THREE-DIMENSIONAL SIMULATION OF SUBWAY BOMB EXPLOSION

August 12, 2004

Because of recent concern dealing with the terrorist of threat explosions produced by bombs placed on subways in Boston and New York, Engineering Analysis Inc. (EAI) has developed a three-dimensional simulation of a subway bomb explosion directly beneath the Hudson Center, a hypothetical high-rise office complex in New York City.  As shown in Figure 1, the complex consists of an entire city block containing a twelve-story hotel, a twenty-six-story office building, a thirty-story office building, a raised plaza terrace, and an underground parking garage.  By means of the HEXMAN concept one hundred pedestrians, each consisting of twenty-eight components, are positioned throughout the complex.  In a subway tunnel located fifty feet directly beneath the Hudson Center two subway trains, each consisting of nine cars, are passing, one northbound and one southbound.  Forty-Five passengers are located aboard each train by means of the HEXMAN concept.  The first car in the northbound train contains a large bomb, consisting of 10,000 pounds of high explosive.  The bomb is detonated beneath the middle of the block where the Hudson Center is located.  As indicated in Figure 1, in representing the subway tunnel and the overlying strata, only those portions directly beneath the Hudson Center are included in the model, in order to provide a means of visualizing the subterranean blast effects.

The HEXDAM software was used to simulate the results of the explosion.  The results consist of color-coded graphics depicting blast overpressure contours, damage to structures, and injury to pedestrians and passengers.  Three sets of figures covering the entire office complex were generated, as shown in Table 1.  In each set five views of the office complex are presented, as indicated in Table 2.

Table 1.  Description of Graphic Sets for Entire Office Complex

   Corresponding
         Figures          Set #                                                    Description
      1, 2, 3, 4, 5           1        Undamaged Hudson Center
      6, 7, 8, 9, 10         2        Undamaged Hudson Center with three-dimensional overpressure contours
  11, 12, 13, 14, 15     3        Hudson Center with color-coded damage and injury and with three-
                                               dimensional overpressure contours
 
 

Table 2.  Description of Graphics Views for Entire Office Complex

        Corresponding
              Figures          View #                                            Description
           1, 6, 11              1         Hudson Center (Northwest View) with an elevation angle of 30°
           2, 7, 12              2         Hudson Center (Northeast View) with an elevation angle of 30°
           3, 8, 13              3         Hudson Center (Southeast View) with an elevation angle of 30°
           4, 9, 14              4         Hudson Center (Southwest View) with an elevation angle of 30°
           5, 10, 15             5         Hudson Center (Southwest View) with an elevation angle of 90°

For Set #1, in the five views shown in Figures 1 through 5, all structural components of the office complex are color-coded blue, while all pedestrians are color-coded fuchsia.

For Set #2, in the five views shown in Figures 6 through 10, all structural components of the office complex are color-coded blue.  Likewise, all components of the bodies of the pedestrians are color-coded fuchsia.  As indicated in these five figures, the three-dimensional overpressure contours are color-coded, ranging from red for 75 psi to yellow for 3 psi.

For Set #3, in the five views shown in Figures 11 through 15, all structural components of the office complex are color-coded for damage, with green representing no damage, yellow representing slight damage, orange representing moderate damage, and red representing severe damage.  Likewise, all components of the bodies of the pedestrians are color-coded in the same manner for no injury, slight injury, moderate injury, and severe injury.  The three-dimensional overpressure contours are also color-coded, ranging from red for 75 psi to yellow for 3 psi.  Close inspection of the figures reveals that the overpressure contours match the location of the crater formed in the center of the plaza terrace.

In addition to the graphical displays covering the entire office complex, nine additional figures, as shown in Table 3, were generated for the plaza terrace in the vicinity of crater produced by the subway bomb explosion.  As indicated in Figure 16, in this view, looking to the south, the twelve-story hotel is to the right, the twenty-six story office building is to the left, and the thirty-story office building is directly ahead.  In all undamaged views (Figures 16 through 23) structures are color-coded blue and pedestrians fuchsia.

