90% NORTH LINK EMI PREDICTION REPORT. F. Ross Holmstrom, Ph.D. September 2012

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2 90% NORTH LINK EMI PREDICTION REPORT F. Ross Holmstrom, Ph.D. September INTRODUCTION AND SUMMARY This report includes updates incorporated from the 60% North Link EMI Predication Report. All 60% review comments have been reviewed, incorporated or responded too accordingly. Reference 5 is the complete list of review comments and responses. There have been no other modifications to the 60% North Link EMI Predication Report. The 60% report brought up-to-date the analysis of predicted B-field levels at critical UW labs due to North Link and U-Link train operations through the UW campus. It updates calculated B-field values predicted to be achieved by implementation of mitigation design concepts covered in Ref. 1 released in 2006; by implementation of specific signal and power system designs presented in Ref. 2; and by adoption of additional design implementations and changes since the 2008 release of Ref. 2 that are discussed in this report. The critical UW labs comprise two groups. The UW has established Requested Threshold B-field levels at the eleven labs in Group 1. Meeting the Group 1 threshold levels is mandatory. The UW also has established Requested Threshold B-field levels for the four labs in Group 2. Meeting the Group 2 Requested Threshold B-field levels is not mandatory; however, exceeding the ST Baseline predicted B-field levels at the Group 2 labs will require negotiations between ST and UW. The Group 1 and 2 labs are: Group 1 Labs UW Requested Threshold (mg) Bagley Hall 0.1 Chemistry Bldg. 0.1 Electrical Engineering/Computer Science 5.0 Physics/Astronomy 0.5 Johnson Hall 5.0 CHDD 0.3 Health Sciences Imaging Center 5.0 Surgery Pavilion 1.0 Fisheries Center 0.1 Marine Sciences 1.0 UW Requested ST Baseline Group 2 Labs Threshold (mg) Prediction (mg) Fluke Hall Mechanical Engineering & Annex Roberts Hall Wilcox Hall

3 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 2 A number of changes have been made in the location of the North Link right-of-way (ROW) in the period since April 2006, the last change taking place since Since 2008 the planned ROW has been moved westward in the vicinity of Roberts and Wilcox Halls, the Mechanical Engineering Building & Annex and Fluke Hall. This move has decreased predicted B-fields at Fluke Hall. However, at Roberts, Wilcox and the ME Bldg. & Annex, where the 2006 predicted B-fields levels already were above those requested by UW, the presently predicted B-field levels are still higher. Sound Transit will have to discuss these increases with the UW. Sound Transit is currently evaluating the tunnel shielding concept suggested by the UW. As far as we know, the proposed application of shielding technology to a segmented tunnel liner has not been attempted before. Changes have been made as well in some of the computational routines used for calculating propulsion and perturbation B-fields. Greater use has been made of three dimensional models of the ROW that allow for curved, rising and falling models of the ROW. In addition to these refinements in the model analysis, we also revisited whether or not adding a mid-campus TPSS or otherwise reducing distances between TPSS to the propulsion system would reduce EMI at the sensitive receivers. The answer is no, the substations spacing has already been studied and are determined at optimal locations. We also considered whether gains were possible in lowering magnetic fields by reducing the riser spacing in the mitigation design. Again, this had already been review at great detail and no additional gains were realized. This report examines B-field levels in depth at four Group 1 buildings: Bagley Hall, Chemistry Bldg., Surgery Pavilion (also known as the Ambulatory Care Facility) and the Fisheries Center. B-field levels also are examined in depth at Fluke Hall on the Group 2 list. It has been found that because of their locations and their Requested Thresholds, if the UW Requested Thresholds are met at these labs then they will be met at all other Group 1 labs as well. In this sense these five labs are salient. At all five salient labs and at all other Group 1 labs as well, the new calculations show that B-field levels are predicted to be below the UW Requested Thresholds by a sufficient margin.

4 90% North Link EMI Prediction Report Holmstrom September 2012 pg MAGNETIC FIELD SOURCES At the Group 1 & 2 UW lab locations magnetic fields (B-fields) were calculated separately for currents in the following B-field sources shown in map of the North Link ROW from Capitol Hill Station to Roosevelt Station in Figure 1: Source No. 1 Rail and OCS currents and geomagnetic perturbations due to trains operating in the B-field mitigated region stretching from Stationing NB , 419 meters (1375 ft) south of the center of the crossover just south of UW Station, to NB near the corner of NE 42 nd St. and University Way, with current supplied by the UW TPSS, Source No. 2 Rail and OCS currents in the non-b-field mitigated region from NB to just south of NE 45 th St. at the northern end of Brooklyn Station (the Brooklyn Stub ); with current supplied by the Brooklyn TPSS, Source No. 3 Rail and OCS currents between Brooklyn and Roosevelt Stations, Source No. 4 Rail and OCS currents between the southern end of B-field mitigation at NB and Capitol Hill Station, i.e., South of Montlake (SOM), currents provided by the Montlake rectifier bank at the UW TPSS and the Capitol Hill and/or Pine Street TPSS, Source No. 5 Propulsion currents in the cables and rectifiers at the UW TPSS, and Source No. 6 Rail and OCS currents in the crossover and adjacent tracks when the crossover is occupied by a train crossing over. For increased accuracy and decreased reliance on approximations, new calculations of propulsion current B-fields (B prop ) were performed for the sections of curved ROW in the South of Montlake and B-field mitigated regions using physical circuit models that describe the shape of the curving, rising and falling ROW in three dimensions. Proximity of the Group 1 & 2 UW labs to the above sources can be visualized by referring to Figure 2.1 on pg. 5 of Ref. 1.

