OTHON Engineering Share: Engineering, CivilEngineering, Consulting OTHON Engineering Visit Website 575 N Dairy Ashford Rd., Ste. 650 Houston, TX 77079 (713) 975-8555 (713) 975-9068 (fax) About Map About Civil, Transportation, Structural, Environmental & CM Services. What's Nearby? Distance: 5 10 15 20 25 50 mi.