Skyway repair triggers extensive traffic planning
When the first bridge was opened
in 1958, the designers of what is now formally known as the Burlington
Bay James N. Allen Skyway Bridge probably did not envisage the
unrelenting growth in traffic volume that would follow.
|Expansion joint edges were milled by a Bitelli |
planer making a 600 mm wide cut.
When the first bridge was opened in 1958, the designers of what is now formally known as the Burlington Bay James N. Allen Skyway Bridge probably did not envisage the unrelenting growth in traffic volume that would follow. Volumes have increased eight fold from average annual daily traffic (AADT) counts of 17,000 in 1960 to 133,500 vehicles/day in 2004, resulting in the addition of a second bridge in 1985. With these volumes, construction zone traffic management has become a major undertaking during any topside bridge repair work.
Tony Thoms is project manager for general contractor ConCreate USL Ltd. on the current round of Skyway repair work. Thoms explains that the two high level bridges on this arterial Ontario highway carry the Queen Elizabeth Way (QEW) over the Burlington Canal. The original 1958 bridge carries four lanes of Toronto bound (northbound) traffic over the canal while the 1985 bridge carries four lanes of Niagara (southbound) traffic. Extensive repair work to bridge expansion joints would, at least on the night of Aggregates & Roadbuilding’s visit, require closure of all four Niagara bound lanes and full traffic diversion around the bridge. With volumes remaining high during the evening and at night, construction zone traffic control involved not only numerous contractor’s personnel but also the Ontario Provincial Police (O.P.P.) as well as City of Hamilton and City of Burlington police. Several Niagara bound access points ahead of the Skyway were closed, with all traffic diverted across the nearby lift bridge and along Eastport Drive before rejoining the QEW south of the Skyway.
The same night, resurfacing work on the Toronto bound lanes being completed under a separate contract would leave only a single bridge lane open for traffic during the night. On that bridge, Thoms notes that the subcontractors’ decision to pave on a Friday night was driven by allowed lane closures: “The four lanes on the section being repaved are numbered one to four from left to right (fast to slow) in the direction of travel. Work that night involved milling and paving a section of lane two and the consequent closure of lanes one, two and three. As a result, all traffic would be confined to lane four, with lane three providing a buffer between live traffic and the construction crews working in lane two. Contract conditions state that the three-lane closure could not begin before 11 p.m., while all lanes had to be fully reopened to traffic by 7 a.m. on the following Saturday morning.
The resurfacing work is part of contract MTO 2007-2034, valued at $5.5 million, of which paving is worth some $1.5 million. Tender documents indicate that resurfacing extends 2.2 km including bridge approaches and involves the removal of 46 858 m2 of existing asphalt to a depth of 40 mm. Some 4 800 tonnes of SP 12.5 FC2 mix will be placed to a compacted thickness of 40 mm, with subcontractors Hard Rock Paving and King Paving and Materials completing milling and paving respectively. Resurfacing began in the first week of June 2008 and is scheduled for completion in October.
King Paving’s vice president of operations John Hutter explained that the night’s paving target was 1200 lane metres of lane two, translating into some 4500 m2 or 450 tonnes of hot mix asphalt. By 11 p.m., the work crews and an impressive array of equipment were in position. Hard Rock kicked off the milling work utilising the company’s Terex PR-800-7 cold planer, with the goal of milling a 1.5 km stretch of the 3.75 m wide lane in about six and a half hours. The PR-800-7 made rapid progress, pausing briefly to raise and lower across expansion joints. The edges of the joints were milled shortly afterwards by a Bitelli planer making a 600 mm wide cut parallel to the joint edge. Several pieces of clean up equipment supporting the planers included a Bobcat S220 turbo with sweeper attachment, a New Holland L170 skid steer loader with sweeper and box attachment as well as a Schwarze Industries M5000 broom sweeper. After giving the milling operation a start of about an hour and a half, the first of King’s paving crew went into action, applying tack coat with an Etnyre Black–Topper asphalt distributor.
Hot mix asphalt for the job was produced at the King Paving plant in Burlington, with the company’s delivery fleet including a Mack Vision tractor unit teamed with a new Trail King Industries Red River Series live bottom construction trailer. On site, the mixture was placed by a new Caterpillar AP1055D paver equipped with Topcon controls and a 10-25B Extend-A-Mat screed. Behind the paver, a Caterpillar CB534D roller in the breakdown position made two passes followed by a Bomag BW11RH nine-wheeled pneumatic roller making eight passes. At the rear of the train, a Bomag 164AD dual steel drum made passes as necessary to finish the mat. Asphalt raw material sources included Canadian Asphalt PGAC 70-28 asphalt cement, coarse and fine aggregates from the Rosewarne quarry of Fowler Construction Company Limited and chip sizes from the Havelock quarry of MRT Aggregates Inc. n