A draft set of half-hourly arc flow data has been provided in this version of the Centralised Dataset. 
It covers the period 1/10/1996-16/6/2009. The data is sourced from SPD final pricing runs obtained 
from the System Operator. 

The data includes (by arc, by half-hour):

Flow into the arc (MW)
Flow out of the arc (MW)
Maximum arc capacity (MW)
Pricing run time
Shadow price

The Authority is currently in the process of developing data management systems for handling final 
pricing market data. It is anticipated that more up-to-date arc-flow data will be made available 
following the completion of that work.