Accessible Table with Sub Headings / Category Separation - html

Question

EDIT: To the person who tagged this as having nothing to do with ADA. This question has everything to do with ADA. I have tons of websites with tables formatted like that which I am trying to figure out how to make them understandable to someone using a screen reader.
Hello I am trying to figure out a way to make a table which has subheadings / separator rows to announce the proper headings when being read by a screen reader.
The first table works as I would like, announcing the rowgroup's TH and then the column heading. However the second table doesn't announce as I was hoping. For example, Jill announces "Field Techs, Name, Jill" Instead of "Office, Name, Jill" as I had expected.
I've tried scope="col" and scope="colgroup" but neither helped. Is this even possible? or just a badly structured table?
Thank you for reading and any help/advice you may offer!
table thead, table th { background:#d3d3d3; }
table { margin-bottom:40px; }
<!-- This table's headings seem to work properly -->
<table width="100%" cellspacing="0" cellpadding="4" >
<thead>
<tr>
<td> </td>
<th id="name_col" scope="col" width="50%">Name</th>
<th id="position_col" scope="col" width="50%">Position</th>
</tr>
</thead>
<tbody>
<tr>
<th id="office_row" scope="rowgroup" rowspan="2">Office</th>
<td headers="office_row name_col">Jill</td>
<td headers="office_row position_col">Office Manager</td>
</tr>
<tr>
<td headers="office_row name_col">Robert</td>
<td headers="office_row position_col">Project Manager</td>
</tr>
<tr>
<th id="field_row" scope="rowgroup" rowspan="2">Field Techs</th>
<td headers="field_row name_col">Jason</td>
<td headers="field_row position_col">Tech</td>
</tr>
<tr>
<td headers="field_row name_col">Mike</td>
<td headers="field_row position_col">Tech</td>
</tr>
</tbody>
</table>
<!-- This table's headings don't announce correctly. Jill announces "Field Techs, Name, Jill"-->
<table width="100%" cellspacing="0" cellpadding="4" >
<thead>
<tr>
<th id="name_col" scope="col" width="50%">Name</th>
<th id="position_col" scope="col" width="50%">Position</th>
</tr>
<tr>
<th id="office_group" colspan="2">Office</th>
</tr>
</thead>
<tbody>
<tr>
<td headers="office_group name_col">Jill</td>
<td headers="office_group position_col">Office Manager</td>
</tr>
<tr>
<td headers="office_group name_col">Robert</td>
<td headers="office_group position_col">Project Manager</td>
</tr>
</tbody>
<thead>
<tr>
<th id="field_group" colspan="2">Field Techs</th>
</tr>
</thead>
<tbody>
<tr>
<td headers="field_group name_col">Jason</td>
<td headers="field_group position_col">Tech</td>
</tr>
<tr>
<td headers="field_group name_col">Mike</td>
<td headers="field_group position_col">Tech</td>
</tr>
</tbody>
</table>

Answer 1

table can only have zero or one thead element (see documentation).
Permitted contents : An optional caption element, followed by zero or more colgroup elements, followed by an optional thead element
By having multiple thead elements only the last one is considered by your browser and your screenreader. You can use ARIA attributes and roles to handle multiple separated heading lines (using for instance aria-labelledby attribute to specify the heading).
One example from WCAG:
ARIA9: Using aria-labelledby to concatenate a label from several text nodes

Answer 2

You are using both the scope method and header/id's method in one table, which will create problems. Also, as others have pointed out, you're using multiple <th> and <tbody> elements, which isn't good either.
I've prepared some code samples here on how to correctly code this table using both the scope method and header/id's method:
https://jsfiddle.net/oody1b8x/
It's worth noting that <th> and <tbody> are not accessibility-related elements, even though they appear to be. These are essentially only used when printing. It lets the printer know that the header rows can be repeated on the next page if the table requires pagination.
Also -- don't use ARIA for this purpose; it will only create more problems. The native HTML semantics are perfectly capable of communicating how this data is structured.