There's a lot to learn in preparation for the exam, and looking at the types of questions that come up frequently in past papers is a good way of working out where to focus your energy for maximum gain. This article takes a look at common features between past papers and recommends an order of revision.

Past Paper Stats

The table below shows some stats for the Bridge Question in each of the past papers up to 2021. Note that the format of the exam changed slightly in 2004, but papers older than this can still be useful for revision.

The exact bridge length and spans are down to the engineer in the exam, however they have been estimated in the table below based on the obstacles crossed and other constraints.

The table also records other notable information about the arrangement, loading, and ground properties given for geotechnical design.

						Features			Ground conditions
Year	Month	Traffic type	Bridge length (m)	Deck width not including parapets (m)	Approx span (m)	Moving bridge?	Skew?	Curved?	SPT N	Cu	Allowable / safe bearing pressure / compressive strength	Max load	Groundwater level given	Temperature range (°C)	Wind speed
1999	April	Rail	210	8.5	83				x	x			x	x
2000	April	Pedestrian	75	2	25			x			x			x
2001	April	Highway	900	9	50					x	x		x	x
2002	April	Pedestrian	40	3.5	35						x
2003	April	Rail	23	11.3	12					x	x		x
2004	April	Waterway	28	12	28				x
2005	April	Highway	28	35	28					x	x		x
2006	April	Pedestrian	23	1.5	10				x				x
2007	April	Highway	60	12	15	x			x		x		x		x
2008	April	Highway	55	23	55					x	x				x
2009	April	Pedestrian	70	6	35		x				x				x
2010	April	Highway	91	24	45						x				x
2011	April	Highway	25	3	25				x	x	x		x		x
2012	April	Highway	150	21.6	80				x	x	x		x
2013	April	Pedestrian	40	2.5	40			x			x	x			x
2014	April	Highway	20	15	20	x				x			x		x
2015	January	Pedestrian	150	4	75					x	x				x
2015	July	Highway	220	14.3	100					x	x				x
2016	January	Airport Taxiway	30	120	30					x	x				x
2016	July	Light Rail	55	12.3	55				x		x		x		x
2017	January	Pedestrian	26	3	26		x		x		x		x		x
2017	July	Rail	182	14	20		x		x		x		x		x
2018	January	Waterway	30	21	15				x		x				x
2018	July	Highway	80	11.3	65				x				x		x
2019	January	Pedestrian	53	6	45				x		x		x		x
2019	July	Light Rail	60	10	30		x				x		x		x
2020	January	Pedestrian	92	3	45				x	x	x				x
2020	September	Pedestrian	95	3	60						x				x
2021	April	Highway	55	12	39						x	x
2021	September	Highway	265	13.3	140				x						x

Past papers can be downloaded from the IStructE's website.

Frequent Structure Types and Spans

The table below summarises the frequency of bridge types and lengths for the past papers in the table above.

			Full bridge length (m)		Average span length (m)
Bridge type	Number of questions		Mean	Median	Mean	Median
Pedestrian	10	33%	66	61.5	40	37.5
Highway	12	40%	162	70	55	47.5
Rail	3	10%	138	182	38	20
Light Rail	2	7%	58	57.5	43	42.5
Waterway (canal)	2	7%	29	29	22	21.5
Airport Taxiway	1	3%	30	30	30	30
Total	30	100%

From the stats you can see that pedestrian and highway bridges are by far the most common, with very few rail / light rail / canal bridges in comparison.

Highway bridges commonly have a ~50m main span; for pedestrian bridges this reduces to ~40m. Rail and canal bridges are even shorter (~20m).

Long span bridges do come up and are worth revising, particularly for highway bridges where there have been a few questions with a very long total bridge length pushing the candidate to devise a solution with multiple long spans, and a few questions with a single very long span. Different forms of construction are often appropriate for these longer bridges e.g. PT concrete boxes and cable stayed or suspension bridges.

Geotechnical Ground Parameters

Questions most commonly give ground properties in the following format:

• Standard Penetration Test blow counts (SPT N) for granular soil
• Undrained shear strength (c_u) for cohesive soil
• Safe / allowable bearing pressures for rock

Occasionally, a maximum load will be given for a particular feature, although this is uncommon.

It is notable that soil properties commonly used in engineering practice for detailed design such as angle of shearing resistance (ϕ') are not typically given in the exam, instead being given as test results i.e. SPT N values. You could either convert these to ϕ', or use SPT N directly in your calculations. The cheat sheets on this website aim to use the N values directly, e.g. preliminary foundation design and bored or CFA pile design.

Loads

Temperature ranges used to be commonly given in the exam, but haven't been included since the format changed in 2004. It's possible but quite unlikely that they would be reintroduced - the most significant effects would be on integral bridges where they would cause large earth pressures behind the abutments.

Wind speeds are often given (in units of m/s) although they rarely drive the design. It's worth commenting on the wind load in your paper, noting whether it is high or low and whether you expect it to affect the design. If you choose a cable structure, this is more likely to be affected by wind due to cable oscillations. The wind loading cheet sheat allows you to quickly convert the wind speed into a peak pressure.

Recommended Revision Order

The following revision order is recommended based on the analysis of common question types above, and aims to give good experience with the most common types while also covering the unusual ones so you don't panic if the examiners set an unusual question:

1. Highway bridges with ~50m main span (attempt several out of 2008, 2010, 2018, Apr 2021)
2. Pedestrian bridges with ~40m main span (attempt several out of 2002, 2009, 2013, 2019)
3. Rail bridges with ~20m main span (attempt one e.g 2017)
4. Canal bridge (attempt one e.g. 2004 or 2018)
5. Long span highway bridge (attempt one of 2001, 2012, 2015, Sep 2021).
6. Moving bridge (attempt one e.g. 2007 or 2014).