4265-10
Geometric Design Guide
for Bridges on Highways Having State Route Numbers, Other Than Interstate
Geometric design standards shall be in
accordance with the AASHTO publication "A Policy on Geometric Design of
Highways & Streets," Collector Roads and Streets, 2004, p. 426.
I.
Minimum
Bridge Widths
A. Rural section (2
lanes without curb)
|
Speed Design |
Design Year |
Bridge Width |
Design * |
|
All Speeds |
0-399 |
TW + 4 ft +4 ft (TW + 1.2 m +1.2 m) |
HS-20 (MS-18) |
|
All Speeds |
400-2000 |
TW + 6 ft + 6 ft (TW + 1.8 m + 1.8 m) |
HS-20 (MS-18) |
|
All Speeds |
Over 2000 |
TW + 8 ft + 8 ft (TW + 2.4 m + 2.4 m) |
HS-20 (MS-18) |
TW
= Traveled Way (Lane Widths)
*For bridges
designed utilizing the LRFD Bridge Design Specifications, the design live loading shall be HL-93.
B. Multilane rural (undivided-- 4 or more
lanes)
|
TW + 16 ft (4.8 m) |
8 ft (2.4 m) shoulders right and
left |
C. Multilane rural (divided)
|
TW + 12 ft (3.6 m) |
4 ft (1.2 m) inside shoulders + |
D.
Urban
section (with curb)
The
minimum clear width for all new or reconstructed bridges shall be the curb to
curb width of the approaches except that the minimum curb to curb width for
two-lane, two-way bridges shall be TW + 4 ft (1.2 m) unless an exception is
obtained from the Chief Engineer. Sidewalks shall be provided on bridges where
curb and gutter is provided on the approach roadway. Minimum sidewalk width on bridges
shall be 5.5 ft (1.7 m).
II.
Vertical
Clearance
Vertical
clearance shall be a minimum of 16.5 ft (5.1 m) on all State Route highway
separations except that 17.5 ft (5.4 m) may be a minimum where the overpass
structure design is such that future jacking to increase clearance is not
feasible. A minimum vertical clearance of 14.5 ft (4.4 m) is permissible for
Rural Secondary or Urban System facilities where a suitable bypass is available
for high vehicles.
III.
Bridge
Widenings
When an
existing bridge is to be widened, its structural capacity will be accepted if
the live load capacity is HS20-44 (MS-18) or greater. If the structural
capacity is less than HS 20-44 (MS-18) and the bridge is to be retained, then a
design variance will be obtained from the Chief Engineer.
IV.
Design
Variances
When a
project is implemented using Federal Funds and the structural capacity and/or
width characteristics do not meet the above criteria, a design variance request
will be submitted to the Chief Engineer for approval.
Document History:
- submitted by the Division of Preconstruction
- issued: 09/02/86
- revised: 10/08/96
- added to TOPPS: 12/31/96
- title changed: 03/30/01
- title changed: 08/22/02
- revised: 12/30/03
- reviewed: 01/27/05
- reviewed: 03/03/08
- revised: 07/12/08
