The shortest manned helper district on both the BNSF and UP is over the NOPB RR between Avondale and the Mississippi River on the Huey P. Long Bridge in Louisiana. BNSF uses a yard crew to shove Eastbounds or Southbounds (depending on what Subdivision they are coming off of as there are 3. The UP Avondale Subdivision is on the extreme Southside of Avondale and runs East/West. The BNSF Lafayette Subdivision is in the middle and is also and East/West Sub. The Livonia Subdivision is to the North of the BNSF and is a North/South Sub.) to the top of the Bridge. UP used to do it quite frequently, but a bad derailment a few Thanksgivings ago, caused Ron Tindell, the then, Director of Terminal Operations for the UP to ban all helper moves over the Bridge period by UP crews, because he really believed that this would solve ALL these problems. So now, a UP train, will knowingly go up the Bridge, knowing in advance they will stall. When they do, a yard crew is told to stop what they are doing, take their power, and help the disabled train. Down there, the BNSF uses the term Helper Engine, but UP calls it the Pusher Engine. If a westbound (all trains are East/West on the NOPB RR) stalls comming up the Bridge, again, a Yard Crew will be told to stop what they are doing, and get flagged past the Red Controlled Signal by the West Bridge Jct. Towerman, and go up the the disabled train and "Pull" it up the Bridge. Hope this is helpful.