app->code->local->Gta->KolupadiRestrict->etc->config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Gta_KolupadiRestrict>
            <version>1.0.0</version>
        </Gta_KolupadiRestrict>
    </modules>
    <global> 
        <models>
            <gta_kolupadirestrict>
                <class>Gta_KolupadiRestrict_Model</class>
            </gta_kolupadirestrict>
        </models>
    </global>   
    <frontend>
        <events>
            <sales_order_place_before>
                <observers>
                    <Gta_KolupadiRestrict_Model_Observer>   
                        <type>singleton</type>
                        <class>Gta_KolupadiRestrict_Model_Observer</class>
                        <method>cartevent</method>
                    </Gta_KolupadiRestrict_Model_Observer>
                </observers>
            </sales_order_place_before>      
        </events>
    </frontend>
    </global>   
</config>

app->code->local->Gta->KolupadiRestrict->Model->Observer.php

<?php
class Gta_KolupadiRestrict_Model_Observer {

    public function cartevent($Observer) {

            $order = $Observer->getEvent();
            $shipping = $order->getShippingAddress()->getShippingMethod();


            Mage::log($shipping->getName(),null,'event.log');
    }   
}
?>

app->etc->modules->Gta_KolupadiRestrict.xml

<?xml version="1.0" encoding="UTF-8"?>

<config>

	<modules>

		<!-- Gta_KolupadiRestrict -->

		<Gta_KolupadiRestrict>

			<active>true</active>

			<codePool>local</codePool>

		</Gta_KolupadiRestrict>

	</modules>

</config>