As both of you will realise, we have to obtain approval from the ORR (or HMRI to old folks) for both the passenger railway – the Apedale Valley Light Railway – and the vehicles which run on it. The days of running narrow gauge passenger trains depending solely on the loco brakes are well and truly over; those of us who recall running passenger trains down slippery grades with minimal brakes breathe a sigh of relief at that. These days, the sighs come from the air brake system. ORR require that we can demonstrate that the train can stop at 0.7ms/s/s or 7% of g for those from the Big Railway. Proving this has not been easy. Our trains do not have speedometers fitted, and the low speeds mean that resolution errors cause significant problems. On the other hand, the low speeds do mean that the simple equations of motions can be employed; we are not subject to Einsteinian relativistic effects, although time dilations have been noticed on site, especially during busy periods in the cafe. The key issue is knowing accurately what the speed of the train is when the train brakes are applied. We tried using GPS devices; both a car sat-nav and one designed for hikers didn’t really work very well. We suspect the steep sides of the Apedale Valley meant that the devices couldn’t “see” sufficient satellites. That was one item which was, shockingly, overlooked in the railway risk assessment. Anyway, we have now cracked the problem using a perception head device sold for bicycles, and (to everyone’s relief) it is clear that the brakes are working just fine. In the top photo you can see the train testing engineer hard at work; we need a spreadsheet to do the maths these days. If you fancy reading a bit more about train testing, see here.
Elsewhere on site, the CME has found something else to point at; it’s the cab from one of the ex-Wolverhampton battery-electric locos, currently being treated for severe tinworm. As ever, get in touch here if you fancy learning how to point.