Prefab City A compendium of strategies for prefabricated building techniques in urban environments
by Ground: Road Transportation of pre fab elements in a urban environment is constrained by a number of obstacles. One of which is the complex network of roads that comprise many cities. In order to deliver pre fab modules to a site many different sized trucks need to be considered as part of the delivery process. Each truck has its own set of limitations for maximum freight weight. All of these factors must be considered when siting a pre fab project in an urban context.
Truck Types Pickup Truck Advantages: Can easily navigate small urban streets Disadvantages: Lowest freight weight capacity, very limited by size
Single Unit Truck Advantages: Comparitively narrow width (fairly easy for navigating small streets). Mid size compacity for freight (panels could fit) Disadvantages: Constrained by height.
Dump Truck
Advantages: Large freight weight compacity Disadvantages: Width could be problematic when trying to traverse complex sites.
Semi Tractor Trailer Truck Advantages: Largest carrying capacity; multiple trailer options to facilitate different sized pieces. Disadvantages: Hardest to maneuver complex street network.
Truck Dimensions Transportation • 14 PRECEDENTS
CONTEXT
DEPLOYMENT
DETERMINANTS
INTRODUCTION
Semi-Trailer Load Capacities Semi-Tractor trailer trucks have the greatest carrying capacity. There are a number of options
48’-0”
for the trailer; some maximize the length, some height of the element that needs to be transported. Outlined below are the options.
8’-6” 8’-6”
48,000 lbs.
Flatdeck Trailer 11’-0” 37’-0” 8’-6”
a
10’-0”
b
8’-6”
48,000 lbs. a: Height restriction for truck (varies by state from 13’-6” to 14’-6”) b: Height limit for vertical clearance (typ. 14’-0” for urban areas, 16’-0” rural)
Vertical Clearance for Semi-Trailers
Single Drop Trailer 10’-0”
52’-6”
29’-0” 9’-0”
8’-6” 11’-6”
9’-2” 45,000 lbs.
Box Trailer
8’-6”
*
45,000 lbs. maximizes height
Double Drop Trailer
10’-0” 8’-6”
INTRODUCTION
48’-0” 80’-0”
8’-6”
45,000 lbs. maximizes length
*Flatdeck Trailer Stretched
DETERMINANTS
8’-6” 14’-0”
48,000 lbs.
8’-6”
Oversized Load
10’-0”
8’-6”
DEPLOYMENT
48’-0”
63’-0”
8’-6” 10’-0”
8’-6”
Single Drop Trailer Stretched
16’-0”
*Way Oversized Load
CONTEXT
43,000 lbs.
48,000 lbs. permits required
10’-0” 50’-0” 11’-6”
9’-0”
PRECEDENTS
8’-6”
10’-0”
*
40,000 lbs. maximizes height
Double Drop Trailer Stretched
8’-6”
*
dimensions contrained by road restrictions of local municipalites
Super Oversized Load Transportation •
16
Roadway Design & Obstacles Roadway design can either help or hinder the transport of prefab elements to site by truck. Outlined below are the guidelines for the dimensions of driving and parking lanes in a city.
a1
b1
c
b2
a2
INTRODUCTION City Utilities
Lighting
Signage
DETERMINANTS
Street Furniture
Pedestrian Utilities
CONTEXT
DEPLOYMENT
Landscape
PRECEDENTS
Truck Turning Obstacles ‘Making the turn’ is one of the challeneges of truck transport when building in an urban environment. The many obstacles the city presents (parked cars, telephone poles, stop signs, etc.) make routing a truck to site one of the most important parts of the process.
Parallel Parking Transportation •
18
Truck Turning Radii The swept path a truck takes as it makes a right
Swept path of truck
60°
turn is a critical moment. To the right is a diagram that explains the logics of how a truck makes a turn. The most common trucks used for transport in the city are the standard semi-truck and the
60’ radius from point on sidewalk
single unit truck. The paths for oversized loads need to be considered if larger elements need to get to site.
Critical points that determine swept path
Truck Making 60° Turn
60°
60°
90°
90° a
a
b b
a: 53’-0”
180°
b: 8’-6”
a: 53’-0”
180°
b: 8’-6” critical swept path
Standard Semi-Truck
critical swept path
Single Unit Truck
INTRODUCTION DETERMINANTS DEPLOYMENT 60°
60°
90°
90°
90°
b
*cannot make a 180° with a 60’ radius
b
a: up to 80’-0”
a: 48’-0”
b: 8’-6”
b: 16’-0” critical swept path
Stretch Semi-Truck
b
180°
critical swept path
Oversized Load (Width)
180° a: 75’-0” or 1/3 truck bed length b: 8’-6” critical swept path
Oversized Load (Length) Transportation • 20
PRECEDENTS
a
a
a
CONTEXT
60°