facilities. The
39 employees per acre, more than triple the study average of 12. corridor's street network is also designed in a pedestrian/
Washington DC's central business district is large as well, with transit-friendly form, with a larger-than-average density of
over 95 million square feet of office space, providing a strong four-legged intersections per square mile, but again, the
set of anchors to the corridor's travel patterns and encouraging upstream street patterns are slightly more suburban than
use of the transit line. These segmented land use patterns--with the downstream street patterns.
automobile-oriented forms upstream and transit-oriented Access to the Blue Line's stations along this corridor is
decidedly transit-oriented in design as well, but with similar
differences upstream and downstream. Its stations have the
1
http://en.wikipedia.org/wiki/Interstate_66 lowest number of park-and-ride spaces of any study case.
