Rail Base Corrosion Detection and Prevention (2007)

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C-1 APPENDIX C Transit Authority: Port Authority Trans-Hudson Corporation Response Received: 01/10/06 Contact: Steven Abramopaulos, Chief Maintenance Supervisor Track (201) 216-7200 SUMMARY The Port Authority Trans-Hudson (PATH) Corporation operates a 50-track mile, 600-V DC third rail traction, passenger transit system. Rail includes 100-lb RB Beth welded and/or bolted. The following table summarizes the operating and inspection conditions used by the PATH: Maximum operating speed 60 mph Wheel load 10,000 lb Frequency of the rail breaks due to rail base corrosion Eight annually Rail defect detection frequency Twice per year Type of ties Wood and concrete ballast Power Source Third rail It has been reported that severe corrosion occurs at various locations for the PATH. The New Jersey transit location experiences a significantly high incident of corrosion because of the tunnel locations. In the tunnels, there are locations where the humidity/water has been identified. In general the corrosion locations are identified in sections with leaks. Over the last few years several locations with corrosion were found, but, on average, eight of these locations caused rail breaks. It has been determined that the major contributor to rail base corrosion is the negative return current that is grounded through the rail. The following photos show samples collected from the PATH line exhibiting severe rail base corrosion.

C-2 PATH Transit System showing (a, b) rail corrosion, (c) ice spikes from sealant used to prevent water leaks in the tunnel, and (d) salts deposited along the tracks. Note: The site visit was conducted during January 2006 and due to the weather conditions in New York and New Jersey, the water leaks froze forming the ice spikes shown in photo (c). (a) (b) (c) (d)

C-3 Transit Authority: Toronto Transit Commission Response Received: 01/25/06 Contact: Brian H. Longson, Superintendent – Maintenance Engineering Track & Structure Department 1138 Bathurst Street Toronto, Ontario M5R 3H2 (416) 393-4419 SUMMARY Toronto Transit Commission (TTC) operates a 42.5-track mile, 600-V DC. Negative returns carry a 500 A at a potential of no more than 30 V above ground. In addition, the other rail carries the signal circuit which is less than 1 amp current and > 10 volts. Their rail facilities are integrated by both, Sysco Standard Carbon (100 lb ARA-A) and 115-lb RE, rails, with nominal rail hardness of 300 Brinell and the tracks are usually flash welded. TTC reported between ½ and 1 corrosion defect/mile/year or between 30 and 60 defects require removal annually with the majority of these defects being in the same location. This transit system consists of a direct fixation line with a heavy transit with a yearly traffic of 25 million gross tones (metric) per year. TTC maintenance is conducted manually in-house when the facilities are closed at night to the public. The rail base corrosion occurs due to electrolysis caused by DC at the contact point with wet debris (mud, slime) building up under the rail base. Stress corrosion cracking is evident and is suspected to result from sulfide corrosive environments often caused by tunnel leakage. These may develop sharp, vertical fissures in the base/web region, which are very difficult to detect. Detection is accomplished primarily by a NDT crew. In addition to declaring rail defective and requiring replacement, the NDT crew notifies the maintenance crew to clean rail base/seal leaks within a specified timeframe; otherwise rail is re-inspected and replaced. Prevention is mainly accomplished by ensuring rail fastening system insulation is functioning and via leakage sealing of tunnels. The following table summarizes the operating and inspection conditions regularly used by TTC-Toronto: Maximum Operating Speed 50 mph Wheel Load 7.5 ton/wheel Frequency of the Rail Breaks due to Rail Base Corrosion Between ½ and 1 corrosion defect/mile/year or between 30 and 60 defects requiring removal annually. Rail Defect Detection Frequency In-house and on daily basis. Type of Ties Direct fixation to invert and large block (double) concrete ties Power Source Third rail The following photos show samples collected from the TTC-Toronto line and exhibiting severe rail base corrosion.

C-4 TTC-Toronto tracks showing deposited salts and resulting corrosion.

