Case Studies

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Project: Skid Resistant Grit Coat on the Newark Airport Monorail in Elizabeth, NJ

In order to alleviate traffic and parking problems around Newark Liberty International Airport, the Port Authority opened the Newark Airport Rail Station in 2001. The Newark Airport Rail Station is a train station that is connected to both the Northeast Corridor and North Jersey Coast train lines, providing train access to New Jersey and New York Residents. The airport can be accessed from the Rail Station via AirTrain. AirTrain is an 8 mile long monorail, opened in 1995 and run by Bombardier, which stops at all airline terminals and several parking areas. AirTrain allows passengers to travel to and from the airport without worrying about traffic, tolls, taxis or shuttle buses. There are two tracks, airside which runs from the rail station to the airport and landside which runs from the airport to the rail station, with a rotating switch system that can transfer trains from airside to landside and vice versa. Operating 24 hours a day, 365 days a year, it is crucial that AirTrain is constantly maintained and in working order.

When AirTrain was built, steel sections of track were prefabricated with a grit coat on the upper surface of the rail, providing more friction for the wheels. After years of use, the grit coat has started to wear away, especially at points near the stations where the train is accelerating and decelerating. At these points the coating is reduced to primer and in some places bare metal, which has rusted over. When the train travels over these sections of track, it is not uncommon for the train wheels to slip. In the case of a wheel slipping, the train will brake as a safety measure, shutting down that side of the track to all trains. Bombardier must then have a recovery operator drive to the nearest station, walk the guideway to the train and manually reset the safety system, an expensive and time consuming process. In an effort to prevent this from happening Bombardier covered the bare sections with grip tape. This provided a temporary fix but a more permanent solution was necessary.

In 2009 Alpine Painting was awarded a time and materials contract to reapply the grit coat system over a three week period. At that time the most efficient way to remove the grit coat was using handheld grinders with cup stones. Our crew at its peak included 16 men, 12 men with grinders and 4 men applying the coating. Although it was a labor intensive process, we found it to be the best way to complete as much as possible in the three weeks allotted. Once the work was complete, Bombardier was satisfied with the end result. Due to safety concerns with such a large crew in close proximity to live trains, they requested we find a new method if any more grit coat repair is to be performed.

In May of 2011 Bombardier decided to begin planning a second phase of grit coat repair. Knowing that the use of a large crew was not preferred we decided to develop an alternate method to perform the work. With a recent purchase of a Farrow 650 Max slurry blasting unit, we could speed up the work, use less labor and provide a higher quality surface profile for the coating system. When compared to the profile from the cup stone grinders, the slurry blast finish has a more aggressive and angular surface profile (2 to 3 mils) with larger peaks and valleys. With slurry blasting we came across a few obstacles. Containment was the first problem; space was limited and we had to be conscious of the active train on the opposite side of the track. Also, underneath the flanges of the track is a power rail on each side, one used to power the train with 60,000 volts and the other is a signal cable used to control the train. Both of these consisted of three separate power lines protected on three sides with a hard plastic sheath. It was imperative that both of these lines remained protected from the blasting & coating work at all times. The second problem was fall protection; the heights we would be working at ranged from 6’ to 40’, so it was necessary for the workers to have adequate fall protection at all times. With safety as our number one concern we looked for an efficient way to solve our containment and fall protection problems.

In the beginning we approached the containment and fall protection as two separate problems. For containment, we used AutoCAD to design a rolling aluminum cage that would have a wheel structure similar to the monorail in order to prevent racking and keep it on the track. The cage would be wrapped in heavy duty tarps around the circumference and then have an additional tarp over the top to cover any seams. We then planned on mounting plywood sheets to extend below the flange and above the two high voltage rails to ensure that they did not get damaged from blasting. For fall protection, we originally planned on using a beam roller & lanyard system from a previous project. This was a steel beam with two wheels that hugged the flange and would travel behind the cage. We began to send our designs out to fabricators to get an estimate on how much the aluminum cage would cost. During this process we contacted the scaffolding company Swing-Lo, whom we’ve worked with in the past, which specializes in unique and custom scaffolding systems for anything from bridges to railways. While browsing through their catalog we found a rolling guardrail system that is designed to sit on top of two parallel I beams, allowing workers to be secured by a fall protection system that meets OSHA requirements at all times. Over the course of the next two weeks we worked with Swing-Lo to custom fit and adapt the work cage to the dimensions of the monorail track and have enough room inside for a blaster to work. We received the final drawings, sent them over to Bombardier and once we received approval we immediately started fabrication.

