Preparation
Ground levels and support structures are probably the two main important areas of consideration when designing a gate system. Please read the following information with care. |
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Ground levels vary from location to location, they can even change during the life of a system. This is often when gates are installed and used for site security before the building works are complete. All medium to high use gate systems need to open over a level plain. If the gate has to open or close up hill or down, excessive load is taken on all the pivot & drive points. As a result the reliable life of the system is greatly reduced. The equipment fitted to a system can have a critical bearing on the importance of ground levels. Typically supplementary locking has the most effect and is very common in multi-user or wide gate systems. Both magnetic and electric locks are normally fitted to the central base of a pair of swing gates. Either type then locates to a keep or armature fitted to the drive surface. This is referred to as the "centre stop" The recommended height of a centre stop is below 65mm (ideally as low as possible) If the stop is any higher it becomes an obstruction to the under side of a car. A requirement for less than 65mm if the drive surface rises directly in front of the stop, as a car travels over it, the car's ground clearance is reduced by the slope and impact is more likely. If the drive surface rises into the property, swing gates would need to be installed higher off the ground, so they do not drive into the ground as they open. This causes two problems, the first is a large unsightly gap under the gate, but more important, the centre stop would need to be taller to reach the new position of the gate. This would then cause the centre stop to be a major obstruction for vehicles. Therefore surfaces that are level or falling away from the under side of the gate as it swings open are ideal, bearing in mind this level should be continued for approximately 1m before the centre stop. All sliding gates open and close on a level plain, however "cantilever gates" may be used to accommodate uneven drive openings. Trenching & DuctingDrive works are required with across drive ducts unless moleing is employed. This disruption to an existing drive is often made a feature of, with three or four rows of granite sets, cobbles or brick sets. Power supply cables, low voltage control, communications and surveillance cables are often required to various pieces of equipment. These will need to be adequately protected from weather and rodent or physical abuse. The protection of all of a systems' cabling is critical to the safety, reliability and durability provided by that system. Correct externally rated cables should be used in every case and are often recommended to be run in anti-crush ducting laid approximately 450mm below finish ground level. N.B. Cable route depths are always subject to site conditions and use. For example, a ploughed field would need runs laid a great deal deeper than the above recommendation. Anti-crush is a flexible duct allowing for sweep bends not elbows. Lengthy runs should be laid with inspection pits to ensure ease of cable installation according to the site layout. Ducting routes vary according to each environment and system design; most commonly ducts will link the control enclosure (M1 box) with each support structure individually, as well as the communication point, command and safety equipment positions and the property itself. Brickwork
Most existing brickwalls and piers were not built with gate automation in mind and although they may appear to be strong and secure the constant pressures exerted by an operator pulling and pushing often causes failure in the support structure itself or weakens its foundation. Existing brickwork may need attention as a precaution. Excavation & Concreting
A number of items of equipment may also require civil or building works of this nature. These include induction loops, barrier arm supports, communications posts and physical gate stops, etc. Cable runs are usually trenched externally taking the most practical route. Each trench is excavated to an adequate depth (450mm+) and laid to avoid obvious obstructions i.e. tree routes, drains, cables and other services, etc. Unforeseen obstructions are often the major reason for re-routing agreed runs, therefore, any background information concerning such obstructions should be provided by the customer before work on site begins. Access ramps can be made available upon request; however, use of the working area should be limited throughout the installation. |
'Brickwork Boxes' are the most common form of brickwork alteration required when installing a system. These are often needed to give an operator clearance to move the gate leaf, commonly installed with ram type operators and are otherwise known as niche boxes. With a ram fitted to the rear of a gate, opening back into the property and hung in the middle of a brick pier. The gate would jam the ram up against the pier before the gate had reached its half-open position unless a‚ 'brickwork box'‚ had been installed. 
When preparing an entrance, the depth of the foundation for the support structures, piers or steelposts etc should be excavated beyond that needed just to support the gate itself. Gate-A-Mation's policy is to build into the support a reasonable safety margin against the likelihood of people climbing onto the gate and that of minor vehicular impact. Sound foundations for each support are also necessary as protection if there is ground movement. When using sliding gates a ground track is often installed. This should be bed into a level concrete foundation that extends across the opening by as much again.
