CE 197 Design Criteria & AASHTO

Design Criteria

• Document that summarizes the owner’s requirements,

standards and governing code provisions of the design project

• Can be in the form of general notes in the engineering

drawings or written design criteria report

• Usually established prior to design implementation

1. Stringent Code References (example: AASHTO LRFD Bridge Design

Specifications; NSCP 2015, DPWH DO, etc.)

2. Geotechnical Investigation – soil bearing capacity, soil properties, etc.

3. Design Loads

a. Dead load

b. Live Load

c. Seismic Load

d. Wind Load

e. Other loads

4. Material Properties

   a. Reinforcing Steel

   b. Reinforced Concrete

   c. Masonry

   d. Prestressed Concrete

   e. Prestressing Steel

   f. Reinforced Pipes

   g. Pavement

5. Pavement Design Requirements (performance period/PCCP,

ESAL, Cbr, drainage coefficient, etc.)

6. Road alignment (start and end points, stationing, horizontal

and vertical control, obstructions, etc.)

7. Design conditions for drainage structures such as culverts,

canal, channels, runoff velocities, rainfall intensity, etc.)

8. Design conditions for embankments and walls

Content in Civil/Structural Design Criteria:

AASHTO Basic Guidelines on Roads and Drainage

Design

Grades

• Maximum of 5% for 110km/h design speed

• 7-12% for 50km/h design speed depending on terrain

• For 60-100km/h, max grade fall between 5-8%

• Ranges 10-17% for mountainous terrain depending on design

speed (higher speed lower grade)

• Grades should be less than maximum grade

• Minimum grade is 0.5% typically but for paved slope it’s 0.3%

ROAD DESIGN grades

Cross Slope/Crown on Tangents

• 1.5 to 2% for paved two-lane roadways, paved single lane

• 2 to 6% for unpaved single lane

• Minimum of 1.5% for curbed pavements

road design cross slope

Lane Width

• 2.7m to 3.6m are generally used

• For high speed and/or high volume, minimum of 3.6m width is

used

• Auxiliary/added lanes at intersection and interchange: not less

than 3.0m

• Continuous two-way left turn lanes: 3.0m to 4.8m

road design lane width

Superelevation

• Maximum of 12% for rural area

ROAD DESIGN

Superelevation

Shoulder

• Usable width for stopped vehicles, emergency use and bikers

ranges from 1.2m to 1.8m

• For higher speed/higher volume: 3m width

• Should be continuous

ROAD DESIGN

Shoulder

Rumble Strips for crash prevention/alert the motorist

• Shoulder rumble strips placed as close to the edge

• Centerline rumble strips for undivided highways in rural areas,

horizontal curves and on tangent sections

• Continuous shoulder rumble strip

ROAD DESIGN

Rumble Strips for crash prevention/alert the motorist

Curb and Gutter

• Sloping curbs with height up to 100mm for high speed due to

drainage control or restricted right of way

• Sloping curbs with 150mm height for high-speed urban/suburban

facilities due to delineation

• Width is 150mm usually for vertical curbs while 130-300mm for

sloping curbs

• Height of vertical curbs ranges from 150mm to 200mm

• Gutter width ranges from 0.3 to 1.8m with a cross slope of 5

to 8%

• Refer to AASHTO Roadside Design Guide

ROAD DESIGN

Curb and Gutter

Borders and Sidewalk

• Minimum border width is 2.4m

• For residential area, the border area should include a sidewalk

and a buffer strip from curb

• Minimum sidewalk width is 1.2m from the back of the curb

• Refer to AASHTO Guide for the Planning, Design, and

Operation of Pedestrian Facilities (AASHTO Pedestrian Guide

• Protecting pedestrians from out of control vehicles

ROAD DESIGN

Borders and Sidewalk

Vertical Clearance

• Minimum of 4.3m for existing structures

• Minimum of 4.9m for newly constructed structures

ROAD DESIGN

Vertical Clearance

EROSION CONTROL AND LANDSCAPE

• Can be incorporated in geometric design

• Should also be noted in drainage design and writing of

specifications

• Inlet's location and spacing

• Includes protective devices to trap sediments

• Groundcovers and planting/vegetation

• Refer to AASHTO Guide for Transportation Landscape and

Environmental Design

EROSION CONTROL AND LANDSCAPE

• Provide enough streetlights depending on traffic volume to

reduce nighttime crashes/accidents

• Refer to AASHTO Roadway Lighting Design Guide

• To minimize glare, luminaires are installed at least 9m

• Poles should be located outside the roadside clear zones and

should not be erected along outside curves on ramps

• Luminaires can also be placed at the median for divided

highway/street

AASHTO Basic Guidelines on Roads and Drainage

Design

LIGHTING

• Includes sanitary sewers, water supply lines, oil and gas,

power and communication lines, cable TV, drainage and

irrigation lines etc.

• should be located on uniform alignment as near as practical to

the right-of-way line not to interfere traffic operation

UTILITIES

DRAINAGE

• Refer to AASHTO Drainage Manual and AASHTO LRFD

Bridge Design Specifications

• Includes bridges, culverts, channels, curbs, gutter and other

various types of drains

• Hydraulic capacities and locations should be designed for

upstream and downstream property damage and traffic

interruption during flood

• Consider the flood return period (e.g. 10-year probability occurrence)

• Surface channels to accommodate surface run-off from

roadways; should be properly located and shaped

• Curb openings/inlets is preferred to be grated and

advantageous in urban areas

• Provide storm drains to prevent ponding of water

• Extra inlets to be installed at low points

DRAINAGE