5 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 4 Figure 1. The North Link right-of-way from Capitol Hill Station to Roosevelt Station showing the sources of B-fields analyzed in this report.

6 90% North Link EMI Prediction Report Holmstrom September 2012 pg MAGNETIC FIELDS FROM SOURCE No. 1 MITIGATED REGION & SOURCE No. 2 BROOKLYN STUB Table 1 shows total B-field due to propulsion currents in OCS and rails in Source No. 1 B-field mitigated region and Source No. 2 Brooklyn Stub. Table 1 EMF Sensitive Site B-field due to propulsion currents in OCS and rails in the B-field mitigated region and the Brooklyn Stub. EMF Site NB ΔX (m) SB ΔX (m) ΔY (m) NB Btot (mg) SB Btot (mg) Sources 1+2 NB+SB Btot (mg) Bagley Hall Chemistry Bldg EE/CS Physics/Astronomy Johnson Hall Fluke Hall ME Bldg. 11a ME Annex 11c Roberts Hall Wilcox Hall CHDD Diagnostic Imaging Surgery Pavilion* - 1st Fl. 10a Surgery Pavilion* - Pking 10b Fisheries Center (FIS) Marine Sciences *Also called the Ambulatory Care Facility Comparison of the B-field values above with those in Table 3.3 of the 2006 North Link Hi-Lo Mitigation EMI Report [Ref. 1] shows that some B tot values have increased and some have decreased. Increases in B tot values for Roberts, Wilcox, ME, ME Room 135 and the ME Annex are due to the movement to the west of the ROW in the vicinity of these buildings. Westward movement of the ROW in that area also has caused the Fluke Hall B tot value to decrease. Other change in calculated B tot values from 2006 to present are due to what is presumed to be better accuracy of the new curved-row model.

7 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 6 Still other changes in predicted B-field levels are due to changes in the model of the ROW that took place when the propulsion circuit design was completed. As shown in Figure 2 in the 2006 model it was presumed that propulsion currents were applied to Source No. 1 the B-field mitigated region at its southern end, and the current in each track flowed in a single continuous loop that passed all the Group 1 & 2 UW labs and extended clear to Brooklyn Station. As shown in Ref. 2 the loop for each track has been cut into three loops. The propulsion feed point for the mitigated region has been moved to the north-south midpoint of the crossover just south of UW Station, and labs in the UW Medical Center area are subjected to B-fields either from the short southern loop or from the southern end of the main central loop, but not from both simultaneously. Additionally, B-fields from the Brooklyn Stub are handled differently than in 2006 and In the models, trains running past the northern end of B-field mitigation clear up to the Brooklyn Station drew currents from the UW TPSS. In the present model trains only draw current from the UW TPSS up to the beginning of the stub. Trains in the Brooklyn Stub draw current from the Brooklyn TPSS. Assuming that at most one train northbound and one train southbound operate between UW and Brooklyn Stations, calculation of B prop is made separately for currents in the mitigated region and in the stub itself; then the larger of the two B prop values is used. Only in the case of Physics/Astronomy was B prop from the Brooklyn Stub larger than B prop from the B-field mitigated region. For this report an updated method of calculating B ptb at labs far from the ROW was used. While measured B ptb values near a light rail train have been found to obey the relation (Ref. 1) B ptb = 2000/r 2.2 mg for r small. It is known that at distances far away from a ferrous object of limited size, B ptb decreases as 1/r 3 with increasing distance r away from the object. Therefore for distances greater than the approx. 110 meter (360 ft) train length the relation used was B ptb = 85930/r 3 mg for r 110 meters. That fact was used to calculate B ptb values at distances from the ROW greater than the 110 meter (360 ft) train length, resulting in smaller calculated B ptb values for the labs at a greater distance. The two equations above yield the same value of B ptb = mg at r = 110 meters.

8 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 7 Figure 2. Propulsion circuit design in 2006 and early 2012.

9 90% North Link EMI Prediction Report Holmstrom September 2012 pg MAGNETIC FIELDS FROM SOURCE NO. 3 THE BROOKLYN-TO- ROOSEVELT ROW To calculate worst-case B prop fields from the Brooklyn-to-Roosevelt segment of the ROW it was assumed that one northbound and one southbound train each drew 2800 A over the entire segment in the same direction, as might occur for instance if the Brooklyn TPSS were out of service and two trains were accelerating out of Brooklyn Station simultaneously, both drawing their current from the Roosevelt TPSS. This configuration is shown in Figure 3. The resulting calculated B prop values at the Group 1 & 2 UW labs are given in Table 2. The XYZ coordinate system in Table 2 has its origin at the center of the crossover just south of UW Station, at sea level. X is measured west, Z north, and Y up from that point. For these calculations it was assumed that the rails were at a constant elevation of Y = 33.5 meters (110 ft) from Brooklyn to Roosevelt. The B prop values in Table 2 are very close to those in Table 4.1 of Ref. 1. The slight differences probably are due to the fact that the model used to calculate these new values took account of the differences in elevation of the ROW and buildings.

