How to access a html form value in python - web2py

Im using web2py for a project and have to use ajax/javascript with a form. Currently when the user makes a selection in the departure choice box the arrival choice box appears. However im not sure how I would go about refining the list of the arrival choices based on what was selected in the first box.

For example if you had option 1, option 2 and option 3 in departure choice and option 2 was selected then only option 1 and 3 would be avaialbe in arrival.

makeBooking.html

{{extend 'layout.html'}}

{{block content}}

<div class="span8">
<div class="pagetitle">
       <h3>Make a Booking</h3>

</div>
<!-- Brandons Code Here -->
<select id="departureChoice">
{{for StopLocation in result:}}

<option value="{{=StopLocation.suburb_name}}">{{=StopLocation.suburb_name}}</option>

{{pass}}
</select>

<br>
<div id="arrive" style="visibility:hidden" >
    <select id="arriveChoice">
   {{for StopLocation in result:}}

<option value="{{=StopLocation.suburb_name}}">{{=StopLocation.suburb_name}}</option>

{{pass}}
</select>
</div>
<br>

{{end}}

<script type="text/javascript">
$('#departureChoice').change(function(event) {
    $.post('bookingFunction.html', { 
        selected: $('#departureChoice').val() 
        },
        function(data) {

            document.getElementById( 'arrive' ).style.visibility = 'visible';

        }
    );            
}); 

Using web2py would it be possible to then submit these two fields to query a database without reloading the page using ajax? I currently have bookingFunction.html set up for this but its blank.

Thanks in advance