Fig. 173.—Center for Culvert at Kalamazoo, Mich.
The invert concrete was brought to form by means of templates, Fig. 173, and straight edges. The side forms were then placed and braced apart by the struts and concreting continued to the skewback plane indicated in Fig. 173. The arch form was then placed; it rested at the edges on the side forms and was further supported by center posts bearing on boards laid on the bottom of the invert. A template, Fig. 175, was used to get the proper thickness and form of arch ring. Outside forms were used to confine the concrete at the haunches but nearer the crown they were not required.
Fig. 174.—Hinged Cross Strut for Center for Culvert at Kalamazoo, Mich.
Much of the work was done when the thermometer, during working hours, ranged from 12° to 25° above zero. When the temperature was below freezing, hot water was used in mixing the concrete and on a few of the coldest days salt was dissolved in the water. In addition each section of the work was covered with oiled canvas as soon as completed, and the conduit was kept closed so far as was practicable to retain the heat. Concreting was never stopped on account of cold weather.
Fig. 175.—Templet for Arch Ring for Culvert at Kalamazoo, Mich.
Account was kept of the cost of all work, and the figures obtained are given in the following tables: