March diversions - what was done?

Stephen Lawrence asked - in a comment to the 9 March posting on that month's Busway diversions - if anyone knew what work was carried out. And lo, as chance would have it, correspondent RichardC provided some very interesting information about the two weekends of work at Histon, together with a number of further questions! If anyogone has further information, please post a comment or email the blog at: buswayblog@btinternet.com

Here's what RichardC reports:

"Quick update on closures over weekends of 17/18 and 24/25 March.  On the first weekend it appears that five beam sets to south-east of Histon overbridge (Bridge Road) were lifted and realigned.  On the second weekend the work concentrated on the area around the Cambridge-bound stop to the west of the bridge.

 

Attached image shows activity in the afternoon of 24 March. 

Lifting frames with hydraulic jacks, apparently under supervision of Ekspan of Sheffield who supplied the original close-tolerance bearing pads.

 

Clearly lifting the beam set is not easy.  At this location, buses will have braked to a standstill at the stop, then accelerated away.  In the mornings the buses will be full almost to capacity, so maybe the beams have shifted, and jammed tightly together?  Surprising to see puddles on the guideway, on what should be a very flat, level surface.  Also at a similar point on the maintenance track.  Wonder what is causing that?"

Busway faults

Cambridgeshire County Council is having to consider how to remedy a number of serious faults with the guided busway.

Some relate to shrinkage and heavage of clay affecting the foundation of the busway. Others concern dropping of the end of the concrete beams.

BAM Nuttall is said to have rectified a fault that required buses to slow to 5mph at Histon in the summer.

But regular travellers on the busway will be aware that buses still traverse some bad sections of track  a short distance east of Histon.

Read Cambridge News article here.

Concrete beams

One of the contributors to this blog has commented recently on research being carried out into the engineering characteristics of the concrete beams, specifically mid beam cracking. This has been evident on the busway from very early on. This picture was taken in 9 October 2011 on the section between St Ives and Fen Drayton, where the track is supported on deep piles.