C-5 Organization: National Railroad Passenger Corporation — New York Response Received: 02/03/06 Contact: Walt Heide, Deputy Chief Engineer – Track John A. Pielli, Director Track Maintenance & Compliance Glenn H. Pedersen, Sr. Engineer Track Cond. & Analysis (215) 349-3139 or 1179 SUMMARY The National Railroad Passenger Corporation (Amtrak) system carries both freight and Amtrak trains. There are two types of passenger trains: Acela and regular passenger trains. The Acela has a wheel load of 16-25½ tons per car. Both types of power are used: AC (overhead catenary) and DC (third rail). Wood ties, direct fixation and embedded tracks are used by Amtrak. Rail life is ~4.5 years due to the excessive corrosion in the system. Although the ~4.5 year life is average, there are some sections of rail that are replaced yearly. The corrosion at the base of the rail is extended in almost all areas of the track including, tie plates, tunnels, curves, tangents, joints, and high and low rail. Yearly traffic running through the seven tunnels in New York is conservatively 200 MGT, and the maximum operating speed is 60 mph. Amtrak conducts its own maintenance and track inspection, with the following regularly performed practices: • Internal inspection twice yearly • Bi-annual dedicated detailed base corroded rail walking inspection • Twice weekly walked daily track inspection The tracks are owned by Amtrak, with dedicated routes for the Long Island Rail Road and New Jersey Transit. Amtrak-NY consists of a heavy rail transit system using 136 lb RE rail. The electric currents passing through the rail are AC traction return with a frequency of 25 Hz and 650 V. Additionally, there is a DC traction return with 91 2/3 Hz signal. The temperature in the tunnels varies between 20 and 80 degrees Fahrenheit within a 1,000-foot section, and inside the tunnel the temperature ranges from 35 to 75 degrees Fahrenheit. There is no rail preparation prior to its installation on tracks. The typical corrosion occurs at the base and works its way up toward the web. It may cause a “hollowing-out effect” or gradually thin out the base until the edge is razor sharp. The major factors that contribute to corrosion for Amtrak are • Moisture in a confined space, • Competing fields of electricity, AC, DC, and uncontrolled stray currents, • Impedance bonds and cab signal assets, • AC power returns to substation through neutral leads in rail from impedance bond cut section, and • Original tunnel design included a sacrificial bank of lead in the bench wall, which is no longer connected.

C-6 The following photos show corroded rail on the south tunnel in New York City. Amtrak tracks showing flooded tracks and pumping system used to remove water from the track.

C-7 Organization: National Railroad Passenger Corporation — Baltimore Response Received: 02/03/06 Contact: Walt Heide, Deputy Chief Engineer – Track John A. Pielli, Director Track Maintenance & Compliance Glenn H. Pedersen, Sr. Engineer Track Cond. & Analysis (215) 349-3139 or 1179 SUMMARY The National Railroad Passenger Corporation (Amtrak) system carries freight, Amtrak, and commuter trains. Amtrak passenger trains have 25.6 gross tons for passengers and 37 gross tons for freight cars. Power types used are overhead catenary (AC) and DC light rail nearby. The system is composed of wood ties encased in concrete due to the excessive corrosion in the system. Rail life is ~4.5 years. The yearly traffic running through two tunnels in Baltimore is ~ 25 MGT, and the maximum operating speed is 30 mph. Amtrak conducts its own maintenance and track inspection, with the following regularly performed practices: • Internal inspection twice yearly • Bi-Annual dedicated detailed base corroded rail walking inspection • Twice weekly walked daily track inspection The Baltimore tunnel is owned by Amtrak and utilizes 136-lb RE rail. Electric currents passing through the rail are 25 Hz AC traction return and 100 Hz signal. Temperatures in the tunnels vary from 20 to 80 degrees Fahrenheit within a 1,000-foot section. Inside the tunnel, temperatures range from 35 to 75 degrees Fahrenheit. No rail preparation is made prior to installation on tracks. The typical corrosion occurs at the base and works its way up toward the web. It may cause a “hollowing-out effect” or gradually thin out the base until the edge is razor sharp. Major factors contributing to corrosion for Amtrak are • Moisture in a confined space. • Competing fields of electricity, AC, DC, and uncontrolled stray currents. • Impedance bonds and cab signal assets. • AC power returns to substation through neutral leads in rail from impedance bond cut section. • Disconnect of neutral through the tunnel. There is a neutral area with a ground at Weehawken and at MP 3 for the 2 North River tunnels. • Original tunnel design included a sacrificial bank of lead in the bench wall, which is no longer connected. The following photos are examples of corrosion occurring in the Baltimore station tunnels.

C-8 Rail donated by Amtrak (Baltimore) and a location on the tracks showing severe corrosion.

