When red light cameras are installed at high$-$risk

intersections, rear$-$end collisions go up$,$ but all

other types of accidents go down, including those

involving pedestrians. Analysis of traffic accidents

in a northwestern city revealed that the total num$-$

ber of collisions at photo$-$controlled intersections

decreased from $33$ per month to $18.$ At the same

time, the number of traffic tickets issued for red

light violations averaged $1100$ per month at an

average cost to violators of $$85$ per citation. The

cost to install the basic camera system at selected