10 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 9 Figure 3. Train configuration leading to greatest B-field contribution from Source No. 3 Brooklyn-to-Roosevelt.

11 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 10 Table 2 B-field due to propulsion currents in OCS and rails in the Brooklyn Station to Roosevelt Station portion of the ROW. EMF Sensitive Site EMF Site X (m) Y (m) Z (m) Source 3 NB+SB Btot (mg) Bagley Hall Chemistry Bldg EE/CS Physics/Astronomy Johnson Hall Fluke Hall ME Bldg. 11a ME Annex 11c Roberts Hall Wilcox Hall CHDD Diagnostic Imaging Surgery Pavilion* - 1st Fl. 10a Surgery Pavilion* - Pking 10b Fisheries Center (FIS) Marine Sciences * Also known as the Ambulatory Care Facility

12 90% North Link EMI Prediction Report Holmstrom September 2012 pg MAGNETIC FIELDS FROM SOURCE No. 4 THE SOUTH-OF-MONTLAKE ROW Analysis of B prop fields from the SOM ROW is more complicated than from the Brooklyn to Roosevelt ROW because of its length, because of the cross bond located approx. 1/3 of the way from the southern end of B-field mitigation to the Capitol Hill Station, and because of the long steep grade from the southern end of mitigation to Capitol Hill that makes the occurrence of regenerative braking very likely. Details of the ROW in this region are shown in Figure 4. The single cross bond noted above adds complexity to the task of determining currents in the rails between Montlake and Capitol Hill and their resulting B-field contributions. It also causes rail current patterns that lead to slightly higher levels of B-field than would occur if it were absent. However, its presence in the rail circuit is required to assure sufficiently low values of train-to-substation rail resistance. Absent the requirements to minimize B-field levels many more cross bonds would have been used between Montlake and Capitol Hill. Because of the requirement to minimize B-field the number of cross bonds was reduced to the barest minimum that the power considerations would allow. Fortunately, the resulting rail circuit design with the single cross bond resulted in prediction of acceptable B-field levels. Because of its proximity to the southern limit of B-field mitigation and its 0.1 mg UW spec B-field level the Fisheries Center is the test case for B prop levels arising from this section of ROW. If B prop levels from SOM currents do not impact the Fisheries Center too badly all other Group 1 & 2 labs will be safe as well. It was assumed that trains could produce a maximum of 3500 A current in regeneration and that a regenerating train could always find a receptive load. Regen current not accepted by a train in the vicinity drawing current would then have to flow back through both NB and SB OCSs to Capitol Hill. It was assumed that a train under forward power could draw a maximum of 2800 A. It was found that a single regenerating train heading northbound just south of the B-field mitigated region and producing 3500 A would give rise to a 0.04 mg B-field at the Fisheries Center. However, this level of regeneration would cause several hundred volts of IR drop from the train to Capitol Hill, and unless the Capitol Hill TPSS were heavily enough loaded to decrease its output voltage by several hundred volts the regen train would exceed its maximum regen voltage limit. One train accelerating while drawing 2800 A and one train in regen producing 2800 A with the trains near each other in the north-south direction also produced approx mg B-field at Fisheries when they were in the vicinity of the cross bond, and they produced slightly less B-field if they were located north or south of the cross bond.

13 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 12 A single train accelerating southbound while drawing 2800 A produced a peak Fisheries Center B-field of 0.03 mg when the train was near the cross bond and lower values when north or south of that point. If the assumption is made that the Montlake rectifier is off-line and two trains are accelerating with each drawing 2800 A, with the southbound train just starting up the northern side of Capitol Hill and the northbound train just north of the grade minimum south of the B-field mitigated region, for instance maintaining its speed prior to braking for UW Station, so that both trains are drawing their current from Capitol Hill, then the B- field at the Fisheries Center is mg. This mg level is mg or 83% above the predicted worst-case level of 0.04 mg achieved with the Montlake rectifier on-line, a fact that indicates the importance of maintaining it or a replacement in service at all times to assure normal North Link operation. Operation of the University Station TPSS will be conducted to assure presence of such a rectifier except under the most extreme circumstances. Capitol Hill and Pine Street rectifiers will never be off-line simultaneously except under the most extreme circumstances. Therefore the Capitol Hill to Montlake tracks always will be driven from both ends except in the most extreme circumstances, thus assuring optimum B-field performance. When a train is operating between rectifiers it tends to receive the greater current from the nearest rectifier, thus minimizing the length of the current loop. Additionally, the current in the OCW-rail loop ahead of the train will flow around the loop in opposite sense to current in the loop behind the train, causing the B- fields from the loops to partially cancel.

14 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 13 Figure 4. Current flow details in the South-of-Montlake region. As an example a southbound train is shown accelerating up the northern side of Capitol Hill while a regenerating northbound train descends. Presence of cross bond leads to SB and NB rails all conducting during any train move.

