Question 1:

Any method of  underground construction generally for utilities that does not involve trenching for their installation . See the attached chart from the UN of construction methods including defined TT methods.

What is the difference between Trenchless technology & other technologies? Are they cost effective?

Not easy to answer the difference is mainly to cause less disruption to the people , the direct cost may be higher but if social cost is included then the total cost is lower. Its also possible that the long term cost is lower as TT may install a better quality product than a trenched product.

Pipe Jacking is a method of utility tunneling so you can not answer this question.

Utility Tunneling includes all methods of tunneling including;

Lined and unlined Unshielded, Shielded;

Pipe jacking is a method and liner form of utility tunneling;

The type of utility tunneling to be used should be determined by the geology , ground water, diameter, length of project and the final use of the tunnel.

“Horizontal Earth Boring”. HEB is generally recognized as small diameter (<2m)  mechanized method of boring, eg auger boring, but could include microtunnelling, moling, ramming and mechanised tunneling etc HEB is such a general expression better to be more specific.

You do not say what the final product pipe is ? Assuming an RCP and you want to use trenchless technology, You need to use a guided method the geology  and ground water will determine the method e.g. if soft ground below the water table then microtunnelling is the best solution. If in dry ground then other methods of utility tunneling are possible such as pipe jacking with a hand shield or pipe jacking with a mechanized shield, if in rock drill and blast or rock splitting could be used but are very slow, mechanized rock tunneling is much faster and is possible with or without a liner. To choose the correct method the geology and ground water are critical factors in the decision.

Several papers have been written on this subject  from research carried out mainly in Europe. Social cost is generally defined

1) As the cost of delay to people measured in time and converted to a monetary value (traffic delays due to construction costs) normally defined as man hours delay at $xx per hour.    When calculated the costs are very high eg. a 15min delay to 10,000 commuters for 3 months runs into $m’s  ( include extra fuel costs, pollution etc)

2) May include loss of sales to a business effected by construction works, however in most developed countries compensation is paid to businesses who prove that the construction has caused them a loss due to restriction of access or loss of parking.

A system of directly installing pipes normally behind a shield by hydraulic jacking the pipes from a drive shaft to a reception shaft such that the pipes form a continuous string in the ground.