Blog Archives

Supports for Traffic Signals and Service Devices

Posted by on 19/ 11/ 15

Supports for traffic signals are not usually of the breakaway type, because of the potential consequences of the loss of the signal at an intersection. Supports in the clear

Supports for Traffic Signals and Service Devices
Подпись: FIGURE 6.11 Breakaway bases for large overhead signs may provide for (a) unidirectional or (b) multidirectional impacts. (From Roadside Design Guide, AASHTO, Washington, D.C., 1996, with permission)

zone should be shielded. Call boxes can often be located behind existing barriers, but a breakaway support is an option. The call box should be securely attached to its support to prevent windshield penetration if dislodged. At highway-railroad crossings, highway and railroad officials should cooperate in deciding on the types of warning devices needed, such as crossbucks, flashing lights, or gates. If the support for the device is located in the clear zone, consider shielding it with a crash cushion. There is seldom room for a longitudinal barrier...

read more

Do Europeans Really Make the Best Windows?

Posted by on 19/ 11/ 15

■ BY MARTIN HOLLADAY

Do Europeans Really Make the Best Windows?

A

good window seals out cold, windy weather and admits as much light as possible into a house’s interior. While those functions seem rather obvious, some claim a new class of window can perform these duties better than any window made in the United States.

Only a handful of window manufactur­ers in the United States and Canada sell high-performance windows suitable for cold-climate homes. Sensing an opportunity, manufacturers from Germany and Austria have eagerly filled the market niche by in­troducing a host of high-performance units to American builders.

Defining High Performance

The two most important measures of a win­dow’s performance are its U-factor and its solar heat-gain coefficient (SHGC), numbers that can be found on a new window’s National ...

read more

The Number of Rollers

Posted by on 19/ 11/ 15

The number of rollers, their types, and number of passes should be selected with regard to the SMA gradation, layer thickness, weather conditions, and the planned paving speed. Obviously the rollers should be in good working order, able to work at low and constant speeds.

The Minimum number of rollers to compact one layer one lane wide is two or three. Many nations’ guidelines stipulate diverse requirements for the numbers of rollers, mainly stating that one should use rollers weighing more than 9-10 tons each. If three rollers are in use, two of them should be responsible for the majority of the compaction, and one should be the finisher. Extra rollers should be added in case of

TABLE 10.1

A Summary of the Usefulness of Equipment for SMA Placement

steel pneu- Triple – matic Wheels Ti...

read more

Luminaire Supports

Posted by on 19/ 11/ 15

Breakaway supports for luminaires are usually a cast-aluminum transformer-type fran­gible base, a slip base, or frangible couplers. These devices have been developed to activate when loaded in shear by impacts at a bumper height of about 20 in (500 mm). If the supports are located so that they may be impacted at a greater height, the perfor­mance may not be as intended. Thus, foreslopes between the roadway and the support should be limited to 1:6 or flatter. The mast arm of a falling support will usually rotate away from the roadway. However, the danger of falling poles striking pedestrians, bicyclists, and other motorists should be considered.

Breakaway supports are suitable for poles that do not exceed 60 ft (18.5 m) in height and 1000 lb (450 kg)...

read more

Quantitative Analysis

Posted by on 19/ 11/ 15

Historically, chemical analysis of water was achieved by titration methods. It is, practically, impossible to use these on water containing a pollutant at a low con­centration due to the need to collect a very large volume of water that can be con­centrated to permit a weighable amount of chemical to be obtained at the end of the procedure. Also, such procedures are very time-consuming and operator sensi­tive. Therefore, modern analysis is based on electrical, atomic and spectrographic techniques.

The most common analytical techniques suitable for determination of the pres­ence of selected pollutants are synthesised in Table 7.3.

Table 7.3 Analytical techniques suitable for determination of the presence of selected pollutants

Technique

Detection limit level

Basic

Common

P...

read more

EXAMPLES FROM THE DEMONSTRATION PROJECTS

Posted by on 19/ 11/ 15

Подпись: Portland, OregonПодпись: Crittenden County, ArkansasThe Portland demonstration subdivision was arranged in clusters of four detached units. The city allowed one 1 1/2-inch PVC water line to run from the main to each cluster and 3/4-inch PVC from there to each unit. This was instead of one 1-inch line from the main to each unit. Cost savings amounted to $32 per unit.

