1. Which is better wood or steel posts?
Both meet AASHTO and Caltrans specifications and perform similar in crash tests. Although some pricing variations exist depending on the current steel market, most choices between wood and steel are based on maintenance or esthetic considerations.
2. How do you bend the guard rail and what is Convex or Concave?
Guard rail panels can be shop rolled to meet your field conditions when a few minor dimensions are supplied. Smaller radius may require the rail to be rolled prior to galvanizing which will increase the material cost and lead time required. Convex and Concave refer to the position of the outside face of rail after being bent. If the rail face is inside the bend it is Concave and outside the bend Convex. Please read this PDF document for more details:
3. How do you determine the length of need and which terminal system to use?
Caltrans standard plans outline various approved designs of terminal systems and alternative designs are available to meet varying site conditions. AASHTO’s roadside design guide contains information to assist in determining the proper application for many roadside safety features. C&W can assist in design advise and many of the details are available in pdf form on the website.
4. Would you like more information about the State Department of Transportation?
https://dot.ca.gov/hq/esc/oe/project_plans/HTM/stdplns-US-customary-units-new10.htm#miscellaneous