Research Help



Dear All,

I'm doing a research on the estimation of "Tunnel Cost" for which I carried out some regression analysis based on data of 30 tunnel projects implemented in the USA. The dataset consists of recorded tunnel construction cost and tunnel size (i.e., tunnel diameter and length). the results of the regression analysis results showed that better correlation coefficient (R2) is obtained when the log10 of parameters are used, i.e., tunnel depth and diameter. below are some of my results for further detail.

Cost(M£)=10^(3.052+3.905Log(L*)+0.867Log(D**).................R2= 0.95 ....................(1)

Cost(M£)=-301.43+53.249(L*)+ 9.341(D**).......................R2= 0.80......................,...(2)

*L is tunnel length in (km), and **D is tunnel diameter in (m)

My question is what do these results statistically mean , I mean having higher correlation coefficient with log10 of the independent variables than their normal values what does statistically mean? Can you please explain this for me , I have tried to find out what are these results statistically mean but could not find any proper explanation for these results!

Thank you very much in advance for your help and support.

Best regards,


"Hidden" relationships

In some situations there is a relationship between two events that is not apparent. For example, the cost of a tunnel may be related to the diameter of the tunnel, but as the diameter increases there are two factors affected: the cost of drilling the hole and the cost of reinforcing the drilled hole. By just measuring the cost of drilling the hole, or only being provided with total cost related and the diameter of the hole, important information is not being considered.

My suggestion is that you obtain the cost of every detailed variable related to constructing the tunnel: drilling, temporary supports, final supports, etc. and use actual measurements rather than logs. Then you can estimate the total cost of a planned tunnel, one variable at a time.

Good luck!