C-9 Transit Authority: Port Authority of Allegheny County Response Received: 06/22/06 Contact: James D. Dwyer, Director Technical Support (Retired) Jimdwyer@nauticom.net SUMMARY The Port Authority of Allegheny County (PAAC) system is a 40-track-mile system. Energy is supplied by an overhead catenary system using a 660 V DC system. The track is made of 115-lb RE standard carbon rail. The rail used by this transit agency is embedded in the concrete roadway slab without insulation or corrosion protection. The corrosion is usually located at the railroad crossings. At this time, this transit authority has no reports of rail failure due to rail base corrosion. Average rail life is between 10 and 15 years. Track condition is not optimum. However, no safety problems have been reported. Currently a new method for rail installation is used. This method consists of embedded rail that is cast in an elastomer (Icoset) that totally seals the rail, which means the rail is encapsulated. The Icoset is poured into a slot located in the concrete slab. No ties are used on the slabs, which are between 10 and 12 feet long. Slab and rail are installed according to procedures described in TCRP Report 71, “Track-Related Research, Volume 6, Direct-Fixation Track Design Specifications, Research, and Related Material, Part A: Direct-Fixation Track Design and Example Specification,” which is used by different transit agencies. The track is owned by the Port Authority of Allegheny County, which is also responsible for its maintenance. The track is inspected weekly by track inspectors, and ultrasonic testing is conducted yearly. The following table summarizes the operating and inspection conditions used by Port Authority of Allegheny County light rail cars: Maximum Operating Speed 10 mph thru ungated rail crossings Wheel Load 12 to 14 tones Frequency of the Rail Breaks due to Rail Base Corrosion None reported Rail Defect Detection Frequency Once yearly Type of Ties Concrete, direct fixation Power Source Overhead catenary The following photo, donated by the Port Authority of Allegheny County, is an example of rail corrosion at the base of a rail.

C-10 Rail donated by PAAC showing severe corrosion at the base.

C-11 Transit Authority: Metropolitan Transit Authority, New York City Transit Response Received: 07/12/06 Contact: Antonio Cabrera. P.E.; Director, Track Engineering 130 Livingston St, Room 8028, Brooklyn, NY 11201 SUMMARY The Metropolitan Transit Authority-New York City Transit (MTA-NYCT) system consists of a heavy rail rapid transit system. NYCT is the largest agency in the MTA regional transportation network. It has the fourth largest subway car fleet in the world. The MTA-NYCT network has approximately 660 miles of passenger service track and 180 miles of nonrevenue service track (e.g., in subway yards). Energy is supplied by a third rail system using a 600 V DC. The track uses 100-lb ARA-B, OH, FT, HH standard carbon rail. Recently, the MTA-NYCT began changing track from 100 lb to 115-lb AREMA rail. Currently, the rail in open areas and some of the tunnels is 115 lb. However, in some locations the transition from 100-lb rail to 115-lb rail is ongoing. The corrosion of the rail base has been observed in several locations, including tunnels, curves, tangent sections, joints, high rail, and low rail. The corrosion of the rails was identified mainly in the tunnels. This corrosion is presumably promoted by the leaks of water coming from the city’s drainage system. In most cases, the corrosion starts at the base of the rail, but in some cases also affects the web of the rail. Contrary to other transit systems, the corrosion at the MTA-NYCT is independent of the weather; that is, the addition of salt to melt the snow during the winter has a negligible effect on the corrosion of the rails. The reports of corrosion indicate that several dozen locations are identified with corrosion and rail breaks per year. In 2005, 121 rail breaks were reported in the MTA-NYCT system, and 20 of them were rail base corrosion related. As of February 28, 2006, the number of rail breaks in the system was 24, and only 4 were due to corrosion. MTA owns and maintains the track on the MTA-NYCT line. Rail defect detection is conducted up to six times per year. The return current is directed to the rail (600 V DC). There is also a superimposed AC for the signal circuits (7-10 V, 60 Hz). The following table summarizes the operating and inspection conditions regularly used by MTA-NYCT. Maximum Operating Speed 50 mph Wheel Load Max. 16,250 lbf, static Frequency of the Rail Breaks due to Rail Base Corrosion 12% of the rail breaks in 2006 were due to corrosion Rail Defect Detection Frequency Up to 6 times per year Type of Ties Wood (oak) blocks embedded in concrete Power Source Third rail

C-12 MTA-NYCT tunnels showing severe water leakage from the walls, severe humidity under the tracks, and erosion of the rail base.

