Great Western Coffee Shop

I am currently conducting a spot of research.

Does the existence of Dean/Mottisfont & Dunbridge stations and/or the level crossings at these locations restrict the speed at which trains can pass through them?

Level crossing can affect line speed, are they traditional gates, open crossing, full or half barriers.  Widths of platforms can affect line speed if the platform is narrow the the HRMI will require a speed restriction

Here are some photos (links below.)
http://www.chiark.greenend.org.uk/~owend/interests/rail/stnpages/dean.html

http://www.chiark.greenend.org.uk/~owend/interests/rail/stnpages/mottisfontanddunbridge.html

Max line speed is 85 from Alderbury Bank to the trout farm approx 1 mile before Romsey Stn. As such, no restrictions for the crossings or stations.

There are other things that effect line speed, type of rail, how rail lengths are jointed, type of sleeper, how it is ballasted.

To attain 125 line speed the rails have to be stressed concrete sleeps the cant on curves has to be maintained.

The main things the civil engineer, route director and TOC will make a judgment of the level of maintenance and renewals against the frequency and level of service which all has to be budgeted.

   From Romsey to Salisbury side the linespeed decreases to 80mph until a chain or two after Kimbridge to allow for the level crossing

Not really connected I know, but good news for regular travellers on the 'Donkey' from Bourne End to Marlow as the two crossing by the marina at Bourne End are being converted from Automatic Open to Automatic Barrier crossings which will result in a linespeed increase (up direction only) from 15mph to 20mph! Watch the journey times get slashed...  ;)