As anyone who has been to Peterborough Station will know, it's the nearest thing to the Gulag this side of the Urals! What a dump!

So, pop in there and have a look at the (soon to be defunct) micro-depot and then get yourself up to this footbridge.

Photography is difficult on the ECML but made easier here by the track layout. To the east, you have Up and Down Main and Up Slow ECML, then a big gap and the Up and Down Leicesters, which also serve as the ECML Down Slow for a while. Thus, you can shoot pictures under the wires. From 10am the sun is on the Down side and makes shooting Leicester-bound traffic difficult but otherwise its ok. The parapets are not too high and the bridge is considerably wider than the lines, thus helping photography a little. In both directions, there are a couple of miles of pretty straight track so you get plenty of warning of approaching trains, not always the case these days. Ignore the nearby signals - automatics.

Traffic? - all the ECML passenger stuff, mostly going pretty slowly towards or away from Peterborough stops, Hull trains, Central units and plenty of freight from about 10am onwards. Of course, you miss a bit - anything south or east bound from Eastfield Yard - but also get bonuses like the Tallington trip (twice), often a 37, which can't be seen from the station. You also miss 6E57, the only freight that uses the Lincolnshire Loop, so you might like to nip up to Werrington footbridge (a much inferior bridge, in my view) or the roadbridge about 4.30 for that - only a Shed though.

Getting there is a bit complicated. From the station, take the dual carriageway towards Bourne/Sleaford, under the Parkway, round another 4 roundabouts, cross over the Sleaford line and at the next roundabout go right round and back on yourself. About 500 yards back is a left turn. Take this and just follow the road round to the right - it doesn't go anywhere, just to a dead end at the footbridge. No road traffic and a few cyclists/runners/walkers.
If relying on public transport, get a blue Delaine bus to Bourne from Queensgate Bus Station (they run hourly) and ask to be put off at Marholm Hurn Road. It would be about a 5 minute walk - you can see the bridge from the road quite easily.

Lovely on warm day but absolutely Arctic on a cold day as it is very exposed, so wrap up well. There are about 8 houses next to the bridge and that's it - no facilities of any kind so a pack-up is a good idea. There is, however, a McD about a mile north on the main road and Burger King / Little Chef about a mile south, that is if you don't eat food!