C-13 Transit Authority: Sistema de Transporte Colectivo Metro and Tren Ligero Mexico City Response Received: 01/31/2006 Contact: Luis Canut Abarca, P.E., Subhead of Operations & Infrastructure +(5255) 5627-4773 SUMMARY The Sistema de Transporte Colectivo Metro (STCM) operates two transit systems: (1) conventional light rail and (2) the Metro with trains running on a concrete guideway. Rubber tires are guided on the concrete guideway with steel rails used for emergencies; that is, when tires fail. The tracks for light rail are composed of 115-lb RE rail. The STCM uses concrete ties in tangents and curves with curvatures of less than 6 degrees. Wood ties are used elsewhere, with direct fixation. The STCM does not report significant corrosion on the rails. In addition, the humidity in the environment is not as high as in the eastern USA, Canada, or Mexico. The 95% + of the light rail tracks are open air with just a small tunnel at the end of the system. In contrast, 70 percent of the Metro is a subway (tunnel) system. However, there is not as much water or brine leakage to the tracks (rails). The Metro operates with a third rail system; the light rail system uses an overhead catenary. The maximum speed for both systems is 56 mph. The power source consists of a DC system of 750 V. A wheel load of 8 metric tons per axle is used for both the Metro and light rail system for a combined total of 20 MGT of traffic per year (metric tones). The tracks are owned by the STCM. A monthly rail flaw inspection is conducted by STCM for the 34 miles of the tracks. In the past, some rail base corrosion was reported that was due to small leaks throughout the subway stations. Improper disposal of cleaning materials (containing NH4OH and/or NaOH), commonly used at every station, also caused corrosion. This occurrence was remedied by proper materials/waste disposal practices. Also, some electro-erosion in isolating joints was detected. This vibrating causing erosion provokes, impacts, and unstabilizes joints.

C-14 Transit Authority: Dallas Area Rapid Transit Response Received: 12/29/05 Contact: Darvin Kelly, Sr. Mgr. Track & Right of Way Dallas, TX 75266-7285 P.O. Box 660163 (214) 928-6239 SUMMARY Dallas Area Rapid Transit (DART) operates at 750-Volt DC. Rail used is 115-lb RE, AREMA Spec from various manufacturers. The environment is dry. Therefore minimal rail base corrosion is detected, reported, or observed. DART is a light rail system, and rail defect detection is conducted twice yearly. The track is owned and maintained by DART. The electrical system consists of an overhead catenary. The following table summarizes the operating and inspection conditions regularly used by DART. Maximum Operating Speed 65 mph Wheel Load 20 ton/wheel Frequency of the Rail Breaks due to Rail Base Corrosion None Rail Defect Detection Frequency Twice per year Type of Ties Concrete ties Power Source Overhead catenary

C-15 Transit Authority: Tri County Metropolitan Transportation District Response Received: 01/10/05 Contact: Kai Looijenga, Engineer III - Systems 710 NE Holladay St Portland, OR 97232 (503) 962-2175 SUMMARY Tri County Metropolitan Transportation District (TRIMET) operates a light rail system using an overhead catenary power supply that has a maximum current of 750 V DC. The rail used is open track — 115-lb RE, control cooled carbon steel rail manufactured in accordance with AREMA specifications. The tracks for TRIMET are paved track — R159 girder rail, manufactured in accordance with ASTM designation A2, Class B. There are some locations where corrosion was detected at the web and base of the rail. These locations are at the tie and at the road crossing panels. However, the detected corrosion levels have been of an insufficient magnitude to warrant repair or replacement of the rail. To date, no failures from corrosion have been detected. The estimated traffic for the TRIMET light rail system is approximately 13.5 MGT. The tracks are owned and maintained by TRIMET. Track is inspected using ultrasonics every two years. Corrosion of the rail occurs mostly at the transition from ballasted track to road crossing panels due to debris build-up. TRIMET also detected corrosion of the web and base of rail on a section of track through a road crossing. This corrosion was caused mostly by current exchange from rail to earth due to incorrect installation of the insulating boot. The crossing was identified as having insufficient insulation from rail to ground during regularly scheduled testing of the cathodic protection levels on a waterline under it. In ballasted track sections with wood ties, corrosion is limited to the spikes. The concrete embedded tracks have no access for corrosion inspection. Therefore, they have not been inspected. Nonetheless, a combination of rail-to-earth potential and earth gradient measurements are conducted and used as an indicator of the level of insulation for the embedded track areas. The following table summarizes the operating and inspection conditions regularly used by TRIMET. Maximum Operating Speed 55 mph Wheel Load 9324 lbs/wheel Frequency of the Rail Breaks due to Rail Base Corrosion Insufficient data Rail Defect Detection Frequency Ultrasound inspection for cracks every 2 years Type of Ties Mix: wood, concrete, embedded track Power Source Overhead catenary

