Saturday, April 19, was a legal holiday, Patriots' Hill Day, in Massachusetts. The plan involved suspending operation of the tunnel by trolley cars at 8:30 p.m. Friday, April 18, and resuming operation with third rail trains Monday morning the 21st. And incredible though it may seem this plan went through on schedule, with a few hours to spare.
As that last trolley car made its way through the tunnel, Friday night, it was followed by construction cars, loaded with men, tools, equipment and material. Inside of fifteen minutes the tunnel became a hive of activity, apparently confused, in reality so well ordered and supervised that about 50 hours of stupendous effort wrought the entire change without a hitch. Gangs at each of the four stations en route threw up temporary wooden platforms to the new level. Other gangs set to work with acetylene torches cutting up and removing the old Z-bar guard rail 20,000 ft. of it in 23 hours. Rail cars followed and picked up the pieces. Third-rail insulators had been placed in advance with third rail laid alongside and bolted up. Now it was picked up and laid in place on the insulators. Special work to the extent of 340 ft. was cut up and removed, and 724 ft. of new special work was installed. Elsewhere, signal crews were at work on the new installation.
In all a total of 1,525 men were employed, with a maximum of 780 on one shift, all in a tunnel 1.7 miles long. Twelve-hour shifts were worked; 2,185 meals were served to the men while on the job. Only two trifling personal accidents were reported during the whole period.
At 1 a.m. Monday morning Mr. Steward told the operating department they could have the tunnel. Power was turned on the third rail, the motorman of a waiting train turned on his controller and the first rapid transit train rolled down through the hole. Others followed, as the transportation and equipment executives hastened to break in their men during the two or three short hours left before the rush of Monday morning commuters was upon them.