DALLAS TX:East-west tunnel proposed

A toll tunnel consisting of a 8km (5mi) pair of 3-lane tubes with two intermediate access/egress points is being proposed to Dallas and two neighboring cities as a way of improving east-west traffic flows just north of the central business district.

The proposal is being made by the Texas Turnpike Corporation (TTC), a previously inactive private company led by John Crew, an investment banker with long experience in researching and financing toll projects. TCC raised $5m capital last year. Crew is currently a senior VP at First Southwest Company, and has been responsible for some toll road financings. He has also held senior positions at Rauscher Pierce Reisnes, and at Dillon Read, both companies having been involved in financing and consulting on toll projects.

The only other member of the board mentioned in TTC documents is Kathy Ingle, a prominent Dallas businesswoman, with a long history of involvement on the boards of local transport agencies.

Mockingbird Tunnel

We’ll call it the Mockingbird Tunnel project since most of it is located under Mockingbird Lane, an east-west signalized arterial 7km (4.3mi) north of City Hall in the CBD. At the eastern end, it would start at US-75 (North Central Expressway) between University Park and Highland Park and be bored under Mockingbird Lane westward to the southern edge of Dallas Love Field, the inner city airport. Then at Harry Hines Blvd it would surface and on the right of way of Regal Row make connections with I-35E (Stemmons Fwy) and TX-183 (John Carpenter Fwy) which is the major route past the front door of Dallas-Fort Worth Airport. Total length of the project is 12km (7.5mi) and TTC says will have a construction cost of about $800m ($17m/lane-km or $27m/lane-mi), about the same cost as quoted for tunnels on I-635 (LBJ Fwy).

Apart from the interchange ramps at I-35E, the proposal only shows an exit/entry at Love Field. It would go clean under the Dallas North Toll Road, just halfway between US-75 and the Love Field IC – connections apparently not warranted. The tunnel would be located for most of its length approximately at the bottom of the 30m deep (100') Austin chalk stratum – deep enough to avoid affecting builds or utilities above.

TTC is preparing presentations on the scheme to the cities of Dallas and University Park and the township of Highland Park, as the municipal jurisdictions affected.

Rationale for the project is that there is no high standard east-west route between I-635 (LBJ Fwy) and the downtown area where the I-30 (Thornton Fwy) and the short northern CBD TX-366 connector (Woodall Rogers Fwy). That’s a distance of about 15km (9mi). The nearest thing to a decent intermediate east-west route is the strangely misnamed Northwest Highway (L-12) a signalized arterial about 3.5km (2mi) north of Mockingbird Lane.

No professional traffic and revenue studies have been conducted, but Lorraine Good, VP at TTC told us they are tentatively working with 60k veh/day as an attainable daily traffic number. The Sauer Corp of Herndon VA, have been engaged as tunneling consultants. The tunnel would be driven through the Austin chalk that underlays much of the Dallas area.

Good says they hope to reach an agreement with the three municipal governments first, then they’d proceed to develop the project. The three cities would engage Texas Turnpike I Ltd, a subsidiary of TTC, as project developer. The cities would form a Central Dallas Joint Transport Authority (CDJTA), a joint powers agency of the three which would finance, own, operate and manage the project. CDJTA would provide oversight for the cities and TTC would develop the project and take development fees. One of its first assignments would be to do detailed financial and engineering assessments.

TTC was formed in May 1991 under the Transp Corporation Act (later repealed) and is regarded as a ‘grandfathered’ corporation, and apparently escapes formal control of the Texas Turnpike Authority Division of TXDOT. TTAD/TXDOT permits and supervises newly formed toll companies. However as a practical matter of making connections to state-controlled highways, TXDOT support for the project would seem essential.

The project would have to justify itself as a standalone project between TX-183 in the west and the US-75, but a look at maps of the Dallas area suggest an extension northeast along a Union Pacific RR right of way.

Precedents

The North Texas Tollway Authority (NTTA) has had a short toll tunnel in operation since Feb 99 under the Addison Municipal Airport, just a few miles north of the proposed Mockingbird Tunnel (TRnl#35 Jan 99 p1). This is a much smaller project, just one lane each direction 18m (60') below the surface and 500m (1640') in length under the main runway and $15m in cost. TXDOT is planning tunnels of similar (2x3-lane) cross-section to the Mockingbird tunnel on the I-635 (LBJ Fwy) reconstruction. 2.1km (1.3mi) in length these have been estimated at $190m construction cost. (TRnl#49 May/June 00 p20)

Swedes dig

Stockholm the Swedish capital has an $800m downtown bypass tunnel under construction. The Sodra Lanken or southern link is the first of three underground sides of a ring system which would intercept major radials on the approaches to the downtown and connect them sub-surface. The link under construction has 5.5km (3.4mi) of twin 3-lane tubes together with three underground interchanges, a total of 16.5km (11mi) of tunnel. (WORLD HIGHWAYS Jul/Aug 00 p48). Other sections of the ring have for the moment been stopped by opposition.

In Madrid there are plans for investors to build tunnelways to a downtown underground ring solely for connections to underground parking and delivery in the central city in order to speed movement while freeing surface streets of road traffic.

In Sydney Australia Dec 99 an investor group Airport Motorway Ltd opened a double deck 2x3-lane tunnel of 1.7km (1.1mi) on the Eastern Distributor route between the airport and the central business district. Together with 1.3km (0.8mi) of walled and lidded roadway the construction cost was $355m (TRnl#44 Nov-Dec 99). The A86/West tunnels under construction in the Versailles area just west of Paris, a missing link in a second Paris-area beltway is a low clearance (2m) facility with 3-lanes atop 3-lanes the other direction is a little longer than the Mockingbird, and through much more difficult geology. It is 10.1km (6.3mi) and is expected to cost about $1b. (TRnl#43 Oct 99 p7) Tokyo, Melbourne, Oslo, and Zurich all have land toll tunnels in operation or under construction. In the US the big one under construction is the Big Dig in Boston at extraordinary cost – about $47m/lane-km ($75m/lane-mi), at which cost the Mockingbird would cost $2.3b! Singapore and Haifa plan land toll tunnels.

In the US, Brooklyn NY (Gowanus), the City of San Francisco and Coronado in San Diego are examining land tunnels.

Trinity River Parkway

Dallas is already actively studying the Trinity River Parkway, a new toll facility to enhance north-south capacity around the central business district, and to relieve congestion in what they call the Canyon-Mixmaster interchange of I-30/I-35E. Mostly 2x4-lanes and about 15km (9mi) long the Parkway, just to the west of the CBD, would be built on the levees of a much larger flood control, bridge renewal and beautification project down what they call the Trinity River – presently a succession of stagnant mosquito breeding pools in a small concrete channel set in a boring featureless grassed flood plain.

The NTTA has an Enviro Impact Study of the Trinity River Parkway under way, hoping for a record of decision mid-01. The Parkway would go from US-175 before its western terminus with I-45 up the flood plain past the CBD and at the north end hook into TX-183 and I-35E very close to the proposed western end of the Mockingbird Tunnel. (Contact Lorraine Good TTC 214 526 5500 texasturnpikecorp.com)