Evening star., 1946-12-25
Traffic Lights
Surveyed for
Moderniization
Centralized Control
More FIexibi|ity Aim
Of Proposed System

Obedient electrical relays which
will act only on orders" intended
for them and ignore others passing
over the same wire are among new
developments in traffic signal con-
troll being considered for Washing
ton.
The large scale modernizatfon
program, now in preliminary
planning stage, is intended to give
the District the benefit Of several
improvements not now enjoyed by
any other city. However, many OF
the contemplated changes have beer
used for years elsewhere, according
to engineers of the Department OF
Vehicles and Traffic.
Greater f1exibility is the goal. In
stallation of a, master control center
is the principal means of achiev-
ing it.
Survey Now Under Way.
The department now is conduct
ing a city-wide survey to determine
specific shortcomings of the present
system. Results of this survey will
be used in planning the type of
master control installation to be
sought for the Capital.
The control board probably will
not be in use for several years, be-
cause of the need for careful de-
signing.
A system of maximum flexibility
Is expensive, and it's installation Is
dependent on the attitude of Con-
gress toward providing the neces-
sary funds.
The thinking" relays could be
particularly useful, engineers feel
Cable having seven conducting ele-
ments is used for traffic signal cir
cults here. Equipment capable of
sending at least three impulses at
the same time over each conductor
could be obtained. Thus, at least
81 ''orders" could move simultane-
ous}y to signal control boxes along
the route of the cable. The three
impulses carried by each conductor
would be of different frequencies,
and each relay would respond only
to that which it had been tuned. "
Practical Value Outlined.
This is the practical value:
An operator at master control
board could set off the relays all
over the city by remote control,
changing the cycles of signal lights
to fit changing traffic conditions.
For regular day-to-day changes to
care for rush-hour variations inflow,
this work could be handled by pro
gram timers" These devices, essen
tally combinations of special clocks,
can be set to change the cycles for
different periods of the day nd diff
ferent days of the week.
A high degree of fexibility could
be attained through use of currents
of different frequencies without the
necessity of laying new cable
throughout the city.
Many things could be done to
speed traffic if a master control and
a large number of program timers
were available. the engineers say.
For example, special left-turn and
right-turn signals could be turned
on only during the hours in which
they are needed. To do this today,
an electrician would have to make
adjustments at the intersections in
most cases.
Emergency Changes.
Furthermore, the control opera
tor could make emergency changes
to meet adverse weather conditions
or ease jams in the vicinity of ac-
cidents or fires. Cooperation with
the Police Department would be
maintained to assure prompt ad-
justment of the signals to meet
needs of police handling traffic.
. Washington has obtained a few
program timers from time to time
One, located at Wisconsin and
Massachusetts, avenues NV, was
demolished in traffic mishap and
has not been replaced.
Another controls the complicated
intersection at Fifteenth street, H
street, Bladensburg road and Ben
ming road NE. 1t favors inbound
traffic in the morning and outbound
vehicles in the afternoon. 1t also
takes into account peak periods of
truck traffic through the week.
The settings of program timers
and traffic signals in general are
based on outmoded prewar traffic
counts.
The current engineering study will
reveal the postwar driving habits
Of washington area residents-the
routes they use and when they use
them most. When it is finished
the experts expect to begin pre-
pairing new master plan for opera
tion of the signals and to design a
master control board capable OF
putting it into effect.
Landlord Held in Attack