15 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 14 It is assumed that with the Montlake rectifier on-line northbound trains having descended Capitol Hill in regen or dynamic braking would only draw current on the upgrade into UW Station through a very short current loop until they got to the B-field mitigated region and any B-fields resulting from current flow in this short loop have been neglected. Table 3 B-field due to propulsion currents in OCS and rails in the South of Montlake portion of the ROW. EMF Sensitive Site EMF Site som X (m) Y (m) som Z (m) Source 4 NB+SB Btot (mg) Bagley Hall Chemistry Bldg EE/CS Physics/Astronomy Johnson Hall Fluke Hall ME Bldg. 11a ME Annex 11c Roberts Hall Wilcox Hall CHDD Diagnostic Imaging Surgery Pavilion* - 1st Floor 10a Surgery Pavilion* - Pkng 10b Fisheries Center (FIS) Marine Sciences *Also known as the Ambulatory Care Facility The XYZ coordinate system used in the calculations for Table 3 has its origin displaced 42 meters (138 ft) west in the X-direction and 419 meters (1375 ft) south in the -Z direction from the origin of coordinates used in Table 2. Note that the SOM B-fields are greater at the CHDD and Surgery Pavilion than they are at Fisheries. However, CHDD s 0.3 mg UW spec B-field level is three times higher than the 0.1 mg level at Fisheries, and the 1 mg level at Surgery Pavilion is ten times higher. Therefore, if the B-field level at Fisheries is OK, the B-field levels at CHDD and the Surgery Pavilion will be OK too.

16 90% North Link EMI Prediction Report Holmstrom September 2012 pg MAGNETIC FIELDS FROM SOURCE No. 5 PROPULSION CABLES AND RECTIFIERS IN THE UW TPSS The cables in the UW TPSS carrying DC propulsion current from the rectifiers to the tracks are predicted to contribute significantly to B-field levels at nearby Group 1 & 2 UW labs. There are three rectifiers, and the cables immediately adjacent to and connected to those rectifiers each will form large loops with areas estimated to be between 12 and 18 m 2 ( ft 2 ). The axis of each loop will be aimed almost directly at the UW Medical School Surgery Pavilion some 95 meters (312 ft) away. B-fields arising from a conducting loop fall off as 1/r 3 with increasing distance r away from the loop. Therefore, it is expected that the greatest effect of B-fields due to the loops will be at the Surgery Pavilion since the other Group 1 & 2 UW labs are very nearly three times as far away from the UW TPSS. Much smaller loops are expected to arise from some but not all propulsion cable groups. Cables from the Montlake rectifier to the tracks have been designed to produce essentially zero B-field, with each positive feed cable placed between a pair of balanced negative feed cables connected to the same track. In the case of cables running from the UW NB and SB rectifiers to their respective tracks the small cable separations and short lengths of runs leads to conducting loops with minimal areas compared to the big loops. Additionally, the design calls for cables to be placed so that under maximum load conditions B-fields from the cables will cancel. Because of these aspects of cable layout design the B-fields arising from cables between the big loops and tracks have been neglected. Detailed calculations have been performed to estimate the anticipated overall B-field levels at the Group 1 & 2 UW labs including fields generated by UW TPSS cables. The results of these calculations predict that under the most extreme LRV traffic conditions, anticipated total B-fields due to LRV operation will come up very close to but will not exceed UW Requested Thresholds. However, under these traffic conditions the previously predicted B-field margins will be nearly reduced to zero at the Surgery Pavilion and at the Fisheries Center. The UW TPSS will be equipped with three traction power rectifiers. The Montlake rectifier will provide power to both NB and SB tracks extending from the S end of the B- field mitigated region to Capitol Hill. The UW NB and SB rectifiers will power the NB and SB tracks respectively from the S end to the N end of the B-field mitigated region. The Montlake rectifier will furnish current through separate feeds to the NB and SB Montlake tracks. The UW NB rectifier will furnish current through separate feeds to the NB track north of and south of the section break located at the N-S midpoint of the crossover. The UW SB rectifier will do the same for the SB track through the UW campus.

17 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 16 Predicted B-field levels were calculated for five operating conditions: Normal University Link operation with 2-car trains - Maximum B-field generation occurs when one train drawing 700 A max occupies the crossover, one 1400 A max train is on the SB Montlake track and one 1400 A max train is on the NB Montlake track. Special Events University Link operation with 4-car trains - Three trains located as above, each with corresponding currents doubled. Normal North Link operation (4-car trains) - One NB and one SB Montlake train; one NB and one SB UW train. Both UW trains are modeled as being powered by the UW NB rectifier (with the largest loop) to simulate service with one rectifier down. All trains draw 2800 A. North Link Extreme Service A operation (4-car trains) - One NB and one SB Montlake train. Two NB UW trains (one south and one north of station) both powered by UW NB TPSS, and two SB UW trains (ditto) both powered by UW SB TPSS. All trains draw 2800 A. North Link Extreme Service B operation (4 car trains) - As immediately above except all four UW trains are powered by UW NB TPSS with its max-sized loop. Table 4 gives the total B-field values for the five cases listed above. Note that in all of the columns in Table 4 the B tpss values are far larger at the Surgery Pavilion (Ambulatory Care Facility) than at any other lab. In assessing the impact of UW TPSS B-fields at specific labs what is important is how much B-field margin exists at each lab from all other B-field sources and how much of that margin is used up or exceeded when the TPSS B-fields are added. Also of importance is the consideration of what large contributors to B-fields can be active at the same time. For instance, the TPSS B-fields and the crossover B-fields yet to be discussed are practically mutually exclusive B-field contributors. There cannot be a great deal of traffic when a train is using the crossover, and when there is a great deal of traffic the crossover will not be in use.

