Dallas Area Rapid Transit (DART), USA

The transportation system for the city of Dallas and its surrounding satellites seems to be dominated by the Dallas Area Rapid Transit (DART). This regional transport authority was set up in 1983 and funded by a 1% local sales tax. The authority covers 13 cities: Addison, Carrollton, Cockrell Hill, Dallas, Farmers Branch, Garland, Glenn Heights, Highland Park, Irving, Plano, Richardson, Rowlett and University Park. DART is administered by a 15-member board appointed by the member city councils based on population size. Dallas dominates by population and can appoint eight members and the remaining cities appoint seven members. Board members serve two-year terms at a time and then they may be reappointed for a further term. DART is now financed from a variety of sources since capital investment in transport systems requires extensive funding. DART gets finance from the 1% sales tax, federal funds, investment income, financing projects through bonds and fares.

DART serves the transportation needs of Dallas and the surrounding cities with 130 bus routes, 44 miles of light rail system (DART Rail), 31 miles of freeway with High Occupancy Vehicle lanes (HOV) and a Paratransit service for the disabled and elderly. DART also runs jointly, with Fort Worth transportation authority, the 35-mile Trinity Railway Express (TRE). This is a commuter railway system connecting downtown Dallas and Fort Worth with stops in the middle of these cities and DFW International Airport. At the present time there are several projects in consultation and underway to expand the DART network of public transport services.

The light rail system was opened in June 1996 and is 44 miles long. The system has 34 stations, a total vehicle fleet of 95 and carries on an average weekday nearly 58,000 passengers. The initial system was constructed in two phases: the starter system (20 miles long with 20 stations requiring an investment of $860 million) and phase two - North Central (24 miles long with 14 stations that required an investment of $1.011 billion). There are two lines: the Red Line, which runs from Park Lane to Westmoreland (Northeast to West), and the Blue Line, which runs from Ledbetter to downtown Garland.

The DART light rail expansion project saw the opening of seven new light rail stations on the Red Line in July 2003 - four in North Dallas and three in Richardson. The seven new stations will extend the DART Red Line by more than nine miles. In Dallas, the new rail stations are located at Park Lane, Walnut Hill, Forest Lane and Lyndon Baines Johnson/Central Expressway Interchange (LBJ). Richardson, a north Texas suburb, has just been made part of the DART light rail network with stations opening at Spring Valley, Arapaho Center and Galatyn Park.

DART RAIL EXPANSION PLANS

The light rail system is due to doubled in length by 2014 to 93 miles. A major extension will be the 17.5-mile northwest extension to connect downtown Dallas with Dallas Medical/Market Center, Love Field airport and the cities of Farmers Branch and Carrollton; this project is an extension of the Blue Line with an estimated cost of $850 million. In addition, a 13-mile branch will extend to the west and connect to Las Colinas Center in North Irving and DFW International Airport; this will be part of the new Yellow Line. Also a 10.2-mile southeast extension will connect Downtown Dallas, Fair Park, South Dallas and Pleasant Grove; this will be the new Purple Line.

The Purple Line will get nine stations and has been budgeted at $459.53 million; construction is due to start in late 2003. Other smaller line extensions due to be started in early 2004 are northeast downtown Garland to Rowlett Park and Ride, Central Business District will get a new line through downtown and South Oak Cliff loop 12 to LBJ freeway (I-20). Most of these projects are due to be completed between 2010 and 2014, however some shortfalls in funds are to be expected and these timescales may be extended.

DART operates more than 130 bus routes covering 13 cities and 700 square miles. Its fleet of nearly 800 buses is powered by either clean diesel or liquefied natural gas (LNG). The buses are equipped with comfortable seating, climate control systems designed for the Texas heat and high-tech features such as audio and digital route announcement systems, wheelchair lifts and kneeling capability to accommodate customers with disabilities.

Texas Department of Transportation (TxDOT) has begun the construction of a new of a new interchange in Dallas. The Lyndon Baines Johnson/Central Expressway Interchange (LBJ) in Dallas routinely experiences massive traffic congestion and backed-up loop ramps that cause much frustration to drivers. Other problems include dead-end frontage roads and confusing left-hand exits. To remedy these problems, TxDOT began the Dallas High Five Project, the largest construction contract it has ever undertaken.

