Page 10 - TunnelTalk Annual Review 2013

Fig 1. Current extent of the LA Metro with the three new lines in dashes
Scoping expansion of
Shani Wallis, TunnelTalk
It is 20 years since the first section of modern mass-transit came into service in Los Angeles. The initial 4.8-mile (7.5km) operating segment of the Red Line, running beneath the streets of downtown LA in twin shield-driven running tunnels and open-cut underground stations, opened to the public in January 1993. This followed the 1990 opening of the 22-mile largely at-grade Blue Line running to the south between downtown LA and Long Beach. Since then a further 67 miles (about 110km) of surface and underground routes have been added, including the 6-mile light rail Gold Line Eastside Extension, with its nearly 2-mile section of twin bored running tunnels, six at-grade stations and two underground stations that opened in 2009 to run services into East LA from the Union Station transportation hub (Table 1, Fig 1).
During a 10-year break in heavy-rail subway construction, much effort has been spent by professional engineers to promote, to the general public and to local and Federal politicians, the ability to build underground transit lines beneath LA safely including through its gassy soils and tar sands.
The success of the effort has culminated in a current extension of the underground heavy-rail system as one of a program of three new lines that are in the process of procurement. Building to a total of nearly 19-miles and nearly $10 billion of new infrastructure, the three Lines are:
The 1.9-mile Regional Connector to link the current terminus of the Blue and Expo Line at the 7th/Metro Center Station to the Gold Line near the Little Tokyo/ Arts District Station in a new underground alignment for a total estimated project cost of $1.399 billion.
The 8.5-mile light-rail Crenshaw/ LAX corridor project, which includes
sections at grade, elevated over major traffic intersections, and underground at LAX International Airport and at additional locations, to link the Expo Line on Exposition Boulevard and the Metro Green Line with its current bus link station to LAX Airport, estimated at $2.058 billion.
The Westside Purple Line beneath Wilshire Boulevard from the existing Wilshire/Western Station to the Wilshire/La Cienega Station as the first of three, entirely underground, construction phases that will continue the Purple Line 9 miles, eventually to Century City and Westwood. Estimated at $6.5 billion and based on a 30-year plan, the last section to Westwood will open in 2036, and the first 3.92-mile phase will contain three underground stations.
The new projects are managed within the Los Angeles County Metropolitan Transportation Authority (Metro) by the Transit Project Delivery Construction Project Management department, headed by Executive Director K.N. Murthy. In his team, the underground Purple Line is managed by Project Director Dennis Mori, who managed Metro’s construction of the Metro Red Line from Hollywood through the Santa Monica Mountains into the San Fernando Valley, and more recently the Gold Line Eastside Extension project into East LA. Project Director Bryan Pennington is managing the Regional Connector and the Crenshaw/LAX Lines.
Parsons Brinckerhoff, the engineering firm which has worked on the LA Metro since its beginning, is the preliminary engineering consultant for the current works with Lead Tunnel Engineers Amanda Elioff for the Purple Line Extension and Bill Hansmire for the Regional Connector. Hatch Mott McDonald is the preliminary engineering consultant on the Crenshaw project and Derek Penrice is Lead Tunnel Engineer. Matthew Crow is technical tunnel design reviewer for Metro’s engineering department.
Design-build procurement
For the current projects, Metro has departed from its previous design-bid- build procurement strategies, and the three new contracts are all procured as design-build contracts based on preliminary engineering designs by Parsons Brinckerhoff for the Purple Line, Aecom/Parsons Brinckerhoff JV for the
Regional Connector, and Hatch Mott McDonald for the Crenshaw/LAX project.
In explaining the new strategy, Executive Director Murthy said, “Metro is now a mature client and has more than 20 years of experience building heavy- and light-rail systems. As comparable projects with these earlier works, we feel there is no need to spend time and money completing 100% detailed design ahead of engaging a design-build contractor for the new works. M&E requirements in the design-build proposals are included as performance specifications and the new civil works are extensions of existing lines and require continuity and compatibility with those earlier installations.”
“Design-build brings two important advantages,” continued Murthy. “First we gain 12-18 months on the overall procurement by overlapping detailed design with construction; and secondly, risk is more equally shared between the client and the contractor with the final design having to comply with strict client requirements. While there is room for innovation on means and methods, there will be no experimenting on these projects. All design-build proposals are required to comply with a selective prescriptive design-bid-build approach.”
Crenshaw/LAX Line
The first of the three new lines into construction is the 8.5-mile Crenshaw/LAX light-rail project following its design-build award in May 2013 to Walsh/Shea Corridor Constructors. As one of four proposals, the contract was awarded to Walsh/Shea as the bid with the highest technical score for the lowest price of $1.272 billion. As well as the guideway, which is mostly at-grade, the contract includes construction of eight surface stations and all M&E installations. HNTB and Arup are design engineers to the Walsh/Shea design-build contract. Heavy construction is scheduled to start in Spring 2014 towards an expected completion date by 2019.
Regional Connector
Preliminary design of the nearly 2-mile Regional Connector by Aecom/Parsons Brinckerhoff is based on an open cut construction along Flower Street in downtown Los Angeles with twin TBM bored running tunnels and an SEM crossover cavern along Second Street to connect the Blue and Expo Line terminus station at the 7th/Metro Center Station to the Gold Line near its Little Tokyo/Arts District Station, which will be replaced underground (Fig 2). The connection will allow a one-seat ride for travel across Los Angeles County from Azusa to Long Beach and from East Los Angeles to Santa Monica (Fig 1).
Proposals for the design-build contract were invited in January 2013 and submitted in September 2013 from the four prequalified teams:
Los Angeles Metro
Table 1. Development of the Los Angeles Metro to date
Service
Length
Opened
Daily ridership
Metro Blue Line
22 miles
1990
88,000
Metro Red Line 1, 2, 3
17.4 miles
1993, 1999, 2000
168,000
Metro Green Line
20 miles
1995
42,000
Metro Purple Line 1
1996
(with Red Line)
Metro Gold Line 1, 2
19.7 miles
2003, 2009
44,500
Metro Orange Line 1, 2
18 miles
2005, 2013
30,250
Metro Expo Line
8.6 miles
2012
27,300
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