Thursday, November 12, 2009
How to read scale in plan?
"Lai, what it means 1 : 500 in your survey plan? " This is one of my customers ask me regarding scale in plan. Basically, our plotting plan paper are in standard ISO paper saiz A1 (594mm x 841mm) , A2 (420mm x 594mm) , A3 (297mm x 420mm) and A4 (210mm x 297mm). Due to the limitation of the paper saiz, we need to "squeeze" the actual length or dimension into the plotting paper with a collect scale and this is the professional of land survey. The customer is able to measure the length or dimension in the plan without going down to the site by apply the factor scale.
There are 2 ways of knowing the actual length or dimension in the scale plan.
a. By using below formula (we learn in primary school)
i. 1km = 1000m
ii. 1 m = 100 cm
iii. 1 cm = 10 mm
For this case 1 : 500 means
1mm : 500 mm or
1mm : 50 cm (by divide 10mm to get cm) or
1mm : 0.5 m (by divide 100cm to get meter)
b. The seconds way is buying a scale ruler and straight forward you can get the answer from the ruler.
Please kindly bear in mind that the digital data is in 1 : 1 even the plan show 1 : xxxx. The scale only apply on hardcopy plan only.