Cover Image

Not for Sale

View/Hide Left Panel
Click for next page ( 27

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement

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 26
26 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

OCR for page 26
27 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

OCR for page 26
28 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.

OCR for page 26
29 Source: Colorado Department of Transportation, T-REX Fact Book. Figure 3-1. Denver's I-25/T-REX corridor alignment.

OCR for page 26
30 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 lowest number of park-and-ride spaces of any study case.