With the new approved system we worked with Bombardier to write up a proposal. The scope of work consisted of cleaning, preparing and reapplying the grit coat system to the outer 8 to 10 inches (both tire paths) of the landside & airside monorail track. Work to be performed on the landside consisted of 150 LF of track at the Rail Link, the station that connects the Newark Airport Rail Station to AirTrain, and another 110 LF of track approximately ¼ mile south. Work on the airside consisted of 250 LF of track located in between the two blocks on landside. Total work area to be approximately 1020 LF of wheel path (510 LF of track).

The coating system that was used was one basecoat of Sikadur 22 Lo-Mod @ 40 SF/gal (approx 35-40 mils) and broadcast to rejection with red Estes sand. Allow basecoat to cure according to Sika recoat schedule and then remove excess sand. Apply one topcoat of Sikadur 22 Lo-Mod @ 30 SF/gal (approx 45-50 mils) and broadcast to rejection with red Estes sand.

Alpine Painting was given a strict two week schedule to complete the work on both landside and airside. If both sides of the track were not active by Sunday, October 2nd, Bombardier faced a monetary penalty from the Port Authority. In order for AirTrain to continue to operate, one side would be in service and the other side would be locked out. After the topcoat was applied, Sika requires a minimum of 24 hours cure time at 70 degrees F before the trains could be returned to service.

Once all of the paperwork, coordination and safety training had been completed, we set out to mobilize on Monday, September 19th. At 5:00 am, we met at our office in Paterson, NJ, where we had gathered all of the necessary equipment to get the job started. With the slurry blasting unit and compressor in tow we headed to the airport. The meeting place for the next two weeks would be a parking lot right outside the security gate to Rail Link. We would wait at this parking lot every morning for our assigned escort from Bombardier to show up. No personal vehicles were allowed so at that point we would either pack into our company van or get into the bombardier truck with our escort. Once inside the security gate, we were under no circumstances allowed to leave the sight of our escort or even more importantly enter the monorail walkway unless under close Bombardier supervision. Throughout our time spent at the airport we were permitted two escort shifts a day, it was up to us when we wanted to use them. We planned to start on the landside track, running two shifts of 4 to 6 men a day, completing all of the work from Monday through Thursday, allowing the coat to cure all day on Friday. Bombardier would then have the weekend to switch the trains from airside to landside, allowing us to start work on the airside track the following Monday.

Before any work could begin, every morning a representative of Alpine would verify that both of the power rails had no current and that the switches were locked out and would not rotate. After a lengthy mobilization we verified the lock out and immediately had four men start grinding the switches. Because the switches have so many mechanical parts Bombardier requested that we use grinders instead of sand blasting.

Once the slurry blasting equipment and containment was setup, work had fully begun. In the beginning we started with crushed glass abrasive and were producing approximately 12 lineal feet per hour of blasted track. By the jobs end, through pressure adjustments and an abrasive switch to coal slag we had increased our production to a maximum of 60 lineal feet per hour of blasted track.

On Tuesday, we started to pay close attention to weather forecast. The report was grim so we knew that our original plans must be open to change. The weather over the course of the next two weeks became some of the worst weather we’ve seen all year.

Since slurry blasting is a wet method of surface preparation, used to mitigate the dust generated from dry abrasive blasting, we were able to continue work in adverse weather conditions. So in order to prevent rust bloom in the newly blasted steel, we used Hold-Tight 102 at a ratio of 50 to 1. Hold-Tight works well as long as the wet surface is allowed to dry and no rain washes it away. Since we had to preserve every ounce of dry weather for coatings work, it rained regularly during our surface preparation. To try to prevent immediate rusting we covered the newly blasted track with plastic, but minor rust bloom still occurred.

Just before each clear weather opportunity, we returned to re-prepare the areas of rust bloom by abrasive blasting. Once dry, the coating work began with the application of the Sikadur epoxy followed by a cast of red Estes sand to rejection. After a 2 to 3 hour cure, the loose sand was vacuumed and we were ready to apply the second coat.

As with all new out-of-the-box ideas, this project got off to a bit of a slow start but we were able to pull it together and get the work done with a high degree of quality and most importantly on time. The biggest obstacle of all was the constant struggle with weather. Throughout the course of two weeks we only had four days with no rain. Despite all the difficulties, the customer was very pleased with the end result. Applying the grit coat was a unique project and we overcame many challenges and obstacles alone the way. Working with Bombardier was a pleasure and with 8 miles of track we look forward to working with them again.

Project Details

  • Project length: Two Weeks Working Two Shifts a Day
  • 1020 LF of Track Grit Coated
  • Sika-Dur Lo-Mod 22 Epoxy
  • HP 40 Red Estes Sand

Credit To

Victor Caratenuto, Bombardier Planning Manager

Tom Cassidy, Field Service Engineer

Andrew Erwin, Alpine Painting's Project Manager

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