18 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 17 Table 4. B-field contributions from UW TPSS cables for various modes of University Link and North Link operation. UW Lab UW Threshold Level B mg University Link 2-car trains Typical Service Btpss mg University Link 4-car trains Special Events Btpss mg North Link 4-car trains Typical Service Btpss mg North Link 4-car trains Extreme Svc. A Btpss mg North Link 4-car trains Extreme Svc. B Btpss mg Bagley Hall Chemistry Bldg EE-CS Physics-Astronomy Johnson Hall Fluke Hall ME Bldg. & Annex Roberts Hall Wilcox Hall CHDD Diagnostic Imaging Surgery Pavilion* - 1st fl Surgery Pavilion* - pkng Fisheries Center Marine Sciences *Also called the Ambulatory Care Facility

19 90% North Link EMI Prediction Report Holmstrom September 2012 pg MAGNETIC FIELDS FROM SOURCE No. 6 RAIL AND OCS CURRENTS WHEN A TRAIN IS CROSSING OVER IN THE CROSSOVER Table 5 gives B-fields arising at Group 1 & 2 UW labs when a train is crossing over from one track to the other in the crossover located just south of UW Station. When a train is crossing over its wheels, axles and car body provide shorting paths around the insulated joints that normally electrically isolate the northbound and southbound rails, creating large current loops that provide multiple paths for propulsion current. These current loops are composed of rails and OCWs in the crossover. Table 5 Magnetic fields at Group 1 & 2 UW labs caused by trains in the crossover. Labs EMF site Bprop from train in Xover (mg) Bptb from train in Xover (mg) Bxover total (mg) Bagley Hall Chem Bldg EE/CS Physics/Astronomy Johnson Hall Fluke Hall ME Bldg. & Annex Roberts Hall Wilcox Hall CHDD Diagn Imaging Surgery Pavilion* - 1st floor 10a Surgery Pavilion* - Parking 10b Fisheries Center (FIS) Marine Sciences *Also called the Ambulatory Care Facility The B xover values were calculated assuming that while the crossover was occupied by a crossing train no other train would draw currents that would flow into or through the crossover. Additionally it was assumed that a train crossing over would be restricted to a maximum speed of 10 mph and therefore could draw at most 350 A per car or 1400 A for a 4-car train, half the normal maximum current.

20 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 19 When occupied, currents in the crossover can flow in large loops. However, at distances greater than loop cross sections the resulting B-fields fall off as 1/r 3 as distance r away from the loops increases. Therefore it is not surprising that the crossover B-fields in Table 5 above are far greater at the nearby Ambulatory Care Facility than at any other lab. Recent calculations showed that there is very little difference in B tpss values whether or not the gaps in the added crossover OCW sections were bridging or non-bridging. Therefore bridging gaps can be used to avoid loss of current to pantographs of cars crossing these gaps. OCS design has been updated by putting a jumper cable from the powered adjacent OCS to the center part of the crossover which was designed unpowered since One key fact about B-fields due to the crossover is that when trains are crossing over it can be expected that other train movements in the area will be greatly curtailed. Therefore, in spite of the 0.74 mg of B xover at the Surgery Pavilion there is little likelihood of additional B-field from other sources pushing the total B-field there over the 1 mg UW Requested Threshold.

21 90% North Link EMI Prediction Report Holmstrom September 2012 pg ADDITIVE MAGNETIC FIELDS AT THE SALIENT LABS AND ALL LABS DUE TO B-FIELDS FROM ALL SOURCES Some of the Group 1 & 2 UW labs are on the front line of impact from transit-caused B- fields. If UW Requested Thresholds for transit-caused B-fields are met at these salient labs, then with the exception of Wilcox and Roberts Halls and the ME Building and Annex they will be met at all other sites. Wilcox and Roberts Halls and the ME Building and Annex are so close to the ROW that their transit-caused B-fields surely will fall above the UW Requested Thresholds. The salient buildings are ones with low Requested Thresholds or proximity to major B- field sources or both. These buildings and their Requested Thresholds are: Bagley Hall (Group 1) 0.1 mg Chemistry Bldg.(Group 1) 0.1 mg Surgery Pavilion (Group 1) 1.0 mg Fisheries Center (Group 1) 0.1 mg Fluke Hall (Group 2) 0.3 mg Bagley Hall (Group 1) Bagley Hall is one of the three labs with a 0.1 mg Requested Threshold. It benefits from its location relatively far from the ROW in general, the UW TPSS, the crossover and the southern end of the B-field mitigated region. It served as one determinant in placing the northern end of the B-field mitigated region in its presently chosen location. Adding up the Bagley Hall B-field values in the right-hand column of Tables 1-5 yields: Sources 1 & 2 Mitig. region + Brooklyn stub mg Source 3 Brooklyn-Roosevelt Source 4 South-of Montlake Source 5 UW TPSS propulsion currents Source 6 Crossover propulsion currents Total mg The mg total is well under the 0.1 mg UW Requested Threshold, and the number would shrink to mg by eliminating the crossover B-field whose