Table 3.  Description of Graphics for Plaza Terrace

            Figure      Overpressure Contour       Damage/Injury
             16                        None                         None
             17                        75 psi                        None
             18                        45 psi                        None
             19                        25 psi                        None
             20                        15 psi                        None
             21                        10 psi                        None
             22                          5 psi                        None
             23                          3 psi                        None
             24                        None                          Yes

Figures 17 through 23 depict the three-dimensional overpressure contours in descending order from 75 psi down to 3 psi.  Damage to structures and injury to personnel are presented in Figure 24.  In this view all structures and pedestrians are color-coded as before.

In addition to the graphical depiction of blast effects in the vicinity of the crater, forty-four figures were generated to provide a detailed description of structural damage and personnel injury aboard the two subway trains, as summarized in Table 4.

Table 4.  Description of Graphics for Subway Trains

    Figure       Location        Car #               Train           View Direction        Damage/Injury
        25        Behind                9            Northbound        Northward                   No
        26        Inside                 9            Northbound        Northward                    No
        27        Inside                 8            Northbound        Northward                    No
        28        Inside                 7            Northbound        Northward                    No
        29        Inside                 6            Northbound        Northward                     No
        30        Inside                 5            Northbound        Northward                     No
        31        Inside                 4            Northbound        Northward                     No
        32        Inside                 3            Northbound        Northward                     No
        33        Inside                 2            Northbound        Northward                     No
        34        Inside                 1            Northbound        Northward                     No
        35        In front               1            Northbound        Northward                     No
        36        Behind                9            Southbound        Southward                     No
        37        Inside                 9            Southbound        Southward                     No
        38        Inside                 8            Southbound        Southward                     No
        39        Inside                 7            Southbound        Southward                     No
        40        Inside                 6            Southbound        Southward                     No
        41        Inside                 5            Southbound        Southward                     No
        42        Inside                 4            Southbound        Southward                     No
        43        Inside                 3            Southbound        Southward                     No
        44        Inside                 2            Southbound        Southward                     No
        45        Inside                 1            Southbound        Southward                     No
        46        In front               1            Southbound        Southward                     No
        47        Behind                9            Northbound        Northward                    Yes
        48        Inside                 9            Northbound        Northward                     Yes
        49        Inside                 8            Northbound        Northward                     Yes
        50        Inside                 7            Northbound        Northward                     Yes
        51        Inside                 6            Northbound        Northward                     Yes
        52        Inside                 5            Northbound        Northward                     Yes
        53        Inside                 4            Northbound        Northward                     Yes
        54        Inside                 3            Northbound        Northward                     Yes
        55        Inside                 2            Northbound        Northward                     Yes
        56        Inside                 1            Northbound        Northward                     Yes
        57        In front               1            Northbound        Northward                     Yes
        58        Behind                9            Southbound        Southward                     Yes
        59        Inside                 9            Southbound        Southward                     Yes
        60        Inside                 8            Southbound        Southward                     Yes
        61        Inside                 7            Southbound        Southward                     Yes
        62        Inside                 6            Southbound        Southward                     Yes
        63        Inside                 5            Southbound        Southward                     Yes
        64        Inside                 4            Southbound        Southward                     Yes
        65        Inside                 3            Southbound        Southward                     Yes
        66        Inside                 2            Southbound        Southward                     Yes
        67        Inside                 1            Southbound        Southward                     Yes
        68        In front               1            Southbound        Southward                     Yes

As indicated in the table, Figures 25 through 35 deal with the northbound train without damage/injury.  These figures are arranged in order from the rear car (#9) to the front car (#1), which contains the bomb.  Likewise, Figures 36 through 46 deal with the southbound train without damage/injury, arranged in order from the rear car (#9) to the front car (#1).  Figures 47 through 57 pertain to the northbound train with damage/injury, in the same order as before, while Figures 58 through 68 pertain to the southbound train with damage/injury in the same order.