|In general, this study provides interesting and useful information for engineers responsible for design, operate and maintain the road network under the risk of lahar impacts. In my view, as a research engineer in the field of river engineering, the paper has some difficulties to read, each can be easily improved. Before the publication, such weakness should be dealt with.|
Point to point comments
Title: the concept of 'bridge failure model', the difference between 'bridge failure' and 'infrastructure overturning and deck sliding', the definition of 'infrastructure' are not clear, this leads the reader to imagine what will come from the manuscript from the title difficult. My suggestion is, something like, 'Development of failure model and fragility curves for road bridges under lahar impact' or simpler 'Development of fragility curves for road bridges under lahar impact'. The ambiguity of terminologies makes difficult to follow the meaning of not only title but remaining part of the manuscript. E.g. 'infrastructure' covers a broad sense. Road network itself can be included in the concept of 'infrastructure' (as used in the first line of the abstract). 'infrastructure' is mainly used to mean a foundation of something in this manuscript, especially for a bridge. If so, it is better to describe 'bridge infrastructure' or 'bridge foundation'.
The word 'abutment' has potentially two meaning, one is the foundation of bridge pier and other is the marginal area between a river bank and the bridge. So the reader wonders what you want to say using the word 'abutment', so it is needed to clarify which do you want to mean or use another word.
You used 'failure model' (singular) so maybe you want to define 'failure model' as the toolbox to identify damage or non-damage for all possible types of failure mode. On the other hand, 'fragility curves' (plural) were made for each failure type. This means, the failure model was actually composed of several sub-models corresponding to each failure mode, and the sub-models were used to develop each fragility curve, if my understanding is correct. What I want to say is that it is better to use 'failure models' instead of 'failure model'.
Page 1, line 35, I'd like to replace 'losses' --> 'restrictions' and remode 'permanent'.
Page 1, line 35, It is not clear how 'highway' and 'road' distinguished in the manuscript.
Page 2, line 2, 'temporary' --> 'temporal'?
Page 2, line 3, 'loss of surface friction' --> 'loss of friction between (road) pavement and tires'?
Page 2, line 10, 'affect(ed)' is quite neutral but here you want to say some negative meaning so ''damaged' or something like this may be better to use here. (not only here but other sentences using 'affect(ed)')
Page 2, line 14, The meaning of 'critical' here is not clear.
Page 2, line 16, put 'a' before 'consequence'.
Page 2, line 27, 'studies' --> 'covers'?
Page 2, line 33, 'effects' --> 'interruption'
Page 2, line 36, 'and' --> 'nor'?
Page 2, line 40, It is not clear how 'calibration' and 'parameterization' distinguished.
Page 3, line 7, What do you mean by 'analytical models'?
Page 3, lines 21-22, 'Debris flows are highly viscous slurries of sediment and water'. I think 'deris' is explained but not about 'flows'.
Page 3, line 28, I think you can remove 'so'.
Page 3, lines 36-37, 'scour of the riverbed drags massive material blocks' doesn't make sense.
Equation (1): Is DS defined? What is the meaning of subscript i?
Page 4, line 26, 'the recently described approaches' --> 'the approaches described above'?
Title of Section 3. I'd like to suggest to replace as '(Development of) failure model(s) for bridge pier/abutment overturning and deck sliding due to lahars'
Page 5, The first paragraph of section 3.1, so do you define that g(X)=D(X)-S(X)? If so, it is better to describe so using equation.
Figure 1: It is not clear how the abutment overturning and the pier overturning were distinguished. Maybe, it is better to specify where are the deck, pier and abutment in Figure 1. Can we discuss the pier overturning using the moment Mn defined in Figure 1? Can you define Fwi, Fws, Fr in Figure 1?
Equations (3) and (5) Are Yso and Fr function of X? If so, how do you change Yso and Fr depending on X?
Page 8, line 5, 'produced' --> 'caused'
Title of Section 4. It is not clear what do you want to mean by 'experiment'.
Page 9, line 10, 'For this case' --> 'In this study'?
Page 9, line 22, 'this study' --> 'Muller (1996)'?
Page 9, line 24, 'the magnitude of the scour' --> 'the scor depth'?
Page 9, line 27, The meaning subscript of Y is not clear. (c-d, e-d, c-o, e-o, etc.) Maybe you can specify this by a figure.
Page 9, line 27, Eq. (8) and (9) --> Eqs. (8) and (9).
Page 11, Can you define h_design, e_super, h_imp etc. using figure?
Page 11, 'grava'-->'gravel'
Table 1, Definition of numbers in Deterministic value/probabilistic distribution is not clear. E.g. what is the meaning of 1.0 and 1.9 for K_gr? What 1.0, 1.06 and 1.06 mean for K_R? What is the meaning of '1,1' for K_3?
Table 2, can you show the type of failure (actual and predicted) for each bridge? Also can you show the predicted failure probability for each bridge?