22 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 21 presence means that operational conditions would cause the other numbers to shrink. Chemistry Building (Group 1) Adding up the same numbers for Chemistry as was done for Bagley Hall yields: Sources 1 & 2 Mitig. region + Brooklyn stub mg Source 3 Brooklyn-Roosevelt Source 4 South-of Montlake Source 5 UW TPSS propulsion currents Source 6 Crossover propulsion currents Total mg This total also is well under the 0.1 mg UW Requested Threshold, and would shrink to mg without the crossover B-field component, repeating the argument used for Bagley Hall. Surgery Pavilion (Group 1) (Ambulatory Care Facility) First Floor For Surgery Pavilion-1 st Floor B-fields we will have to recognize that if the crossover is occupied then minimal other train operation will be taking place. It is conceivable that in addition to the train in the crossover the UW TPSS might be powering one other accelerating train, possibly going up Capitol Hill. There likely would be no other train current delivered to the B-field mitigated or Brooklyn-to-Roosevelt regions. Therefore, the maximum value of B tpss would be (1.5/4)x0.443 = mg, the figure coming from the last column in Table 4. And the B-field contributions would add up as follows: Sources 1 & 2 Mitig. region + Brooklyn stub mg Source 3 Brooklyn-Roosevelt Source 4 South-of Montlake Source 5 UW TPSS propulsion currents Source 6 Crossover propulsion currents Total mg This value is below the 1 mg UW spec B-field limit for the Surgery Pavilion 1 st Floor.

23 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 22 Fisheries Center (Group 1) Sources 1 & 2 Mitig. region + Brooklyn stub mg Source 3 Brooklyn-Roosevelt Source 4 South-of Montlake Source 5 UW TPSS propulsion currents Source 6 Crossover propulsion currents Total mg This B-field level is below the 0.1 mg UW spec level, and it would decrease further if the same arguments regarding crossover B-fields were made as for the Chemistry Bldg. and Bagley Hall. Maintaining the mg level requires that the Montlake tracks be driven by a rectifier at the UW end to provide power to trains maintaining their speed from the bottom of the grade under the Montlake Cut until they enter the B-field mitigated region. Fluke Hall (Group 2) Fluke Hall benefits from the fact that the ROW has been moved farther away. And the magnitude of calculated B-fields benefit from the adoption of a three-dimensional model of the ROW that is believed to more accurately calculate propulsion B-fields at Fluke Hall s location outside of the curve of the ROW. The B-field numbers at Fluke Hall are as follows: Source 1 & 2 Mitig. region + Brooklyn stub mg Source 3 Brooklyn-Roosevelt Source 4 South-of Montlake Source 5 UW TPSS propulsion currents Source 6 Crossover propulsion currents Total mg This total is well below the 0.3 mg UW Requested Threshold for Fluke Hall.

24 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 23 Mechanical Engineering Building & Annex, Wilcox Hall, Roberts Hall and Fluke Hall (the Group 2 buildings) The ME Building & Annex and Wilcox and Roberts Halls are located closer to the North Link ROW than any other Group 1 & 2 UW labs, and these are locations where B-field levels from North Link operations are predicted to exceed the UW Requested Thresholds. Final design of the ROW alignment has moved the ROW still closer to these buildings causing predicted B-field levels to rise. In the new ROW alignment the southbound track actually passes directly under a corner of the M.E. Annex. Table 6 below compares the distances from the ROW to the nearest labs in 2006 and The April 2006, June 2008 and recently predicted B-field levels from trains directly passing the Group 2 buildings are given in Table 7. The April 2006 values are from Ref. 1, Table 3.3, pg. 39. The June 2008 levels are from Ref. 3, Table B.1, Appendix B. Three levels are seen to have increased. The ME Annex level has decreased because at very close distances the maximum B-field points lie a short distance to either side of the ROW and the bottom of the trough between the maxima has been moved under the M.E. Annex. Table 8 compares April 2006, June 2008 and presently predicted B-field levels at the four labs from all sources. B-field contributions from the crossover have been omitted because if a train is in the crossover other contributions are diminished. Note especially that the B-field values in the April 2006 column in Table 8, when rounded to two decimal places, yield the ST Baseline Prediction values for Fluke Hall, ME Bldg. & Annex, Roberts Hall and Wilcox Hall stated in Exhibit B.2 of the UW-ST Master Implementation Agreement. The predicted total B-field levels at three of these labs are seen to have increased, largely because of the increase in contributions from the B-field mitigated region due to the ROW alignment moving closer to the labs. According to the UW-Sound Transit Master Implementation Agreement these increases will have to be discussed with UW.

25 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 24 Table 6 Shifts in ROW to lab distances for the closest Group 1 & 2 UW labs 2006 to to to 2012 EMF Sensitive Site EMF Site ΔH = Horiz. Dist. (m) ΔV = Vert. Dist. (m) r = slant dist (m) ΔH = Horiz. Dist. (m) ΔV = Vert. Dist. (m) r = slant dist (m) ΔH = Horiz. Dist. (m) ΔV = Vert. Dist. (m) r = slant dist (m) Δr 2006 to 2012 (m) Δr % 2006 to 2012 Δr 2008 to 2012 (m) Δr % 2008 to 2012 Fluke Hall ME Bldg & Annex 11c Roberts Hall Wilcox Hall Surgery Pav.-1st Fl. 10a

26 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 25 Table 7 Magnetic field levels from Sources No s 1 & 2 for the Group 2 buildings B-field mitigated region and Brooklyn Stub; from Ref s 1 & 3 and from Table 1 of this report. Sources (mg) B,mitig lab April 2006 June 2008 Jan M.E. Building M.E. Annex Roberts Hall Wilcox Hall Fluke Hall Table 8 April 2006, June 2008 and January 2012 Magnetic field levels from Sources 1-5 for the Group 2 buildings; from Ref s 1 & 3 and from Table 1 of this report. lab Jan B-field levels (mg) from Sources 1-5 Sources Source 3 Source 4 Source 5 Jan. '12 B,tot (mg) June '08 B,tot (mg) Apr. '06 B,tot (mg) M.E. Bldg M.E. Annex Roberts Hall Wilcox Hall Fluke Hall

