صوت مشترک

UNIT 15: SURVEYING AND MEASUREMENT Page 73 INTRODUCTION Before building, engineers must measure the land. They need to know how big the site is. They need to know if the ground is flat or sloped. This work is called surveying. Surveying makes sure the building is in the right place. STORY 1: The Total Station A total station is a surveying tool. It measures distances and angles. It sits on a tripod. The surveyor looks through it at a special pole called a prism. The total station sends a