C-16 Transit Authority: Southeastern Pennsylvania Transportation Authority (SEPTA) Response Received: 07/14/06 Contact: Anthony Bohara Director of Engineering 1234 Market St. Philadelphia, PA 90017 (215) 580-82780 SUMMARY SEPTA is a light and heavy rail transit system. The systems run between 2 and 3 MGT per year on 100-lb RB and 115-lb RE rail. Usually, the corrosion is observed at the ties in the tunnels. One of the major issues with corrosion is the low corrosion rate, which lowers attention toward corrective actions and in one case up to 100 spots with corrosion were found in a single location. The tracks are ultrasonically inspected on a yearly basis and visual inspection is usually conducted twice a week. The power is supplied using third rail and overhead catenary and is a DC current of 600V. The tracks are owned by SEPTA and SEPTA also conducts the maintenance. The corrosion is usually detected in the locations where water is present. Usually, the corrosion goes from the base to the web of the rail. In general the fastening system is severely affected. SEPTA has reported rail failures due to corrosion; typically, rail fastener/fixation is destroyed as well as rail. Unfortunately, most of the rail base corrosion is not easy to identify using ultrasonic rail inspection methods. SEPTA has found that insulated anchors and insulation of rails on direct fixation tracks help reduce corrosion. In addition, SEPTA tries to control water leaks to reduce the humidity, thus corrosion media. The following table summarizes the operating and inspection conditions regularly used by SEPTA. Maximum Operating Speed Light rail (50 mph) and heavy rail (70 mph) Wheel Load 15 ton Frequency of the Rail Breaks due to Rail Base Corrosion Non reported Rail Defect Detection Frequency Ultrasound inspection once a year - 2 times per week visual Type of Ties Wood Power Source Conventional DC circuit only (third rail and overhead catenary)

C-17 Light rail SEPTA tunnels showing severe corrosion.

C-18 Transit Authority: Southern California Regional Rail Authority Commuter rail with freight and Amtrak trains Response Received: 12/28/06 Contact: Michael E. McGinley, Director of Engineering and Construction 700 So. Flower St., Suite 2600 Los Angeles, CA 90017 (213) 452-0250 SUMMARY The Southern California Regional Rail Authority (SCRRA) system carries commuter, freight, and Amtrak trains. The power supply is conventional DC track circuits only. The rail is 136-lb CF&I CC, some from 1973 and 1983. The rail is almost all tangent, placed on wood ties in crushed rock ballast on a native sandstone tunnel floor. The corrosion at the base of the rail occurs in water flooded locations; some of the rails have lost of up to 1/8”of the base. All observed corrosion has been at the rail base/tie plate interface in wet conditions. These are 14” AREA tie plates on wood ties with cut spike fasteners. Anti-creeper anchor boxes are located on every other tie. The temperature in the longest tunnels is ~50°F during the winter and ~70°F during the summer. In the shorter tunnels temperatures range between 40 and 90°F. The estimated traffic for the SCRRA tracks is approximately 15 MGT for the light rail. The tracks are owned by SCRRA, and Herzog was hired to conduct maintenance. The tracks are inspected using ultrasonic techniques every two years. The corrosion detection operation is conducted every 120 days. To date, no corrosion has caused rail fractures, and no defects have been detected by ultrasonic testing. Nonetheless, the base of rail is too irregular to re-use, even to the point of spotting in replacement crossties. Of 16,000 feet of tunnel, 4,000 feet have corrosion and water problems in three of the six tunnels. SCRRA installed pumps every 100 feet to keep the water drawn down below the base of the rail, which appears to help. The following table summarizes the operating and inspection conditions regularly used by SCRRA. Maximum Operating Speed 50 mph Wheel Load Vary depending on the type of car from 18 ton/car to 143 ton/car Frequency of the Rail Breaks due to Rail Base Corrosion None Rail Defect Detection Frequency Ultrasound inspection every 2 years Type of Ties Treated timber Power Source Conventional DC circuit only