27 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 26 Predicted Magnetic Field Levels at All Labs 2006 and early 2012 Table 9. Summary of B-field levels predicted in early 2012 and in 2006 for all critical UW labs. The 2006 levels are from Ref. 1, Table 4.1. Group 2 labs with B-field levels exceeding ST Baseline Predictions are shown in bold. EMF Sensitive Site UW Req. T'hold (mg) 2012 Sources 1+2 (mg) 2012 Source 3 (mg) 2012 Source 4 (mg) 2012 Source 5 (mg) 2012 Source 6 (mg) 2012 Btot (mg) 2006 Btot (mg)** Bagley Hall Chemistry Bldg EE/CS Physics/Astronomy Johnson Hall Fluke Hall ME Bldg. & Annex Roberts Hall Wilcox Hall CHDD Diagnostic Imaging Surgery Pavilion* - 1st Fl Surgery Pavilion* - Pking Fisheries Center (FIS) Marine Sciences * Also called the Ambulatory Care Facility. At Surgery Pav. max Source 5 and Source 6 B-fields cannot be present simultaneously. **From Table 4.1 in Ref. 1 Source 1 - B-field mitigated region rails & cables Source 2 - Brooklyn stub Source 3 - Brooklyn-Roosevelt rails & cables Source 4 - South-of-Montlake rails & cables Source 5 - UW TPSS propulsion currents Source 6 - Crossover propulsion currents

28 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 27 Examination of Table 9 shows that the only critical UW labs at which the 2012 predicted B-fields exceed the UW Requested Thresholds are the three at which the 2006 predicted B-fields also exceeded the UW Requested Thresholds, namely the three Group 2 labs ME Bldg. & Annex, Wilcox Hall and Roberts Hall. As noted previously in this report, since the 2012 levels at two of these labs, namely Wilcox and Roberts Halls, also exceed the 2006 levels that constituted the ST Baseline Predictions, this matter will have to be discussed by the UW and ST. 9. MAINTENANCE OF B-FIELD MITIGATION DURING A UW TPSS RECTIFIER SHUTDOWN There are a number of B-field mitigation circuit designs that have been implemented at other transit systems. [Ref. 3] The design being implemented at the UW campus was chosen because it meets the need for sectionalizing the propulsion power system while avoiding rail cross bonds with series switches and NB-to-SB OCS jumpers with series switches at the northern and southern ends of the B-field mitigation region positions in the tunnels remote from stations. To guarantee proper operation of the U-Link/North Link B-field mitigation propulsion circuitry in the mitigated region electrical isolation of the B-field mitigated region from the non-mitigated regions north and south must be maintained at all times, except when trains short across the rail insulated joints at the corners of the mitigated region in prescribed fashion. The analysis of B-field levels undertaken for this report led to the conclusion that additionally, to minimize the maximum length of rectifier-to-train current loops in the South-of-Montlake region, which is important for meeting the UW spec B-field levels at certain labs, the South-of-Montlake tracks must have power fed from both the northern and southern ends at all times. It is envisioned that occasionally the single rectifier at the Capitol Hill TPSS or one of the three rectifiers at the UW TPSS will be taken out of service for maintenance or repair. To allow this while simultaneously meeting the operating conditions noted above modifications [Ref. 4] have been made to the design of the UW TPSS outlined in Ref. 2. Switches have been added and wiring modified to allow the following operation: As detailed in Ref. 2, during normal operation the Montlake, NB UW and SB UW rectifiers all will be electrically isolated from each other. Electrical isolation of the NB and SB UW rectifiers will allow suppression of unwanted return current paths provided no more than three of the IJ pairs at the four corners of the B-field mitigated region are shorted by trains crossing them at once.

29 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 28 Also as detailed in Ref. 2, during shut-down of either the NB or SB UW rectifier the remaining UW rectifier will power both NB and SB UW tracks. Under this operating condition suppression of unwanted return current paths will require that only one of the IJ pairs at the northern end of the B-field mitigated region may be shorted by trains crossing at once; and the same constraint exists at the southern end. However, during shut-down of the Montlake rectifier the modified propulsion circuitry [Ref.4] will allow the SB UW rectifier to serve in its place, electrically isolated from the NB unit. The NB unit will then power both the SB and NB UW tracks in the B-field mitigated region. The operating constraints imposed to suppress unwanted return current paths will be the same as when the NB or SB rectifier is out of service as described above. These constraints on train movement described above will be addressed by contingency train operating procedures. Under conditions of multiple rectifier outages it may not be possible to guarantee B-field mitigation. Safety of passengers and equipment will have to be given priority.

