Third rail not the first op­tion for Metro-North

Why do they rely on over­head wires?

New Haven Register (New Haven, CT) - - NEWS - Jim Cameron is a long­time com­muter ad­vo­cate based in Fair­field County. Con­tact him at Com­muterAc­

There is hardly a sea­son that goes by with­out Metro-North ser­vice dis­rupted by a “wires down” ac­ci­dent.

That’s when the over­head cate­nary that pow­ers the trains breaks or is ripped from its poles, cut­ting elec­tric­ity and ser­vice, ru­in­ing the com­mute for thou­sands.

But why do we rely on such frag­ile wires, some of them in­stalled 100 years ago? Isn’t there a bet­ter way of pow­er­ing our trains? Prob­a­bly not.

Con­sider this: MetroNorth is the only com­muter rail­road in the U.S. that re­lies on three modes of power: AC, DC and diesel.

Trains leav­ing Grand Cen­tral first op­er­ate on 750 DC cur­rent picked up from the third rail, just like New York’s sub­ways. Around Pel­ham, N.Y., the trains raise their pan­tographs (those tri­an­gu­lar-shaped con­trap­tions atop the cars) and con­vert to 12,500 volt AC cur­rent picked up from the cate­nary, hence the Jim Cameron phrase “op­er­at­ing un­der the wire.”

There is no elec­tric­ity on the Dan­bury and Water­bury branch lines, so those trains are powered by diesel. But even those diesels must op­er­ate on third-rail power in the Park Av­enue tun­nels for en­vi­ron­men­tal and safety rea­sons.

That’s a lot of tech­nol­ogy for one rail­road to ad­min­is­ter and a lot of elec­tron­ics. That is why the M8 cars that op­er­ate on AC and DC re­quire sep­a­rate power pro­cess­ing, adding to their cost. The third-rail M7 cars that run on the Hud­son and Har­lem lines each cost about $2 mil­lion. But our newer and more com­pli­cated M8s cost about $2.75 mil­lion apiece.

So a lot of peo­ple ask: “Why not just use one power source by con­vert­ing the en­tire line to third rail?”

As with so many other seem­ingly sim­ple so­lu­tions, there are sev­eral good rea­sons why it would not work.

The state Depart­ment of Trans­porta­tion stud­ied the idea in the 1980s, but it re­jected it for these rea­sons:

There is not enough room to add a third rail along most of the four­track sys­tem. The tracks would need to be moved, the right-of-way widened and the bridges and tun­nels ex­panded. Imag­ine the cost.

Even if we did con­vert to third rail, we would still have to main­tain the over­head cate­nary sys­tem for Am­trak whose lo­co­mo­tives are powered un­der the wire.

A third-rail power sys­tem needs more real es­tate. Power sub­sta­tions are needed ev­ery few miles, adding to con­struc­tion and cost.

Third-rail DC power is nowhere near as ef­fi­cient as over­head wire AC power. That means slower ac­cel­er­a­tion in third-rail ter­ri­tory and speed lim­its of about 75 mph vs 90 mph un­der the wire. The fastest trains in the world (like the TGV and Shinkansen) op­er­ate un­der the wire, though theirs is not as aged and brit­tle as ours.

A third rail is much more dan­ger­ous to track work­ers and tres­passers com­pared to over­head wires.

The third rail can ice up and get buried in bliz­zards, caus­ing short-cir­cuits. We have had some amaz­ing win­ter weather in Con­necti­cut, but noth­ing that piled snow high enough to touch the over­head wires.

Weather does cause prob­lems for the cate­nary. In ex­treme heat, it can ex­pand and sag. In bit­ter cold, it can be­come brit­tle and snap. Both con­di­tions re­quire our trains to op­er­ate even more slowly, but they still reach their des­ti­na­tion.

So what is the so­lu­tion to our “wires down” prob­lems? Ac­cel­er­ated re­place­ment of old wire, bet­ter main­te­nance of pan­tographs and a lit­tle com­mon sense — and not con­ver­sion to third-rail.

Peter Ca­solino / Hearst Con­necti­cut Me­dia

Metro-North is the only com­muter rail­road in the U.S. that re­lies on three modes of power: AC, DC and diesel.

Newspapers in English

Newspapers from USA

© PressReader. All rights reserved.