Rough plumbing was installed in a trough above the slab so the plumber would make only one site visit. All plumbing was clustered to reduce DWV and supply pipe lengths. A standard­ized DWV plumbing "tree" was used; therefore, much of the DWV system could be prefabricated. The plumbing wall was prefabricated with supply pipe and DWV installed. Polybutylene plastic pipe was used instead of copper. Total plumbing cost savings averaged $182 per unit.

Подпись: Santa Fe, New MexicoEXAMPLES FROM THE DEMONSTRATION PROJECTS

Polybutylene supply pipe, fibe...

read more

Fastening the Timber Frame to the Foundation

Posted by on 19/ 11/ 15

Whatever foundation method is selected, local codes will vary on their requirements for tying the timber frame down to it, depending on the likelihood of hurricanes, tornadoes and earthquakes. In most areas, a heavy timber frame will not vertically leap off of the foundation so the main consideration is to prevent the sill plate or the posts from moving laterally. This is most easily accomplished by joining the posts to the foundation with positioning pins. As northern New York does not suffer from any of the aforementioned natural disasters, this is what I have been doing with all our buildings since 1975.

The joint between posts and foundation...

read more

STEP 2 INSTALL THE HOUSEWRAP AND FLASH OPENINGS

Posted by on 19/ 11/ 15

Covering the wood house frame with house – wrap, a thin protective layer, is the next step be­fore finish siding is applied. You can use the old, reliable housewrap—rolls of 30-lb. felt paper, or you can try one of the modern housewraps, such as Tyvek®, Barricade®, and Typar®. These are lightweight, fabric-like materials that come in rolls and are literally wrapped around the walls of a house. The main purpose of this treatment is to form a drainage plane behind the siding to stop wind-driven water from penetrating into the wall cavity. No siding is completely water­tight, so in areas where hard, wind-driven rain is common, housewrap can help protect the walls from moisture damage. However, house – wrap is not a replacement for good flashing around doors, windows, and decks...

read more

Techniques HOISTING MATERIALS TO THE ROOF

Posted by on 19/ 11/ 15

Techniques HOISTING MATERIALS TO THE ROOF

HERE IN THE WEST, we try to order shingles the day before they will be installed. Suppliers arrive with a hoist and stack both shingles and felt paper directly onto the roof. An expe­rienced celivery person knows to stack bundles of shingles about 6 ft. apart on both sides of the roof.

The other way to get shin­gles onto the roof is the hard way—hoisting one bundle at a time. If you must haul roofing shingles up to the roof yourself, make sure you have a secure ladder that is positioned prop­erly and is 2 ft. to 3 ft taller than the roof. It’s a good idea to nail a temporary 2x tread at the spot on the roof where you will step off the lad­der. This tread provides a solid foothold where you need it most.

Bust the bundle...

read more

The Nimes Aqueduct and the Pont du Gard[242]

Posted by on 19/ 11/ 15
Подпись: Figure 6.14 The Roman aqueduct of Nimes (after Fabre, Fiches, Leveau, Paillet, 1992).
The Nimes Aqueduct and the Pont du Gard[242]

The Roman Nemausus (Nimes) is much older than Lyon, founded in the 6th centu­ry BC, even before the conquest of Gaul by the Romans. Nimes was the capital of the Arecomic Volques, a Gallic people often allied with the Romans. Nimes is naturally well supplied with water, from wells and especially from the Fontaine spring, abundant and perennial. Under Augustus the spring was the subject of major construction, including a masonry canal and basin at its outlet. The need for an aqueduct only came later under the pressure of urban development (20,000 inhabitants in the Gallo-Roman Nemausus), with the objective of supplying water to the highest areas of the city above the level of the Fontaine (at an elevation of 51.1 m). Under Claudius, in the middle of the 1st cen­tury AD,[243] th...

read more