30 90% North Link EMI Prediction Report Holmstrom September 2012 pg. 29 REFERENCES 1. North Link Hi-Lo Mitigation EMI Report, F. Ross Holmstrom & LTK Engineering Services, Document No. LTK.ST , April ST Link Light Rail Project, 100% EMI Prediction and Mitigation Design Report, LTK Engineering Services, Document No. LTK.ST , November ST Link Light Rail Project, 90% EMI Prediction and Mitigation Design Report, LTK Engineering Services, Document No. LTK ST , June Appendix C, Configuration of UW TPSS for U-Link, pg. 3, Description of Options. (Attached) 4. U830 Contract Plan L10-JT502 REV 1, LTK Engineering Services, 01/10/12. (Attached) 5. N-Link 60% EMI UW Comments - Complete (Attached)

31 Reference. 3 Appendix C Configuration of UW TPSS for U-Link LTK Memo November % EMI Prediction Appendix C June 11, 2008 and Mitigation Design Report

32 Reference. 3 LTK Engineering Services ST Link Project Office MEMORANDUM To: George Hodges File: Doc: IMK-004 From: Denny Porter, Ming Li, Ed Rowe Date: November 16, 2007 Subject: Configuration of UW TPSS for U-Link Background and Purpose The purpose of this memo is to recommend the number of traction power rectifiers located in the substations at the University of Washington (UW) passenger station, and how these rectifiers should be configured to connect to the overhead distribution system and the running rails on Sound Transit s University Link extension. Due to predicted EMI magnetic field levels generated from operating Sound Transit (ST) light rail vehicles, the North Link light rail alignment has been designed with special mitigation features to limit the influence of these magnetic fields. The rail alignment will pass under the UW campus where sensitive instruments and experiments are located in several nearby UW buildings. Sound Transit s design will protect these instruments and experiments. The primary component of LTK s conceptual design, known as the hi-lo mitigation design, involves substantial changes to the normal overhead contact system (OCS) design. The basic concept of this hi-lo design uses a buried DC cable with a large cross sectional area to carry the majority of the positive traction current. The messenger wire will be used to provide only mechanical support for the contact wire. Closely spaced risers will connect the buried cable to the contact wire. This DC cable will be placed beneath the centerline of the two parallel running rails which serve as the return path of the traction power current. As a result, the magnetic fields generated by the currents flowing through the buried cable and the running rails will largely cancel each other to achieve the mitigation of the EMI. This basic design concept is similar to that which has been placed into service and tested in St. Louis and previously to that in Bielefeld, Germany. The configuration of the traction power substation (TPSS) at UW Station has also been considered a component of the EMI mitigation concept for some time. North Link Preliminary Engineering (PE) work suggested the mitigation section be electrically isolated from the rest of the traction power system and be independently fed by a single

33 Reference. 3 To: George Hodges Page 2 of 10 From: Denny Porter, Ming Li, Ed Rowe November 16, 2007 TPSS with two separate rectifier units; one to feed only the northbound (NB) track and the other to feed only the southbound (SB) track. It was also suggested that the Montlake TPSS, which feeds the section south of the mitigation section, be used as back-up to feed the mitigation section in the event that the UW TPSS loses power. Thus, the two TPSS would have a total of four rectifiers. Since this mitigation design is a relatively new concept, it has taken some time to evaluate and determine how the design of the traction power substations will contribute to the mitigation of EMI. LTK is concentrating on the traction power overall design to determine how the design could be optimized by reducing the number of transformer rectifier units from four units to three, or even two units. This discussion is further presented herein. To progress the design of the traction power system for U-link and the civil work of the UW Station, a timely conclusion of the TPSS configuration for the UW Station is required. This report summarizes previously proposed UW TPSS designs, reviews design options and recommends a final design configuration. Overview of Options In the UW passenger station box, there will be two traction power substations; Montlake (ML) TPSS which will feed the Capitol Hill to UW section (South of EMI mitigation section), and UW TPSS, which will feed the EMI mitigation section. Due to space limitations of the alignment, ML TPSS will be located several hundred feet away from its preferred location at the south end of the EMI mitigation section. Geographically, ML TPSS will share the space with UW TPSS, in UW passenger station (See Figure 1) The Power Supply Configuration of EMI Region Capitol Hill Passenger station Capitol Hill TPSS UW Passenger station Mont Lake TPSS UW TPSS Non-Mitigation Section EMI Mitigation Section Figure 1 UW TPSS will feed the EMI mitigation section singly without the double end-fed application (a feed from two substations at opposite ends) of normal traction power

34 Reference. 3 To: George Hodges Page 3 of 10 From: Denny Porter, Ming Li, Ed Rowe November 16, 2007 system design. The design also considers a single TPSS outage situation which could occur to either UW TPSS or ML TPSS. Disconnect switches will be used to link UW TPSS and ML TPSS to provide back-ups for these substations should either fail. Except for the single line diagram design of arranging the switching devices, the capacities of the transformer rectifier units also need to be taken into consideration for emergency situations. LTK commenced preliminary TPSS design a few years ago to provide a basic overall EMI mitigation design. There were several options for the TPSS designs at early project stages. LTK chose the most conservative (and highest cost) option to be presented in the EMI mitigation report during the PE phase. As additional data recently became available from St. Louis Metro Cross County EMI design, LTK discovered that some of the St. Louis design concepts could be utilized on our U-link design. LTK recently reviewed the St. Louis EMI mitigation test report and found that the design provides a very high level of EMI mitigation. Those findings have encouraged us to further study the St. Louis case. Currently, LTK has developed a new design which combines the advantages of both our original design and the St. Louis design. Description of Options Four options have been developed, as follows: Option 1 Option 2 Option 3 Option 4 Bielefeld style St Louis style Single rectifier Seattle style Hybrid style The following outlines the basic concepts of each option.