Grade Diagram Examples?

[paxman]

Hi everyone

I'm trying to re-do the grade (ie gradient or topographical) diagrams for the major lines on our network. Our existing diagrams are 40 years old and are of limited use.

I'm curious about ways of depicting this sort of information. How do other railways go about showing grades? I would greatly appreciate seeing how it's done elsewhere so that our new grade diagrams, which I'm compiling with the help of GPS-based surveying equipment, will be able to incorporate best practices from around the world.

In case the term 'grade diagram' isn't well understood, I'm including a sample with this post. It depicts road crossings, stations, curves and gradients. Any and all feedback is welcome!

Many thanks to all.

 

[edwin_m]

I've never seen anything other than this format or something closely related to it. Five Mile Diagrams and Profiles on engineering alignments are similar too.

 

[paxman]

Thanks for your response.

My intention is to color-code the gradients (eg dark red for 2%, a lighter shade of red for 1.75%) and include signals and other important features. I can't imagine I'm the only person to have thought of that.

 

[CW2]

My advice would be to steer clear of including signals, as they tend to get moved around during remodelling, so your work would be never-ending. Once the railway goes for ETCS, lineside signals might laregely disappear in any case. On the other hand, significant bridges, viaducts, and tunnels would be useful.

 

[paxman]

There's no chance we'll be switching to in-cab signalling any time soon - or ever. (I'm not in the UK.)

I'm putting together the new grade diagrams with Adobe Illustrator, rather than painfully drawing them out on paper. The raw data comes from an Excel sheet populated by GPS location and altimeter readings.

The advantage of such a software-based approach is that features - curve speeds, signal types and locations, whatever - can be altered with the click of a mouse.

 

[David Burrows]

I suggest http://www.railwaydata.co.uk/ and click on 'Line Files and Gradient Profiles. Then go through the list until you find the line you want to know about.

 

[edwin_m]

If the OP is not in the UK then the UK data sources I and others have posted aren't relevant. However the profiles on the Railway Data site linked above show what could be (and possibly was) generated in Excel. They also show the disadvantages of that sort of approach, such as overlapping labels and no vertical lines at gradient changes.

Are altimeter readings accurate enough for this task? An error of a metre or two vertically could make a big difference if the route is one of those where gradient changes every few hundred metres.

 

[splashoutradio]

I'm not sure how it works in the OPs home country, but here in the UK, the infrastructure owner (Network Rail) hold data on gradients, bridge, tunnel, level crossing & station locations. They require a fair amount of manual processing, as data formats aren't always consistent and there are a number of contrasting records, but if you ask nicely in a freedom of information request, they tend to release them.

The Railway Data files use these files, and are processed using 'home-made' software. It takes the software about 4 hours to work through the data and produce all the files once the data has been manually cleaned. There are plans to make it look a little more like 'Signal Box Diagram Gradient Profiles', though.

It may be worth getting in touch with whoever owns the infrastructure where you are. You never know, they may have the data you're looking for. And, if I can help at all, let me know

 

[paxman]

Thanks everyone for your helpful answers. I'll definitely follow up on splashoutradio's excellent suggestions.

As regards the accuracy of GPS altimeter recordings - it's a tough call. I've been taking the average of three readings. The results are often slightly inconsistent with official surveying data, which tends to be a few decades old.

 

[edwin_m]

Thanks everyone for your helpful answers. I'll definitely follow up on splashoutradio's excellent suggestions.

As regards the accuracy of GPS altimeter recordings - it's a tough call. I've been taking the average of three readings. The results are often slightly inconsistent with official surveying data, which tends to be a few decades old.

Unless you're in an area of mining subsidence or someone's built a new flying junction, gradients won't change much. I suspect most routes in the UK haven't been re-surveyed since they were first built. Even with subsidence, the extra downhill on the way in to a dip is compensated by the extra uphill on the way out, so there may be a risk of a slow-moving train getting stuck in the dip but the effect mostly cancels out for a train moving reasonably quickly.