Dear Tom

I have not done work which could be precisely described as research into 
the Mohring Effect but I have checked the likely long run effects of 
exogenous demand increases on the choice between frequency and vehicle 
size both buses and passenger rail in the past and more recently on sea 
freight in the South Pacific.

Briefly, in the longer run, the key additional factor not mentioned here 
is the potential economies of scale relating to changes in vehicle size 
(bus size and capacity, train length and hence capacity and freight 
vessel size) as an alternative to frequency increases.  For subsidised 
services where there is already a publicly acceptable frequency, the key 
driver appears to be satisfying any increase in demand at minimal 
marginal cost (and hence if possible lowering average cost) by seeking 
economies of scale (often labour related but sometimes infrastructure 
related) where possible.  This reduces unit costs and leads to a choice 
between fare reductions and subsidy reductions.

It is easier where there is an available range of vehicle sizes, train 
lengths and vessel sizes and and in the short run, a market for 
vehicles.  In the cases where reasonable service frequencies had already 
been achieved, adequate service capacity, schedule reliability and 
passenger information or freight forwarder information appeared to be 
the key service quality factors and cost reductions were sought by 
changes in vehicle size, the choice between subsidy and fare or tariff 
being a further political consideration.

I don't see what we did as being of universal applicability and don't 
personally believe there is a one solution fits all answer even for 
urban bus, but I hope this helps.

Regards

Robert Cochrane

On 14-Jan-20 12:13 PM, Tom Sansom wrote:
> Good afternoon,
>
>
>
> Has anyone done any research that estimates the extent to which the Mohring Effect would be expected to magnify the effects of an initial exogenous increase in bus patronage?
>
>
>
> An exogenous increase in bus patronage would be expected to set off a process of higher frequencies and/or lower operator average costs (hence lower fares) leading to a further patronage increase, leading to higher frequencies and/or lower fares, and a further increase in patronage etc.
>
>
>
> A search of the literature suggests that the long run aspect hasn't been picked up on, but we could well be missing a key reference.  Any responses within the week particularly welcome!
>
> Regards,
> Tom
>
> Tom Sansom | Evaluation Officer  | Transport for Greater Manchester | 2 Piccadilly Place, Manchester, M1 3BG
> 0161 244 1262 | [log in to unmask]<mailto:[log in to unmask]>
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