Franklin & Marshall College Franklin & Marshall College

Truck Diversions

Below is an explanation of the project's benefit to divert 55,000 truck trips to rail delivery.

One of the many benefits to the Norfolk Southern Dillerville Yard Consolidation Project is the number of tractor trailer trips it will remove from Central and South Central Pennsylvania roadways, which in turn decreases air pollution and reduces highway maintenance costs to repair the wear and tear created from these trucks.  By using a federal government formula and customer information supplied by Norfolk Southern, the projected “truck diversions” are 55,000 annual trips. Truck diversions are an acceptable and recognizable means used by government and industry to evaluate the impact of a transportation project.

This truck diversion number was calculated by Gannett Fleming using information supplied by Norfolk Southern for their customers that have asked for expanded rail deliveries, which Norfolk Southern has been unable to provide because of the lack of space in the Dillerville Yard, coupled with Norfolk Southern’s expected growth of the overall Lancaster market.  This information was inserted into a federal government air quality formula that resulted in the 55,000 truck diversion number.   This number is a ”real estimate” based upon existing customer requests and projected demand based upon historical growth rates. 

Truck diversions represent the shipment of goods that will shift from tractor trailers to rail with the completion of this project.  Rail delivery is generally considered to be a more efficient and environmentally friendly method of moving goods.

Several points to keep in mind when considering this truck diversion number are:

- the diversion number accounts only for existing Norfolk Southern customers that have rail sidings to their facilities in the Lancaster market.
- the diversion number does not involve any intermodal activities.  (Intermodal activities combine transportation methods to complete the delivery of goods such as moving materials from a ship to rail to truck before reaching the customer.)
- The Dillerville Yard is not an intermodal facility.  The closest intermodal facility is the Rutherford Yard in Harrisburg, Pennsylvania where rail and truck modes are combined to complete the delivery of goods.

Truck diversions are a transportation industry concept and might be difficult to comprehend for some.  However, it could be compared to a business concept used to decide on whether or not to introduce a new product or service.  The company surveys its customers and proposes a new offering and inquires if the customers would be interested in purchasing it.  From this information a business plan is constructed that is based upon expressed demand from customers as well as predicted demand using historical data about similar products or services.

Several years ago in an effort to address the overburdened Dillerville Yard, Norfolk Southern did a short-term test of offloading goods onto trucks in the Enola Rail Yard near Harrisburg and delivering them to their Lancaster customers.  This experiment failed for a number of reasons and Norfolk Southern realized it needed to expand the Dillerville Yard for greater rail service or risk not being able to serve their expanding customer base in Lancaster.

The assumptions and method of calculating the truck diversion are listed below.

Determination of Truck Trip Elimination due to Dillerville Yard Capacity Improvements

Input/ Assumptions on Rail Operations:

  • Dillerville Yard operates 6 days per week
  • Largest Train, “Enola Cut”, comes in from Enola Yard – West of Harrisburg
  • ‘Enola Cut’ has capacity to pull approx. 115 rail cars given tractive power.
  • ‘Enola Cut’ presently carries approx. 60+ rail cars on average.
  • Maximum increase of 55 rail cars/day possible but average of 40 rail cars/day assumed to be conservative.
  • The present Yard Capacity is 303 Railcars.
  • The proposed Yard Capacity is 475 Railcars, an increase of 172 Railcars.
  • Federal CMAQ formula states a single railcar is assumed to have capacity of 3.5 Trucks.  For our calculations, we assumed a single railcar equaled 3.0 Trucks to be conservative.


If calculations were based on additional capacity of yard, the truck trips would be as follows;

Total Truck trips reduced annually
= 172 Rail cars/day x 312 Days/year
= 53,664 Rail cars/yr. x 3.0 trucks/Rail car
= 160,992 Trucks x 2 Trips
= 321,984 Truck Trips per year

However, calculations were based on additional capacity of the “Enola Cut” Train, therefore the truck trips would be as follows;

Maximum Truck trips reduced annually
= 55 Rail cars/day x 312 Days/year
= 17,160 Rail cars/yr. x 3.0 trucks/Rail car
= 51,480 Trucks x 2 Trips
= 102,960 Truck Trips per year

Average Truck trips reduced annually  
= 40 Rail cars/day x 312 Days/year
= 12,480 Rail cars/yr. x 3.0 trucks/Rail car
= 37,440 Trucks x 2 Trips
= 74,880 Truck Trips per year

Round to 75,000 Truck Trips per year*

* Of the diverted 75,000 Truck trips per year, 7,000 were credited to Phase I of the Dillerville Project in the CMAQ document justifying the funding of the initial additional capacity effort completed in 2007.  Of the remaining 68,000 Truck trips per year, Franklin & Marshall College conservatively reduced the figure to 55,000 Truck trips per year for purposes of not overestimating the truck diversions possible.   

The 55,000 truck diversion number is also conservatively estimated because: 1) the lower conversion factor of the number of trucks equaling the number of rail cars to haul the same amount was used, and 2) the average number of rail car increase versus the maximum for the Enola cut.