TxDOT has sought advice in the design phase and at the start of construction from the Centre for Transportation Research (CTR). CTR's main objectives with the project are to minimize traffic problems throughout the construction process, to maximize cost and time efficiency during the construction process and to minimize the impact on users and adjacent businesses. The benefits on completion of the project are expected to be millions of dollars of savings for road users, in addition to improving safety, mobility, air quality and flexibility to meet future traffic needs.

US 75 / I-635 INTERCHANGE - EXISTING PROBLEMS

The interchange in question is between I-635 and US route 75; the roads leading to the interchange have already been upgraded to four lanes (US 75), however the interchange is still only two lanes and so automatically forms a bottleneck. The project will add the following to the interchange: two lanes in each direction along the US 75; two lanes westbound along I-635 and one lane eastbound along I-635. Another problem is frontage roads serving local commuters that also lead into the interchange and cause even further congestion. This matter will be resolved by the construction of new continuous frontage roads on the two freeways to serve local routes. The interchange also encompasses two successive left hand exits, which cause much confusion particularly with drivers unused to this type of road exit. The remedy will be to replace the two left hand exits with standard right hand exits. The final problem on the existing interchange is the backed-up loop ramps, the partial cloverleaf design which spans three levels, is out of date. The loop ramps are to be replaced with direct connection ramps. TxDot is to construct a five-level fully directional interchange with continuous frontage roads.

DALLAS HIGH FIVE PROJECT CONSTRUCTION

The project began in 2001 with some preliminary work and the appointment of the contracting engineers and designer JV Zachary Construction Corporation. The construction activity began in January 2002. The project is costing approximately $261 million and is due to be completed in 2006, taking just under five years to complete. The project at the end of 2003 is seven months ahead of schedule. This is due to the contractor instigating evening and night working so as to cause less disruption to the still busy road system. The project title High Five does provide a good description of the project. The interchange will be elevated and consist of roads running on five different levels:

• Level 1: four lanes of travel northbound and southbound US 75
• Level 2: frontage road box (named for the rectangular shape created by the intersection of continuous east-west and north-south frontage roads through the interchange)
• Level 3: five lanes of travel eastbound and westbound I-635 and two lanes each way barrier-separated HOV lanes on I-635
• Level 4: direct connection ramps from US 75 to I-635
• Level 5: direct connection ramps from I-635 to US 75 and reversible HOV lanes to/from I-635 west and US 75 north

DALLAS HIGH FIVE PROJECT ERECTION TECHNOLOGY

The road flyover system is being constructed using a state-of-the-art segment erector. This is a highly mobile hoist for moving segments of bridge and flyover into position. The big yellow and blue segment erector is the first of its kind in the US. It was designed and constructed by Deal S.R.L, of Italy. Deal is a subsidiary of Rizzani de Eccher, an Italian company with whom Zachry Construction has partnered to design and build the segmental portions of the direct connection ramps.

The erector weighs 101t and measures 97ft long by 38ft wide by 37ft tall and cost approx. $1 million to build. It will be used to hoist around 600 pre-fabricated segments to heights of 120ft on 18 columns. It is capable of lifting a load of 70t from the ground to the top of the pier at the rate of 30ft per minute. The columns will be constructed as normal using a ground based crane; after this the first three segments will be placed on top of the column also using the ground-based crane. Finally, the erector will be assembled on the platform formed on top of the column to hoist the other segments into position. Each segment can weigh from 35t to 70t and measure15ft tall and 10ft wide. The erector has the advantage of mobility; it can be moved on tires from one side of the bridge to the other. When the structure is finished the machine can be disassembled and reassembled in about two weeks to start on the next pylon.

The Trinity Railway Express (TRE) links Dallas - Fort Worth downtown areas with Dallas Fort Worth International. The scheme is jointly run by DART and the T (Fort Worth transit authority). The line is currently experiencing problems with its automatic ticketing system. The ticketing system at the nine stations is being replaced with a new more user-friendly system during 2003, which will also be able to process credit card transactions.