For roadways there are many choices of pole location depending on the type of roadway. For example, if there is a median, then it may be possible to light the entire roadway with poles located only in the median. Let's discuss some possible arrangements for roads with and without a median.
For a roadway with no median our choices are:
A one side arrangement allows easier installation usually because only one
trench is needed for underground wiring. Wide roadways are difficult to light
uniformly and the side nearest the light fixtures will be brighter. Generally, a
two sided arrangement will allow for more uniform lighting. Again, the width of
the roadway can determine whether a staggered arrangement or opposite should be
used. Wider roadways will need an opposite arrangement. A staggered
arrangement can reduce the number of poles needed, thus reducing costs.
Roadway layout can be greatly affected by obstacles in the field such as trees, driveway entrances and existing poles. These obstacles should be noted so that they can be accounted for in the design process. In general, it is best if poles can be located on the inside of curves in the road. Should a car swerve out of control, its trajectory will be outside the curve and thus avoid the pole. The IES handbook has a more detailed discussion of design for tunnels and roadway interchanges of different types.