C-19 Transit Authority: New Jersey Transit Corporation Response Received: 01/12/2006 Contact: Stelian Canjea, P.E., Light Rail Program Manager (973) 566-6704 SUMMARY The New Jersey Transit Corporation (NJ Transit) is currently operating three light rail systems: • Newark City Subway • Hudson-Bergen LRT • River Line The Newark City Subway is the oldest and was opened in 1935. In 1982, the entire 5-mile double track system was rehabilitated. The old 100-lb rail has been replaced with 115-lb RE. The Hudson-Bergen LRT is a brand new system opened in 2000 and uses 115-lb RE rail. The River Line is also a brand new system operating diesel-electric cars from Trenton to Camden and was opened in 2004. All tracks are 115- lb RE rail. Until now, the New Jersey Transit Corporation had not reported rail base corrosion. The operation conditions of the tracks have variable wheel loads for the NCS and HBLRT LRT cars; the wheel loads vary from 8500 lb to 12,000 lb. The River Line car also has a variable wheel load from 10,000 lb to 18,000 lb. The tracks consist of wood ties (90%) and direct fixation ties embedded in track (10%). The traffic for the Newark City Subway and the Hudson-Bergen LRT is approximately 15 trains per hour 12 hours a day. For the River Line, the traffic is approximately 24 trains per day. Freight trains utilize a major part of the River Line. The tracks are owned by New Jersey Transit. Overhead catenary is used by both the Newark City Subway and Hudson-Bergen LRT. This is a light rail system using DC of 750 V. The maintenance is conducted by the New Jersey Transit and DBOM Contractors for the Hudson-Bergen LRT and River Line. None of the above described lines present evidence or report rail base corrosion.

C-20 Transit Authority: St. Louis, Missouri, Metro Response Received: 01/17/2006 Contact: Paul Genisio, Chief Engineer – Track (314) 982-1411 SUMMARY The St. Louis, Missouri, Metro is a light rail system. The tracks are composed of 132-lb RE rail manufactured in 1968 with heat numbers 78 T 131 D2. The corrosion is usually found at the base and web of the rail with a considerable amount of moisture with sand and dirt. The top of the head of the rail receives brine dripping rain in the tunnels. Rail was changed out at Mileposts 14.5-15.1 and 13.5-13.6, where corrosion was reported. The load per car is approximately 12 tons per axle. The tracks are owned by Metro. The tracks have direct fixation ties with a catenary power source system. The maximum speed is 55 mph. Maintenance and track inspection are conducted by Mr. Paul Genisio and Weather Ford. The tracks are ultrasonically inspected twice a year. There is also a weekly inspection of the tracks (rails) to identify moisture and deposited sand at the e-clip location. Based on their reports, the corrosion located in the tunnels is due to brine that runs off the bridges. In addition, the tunnels themselves are damp and when dirt and sand accumulate on top of the e-clips and fasteners (MP 14.5 - 15.1), or on the spikes with anchors (MP 13.5 - 16.6). A detrimental environment results for the integrity of the rails/tracks. It is important to point out that welded sections of rail that were preheated are not an issue. The ambient temperature in the tunnels varies on average from 55– 60°F.

C-21 Transit Authority: Edmonton Transit Response Received: 04/25/06 Contact: Jim Stein; General Supervisor, Right-of-Way & Facilities (780) 496-4364 SUMMARY The Edmonton Transit system is a light rail system that operates on 7.7 track miles. Energy is supplied by an overhead catenary system using a 600 V DC. The entire track uses 100-lb ARA standard carbon rail. Corrosion of the rail base has been observed at the main line grade (road) crossings. Currently, measurements conducted indicate that in some locations, the rail base thickness is approaching the condemning limit, and a number of Pandrol fasteners have failed as a result of corrosion. Corrosion appears to be related to high salt content; that is, from the salt-sand mixture used on roads during the winter and high moisture content; that is, the ground does not dry in road crossings because it is covered by crossing panels. All road crossings have some degree of rail base corrosion. The Edmonton Transit line has seven road crossings, all installed between 1991 and 2000. Corrosion is more severe where there are high salt concentrations and/or where the wheel flange does not fit tight to the running rail and crossing panels. Current leakage through the concrete crossing ties may also be a contributing factor. The track is owned and maintained by Edmonton Transit. Ultrasonic testing is conducted yearly. Because of the corrosion that is occurring at the existing grade crossings, the Edmonton LRT Design Guidelines have been changed to require: (a) rubber flange rail covering the full width of the rail base on both the gauge side and field side and (b) use of hardwood ties. The following table summarizes the operating and inspection conditions regularly used by Edmonton. Maximum Operating Speed 70 kmph Wheel Load 5.8 metric tones Frequency of the Rail Breaks due to Rail Base Corrosion None reported Rail Defect Detection Frequency N/A Type of Ties Concrete ties in road crossings; wood elsewhere Power Source Overhead catenary