input_routes.rou.xml

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

<routes xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://sumo.dlr.de/xsd/routes_file.xsd">
    <vType id="train" vClass="rail" length="20" accel="2"/>
    <vehicle id="train" type="train" depart="0">
        <route edges="a b c d"/>
    </vehicle>
    <vehicle id="train2" type="train" depart="1">
        <route edges="-d2 -c -b -a2"/>
    </vehicle>
</routes>