The
Current Track Usage Graph
shows Tacoma Rail's yard divided into 9 major groups. It shows data collected from the beginning of the month.
Please select a date for an archived chart.
Tacoma Rail tracks infrastructure occupancy within its rail infrastructure.
Rail yard space is essential in maintaining a continuous flow of rail traffic without disruption.
Uninterrupted flow is when all activities are planned
and sequenced to avoid delay. Yard congestion can have a profound impact on these activities.
First, Tacoma Rail yards must first be able to receive inbound trains from either
of the mainline carriers(UP, BNSF) that serve the Tideflats as they arrive in the Tacoma area. Inbound deliveries can range from
300 foot trains to 8,000 foot trains and actual arrival times for inbound
trains can vary widely from schedule. Often, an eight hour window is the best available information.
If an inbound train cannot be
delivered to Tacoma Rail, it may be routed out of the Fife/Tacoma area and may not be available again for up to 24 hours.
Second, Tacoma Rail yards must have enough room to switch out, stage and position
railcars for efficient delivery. Inbound loads are not presorted for destination within the Tideflats. Inbound trains may
have mixed loads of commercial and intermodal equipment. The intermodal traffic may be destined to Evergreen, K-Line,
Hyundai, and Northwest Container while the commercial traffic could be destined to any number of Tacoma Rail's 60+ customers.
Sorting inbound railcars for internal destinations (called classification) can be excessively time consuming and expensive. Staging
and support tracks along with a clear switching lead have to be available in order for this sorting to be accomplished efficiently.
Third, Tacoma Rail's staging and support infrastructure
must have sufficient room to pull completed trains or empties from its customers. That way, when the pull is completed,
the next railcars in the yard can then be spotted at their facility.
So what should a Railroad's infrastructure utilization be? A rail industry rule of thumb confirmed by detailed
studies is that available track should not be utilized in excess of 60% by railcars. Utilization in the range of 50-60% indicates mild
congestion. At that level there are some restrictions of operations. Ratios in excess of 60% indicate significant congestion
and reduced responsiveness.
At a time of significant utilization, railcars have to be moved and shuffled excessively to make room for other cars while attempting
to keep cars in logical sequences. Utilization in
excess of 80% indicates a yard is in gridlock and all activities are severely delayed.
A simple analogy is the puzzle game consisting of 15 numbered squares in a 16
square field. To create a particular sequence of numbers several moves are required. Impatient players often remove
one or two squares to create more 'empty' space. In doing so they find that completing puzzle is very easy and each classification
requires less moves.
