Is It Time to
Go Off -Wire Yet?
I THE REIMS Citadis
N THE PAST DECADE, THERE HAS BEEN A TREND TOWARD USING
alternative off -wire power distribution technologies to minimize, and in some
cases, eliminate overhead contact systems (OCS) for electrifi ed transit systems.
Th e visual eff ect of OCS to cityscapes, installation challenges and cost in urban
areas, and the operating issues in shared rights of way have been the primary
impetus for the development of these new technologies. Th ere are many off -wire
traction power systems, including in-ground contact systems, hybrid vehicles
with onboard energy storage systems (OESS), and alternative fuel onboard energy
generation systems.
Ground contact systems are like OCS in that vehicles,
when moving, continuously collect power from a
rigid conductor or distribution system as they travel.
Th e main diff erence is collection occurs at ground level
as opposed to 20 feet in the air. Hybrid systems rely
partially on contact distribution systems, but also
store energy onboard to provide traction power
where OCS or other distribution systems
56 | Mass Transit | MassTransitmag.com | SEPTEMBER/OCTOBER 2018
operates on Alstom’s
SRS catenary-free
solution in the city
center. Outside
the downtown, the
pantograph raises and
operates on-wire.
Wireless traction
power systems provide
benefi ts in specifi c urban
applications, and each
method has advantages
and disadvantages.
By Jason Krause
/MassTransitmag.com