DRAINAGE AT STREET INTERSECTION. In most cities it is customary to construct catch basins at the corner of the curb, using an inlet with a curved face. This practice is very objec tionable.
If the walk across the street is elevated above the pavement, it is necessary either to carry the water under the walk in a pipe, or to stop the cross walk within a short distance of the curb to leave a channel for the water. The latter method is necessary where there is much water. Frequently this channel is left open at the top, and sometimes it is covered with a cast-iron plate with one edge resting in a rabbet in the curb and the opposite one in a head stone or false curb set at the end of the cross walk. The covered gutter is much better than the open one, although the cast plates are frequently struck by wheels and broken. This solution of the problem is fur ther objectionable since a wheel in turning the corner must sur mount the first raised cross walk, then descend to the bottom of the gutter, and finally climb over the second cross walk. The face of the inlet usually has a depth of 8 to 12 inches below the top of the curb; and hence if the sidewalks are wide or the parking is narrow, the shock to a vehicle going around such a corner is con siderable.
If the cross walk is not elevated, the step from the curb to the bottom of the gutter is uncomfortably high, and besides pedestrians are compelled to cross the gutter where there is the most water.
A much better arrangement than either of the above is. to place an inlet at each side of the corner. Each inlet may have its own catch basin, or the two may connect with a single pit by means of tile or vitrified pipe underground. Fig. 107 shows such
an arrangement. Instead of this plan, the two inlets at each of the four corners of the street intersec tion may be connected with a single catch basin placed in the middle of the intersection or in other suitable location. The inlet not connected directly with a catch basin can be made by inserting the hub of a curved vitrified pipe in the bottom of a cast inlet box (see Fig. 105 and 106, page 342).
The advantage of the method shown in Fig. 107 is that it allows the intersection to be paved almost level with the top of the curb, and hence there is no obstruction to either pedestrian or vehicular traffic. The only objection to it is the expense for either the extra catch basin or the extra inlet and the connecting pipe, but the advan tage is well worth this comparatively small expense.
Where there are no storm-water sewers, the gutter is sometimes carried across the street intersection. This is objection able at any season, and particularly so when the gutter is filled with snow or ice. If the gutter is deep or the grade is steep, the water may be carried under the intersection by a shallow culvert with cast-iron top, or better in a cast-iron pipe; but if the gutter is shal low or the grade nearly level, the road surface should be raised a little to give room for a cast-iron storm-water drain under the road way. The elevated intersection may be a slight obstruction to travel, but it is preferable to two open gutters.