This one tells the priority of BSK.
12488 Seemanchal departs Anvt at 7:30 am and reaches Sonpur at 7:55 am whereas 12566 BSK departs New Delhi @14:15 and arrives Sonpur at 7:57 and overtakes 12488.So,after leaving almost 7 hours of Seemanchal whose avg speed is also more than Bsk due to superb priority gets overtakes at SEE.