What is mean by a Site Benchmark & Temporary benchmark (TBM)

Read the Full Blog to know what is Site benchmark in surveying & a Temporary bar is and why this is important before building houses complete practical knowledge from the site benchmark.  

14 Dec 2021

Do you know about Site Benchmark - In the Picture below, you can see-Written there 301.300 Hospital Plinth Level. Meaning, Whatever we construct in the Excavation site, Everything, Including these (Excavation, building height, Road, Drain), will be taken from this Reference only.

Site Benchmark


Because Site Benchmark is made concerning the Road Level and transferred to this, you'll know how the site construction works starts from zero. You'll find the surveying team has set this kind of Benchmark. they take these becnchmark with respect to the mean see level. with the help of this benchmark, every building components contruct. And this is distributed all over the site boundary.

This Benchmark is also known as an arbitrary benchmark GTS Benchmark- Great Trigonometrical Survey- was a part of the more extensive Survey of India. Whereas the Survey of India acquired geographical information mainly through "route surveys" (like the recordings of the pundits), the GTS created more scientific maps through instruments.

These BMs served as local reference of precisely measured elevation and They were often on stone posts, milestones, stone embedded into culvert walls, bridges, Railway Platform, temple/church. These indicate current day survey of India Topo Maps.

In every 100 Km Distance, you'll find a permanent benchmark taken concerning the mean sea level. 

A temporary benchmark (TBM) is a point with a known elevation used for level control during drainage construction works of houses and surveys. For example, nails on road level or marks on drainage channels are use as temporary benchmarks.

Your House drainage pipes must be drop at somewhere in the main drain line, and the position of your house drainage pipe (Inside) must be above the main drain line. 

For that, you have to establish TBM (Temporary benchmark) concerning that Drain Line (House drain). Below you can see the Temporary benchmark taken from the site benchmark. 

What is a Temporary Benchmark (TBM)?

A temporary benchmark (TBM) is a point with a known elevation used for level control during drainage construction works of houses and surveys. For example, nails on road level or marks on drainage channels use as temporary benchmarks.

Your House drainage pipes must be drop at somewhere in the main drain line, and the position of your house drainage pipe (Inside) must be above the main drain line. also to maintaing the slope of the drain line.

For all these, you have to establish TBM (Temporary benchmark). 

Important Points-

A temporary benchmark (TBM) is a fixed point with a known elevation used for level. 

Road Level as the TBM- Most of the time, Even Road level also matters for the TBM Benchmark.

You have to see the present road level and consider that one-day road level will be high. 

In the future, the road level would go up, your House might be down, and water will flow to your House.
You have seen this with many Houses.

TBM should not take from the Neighbour’s House- You have to take TBM according to the final destinations. 

The Site Benchmark should not take from the Neighbours because you don’t know if they have taken the measures correctly or not. Otherwise, If the person’s House is drowning, your House will drown too.

How to take it?

These 3 methods are considered as the TBM for your House Drainage system. 

 1. Water Level Pipe 

 2. Auto Level 

 3. Total Station

For that, you have to follow these Rules-

Plumbing Code- These are all according to the Plumbing Code specification-

1. For Open-drain Line- Where, for 1 m distance, 20.8 mm Slope is considered. 

2. For Closed-drain-Line- For 1 m Distance, A 10.4 mm slope is considered.

Even a Little slope is sufficient to free the water flow from the house 5mm to 10 mm per meter. 

So till now, you have understood what is Benchmark in surveying and Temporary benchmark. So if you want to know such amazing Practical things- Click Here! 

Read- Does the Depth of Excavation Include the depth of the Soling work?

Also, Read- How to Center Line Layout Done at site

Read the practical training- What is- Evening Planning/ Morning distribution sheet?


CIVIL GURUJI 

CIVIL ENGINEERS TRAINING INSTITUTE

 Hello Civil Engineers, if you are looking for Corporate Sector jobs we are here to provide you with the right platform to learn job-ready courses. For free career counseling sessions, you can call us on +91-9111001234.

call now