Page 43 - Bridge and Highway Structure Rehabilitation and Repair

18 SECTION 1 ADMINISTRATIVE ISSUES

Type 2–Medium span 50 to 500 feet
Type 3–Long span > 500 feet
9. Structural system
The design of a bridge is related to the structural system. Beam, truss, and arch confi gura-
tions may be used for medium span lengths:
Type 1–Slab
Type 2–Through
Type 3–Slab-beam
Type 4–Truss
Type 5–Arch
Type 6–Cable stayed
Type 7–Segmental
Type 8–Suspension

1.6.2 Geometric Requirements for Surface Elements
1. The components of surface elements are lane, shoulder, sidewalk, approaches, and ramps.
2. A typical travel lane is 12 feet wide. For staged construction, it can be less than 12 feet
(but not less than 10 feet). Minimum width of a vehicle is 4 feet between wheel centers and
generally 6 feet overall. A vehicle with wide load is required to display warning sign “WIDE
LOAD.”
3. The minimum width of a shoulder is 3 feet between the edge of the travel lane and the concrete
barrier and less than 3 feet between the edge of the temporary lane and the concrete barrier
during staged construction. Small shoulder widths serve as buffer zone to avoid accidents.
Standard shoulder width is 10 feet with a minimum 6 feet width for emergency.
4. For safety reasons, a sidewalk is generally provided on both the sides of the roadway. Even
during staged construction a provision for temporary pedestrian bridge and utility support
is usually required (Figure 1.7). Sidewalks are elevated by 8 inches from the outer edge of

the shoulder or the outer edge of the lane. For heavy traffic, a safety fence is required. The
typical width of a sidewalk is 5 feet.

Figure 1.7 Proposed bridge typical section.