Wednesday, August 10, 2011

Spine Line Analysis

Spine Line Corridor
Source: PAT
"The Spine Line" Corridor Study, which was conducted in 1992 and published in 1993, explores alternatives to traffic congestion in Pittsburgh's main corridor, focusing mainly on 3 light rail designs that would extend the city's current LRT system. The area studied is the most developed area of Pittsburgh, extending east from Downtown, through the Hill District, Oakland and terminating at Squirrel Hill. There were "114,000 residents and over 229,000 jobs located in this corridor" in 1993 and the highest volumes of Pittsburgh Port Authority (PAT) riders, "115,000 of the 285,000 weekday riders" began or ended their commute within this area. The study explored a wide range of environmental impacts including land use, economic, displacements and relocations, neighborhood character, visual and aesthetic qualities, air quality, noise, ecosystems, wetlands, water resources, utilities, historical and archaeological sites, resources, and parklands. 

Three main alternatives were explored for extension of the LRT system from downtown to Oakland: 
-the Center Avenue Ave. Alternative
-The Colwell Alternative
-The Technology Center Alternative
All of these alternatives would connect to the Squirrel Hill Extension
LRT Alternatives
Source: Modified PAT image

The report describes each alternative as follows:

The Centre Avenue Alternative-  would have its junction with the existing "T" at the Manor Building and would be constructed as a subway for its entire length. The line would curve and follow Centre Avenue to Soho Street. It then would turn southeast to enter Oakland at Craft Avenue. Stations Nould be located at the Civic Arena, Dinwiddie Street, and Soho Street near Kirkpatrick.

The Colwell Alternative- would also connect with the "T" at the Manor Building. It could be built either at-grade or in a subway configuration along Colwell Street parallel to Fifth Avenue through the Hill.and Midtowncommunities. Stations would be located at the Central Medical Center and Hospital near the Civic Arena, at Dinwiddie Street and at Kirkpatrick Street.

The Technology Center Alternative- would have its junction with the "T" at the site of the former B & 0 Railroad Passenger Terminal and be constructed at-grade to the Pittsburgh Technology Center where it would rise up over the Parkway East before entering Oakland. Stations would be located by Duquesne University and at the Pittsburgh Technology Center. This alternative would also serve the proposed First Avenue station, which may be built even without the Spine Line

The Squirrel Hill extension.-It would be built in a subway configuration under Forbes Avenue from Morewood to its terminus east of Dallas Avenue. Stations would be located at Murray Avenue and adjacent to the Homewood Cemetery across Forbes Avenue from Frick Park.

These schemes generally were not expected to alter land-use or economic patterns within the study area. They also wouldn't have displaced a great number of residents or businesses. "The Technology Center Alternative would require the fewest displacements, with just two businesses affected. The Centre Avenue Alternative would displace 9 residences and 5 commercial uses. The Colwell Alternative would require relocation of 52 residences and 5 commercial structures." However, according to the study, there is more than adequate replacement housing and commercial building sites. Additionally, the schemes would offer no permanent loss of parklands.

I have found two designers, Craig Toocheck and Edward Shin, who have created informal schemes for LRT extensions for Pittsburgh in recent years. Craig Toocheck, a Catholic University Architecture Alumus, has a scheme that combines the Colwell and Centre Ave schemes. The yellow line from downtown eastward is his version of the "Spine Line." It has many stops along this corridor and in my opinion would be best to combine a local and express trains along its length. 
LRT Concept Map
Source: Toocheck

Shin, designer of Extra Cogent, has developed a map with far fewer stops. The equivalent of the "Spine Line" on his map includes two lines, the purple and green, which have stops at Mellon Arena, CMU, Pitt, Duquesne and Oakland. His scheme roughly includes both the Technology Center Alternative and one stop on the Colwell or Centre Ave Alternatives. 
LRT Concept Map
Source: Extra Cogent

The main difference between the schemes outlined in the "Spine Line" Study, besides which streets to follow, is the grade level of the tracks. The Colwell and Technology Center schemes deal mainly with at-grade tracks while the Center Ave scheme is below-grade for the majority of the scheme. The choice between at-grade and below-grade greatly affects the cost of the scheme as well as its presence in the city. The study calls this presence  "Visual Impact" and describes the consequences of the different lines:
 "The Colwell at-grade Alternative would be visible along Colwell Street and in the vicinity of Dinwiddie and Kirkpatrick Streets. The Technology Center Alternative would be visible along the Monongahela River segment, mostly in an existing railroad right-of-way where it would constitute no significant change. As that alignment rises onto aerial structure to cross the Parkway East, the bridge would be visible from that highway and Second Avenue, but would be isolated from sensitive uses and would be but one more of a series of bridges crossing over those roadways."

The "Visual Impact," or physical presence, is a critical architectural aspect of any new LRT within the city. It can attempt to blend in with its surroundings or stand out. If the city plans on celebrating the new LRT or BRT system that it builds, it "visual impact" must be positive on the city. The question is if at- or above-grade  designs, which are far cheaper, can actually greater serve the city's image. It is possible that a more visible system would better portray Pittsburgh's image as a modern city. As long as the at-grade lines don't sever the neighborhoods they passed through or obstructed traffic, they could potentially greater serve the city with a more dominant presence. (By no means am I suggesting building all of the lines above grade, but I am suggesting using this in key spots to "show off" the city's technology).

Much like designers Toocheck and Shin, I believe that having only one line run through the Spine Line corridor might be a mistake. This study was developed in 1993 and was not intended to be a complete comprehensive LRT system. If I am going to be examining this corridor as part of a greater citywide network, then many more factors will arise when designing this line and adjacent lines together. That said, it is true that the all three of these alternatives (Colwell, Tech Center and Centre Ave) are the major corridors within the larger district of the city and that ideally there would be lines running along all of these routes. However, if I were to choose which institutions to include in the Spine Line, I would prioritize Duquesne University, Consol Center (new home of the Penguins), UPitt and CMU, with the residential neighborhoods in the area being the second highest priority. 

Spine Line Corridor Study
Extra Cogent
Craig Toocheck Maps