Apparently last night there has been another landslip on the line, This time on the down line country end of Ockley station.
Although I actually live 0.5 miles from Ockley Station as the crow flies (about 0.75 miles on foot) and 0.3 miles from the railway line south of Ockley station I haven't been there for the last two weeks due to being away elsewhere over xmas.
I should be back there tomorrow so will go and have a look at the line from both Ockley station and from the Stylehurst foot crossing of the line about 0.2 miles south of Ockley station and let you know how the bad situation really looks.
I clearly don't know how the contractual relationship between Southern (the only normal users of the line south of Dorking as South West trains services all terminate at Dorking) and Network Rail operates but if it is possible I would suspect that Southern have a much lower priority lower cost Service Level Agreement with Network Rail for repairs on this section of line than on main lines like the lines to Gatwick and Brighton from London Victoria via East Croydon and Gatwick Airport.
Personally even before the second landslip I would not have trusted the "some time in early February" estimated completion date due to the amount of work involved in doing the repairs and the very small number of passengers very seriously adversely affected by the closure. With the news of the second land slip I would now fear the line could easily be closed and replaced by bus services to Easter or even until the middle of the year.
Regarding the current Southern timetable to Dorking from London Victoria the only serious problems I can see are with the extra half hourly morning and evening rush hour services for an hour and a half period as these can no longer be easily provided as the extra morning services were provided by introducing extra trains on to the line at Horsham and the evening services involved trains that terminated at Horsham but then became other services back via Gatwick or down the Arun Valley line instead of returning vis Dorking.
So I suppose this means that in addition to no trains at all between Dorking and Horsham the frequency of morning and evening peak services run between Dorking and Leatherhead in particular by Southern has probably been halved. However as the other two trains in the hour are run by South West Trains these ought to be able to still run as normal. The only actual change in terms of any overcrowding problems at Dorking station are that one train per hour that used to carry on southbound at the station to Horsham now also has to have a dwell time at the station before turning around and heading back up the line. However this clearly requires rescheduling of the timetable and driver's rosters in order to be achieved.
I suppose the once an hour Southern train that used to go through to Horsham might have to actually carry on South of Dorking and wait between Dorking and Holmwood in order to avoid blocking up the other platforms at Dorking for the other terminating services with shorter dwell times at the station. Alternatively a completely new emergency timetable for all services to Dorking that takes account of the closure needs to be introduced. Either way the additional half hourly services in the rush hour morning and evening periods will probably have to be cancelled entirely.
It should however be remembered that for several years in the 1980s all trains from London Victoria only ran as far as Dorking where they terminated while a separarte shuttle service ran from Dorking to Horsham. So all Southern have to do in order to cope is to introduce a new Dorking only rail timeable from London Victoria during the period of the closure and then operate a separate hourly replacement bus service from Dorking to Horsham to roughly tie up with times of one of the two trains per hour arriving at Dorking from London Victoria.
Bottom line is I strongly suspect these works may now take up to six months to complete because working in the daytime only is cheaper and safer and also I suspect that whether Network Rail is willing to pay for much longer working hours or night time working depends on the number of passengers affected by the closure. Whilst I agree Dorking to Horsham provides useful connections for some people the total number of passengers involved is very small and it is the number of passengers affected which I am sure will usually affect Network Rail's planning in terms of how quickly the repairs are carried out.
I do also hope that the substantial nature of the repairs involved will not be used as any form of opportunity to try to close the line permanently from Dorking to Horsham although I am not up to speed with issues such as how many years the current franchise has left to run and how easy it would be to try and close down a line during the middle of a franchise period for which an operator has a contract. On the whole I expect it will reopen in the end but closures have been a regular feature of this section of line throughout its history including a protracted period of closure when there was a major tunnel fall south of Dorking only a few years after the line first opened.
EDIT:-On checking the southernrailway.com website's timetable I see that a quarter hourly service to Dorking from Leatherhead being maintained but that some services to Dorking are now commencing from and terminating at Capham Junction instead of London Victoria. This is presumably because there will not be any platform room for them left at Victoria given that they will not able to arrive at or depart from that very busy station in their normal timetabled rush hour slots.