you can use the following regular Expression:
$re = "/<TD class=\"table_border_both\"><b>([0-9][0-9])
<\/b><\/TD>/";
$str = "<table width=\"100%\" border=\"0\" cellpadding=\"0\" cellspacing=\"1\" class=\"table_border\">
<tr>
<td colspan=\"9\" class=\"heading_table_top\">Journey Details</td>
</tr>
<TR class=\"heading_table\">
<td width=\"11%\">Train Number</Td>
<td width=\"16%\">Train Name</td>
<td width=\"18%\">Boarding Date <br>(DD-MM-YYYY)</td>
<td width=\"7%\">From</Td>
<td width=\"7%\">To</Td>
<td width=\"14%\">Reserved Upto</Td>
<td width=\"21%\">Boarding Point</Td>
<td width=\"6%\">Class</Td>
</TR>
<TR>
<TD class=\"table_border_both\">*12559</TD>
<TD class=\"table_border_both\">SHIV GANGA EXP </TD>
<TD class=\"table_border_both\"> 5- 7-2014</TD>
<TD class=\"table_border_both\">BSB </TD>
<TD class=\"table_border_both\">NDLS</TD>
<TD class=\"table_border_both\">NDLS</TD>
<TD class=\"table_border_both\">BSB </TD>
<TD class=\"table_border_both\"> SL</TD>
</TR>
</table>
<TABLE width=\"100%\" border=\"0\" cellpadding=\"0\" cellspacing=\"1\" class=\"table_border\" id=\"center_table\" >
<TR>
<td width=\"25%\" class=\"heading_table_top\">S. No.</td>
<td width=\"45%\" class=\"heading_table_top\">Booking Status <br /> (Coach No , Berth No., Quota)</td>
<td width=\"30%\" class=\"heading_table_top\">* Current Status <br />(Coach No , Berth No.)</td>
<td width=\"30%\" class=\"heading_table_top\">Coach Position</td>
</TR>
<TR>
<TD class=\"table_border_both\"><B>Passenger 1</B></TD>
<TD class=\"table_border_both\"><B>S1 , 33,CK </B></TD>
<TD class=\"table_border_both\"><B>S1 , 33</B></TD>
<TD class=\"table_border_both\"><b>11
</b></TD>
</TR>
<TR>
<TD class=\"table_border_both\"><B>Passenger 2</B></TD>
<TD class=\"table_border_both\"><B>S1 , 34,CK </B></TD>
<TD class=\"table_border_both\"><B>S1 , 34</B></TD>
<TD class=\"table_border_both\"><b>11
</b></TD>
</TR>
<TR>
<TD class=\"table_border_both\"><B>Passenger 3</B></TD>
<TD class=\"table_border_both\"><B>S1 , 36,CK </B></TD>
<TD class=\"table_border_both\"><B>S1 , 36</B></TD>
<TD class=\"table_border_both\"><b>11
</b></TD>
</TR>
<TR>
<TD class=\"table_border_both\"><B>Passenger 4</B></TD>
<TD class=\"table_border_both\"><B>S1 , 37,CK </B></TD>
<TD class=\"table_border_both\"><B>S1 , 37</B></TD>
<TD class=\"table_border_both\"><b>11
</b></TD>
</TR>
<TR>
<td class=\"heading_table_top\">Charting Status</td>
<TD colspan=\"3\" align=\"middle\" valign=\"middle\" class=\"table_border_both\"> CHART PREPARED </TD>
</TR>
<TR>
<td colspan=\"4\"><font color=\"#1219e8\" size=\"1\"><b> * Please Note that in case the Final Charts have not been prepared, the Current Status might upgrade/downgrade at a later stage.</font></b></Td>
</TR>
</table>";
preg_match_all($re, $str, $matches);
Most useful website for regex: http://regex101.com/