Take the No.9 bus. Get off at Jintai Road, the terminal. Just ask around.
The opposite of Beijing Urban Construction School seems to be the Urban Construction Workers' Hospital.
Contact information: school office tel: 0 10-85982066
Admissions Tel: 0 10-85963620 85982036
Telephone number of training department: 010-8598204185982048 85982058
I have also been trained in urban construction schools before, and I usually attend classes on weekends.