HOUSTON, Aug 23 (Reuters) - S&P Global ( SPGI ) on

Friday said its Platts commodities unit will launch a daily

freight assessment in October for Aframax ships moving between

Canada's Vancouver and the U.S. West Coast.

Trans Mountain pipeline expansion began commercial

operations in May, nearly tripling, to 890,000 barrels per day

(bpd), the flow of crude from landlocked Alberta to Canada's

Pacific coast.

The assessment will be for 80,000 metric ton Aframaxes and

comes as the recent startup of the Trans Mountain oil pipeline

expansion has boosted shipments on the route.

Aframaxes, which can weight up to 120,000 metric tons and

carry about 800,000 barrels, only load about 550,000 barrels at

the Westridge terminal in Vancouver due to draft restrictions.

Most of those cargoes have headed to refineries along the

U.S. Gulf Coast, including Marathon Petroleum's ( MPC ) Los

Angeles Refinery, Valero Energy's ( VLO ) Benicia refinery,

Chevron Corp's ( CVX ) El Segundo refinery and Phillips 66's

Ferndale refinery.

Just over 92% of all Aframax ships loading Trans Mountain

Pipeline barrels at Westridge terminal since the startup either

discharged onshore U.S. West Coast or offshore at the Pacific

Area Lightering terminal, where the crude is transferred onto

super tankers for final delivery into Asia, according to S&P

Global Commodities at Sea data.

"Spot freight market activity has ramped up significantly

since the expansion began commercial operations May 1," Platts

wrote in its note.

The freight assessment will reflect the cost of voyages on

Aframaxes delivering barrels directly to U.S. West Coast

refineries unloading at Long Beach in California, as well as for

Aframaxes shuttling crude to Pacific Lightering Area, Platts

said.