Evening star., 1926-05-23

south lights at i and * streets are
green, Reckoning him to continue
past these streets. At the same
time traffic on I and X streets is
halted by red lights showing east
ward and westward.
Lights Change During Trip.
When L street is reached. if the
motorist has been proceeding judi
ciously. the light facing southwark
has shifted to amber and. within five
seconds, to green At the same time,
the signal at NJ street has changed.
as has that at Scott Circle. There.
the northbound motorist takes the
roadway inside the safety island
and when he reaches the end of this
concrete segment he finds the light at
the Sixteenth street intersection has
changed to green and he proceeds on
his way.
The signals at p and @ streets
are showing red as the motorist
leaves the circle, but by the time the
first intersection is reached the shift
to green at both streets has been
made.
Timing Of the electric control sys-
tenn has been the subject of eXacting
study by the traffic directors office.
During its period Of trial, constant
experimentation was made and con-
clusions were reached only after ac
tual driving tests. AS pointed out
by Col. Moller. the system cannot be
operated successfully after mere cal
culations on paper. The test comes
when conclusions are put into prac-
tice.
Notifications planned by traffic Of
ficials were checked in actual opera
iprht
traffic was light. Daylight counts of
vehicles at various intersections also
have been taken as indications of
proper timing of the electric signals.
First Plan Undesirable.
The first intervals were one minute
for crosstown traffic and a. minute
and a half for traffic on Sixteenth
street. The longer interval. naturally,
would seem more appropriate for the
north and south movement, but
checks at intersections showed the
crosstown flow uneven and heavier
at certain crossings than on Sixteenth
street. Within 10 minutes, for ex-
ample, 81 vehicles were counted cross.
ing at K street, while only 72 vehicles
were clocked at the same time moving
on Sixteenth street.
At intersections where crosstown
was heavier than that on Sixteenth
street, delays were occasioned by the
longer interval for north and south
traffic. Cars piled up until they
stretched a block in either direction.
The block plan of timing was put into
operation and traffic officials i'm
mediately found improvement. The
green and red lights were changed to
show for 35 seconds in either direc-
ton with a five-second lighting of the
amber caution signal. Shortening of
the time prevented piling up of traffic
to any great degree even during the
rush hours.
Timing now provides for 45second
intervals from 8 am. to 9:1o am. and
from TO pm. on week days and
40second intervals from 2 to pm.
on Sundays. During the remainder of
the day the signals change every 35
seconds. Amber caution" signals are
5 seconds in duration.
Foresight Is Needed.
Motorists who want to avoid delays
and who does not?-can succeed IN
so doing by exercising a. little fore.
sight. The rate of motion Of a. car
travelling at % miles an hour is ap-
proximately 80 feet a. second. II the
motorist will get a. rough notion Of 165
feet and on approaching an intersec-
ton where the light has just changed
to amber will see to 1t that he keeps