I know you specifically asked how to do this on the RouteConfig, but you can also accomplish the same using IIS Rewrite Rules. The rules live on your web.config so you don't even need to use IIS to create the rules, you can simply add them to the web.config and will move with the app through all your environments (Dev, Staging, Prod, etc) and keep your RouteConfig clean. It does require the IIS Module to be installed on IIS 7, but I believe it comes pre installed on 7.5+.
Here's an example:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<rewrite>
<rules>
<rule name="Redirect t and c" stopProcessing="true">
<match url="^terms_conditions$" />
<action type="Redirect" url="/TermsAndConditions" />
</rule>
</rules>
</rewrite>
</system.webServer>
</configuration>